twossiderotic

An F may mean failure in school, but the letter earns high marks in your diet. The two biggest dietary Fs — fiber and fermented foods — are top priorities to help maintain healthy digestion, and they potentially offer much more. How can you fit these nutrients into meals? Can this help your overall health as well as gut health?

Fiber, fermented foods, and the gut microbiome

The gut microbiome is a composed of bacteria, viruses, fungi, and other microorganisms living in the colon (large intestine). What you eat, the air you breathe, where you live, and many other factors affect the makeup of the gut microbiome. Some experts think of it as a hidden organ because it has a role in many important functions of the body — for example, helping the immune system function optimally, reducing chronic inflammation, keeping intestinal cells healthy, and providing some essential micronutrients that may not be included in a regular diet.

Your gut communicates with your brain through pathways in the gut-brain axis. Changes in the gut microbiome have been linked with mood and mental health disorders, such as depression and anxiety. However, it's not yet clear that these changes directly cause these types of problems.

We do know that a healthy diet low in processed foods is key to a healthy gut microbiome. And increasing evidence suggests that fiber and fermented foods can play important parts here.

Fiber 101

Fiber's main job is to make digestion smoother by softening and adding bulk to stool, making it pass quickly through the intestines.

But fiber has other benefits for your microbiome and overall health. A high-fiber diet helps keep body weight under control and lowers LDL (bad) cholesterol levels. Research has found that eating enough fiber reduces the risk of heart disease, type 2 diabetes, and some cancers.

What to know about fiber

There are two types of fiber: insoluble (which helps you feel full and encourages regular bowel movements) and soluble (which helps lower cholesterol and blood sugar). However, recent research suggests people should focus on the total amount of fiber in their diet, rather than type of fiber.

If you're trying to add more foods with fiber to your diet, make sure you ease into new fiber-rich habits and drink plenty of water. Your digestive system must adapt slowly to avoid gas, bloating, diarrhea, and stomach cramps caused by eating too much too soon. Your body will gradually adjust to increasing fiber after a week or so.

How much fiber do you need?

The fiber formula is 14 grams for every 1,000 calories consumed. Your specific calorie intake can vary depending on your activity levels.

"But instead of tracking daily fiber, focus on adding more servings of fiber-rich foods to your diet," says Eric Rimm, professor of epidemiology and nutrition at Harvard's T.H. Chan School of Public Health.

Which foods are high in fiber?

Fruits, vegetables, legumes, nuts, seeds, and whole grains are all high in fiber. The Dietary Guidelines for Americans has a comprehensive list of fiber-rich foods and their calorie counts.

What about over-the-counter fiber supplements that come in capsules, powders that you mix with water, and chewable tablets? "If you have trouble eating enough fiber-rich foods, then these occasionally can be used, and there is no evidence they are harmful," says Rimm. "But they should not serve as your primary source of dietary fiber."

Fermented foods 101

Fermented foods contain both prebiotics — ingredients that create healthy changes in the microbiome — and beneficial live bacteria called probiotics. Both prebiotics and probiotics help maintain a healthy gut microbiome.

What to know about fermented foods

Besides helping with digestion and absorbing vital nutrients from food, a healthy gut supports your immune system to help fight infections and protect against inflammation. Some research suggests that certain probiotics help relieve symptoms of gut-related conditions like inflammatory bowel disease and irritable bowel syndrome, though not all experts agree with this.

Many foods that are fermented undergo lacto-fermentation, in which natural bacteria feed on the sugar and starch in the food, creating lactic acid. Not only does this process remove simple sugars, it creates various species of good bacteria, such as Lactobacillus or Bifidobacterium. (Keep in mind that some foods undergo steps that remove probiotics and other healthful microbes, as with beer or wine, or make them inactive, like baking and canning.)

The exact amounts and specific strains of bacteria in fermented foods vary depending on how they are made. In addition to probiotics, fermented foods may contain other valuable nutrients like enzymes, B vitamins, and omega-3 fatty acids.

How often should you eat fermented foods?

There is no recommended daily allowance for prebiotics or probiotics, so it is impossible to know precisely which fermented foods or quantities are best. The general guideline is to add more to your daily diet.

Which fermented foods should you choose?

Fermented foods have a range of tastes and textures because of the particular bacteria they produce during fermentation or that are added to foods. Yogurt is one of the most popular fermented foods (look for the words "live and active cultures" on the label). Still, many options are available if you are not a yogurt fan or want to expand your fermented choices. Kimchi, sauerkraut, kombucha, and pickles are a few examples.

As with fiber, probiotics are also marketed as over-the-counter supplements. However, like all dietary supplements, they do not require FDA approval, so there is no guarantee that the types of bacteria listed on a label can provide the promised benefits — or are even in the bottle. "Therefore, it is best to get your probiotics from fermented foods," says Rimm.

To learn more about the value of fiber, fermented foods, and a healthy gut microbiome, listen to this episode of the Food, We Need to Talk podcast, "Understanding the Microbiome."

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Ever heard of mpox? Wondering why it’s back in the news?

Many of us first learned about mpox (formerly called monkeypox) in 2022, when the largest known outbreak spread to nearly 100,000 people in more than 100 countries. While mpox often circulates in central and western Africa, the 2022 outbreak quickly spread from the Democratic Republic of the Congo (DRC) to places it had never been detected before. In the US alone, it caused more than 32,000 infections and 58 deaths.

Now, a new outbreak of mpox has put it back in the news. What should you know — and do — about this latest international health emergency? What are your risks? Are vaccines available? If you get mpox, how can you avoid spreading it?

What’s different about the 2024 mpox outbreak?

This time, a new strain of the virus (called Clade 1b) is spreading quickly. That’s why the World Health Organization (WHO) declared a second mpox global health emergency in August 2024.

Already, more than 15,600 cases and 500 deaths have been reported, mostly in the DRC. And mpox has been found in countries that previously hadn’t identified any cases, including Burundi, Kenya, Rwanda, and Uganda. Recent cases diagnosed in Sweden and Thailand have public health officials bracing for additional international spread, including to Asia, Europe, and the US.

6 things to know about mpox

What is mpox and how does it spread?

Mpox is a viral infection caused by the same family of viruses as smallpox. In central and western Africa it’s common in certain animals, including squirrels and rats. People can become infected after contact with infected animals. Mpox can spread from person to person through close physical contact, including sex.

What are the symptoms of mpox?

Mpox causes flulike symptoms, fever, headache, enlarged lymph nodes, and a unique rash. The rash usually begins a few days into the illness as small flat spots. The spots evolve over a week or two to become small fluid-filled bumps (vesicles) similar to chickenpox, and then larger pus-filled blisters. Over another week or two, the blisters scab over and heal. Once that happens, a person is no longer contagious.

Although the disease is usually mild, some people develop complications. Serious complications include pneumonia, vision loss due to eye infection, and sepsis, a life-threatening infection.

What is your risk of getting mpox?

Location and activities factor into your risk for developing mpox.

Risk increases if you

• have close physical contact with an infected animal or person
• have contact with bedding, clothes, or other objects or surfaces touched by an infected person
• live in or visit a place where the mpox virus is endemic — that means present in the environment, such as in the soil or infected animals or people
• are a man who has sex with men
• have many sexual partners.

When people get mpox, risk factors for experiencing more severe disease or complications like pneumonia include:

• pregnancy
• young age (especially children younger than age 1)
• having a weakened immune system
• having eczema (because this weakens the protective skin barrier).

Why is the new mpox outbreak so worrisome?

The new outbreak of mpox is especially worrisome because the strain of the virus is deadlier than in 2022. The virus is spreading more quickly and reaching places where mpox had not previously been found.

In addition, the new outbreak has disproportionately affected kids and teens in resource-poor countries. Many are already suffering with malnutrition, or other infections such as cholera.

It’s worth noting that the strain of mpox from the 2022 outbreak (Clade 1) is still circulating at a low level in the US. Right now, fewer than 15 people a week are diagnosed with it and treatment is available.

Are there mpox vaccines and treatments?

There are two vaccines available to prevent mpox in the US:

• Jynneos is approved to prevent mpox and smallpox. It requires two doses four weeks apart.
• A vaccine called ACAM2000 is approved for preventing smallpox and is considered effective for mpox. It could be made available if needed, but its potential side effects make it a second choice.

Resource-poor countries in Africa, Asia, and elsewhere have had limited access to vaccines. Even in resource-rich countries like Europe and the US, vaccine hesitancy has been an obstacle to containing the outbreak. In one study, only half of a vulnerable population in Illinois received the initial dose of the mpox vaccine, and only a quarter received both recommended doses.

An antiviral drug called tecovirimat is approved to treat smallpox. Animal studies suggest it may be effective in treating mpox as well. Now being investigated as an mpox treatment, the drug may be available by enrolling in a study. A 2024 study found tecovirimat did not reduce the length of time adults and children with Clade 1 mpox had symptoms. However, the death rate (1.7%) was half of what was expected. But it’s unclear whether the low death rate was actually due to drug treatment.

How can someone with mpox avoid spreading it?

If you are diagnosed with mpox, it’s important to take these measures to avoid infecting others:

• Avoid close contact with others until your skin lesions have healed.
• Wear a well-fitting medical mask while near others; those visiting you should wear a mask as well.
• Stay several feet or more away from others.
• Use a separate bedroom and bathroom.
• Clean all surfaces you’ve touched.
• Don’t share eating utensils, towels, or bedding with others.
• Increase room ventilation by opening windows or using a high-efficiency particulate air (HEPA) purifier.

Some experts recommend avoiding contact with pets or other animals because they could become infected and spread the disease to new animal species in new places.

The bottom line

Will mpox be the next pandemic? That’s unlikely. The virus that causes mpox spreads mainly by direct contact — unlike the virus that causes COVID-19, which spreads through small respiratory droplets that are easily breathed in. Also, people with mpox who are contagious typically have obvious symptoms, so they can take steps to avoid spread.

Currently, the risk mpox poses to most people in the US appears to be quite low. To help make sure it stays that way and to help countries where mpox is common, US public health officials are working with their counterparts in other countries to contain the outbreak. To be successful, we’ll need a robust. well-coordinated international effort, including financial support to resource-poor countries to fund educational programs, vaccination, testing, and treatment.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Several evenings a week, as Tyler VanderWeele gathers around the dinner table with his wife and two young kids, the family deliberately pauses during the meal to do something simple but profound. Each member shares several things for which they’re grateful — an act that VanderWeele, co-director of the Initiative on Health, Spirituality, and Religion at the Harvard T.H. Chan School of Public Health, feels changes his family dynamic for the better.

“I do think it makes a difference and can be a very powerful practice,” he says. “Even on those bad days where life seems difficult, that effort is worthwhile.”

Gratitude, health, and longevity

How can the power of gratitude affect our lives? Recent research has pointed to gratitude’s myriad positive health effects, including greater emotional and social well-being, better sleep quality, lower depression risks, and favorable markers of cardiovascular health. Now, new data from the long-term Nurses’ Health Study shows that it may extend lives.

“Gratitude has been one of the most widely studied activities contributing to well-being, but we couldn’t find a single prior study that looked at its effects on mortality and longevity, much to our surprise,” says VanderWeele, co-author of the new research.

What did the study look at?

Published July 2024 in JAMA Psychiatry, the new study drew on data from 49,275 women enrolled in the Nurses’ Health Study. Their average age was 79. In 2016, participants completed a six-item gratitude questionnaire in which they ranked their agreement with statements such as, “I have so much in life to be thankful for,” and “If I had to list everything I felt grateful for, it would be a very long list.”

Four years later, researchers combed through participants’ medical records to determine who had died. There were 4,608 deaths from all causes, as well as from specific causes such as cardiovascular disease, cancer, respiratory diseases, neurodegenerative disease, infection, and injury. Deaths from cardiovascular disease — a top killer of women and men in the United States — were the most common cause.

What did the researchers find?

Participants with gratitude scores in the highest third at the study’s start had a 9% lower risk of dying over the following four years than participants who scored in the bottom third. This did not change after controlling for physical health, economic circumstances, and other aspects of mental health and well-being. Gratitude seemed to help protect participants from every cause of death studied — including cardiovascular disease.

But what does this actually mean?

“A 9% reduction in mortality risk is meaningful, but not huge,” VanderWeele says. “But what’s remarkable about gratitude is that just about anyone can practice it. Anyone can recognize what’s around them and express thanks to others for what’s good in their life.”

While the study couldn’t pinpoint why gratitude is associated with longer life, VanderWeele believes several factors may contribute.

“We know that gratitude makes people feel happier. That in itself has a small effect on mortality risk,” he says. “Practicing gratitude may also make someone a bit more motivated to take care of their health. Maybe they’re more likely to show up for medical appointments or exercise. It may also help with relationships and social support, which we know contribute to health.”

What are the study’s limitations and strengths?

The study was observational. This means it can’t prove that gratitude helps people live longer — only that an association exists. And the particular sample of people analyzed is both the biggest strength and limitation of the research, VanderWeele says. All were older female nurses with high socioeconomic status. The vast majority were white.

“Does the longevity effect extend to men, to those who are younger, and to those with lower socioeconomic resources?” VanderWeele asks. “Those are all open questions.”

On the plus side, he says, the study sample’s large size is one of its biggest strengths. So is the extensive data gathered on potential confounding factors such as participants’ physical health, social characteristics, and other aspects of psychological well-being.

“Between the quality of the data and the size of the sample, we were able to provide reasonable evidence for this modest longevity effect,” he says.

Try this: Six questions to evoke gratitude

Not feeling especially grateful today? You have the power to change that. Asking yourself certain questions can evoke gratitude, such as

• What happened today that was good?
• What am I taking for granted that I can be thankful for?
• Which people in my life am I grateful for?
• What is the last book I read or movie, show, or social media clip I saw that I really appreciated, and why?
• What am I most looking forward to this week, month, and year, and why?
• What is the kindest thing someone has said or done lately?

Similarly, a few simple actions can infuse gratitude into your days. Try VanderWeele’s family routine of regularly expressing gratitude around the dinner table. Another well-known practice — that’s perhaps becoming forgotten in this digital age — is penning thank-you notes.

“I do think writing a thank-you note or gratitude letter gets your mind to dwell on something positive for a longer period, to think more deeply about it, because you have to put it not just in words, but in writing,” VanderWeele says. “It also deepens the relationship and builds that bond.”

One less-recognized but valuable gratitude practice is called a “savoring exercise,” which builds on aspects of mindfulness. All that’s required is “pausing, looking around you, and taking in and enjoying everything that’s good in your current setting,” VanderWeele says. “It’s not a big leap to go from recognizing the good to expressing gratitude for what you have.”

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

You’re huffing and puffing and starting to sweat — and that’s just from walking across the parking lot in blistering heat and humidity. This summer has left us all struggling to stay cool.

“The last 13 months have been the hottest on record. We’re seeing increased levels of heat-related illness, and it started earlier in the season we’re used to,” says Dr. Tess Wiskel, a climate change and human health fellow at the Center for Climate, Health, and the Global Environment, and an emergency physician at Beth Israel Deaconess Medical Center.

Don’t wait until you’re overheated to figure out how to cool down. Be wary of high temperature risks throughout your day and practice ways to avoid them. Here are 14 ideas to get you started.

Cover the basics

• Become a weather expert. Use a weather app on your smartphone and pay attention to the hourly temperatures, not just daily highs and lows. Note the hottest points of the day and plan your schedule around them.
• Stay hydrated. One way the body cools down is by sweating. As moisture on the skin evaporates, it takes heat with it. That’s called evaporative heat loss. But you must replace the fluids you lose through a combination of drinks and water-rich foods. Generally, the National Academy of Medicine recommends totals of about 11 cups (88 ounces) per day for women and 15 cups (120 ounces) per day for men. If you spend a lot of time outdoors or are sweating a lot, you’ll need even more fluids.
• Seek air-conditioned environments. As much as possible, hang out in air-conditioned indoor spaces during the hottest points of the day. If you don’t have AC, go to a shopping mall, public library, movie theater, or a community cooling center.
• Use fans correctly. Another way the body cools down is by channeling blood and body heat to vessels near the skin’s surface, where heat escapes. A fan can blow that heat away from your body and keep you cool, but not if the surrounding air is hot. “In that case, wet your skin, even with a spray bottle or a wet wipe. The fan will promote evaporative heat loss,” Dr. Wiskel says.
• Take breaks. Pace yourself when doing outdoor activity. “Physical work produces its own heat at the same time you’re being heated from outside,” Dr. Wiskel says. “Be active for short periods and rest in between.”

Pack and dress for heat

• Bring cool-downs with you. Any time you leave your home, bring plenty of water. Even better: bring a handheld fan, wet wipes, and ice packs. That way you’re prepared if you get stuck outside.
• Wear loose clothing. Lightweight, loose-fitting garments allow air to get to your skin, promoting evaporative heat loss to keep you cool when you sweat.
• Try high-tech clothes. Consider wearing clothes with cooling technology (such as tops, bottoms, hats, or neck gaiters). They work in various ways. For example, a garment might be made of a special fabric that’s activated with water and stays damp for a long period, continually pulling heat from your body.

Try DIY cool downs

• Make a DIY cooling garment. Dunk a kitchen towel or cotton T-shirt in cold water, wear it on your head, neck, or torso, and then rewet the fabric as it dries. Or buy higher-tech versions made with fabrics and gels designed to stay cool longer.
• Eat or drink something cold. A cool glass of water, ice chips, or a popsicle help fight dehydration and might help lower your body’s core temperature. Just don’t ingest anything too quickly. Dr. Wiskel says it might cause gastrointestinal upset.
• Cool off with a shower or bath. Experts debate the best temperature for water to cool you down. Some maintain that cool water constricts blood vessels and sends heat back to the core, making you hot again. Others maintain that chilly water cools the blood vessels and sends cooled blood to the core. Dr. Wiskel’s take: “Immerse yourself in water that’s cooler than your body temperature. The water can be tepid. Once you’re out of the water, stand in front of a fan to promote evaporative heat loss.”
• Submerge your forearms. If you can’t take a shower or bath, try a trick used by the US Army: submerge your hands, forearms, and elbows in ice water for five minutes. This helps send cooled blood moving through blood vessels back to your core.
• Apply ice or cold packs. A water-free method to cool blood vessels involves placing ice packs in areas near large blood vessels such as the elbows, underarms, neck, or inside the legs near the groin area.

Know when to get help

If you’re not cooling down after trying numerous methods, Dr. Wiskel advises that you seek care. Call your doctor’s office or call 911 if you’re exhibiting signs of heat exhaustion, such as

• excessive sweating
• headache
• feeling faint or dizzy
• cold, clammy skin
• a fast or weak pulse
• extreme fatigue
• muscle cramps.

Pay extra attention to those symptoms, especially if you’re vulnerable to heat and aren’t able to regulate your temperature well.

“People at high risk include older adults, babies and children, those who are pregnant, people who take medications that make them less able to sweat, people who work outdoors, and people with certain health conditions, including cardiovascular disease,” Dr. Wiskel says. “And if you’re not high risk, check in on people who are.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

We all want our child to have friends. We want them to be happy, and to build the social skills and connections that will help them now and in the future.

Sometimes, and for some children, making friends isn’t easy. This is particularly true after the COVID-19 pandemic. Because of isolation and remote school, many children either didn’t learn the skills they need to make friends — or those skills got rusty.

Here are some ways parents can help.

Start at home: Learning relationship skills

Making and keeping friends involves skills that are best learned at home with your family. Some of them include:

• Empathy. Make sure that everyone in the family treats each other fairly and with kindness. Sometimes we turn a blind eye to sibling fights, or feel justified in snapping at our partner when we have had a long day. No matter what we say, our children pay attention to what we do.
• Curiosity about others. Make a family habit of asking each other about their day, their interests, their thoughts.
• Communication skills. These days, devices endanger the development of those skills. Shut off the devices. Have family dinners. Talk with each other.
• Cooperation. Do projects, play games, and do chores as a family. Work together. Help your child learn about taking turns and valuing the input of others.
• Regulating emotions. It’s normal to have strong feelings. When your child does, help them find ways to understand big emotions and manage them.
• Knowing when and how to apologize — and forgive. This really comes under empathy, but teach your child how to apologize for their mistakes, make amends, and forgive the mistakes of others.

All of these apply also to how you and your partner talk about — or with — other people in front of your children, too!

Be a good role model outside the home, too

When you are outside your home, be friendly! Strike up conversations, ask questions of people around you. Help your child learn confidence and strategies for talking to people they don’t know.

Make interactions easier

Conversations and interactions can be easier if they are organized around a common interest or activity. Here are some ways parents can help:

• Sign your child up for sports or other activities that involve their peers. Make sure it’s something they have at least some interest in doing.
• Get to know the parents of some of your child’s peers — and invite them all to an outing or meal. It could allow the children to get to know each other while taking some of the pressure off.
• When planning playdates, think about fun, cooperative activities — like baking cookies, or going to a park or museum.

Keep an eye on your child — but don’t hover

Ultimately, your child needs to learn to do this — and you don’t want to embarrass them, either. The two exceptions might be:

• If the children aren’t interacting at all, you might want to suggest some options for activities. Facilitate as necessary, and step back out again.
• If there is fighting or meanness on either side, you should step in and make it clear that such behavior isn’t okay.

Keep an open line of communication, and be supportive

Talk with your child regularly about their day, about their interactions, and how things made them feel. Listen more than you talk. Be positive and supportive. Remember that part of being supportive is understanding your child’s personality and seeing the world from their eyes. You can’t make your child someone they are not.

If your child keeps struggling with making friends, talk to your doctor

All parents need help sometimes — and sometimes there is more to the problem than meets the eye. This is particularly true if your child has ADHD or another diagnosis that could make interactions more challenging.

For information on supporting friendships at different ages, check out the advice from the American Academy of Pediatrics.

Follow me on Twitter @drClaire

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD

Global average temperatures have soared in 2024, surpassing records set just last year. Extreme heat poses numerous health risks, some of which are visible on our skin. Understanding how heat affects your skin can help you take measures to prevent or ease heat rash, eczema, rosacea, the discoloration of melasma, and many other skin conditions sparked or worsened by high temperatures.

How does heat affect your skin?

Heat waves can provoke or worsen several skin conditions.

• Heat rash (miliaria) occurs due to obstruction of sweat ducts on the skin, which are responsible for helping the body maintain a normal temperature by releasing water to the surface of the skin. As these sweat glands get blocked with excessive sweat on an extremely hot day, they do not function properly and red itchy bumps develop.
• Grover disease, a rash of small, red, itchy bumps on the chest and back, can also be triggered or worsened by excessive heat and sweating. Often this clears up within a few weeks or months. Less often symptoms may persist for years, with flares during the summer months.
• Eczema is a chronic skin condition characterized by dry, itchy plaques that affects millions of people in the United States. Increased sweating during heat waves can lead to skin irritation and inflammation, aggravating eczema symptoms. Dehydration caused by fluid loss through sweating can make the skin more susceptible to eczema flare-ups.
• Rosacea, which causes facial redness, visible blood vessels, and acne-like bumps, is also heat-sensitive. Heat causes blood vessels to dilate as the body attempts to cool itself, resulting in visible redness and flushing. High temperatures, especially combined with sun exposure, can cause flare ups.
• Melasma. Hyperpigmentation disorders like melasma also worsen with heat. Melasma is characterized by irregular dark patches on the face and is often triggered by UV exposure from the sun. Heat can increase the activity of melanocytes, the cells that produce pigment, making these patches more pronounced. Additionally, the combined effects of heat and UV radiation accelerate collagen and elastin degradation, leading to premature aging and loss of skin elasticity.
• Skin cancer risk rises with increased exposure to UV radiation. Heat waves — now beginning earlier, ending later, and lasting longer — contribute to UV exposure, particularly among people who work outdoors. And preliminary research suggests prolonged exposure to high temperatures may further boost skin cancer risk. This could be of particular concern for firefighters, who face extended exposure to extreme heat.

Heat waves, air pollution, and skin

During heat waves, levels of environmental pollutants like ozone and particulate matter can rise. And reactions between these pollutants, heat, and UV radiation spawn secondary pollutants such as peroxyacetyl nitrates (PANs). Pollutants like these can irritate the skin and contribute to inflammation through oxidative stress and DNA damage, so inflammatory conditions such as eczema and rosacea may worsen.

Can heat affect medications?

High temperatures compromise the effectiveness of certain medications. For instance, EpiPens, which are crucial for managing life-threatening allergic reactions, can lose their potency when exposed to high temperatures. Check the instructions on all of your medicines to see which ones should be stored in a cool, dry place or refrigerated. If you’re not sure which medicines might be affected by heat, talk to your pharmacist or doctor.

Retinoids in skin care products, antibiotics taken for acne, and immunomodulators for autoimmune diseases can make skin more susceptible to sun damage. This can lead to severe sunburns or rashes known as photodermatoses. If you experience this, contact your health care team for advice.

Protect your skin when temperatures climb

Keep skin cool

• Wear light, breathable clothing. Choose natural fibers like cotton and linen to help regulate body temperature and prevent sweat-induced skin issues. Avoid synthetic fabrics, which can trap heat and moisture.
• Take cool baths or showers. Use cool or tepid water to bathe. Avoid hot showers, which can strip the skin of natural oils, leading to dryness and irritation.
• Find cool spaces. If your home is not air-conditioned, seek out cooler places and ways to cool off during heat waves.

Keep skin hydrated

• Drink ample water and eat water-rich foods. Foods like watermelon and cucumbers can provide additional hydration.
• Moisturize your skin. Apply light, non-comedogenic moisturizers immediately after bathing. Look for ingredients such as hyaluronic acid and glycerin, which are beneficial for enhancing skin hydration.

Limit exposure to sun and pollution

• Use protective clothing. Wear wide-brimmed hats, UV-blocking sunglasses, and long-sleeved shirts to shield the skin from harmful radiation.
• Wear sunscreen. Apply broad-spectrum mineral sunscreens containing zinc oxide, titanium dioxide, or iron oxide to protect against UV radiation and pollutants.
• Use topical antioxidants. Use products like vitamin C in your morning skin care routine to mitigate oxidative stress.
• Wash up. Cleansing face and body at the end of the day may help you limit skin exposure to pollutants while also rinsing off any sunscreen residue.

About the Authors

Kathyana P. Santiago Mangual, Contributor

Kathyana P. Santiago Mangual is a clinical research fellow in dermatology at Massachusetts General Hospital and Harvard Medical School. She is also a medical student at the University of California, Los Angeles, and will be graduating … See Full Bio View all posts by Kathyana P. Santiago Mangual

Arianne Shadi Kourosh, MD, MPH, Contributor

Arianne Shadi Kourosh, MD, MPH, is a board certified dermatologist and associate professor of dermatology at Harvard Medical School. She is a graduate of the Harvard T.H. Chan School of Public Health and the University of … See Full Bio View all posts by Arianne Shadi Kourosh, MD, MPH

Ever ridden an e-scooter or e-bike? The convenience, affordability, and flat-out fun of these “micromobility” modes of transportation are undeniable. But did it also seem a bit dangerous?

In fact, the rate of accidents involving e-bikes and e-scooters is climbing. Maybe that shouldn’t be surprising given their dramatic jump in popularity. And then there’s the way riders often use them: at high speed, near cars and pedestrians, and on roads and sidewalks that weren’t designed for them.

Disruptive innovations, such as e-bikes and e-scooters, inevitably come with downsides. So, how can we minimize risks for accidents?

E-bikes, e-scooters, and injuries

Between 2018 and 2022, sales of e-bikes rose from around 250,000 per year to more than a million. E-bike and e-scooter rentals have also increased dramatically. As their popularity grows, emergency rooms are seeing many more people injured while riding e-bikes and e-scooters.

A 2024 study in JAMA Network Open highlights this. Researchers drew data from the National Electronic Injury Surveillance System, which is run by the US Consumer Product Safety Commission. They analyzed ER care between 2017 and 2022 for people injured while riding an e-bike or e-scooter, compared with people injured while riding conventional bikes and scooters.

What did the study find?

During the six-year study period, roughly three million people riding e-bikes, e-scooters, or their conventional counterparts sought care in the ER, including about 45,500 e-bike riders and 190,000 e-scooter riders, and about 2.5 million conventional bike riders and 305,000 conventional scooter riders.

Certain themes emerged around e-micromobility:

ER care spiked upward

• E-bike injuries more than doubled every year, going from 751 in 2017 to 23,493 in 2022.
• E-scooter injuries increased by more than 45% every year, going from 8,566 in 2017 to 56,847 in 2022.

More risky behavior

• 43% of e-bike and e-scooter riders wore helmets versus 52% for conventional micromobility riders
• 7% of e-bike riders and 9% of e-scooter riders were drinking before their accidents versus 4% of conventional bike riders and 3% of conventional scooter riders.

More accidents occurred in urban areas compared with rural settings:

• 83% of e-bike and e-scooter accidents
• 71% of conventional bike and scooter accidents.

All riders experienced similar types of injuries: scrapes, bruises, broken bones, and head and neck injuries were most common.

What are the limitations of this study?

This study only included people evaluated in an ER, so it excluded people with less severe injuries — and even those with significant injuries who didn’t go to an ER. Some may have sought no care at all, or gone to a primary care practice or walk-in clinic to avoid costly ER care or for other reasons.

Nor did the study count injuries suffered by pedestrians injured by e-bike or e-scooter riders. Property damage, such as damage to a car, wasn’t calculated.

And ultimately the study cannot compare the safety of e-bikes and e-scooters with conventional options. That’s because no data were collected on the number of miles traveled using a particular mode of transportation, or over how much time.

How can you avoid e-bike or e-scooter injuries?

Ten common-sense precautions can help you avoid injuries and ER visits:

• Wear a helmet. If you’re renting an e-bike or e-scooter, you may need to bring your own since many rental systems do not provide helmets.
• Practice. E-bikes are much heavier than conventional bicycles and may handle differently. And many adults have not ridden a scooter since elementary school! So if you aren’t familiar with riding an e-bike or e-scooter, practice in a safe location where there’s no traffic or pedestrians.
• Follow road rules. Ride on available bike lanes and avoid sidewalks. On an e-bike, use arm signals to alert those nearby of your intentions to turn or change lanes. (On an e-scooter, it’s best to keep both hands on the handle bars at all times.).
• Slow down. Some e-bikes approach speeds of 30 miles per hour. The faster you go, the less time you have to react to unexpected potholes or veering vehicles, and the more serious an injury is likely to be if you have an accident.
• Lower risks. Don’t ride while under the influence of alcohol or drugs, or use your phone while moving.
• Go it alone. Don’t add riders. Most e-bikes and e-scooters are built for one rider at a time.
• Ride defensively. Watch out for potholes or opening car doors.
• Reflect. Wear reflective clothing or attach a light if riding at night.
• Call out. Announce your presence to others. For example, shout “on your left!” as you approach pedestrians or slower riders that you intend to pass.
• Lobby. Reach out to local politicians to create bike lanes and other infrastructure to make micromobility safer.

The bottom line

Whether it’s part of your daily commute, an occasional quick zip from point A to point B, or just a ride for the fun of it, e-bikes and e-scooters are a great way to get around. Though they do come with some risk, you can do a lot to minimize the odds of wrapping up your travels with a trip to an ER.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Trees enhance life in a multitude of ways. They combat climate change by reducing greenhouse gases in the atmosphere. They muffle sound pollution and reduce air pollution, drawing in carbon dioxide and releasing oxygen. When rain pours from the skies, trees decrease stormwater runoff, preventing flooding and soil erosion. They also provide valuable habitats to support biodiversity in insects, birds, and other animals, and microorganisms. The list goes on.

Equally important is accumulating evidence that simply spending time around trees and green spaces uplifts our health and mood. Below are a few of the biggest benefits we reap.

Keeping it cool: Trees help prevent heat-related illness

Climate change is causing rising temperatures and more heat waves across the US. These effects are worse for those who live in neighborhoods known as urban heat islands, where asphalt and concrete soak up heat during the day and continue to radiate it at night. Temperatures can reach 7° F hotter than suburban, rural, or simply wealthier and leafier neighborhoods.

Trees and their leafy canopy provide shade that helps to prevent urban heat islands. What does that mean for individuals? It translates to fewer heat-related health illnesses, which strike outdoor workers and younger, older, and medically vulnerable people more often. A study published in The Lancet calculated that increasing tree canopy to 30% coverage in 93 European cities could prevent an estimated four in 10 premature heat-related deaths in adults in those cities.

How trees help children: Better mood, behavior, attention, and more

Spending more time in nature has been linked with better health outcomes like lower blood pressure, better sleep, and improvement in many chronic conditions in adults. These findings are prompting a growing interest in forest therapy, a guided outdoor healing practice that leads to overall improved well-being. But what’s also remarkable are the varied benefits of trees and nature for children.

One study of children 4 to 6 years old found that those who lived close to green space demonstrated less hyperactive behavior and scored more highly on attention and visual memory testing measures compared with children who did not.

Just seeing trees can have mental health benefits. In Michigan, a study of children between the ages of 7 and 9 demonstrated that students who could see trees from their school windows had fewer behavioral problems than those with limited views.

In Finland, researchers modified daycare outdoor playscape environments to mimic the forest undergrowth. These daycares were compared to control standard daycares and nature-oriented daycares where children made daily visits to nearby forests. At the end of 28 days, the children in the daycares with modified forest undergrowth playscapes harbored a healthier microbiome and had improved markers of their immune systems as compared to their counterparts.

How green space helps communities

Having green space in neighborhoods also does a lot to enrich the well-being of communities. A randomized trial in a US city planted and maintained grass and trees in previously vacant lots. Researchers then compared these green spaces to lots that were left alone.

In neighborhoods below the poverty line, there was a reduction in crime for areas with greened lots compared to untouched vacant lots. Meanwhile, residents who lived near lots that were greened reported feeling safer and increased their use of the outside space for relaxing and socializing.

How can you help?

Unfortunately, urban tree canopy cover has been declining over the years. To counter this decline, many towns and nonprofit organizations have programs that provide trees for planting.

A few examples in Massachusetts are Canopy Crew in Cambridge and Speak for the Trees in Boston. (Speak for the Trees also offers helpful information on selecting and caring for trees). Neighborhood Forest provides trees for schools and other youth organizations across the US. Look for a program near you!

Planting trees native to your region will better suit the local conditions, wildlife, and ecosystem. Contact your regional Native Plant Society for more information and guidance. If you are worried about seasonal allergies from tree pollen, many tree organizations or certified arborists can give you guidance on the best native tree selections.

If planting trees is not for you but you are interested in contributing to the mission, consider donating to organizations that support reforestation, like The Canopy Project and the Arbor Day Foundation.

About the Author

Wynne Armand, MD, Contributor

Dr. Wynne Armand is a physician at Massachusetts General Hospital (MGH), where she provides primary care; an assistant professor in medicine at Harvard Medical School; and associate director of the MGH Center for the Environment and … See Full Bio View all posts by Wynne Armand, MD

Heavy rains and sea level rise contribute to major flooding events that are one effect of climate change. Surging water rushing into buildings often causes immediate harms, such as drowning deaths, injuries sustained while seeking shelter or fleeing, and hypothermia after exposure to cold waters with no shelter or heat.

But long after news trucks leave and public attention moves on, flooding continues to affect communities in visible and less visible ways. Among the less visible threats is a higher risk of respiratory health problems like asthma and allergic reactions. Fortunately, you can take steps to minimize or avoid flooding, or to reduce respiratory health risks after flooding occurs.

How does flooding trigger respiratory health issues?

Flooding may bring water contaminated with toxic chemicals, heavy metals, pesticides, biotoxins, sewage, and water-borne pathogens into buildings. Afterward, some toxic contaminants remain in dried sediments left behind. When disturbed through everyday actions like walking and cleaning, this turns into microscopic airborne dust. Anything in that dried flood sediment — the toxic chemicals, the metals, the biotoxins — is now in the air you breathe into your lungs, potentially affecting your respiratory health.

Buildings needn’t be submerged during flooding to spur respiratory problems. Many homes we studied after Hurricane Ida suffered water intrusion through roofs, windows, and ventilation ducts — and some were more than 100 miles away from coastal regions that bore the brunt of the storm.

The growth of mold can also affect health

Another common hazard is mold, a fungal growth that forms and spreads on damp or decaying organic matter. Indoor mold generally grows due to extensive dampness, and signals a problem with water or moisture. Damp materials inside buildings following a flood create perfect conditions for rapid mold growth.

Mold can be found indoors and outdoors in all climates. It spreads by making tiny spores that float through the air to land in other locations. No indoor space is entirely free from mold spores, but exposure to high concentrations is linked with respiratory complications such as asthma, allergic rhinitis, and sinusitis. Thus, flooding affects respiratory health by increasing the risk of exposure to higher concentrations of mold spores outdoors and indoors.

For example, after Hurricane Katrina in New Orleans in 2005, the average outdoor concentration of mold spores in flooded areas was roughly double that of non-flooded areas, and the highest concentrations of mold spores were measured indoors. A study on the aftermath of Hurricane Katrina and the flooding in the UK in 2007 showed that water damage accelerated mold growth and respiratory allergies.

Children are especially vulnerable to health problems triggered by mold. All respiratory symptoms — including asthma, bronchitis, eye irritation, and cough — occurred more often in homes reporting mold or dampness, according to a study on the respiratory health of young children in 30 Canadian communities. Other research demonstrates that mold contributes to development of asthma in children.

What can you do to protect against the health harms of flooding?

Our research in New Orleans, LA after Hurricane Ida in 2021 identified common factors — both in housing and flooding events — with great impact on respiratory health. Preliminary results suggest two deciding factors in whether substantial indoor mold appeared were the age of a building’s roof and how many precautionary measures people took after flooding from the hurricane. The impact on respiratory health also varied with flood water height, days per week spent at home, and how many precautionary measures were taken after Ida swept through.

Informed by this and other research, we offer the following tips — some to tackle before flooding or heavy rains, and some to take afterward. While you may not be able to entirely prevent flooding from hurricanes or major storms, taking these and other steps can help.

Before seasonal storms, flooding, or heavy rains start: Protect against water intrusion

• Repair the roof, clean gutters, and seal around skylights, vent pipes, and chimneys to prevent leaks. These are some of the most vulnerable components of a building during storms and hurricanes.
• Declutter drains and empty septic tanks.
• Construct barriers and seal cracks in outer walls and around windows, to prevent heavy rain and floodwater from entering.
• Install a sump pump to drain water from the basement, and backflow valves on sewer lines to prevent water from backing up into the home.

After flooding or major rainstorms: Move quickly to reduce dampness and mold growth

The Environmental Protection Agency recommends limiting contact with flood water, which may have electrical hazards and hazardous substances, including raw sewage. Additionally:

• Minimize your stay in flooded regions (particularly after hurricanes) or buildings until they are dry and safe.
• Check building for traces of water intrusion, dampness, and mold growth immediately after flooding.
• Drain floodwater and dispose of remaining sediment.
• Remove affected porous materials. If possible, dry them outdoors under sunlight.
• Increase the ventilation rate by leaving all windows and doors open, or use a large exhaust fan to dry out the building as fast as possible.
• Use dehumidifiers in damp spaces such as basements.
• Upgrade the air filters in your HVAC system to at least MERV 13, or use portable air cleaners with HEPA filters to reduce your exposure to airborne mold spores.

What to do if you spot mold growth

• Wear a well-fitted N95 face mask, gloves, and rubber boots to clean.
• Clean and disinfect anything that has been in contact with water using soap, detergents, and/or antibacterial cleaning products.
• Dispose of moldy materials in sealed heavy-duty plastic bags.

Taking steps like these — before and after a major storm — goes a long way toward protecting your respiratory health.

Read Flooding Brings Deep Trouble in Harvard Medicine magazine to learn more about the health hazards related to floods.

About the Authors

Parham Azimi, PhD, Contributor

Dr. Parham Azimi is a research associate in the department of environmental health at the Harvard T.H. Chan School of Public Health, investigating the indoor environment’s impact on occupant health and wellness and strategies to improve … See Full Bio View all posts by Parham Azimi, PhD

Joseph Allen, DSc, MPH, CIH, Contributor

Dr. Joseph Allen is an associate professor in the department of environmental health at the Harvard T.H. Chan School of Public Health, and the director of Harvard’s Healthy Buildings Program. He is the coauthor of Healthy … See Full Bio View all posts by Joseph Allen, DSc, MPH, CIH

Need another jolt of motivation to shore up a resolution to shed weight, sleep more soundly, boost nutrition or exercise levels, or cut back on alcohol? Then you'll be pleased to learn that any (and all) of these efforts can also add up to better brain health.

An international study led by researchers at the McCance Center for Brain Health at Massachusetts General Hospital devised and validated a Brain Care Score (BCS) card that makes it easy to total up what you're doing well and where you might do better. The prize is a healthier brain — specifically a lower risk for dementia and strokes.

Designed to predict how current habits might impact future brain health, the user-friendly scorecard is apparently the first of its kind, says Dr. Andrew Budson, a lecturer in neurology at Harvard Medical School.

"It's a real service that the researchers have developed a scale like this and completed the first study to determine if scoring worse on this scale raises your risk for dementia and stroke," says Dr. Budson, who wasn't involved in the analysis. "On one hand, no one's done something quite like this before. On the other, however, it's really wrapping together health factors everyone has known for a number of years in new packaging."

What's included on the scorecard?

Called the McCance Brain Care Score, the card tallies points from 12 physical, lifestyle, and social-emotional domains.

Physical components relate to

• blood pressure
• blood sugar
• cholesterol
• body mass index (BMI).

Lifestyle components include

• nutrition
• alcohol intake
• smoking
• aerobic activities
• sleep.

Social-emotional factors inquire about

• stress management
• social relationships
• meaning in life.

Each response is given a score of 0, 1, or 2, with the highest possible score totaling 21. Higher scores suggest better brain care.

"All these physical and lifestyle factors can contribute to the risk of dementia to some extent through strokes," Dr. Budson says. "Those that aren't a risk through strokes are usually related to the fact that a healthy brain is a brain that's using all of its parts. Engaging in healthy relationships and meaningful activities helps us maintain good brain structure and function."

What did the analysis involve?

The study was published online in Frontiers of Neurology in December 2023. It involved nearly 399,000 adults ages 40 through 69 (average age 57; 54% women) who contributed personal health information to the UK Biobank.

During an average follow-up period of 12.5 years, participants recorded 5,354 new cases of dementia and 7,259 strokes. Researchers found that participants with higher Brain Care Scores at the study's start had lower risks of developing dementia or strokes over time.

These threats to health and independence take a stunning — and growing — toll on people in the US. Dementia affects one in seven Americans, a rate expected to triple by 2050. Meanwhile, more than 795,000 people in the United States suffer a stroke each year, according to the CDC.

What did the study find?

Each five-point step higher in the BCS rating assigned when the study began was linked to significantly lower risks of dementia and stroke, with those odds varying by age group:

• Participants younger than 50 at the study's start were 59% less likely to develop dementia and 48% less likely to have a stroke with each five-point higher score on BCS.
• Participants 50 through 59 at the study's start were 32% less likely to develop dementia and 52% less likely to have a stroke with each five-point higher score on BCS.

But those brain disease benefits appeared to diminish for those older than 59 at the study's start. This group experienced only 8% lower odds of dementia and a 33% lower risk of stroke with each five-point higher score on BCS. Study authors theorized that some of these participants may have already been experiencing early dementia, which is difficult to detect until it progresses.

"I feel very comfortable that the study's conclusions are entirely correct, because all the factors that go into its BCS are well-known things people can do to reduce their risk of stroke and dementia," Dr. Budson says.

What are the study's limitations?

However, Dr. Budson notes that the study did have a couple of limitations,. The UK Biobank fell just short of collecting all the components of the BCS in its dataset, lacking meaning-of-life questions. So its scores ranged from 0 to 19, not up to 21. "It's a practical limitation, but it should be acknowledged that so far, there have been no studies to validate the actual 21-point scale they're recommending we use," he says.

The analysis also evaluated participants' scores at just one point in time instead of several, Dr. Budson says. Future research should determine whether people can lower their stroke and dementia risk by improving their BCS over time with behavior and lifestyle changes.

How can you play this game at home?

While better brain health may be the clear prize of a higher score, it's far from the only benefit. That's because improving any health component of the BCS also benefits our overall well-being.

"By improving these factors, not only will people help their brain, but they'll also help their heart and reduce their risk of cancer," Dr. Budson adds. "These factors will absolutely also improve your psychological health, which is certainly an important part of brain health."

The scale's simple breakdown of health factors also makes it easy to focus on tweaking one or two without getting overwhelmed.

"Let's say someone's nutrition isn't perfect — and they know it — but they're not willing to change their diet. Fine. They can then decide to do more aerobic exercise, for example, or to stop drinking, or to get the sleep their body needs," he says.

What one change could put you on a path to better brain health?

If he had to choose just one factor to improve brain health, Dr. Budson would focus on meaning of life, "which means you generally feel your life has meaning or purpose," he says. To do that, he suggests giving deep, quiet thought to what you wish your life's purpose to be, whether you expect to live a long time or just a few years.

"Once you have a purpose, then you have a reason to follow through with assessing all the other items on the BCS scale and seeing what you can do so you'll be around longer, and be competent and capable longer, to help fulfill the meaning and purpose of your life," he says.

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD