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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

By the time boys are 8 or 10, they’re steeped in Marvel action heroes with bulging, oversized muscles and rock-hard abs. By adolescence, they’re deluged with social media streams of bulked-up male bodies.

The underlying messages about power and worth prompt many boys to worry and wonder about how to measure up. Sometimes, negative thoughts and concerns even interfere with daily life, a mental health issue known body dysmorphic disorder, or body dysmorphia. The most common form of this in boys is muscle dysmorphia.

What is muscle dysmorphia?

Muscle dysmorphia is marked by preoccupation with a muscular and lean physique. While the more extreme behaviors that define this disorder appear only in a small percentage of boys and young men, it may color the mindset of many more.

Nearly a quarter of boys and young men engage in some type of muscle-building behaviors. “About 60% of young boys in the United States mention changing their diet to become more muscular,” says Dr. Gabriela Vargas, director of the Young Men’s Health website at Boston Children’s Hospital. “While that may not meet the diagnostic criteria of muscle dysmorphia disorder, it’s impacting a lot of young men.”

“There’s a social norm that equates muscularity with masculinity,” Dr. Vargas adds. “Even Halloween costumes for 4- and 5-year-old boys now have padding for six-pack abs. There’s constant messaging that this is what their bodies should look like.”

Does body dysmorphic disorder differ in boys and girls?

Long believed to be the domain of girls, body dysmorphia can take the form of eating disorders such as anorexia or bulimia. Technically, muscle dysmorphia is not an eating disorder. But it is far more pervasive in males — and insidious.

“The common notion is that body dysmorphia just affects girls and isn’t a male issue,” Dr. Vargas says. “Because of that, these unhealthy behaviors in boys often go overlooked.”

What are the signs of body dysmorphia in boys?

Parents may have a tough time discerning whether their son is merely being a teen or veering into dangerous territory. Dr. Vargas advises parents to look for these red flags:

• Marked change in physical routines, such as going from working out once a day to spending hours working out every day.
• Following regimented workouts or meals, including limiting the foods they’re eating or concentrating heavily on high-protein options.
• Disrupting normal activities, such as spending time with friends, to work out instead.
• Obsessively taking photos of their muscles or abdomen to track “improvement.”
• Weighing himself multiple times a day.
• Dressing to highlight a more muscular physique, or wearing baggier clothes to hide their physique because they don’t think it’s good enough.

“Nearly everyone has been on a diet,” Dr. Vargas says. “The difference with this is persistence — they don’t just try it for a week and then decide it’s not for them. These boys are doing this for weeks to months, and they’re not flexible in changing their behaviors.”

What are the health dangers of muscle dysmorphia in boys?

Extreme behaviors can pose physical and mental health risks.

For example, unregulated protein powders and supplements boys turn to in hopes of quickly bulking up muscles may be adulterated with stimulants or even anabolic steroids. “With that comes an increased risk of stroke, heart palpitations, high blood pressure, and liver injury,” notes Dr. Vargas.

Some boys also attempt to gain muscle through a “bulk and cut” regimen, with periods of rapid weight gain followed by periods of extreme calorie limitation. This can affect long-term muscle and bone development and lead to irregular heartbeat and lower testosterone levels.

“Even in a best-case scenario, eating too much protein can lead to a lot of intestinal distress, such as diarrhea, or to kidney injury, since our kidneys are not meant to filter out excessive amounts of protein,” Dr. Vargas says.

The psychological fallout can also be dramatic. Depression and suicidal thoughts are more common in people who are malnourished, which may occur when boys drastically cut calories or neglect entire food groups. Additionally, as they try to achieve unrealistic ideals, they may constantly feel like they’re not good enough.

How can parents encourage a healthy body image in boys?

These tips can help:

• Gather for family meals. Schedules can be tricky. Yet considerable research shows physical and mental health benefits flow from sitting down together for meals, including a greater likelihood of children being an appropriate weight for their body type.
• Don’t comment on body shape or size. “It’s a lot easier said than done, but this means your own body, your child’s, or others in the community,” says Dr. Vargas.
• Frame nutrition and exercise as meaningful for health. When you talk with your son about what you eat or your exercise routine, don’t tie hoped-for results to body shape or size.
• Communicate openly. “If your son says he wants to exercise more or increase his protein intake, ask why — for his overall health, or a specific body ideal?”
• Don’t buy protein supplements. It’s harder for boys to obtain them when parents won’t allow them in the house. “One alternative is to talk with your son’s primary care doctor or a dietitian, who can be a great resource on how to get protein through regular foods,” Dr. Vargas 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

It’s not often that a new drug comes along that could help nearly a quarter of the adult population. But when it does, you can bet you’ll see ads for it on TV and the Internet.

That’s the case with Veozah (fezolinetant), a medicine for hot flashes and night sweats due to menopause that was approved by the FDA in May 2023. One ad has this inventive tagline: “You can have fewer hot flashes and more not flashes.”

So, what is a not flash and what does the ad tell us about this new drug?

The ad: This is a not flash

The ad begins with an upbeat song, “Good Feeling,” a hit by Flo Rida released in 2011. A woman in a crowded elevator is clearly distressed and soaked in sweat as the voiceover declares, “This is a hot flash.” A second woman appears, awakening in her bedroom covered in sweat. Again, the narrator declares “This is a hot flash.” Cut to two smiling women on a dock taking selfies as boats sway behind them: “But this is a not flash.”

The voiceover tells us that Veozah is a prescription treatment for women with moderate to severe hot flashes and night sweats — or vasomotor symptoms, as medical experts say. (Hot flashes may or may not prompt sweating, while night sweats are exactly as billed.)

When the voiceover tells us the drug is “hormone free,” the words “100% hormone-free” appear on the screen. Got it? Apparently, this drug contains no hormones.

Does Veozah work?

But is it effective? The ad voiceover says, “Veozah has been proven to reduce the number and severity of hot flashes day and night. For some women, it can start working in as early as one week.”

The details are easy to miss. They appear in fine print briefly at the bottom of the screen: “At 12 weeks, women taking Veozah experienced 63% fewer hot flashes vs. 42% on placebo.” Sounds good, right? More on what this actually means below.

What does the ad tell us about risks?

The FDA requires drug manufacturers to review the most common or serious risks of taking the drug. So while the catchy song continues, images appear of women peacefully sleeping, teaching a classroom full of students, or working in a hectic office. The voiceover warns that some people shouldn’t take Veozah: anyone with cirrhosis (a form of liver disease) or severe kidney problems, and anyone who takes a medicine known as a CYP1A2 inhibitor.

Next comes the litany of possible side effects, including:

• the need for repeated liver blood tests before and during treatment
• stomach pain
• diarrhea
• difficulty sleeping
• back pain.

What does the ad get right?

This ad highlights significant suffering caused by hot flashes and night sweats, which affect about 80% of women during menopause. Currently, treatment options (and, truth be told, actual research on those dealing with these problems) are quite limited. Hormone replacement with estrogen and related medicines was often prescribed in past years. But concerns about risks associated with estrogen use led many physicians to stop prescribing hormone replacement, and many women decline it when it’s offered.

But Veozah works without hormones: it blocks a protein in the brain that helps regulate body temperature. That’s why the “hormone free” message is emphasized in the ad.

Just how effective is Veozah for hot flashes and night sweats??

Unfortunately, digging more closely into the data shows the difference between Veozah and placebo in reducing hot flashes and night sweats is relatively small. And some important information is missing or incomplete in the ad. I filled in gaps by looking at two pivotal trials of Veozah (called SKYLIGHT 1 and SKYLIGHT 2).

What exactly are “moderate” and “severe” symptoms?

For this study, women had to have at least seven moderate to severe hot flashes per day, although the average was 10 to 12. A moderate hot flash was defined as a sensation of heat with sweating that did not interfere with activities. A severe hot flash was a sensation of heat with sweating that did interfere with activities. So, the number of moderate or severe hot flashes tallied by the researchers in this study included sweats, regardless of what time of day they occurred.

How many hot flashes or night sweats were prevented?

The ad provides data on effectiveness as a percent reduction: 63% fewer hot flashes. Importantly, that doesn’t tell you the actual number of hot flashes prevented. During 12 weeks of treatment, women given the medicine went from experiencing an average of about 11 hot flashes a day at the start to about four a day. By comparison, the group taking a placebo (an inactive pill) dropped from 11 hot flashes a day to 6.5 a day. So, that’s about 2.5 fewer hot flashes a day in total for women taking the drug.

• What about effectiveness after 12 weeks? Based on the published studies (including SKYLIGHT 4), effectiveness persists for at least a year with continued treatment. While that’s good news, it would be helpful to know whether effectiveness wanes or persists beyond one year, because menopausal hot flashes and night sweats can come and go for many years. The average is about seven years, and it’s not rare for them to last a decade or more.
• How diverse were the study participants in the clinical trials that led to FDA approval? More than 80% of study participants identified as Caucasian, 17% as African American, 24% as Hispanic/Latina, and 1% as Asian. Studies of a more diverse population are needed.

What else should you know about possible downsides of Veozah?

The ad covers the most common side effects reported during trials of this drug. Yet advising people to avoid Veozah if they take a CYP1A2 inhibitor is likely to perplex most viewers. This warning relates to an enzyme that helps the body metabolize many medicines, including Veozah.

If you’re already taking a medicine that inhibits the action of this enzyme and you start taking Veozah, the blood levels of Veozah may rise higher than intended and increase the risk of side effects. Many common medicines can cause this interaction (including ciprofloxacin, some oral contraceptives, and cimetidine). Ask your doctor about this before starting Veozah.

Finally, the ad provides no information about cost. According to the drug maker’s website, the list price is $550 a month. That’s the amount you’d be charged if you have no health insurance.

But the average price for people with commercial health insurance is $41 a month. It’s about $77 a month for people covered by Medicare Part D, and $12 a month for people with Medicaid. The drugmaker’s Patient Assistance Program may provide the drug at no cost for some people who are eligible — though eligibility criteria aren’t easy to find and aren’t included in the ad.

The bottom line

A newly approved, nonhormonal drug for hot flashes and night sweats during menopause is big news. But it remains to be seen whether this is a small step forward or a major advance. Either way, the ad mostly does its job: it introduces us to a new medication for a common and burdensome condition that currently has limited treatment options.

Of course, this one-minute ad for Veozah isn’t intended to cover everything a viewer might want to know about it; it’s intended to get people with significant hot flashes and night sweats to ask their doctor about the advertised drug. Keep that in mind when you see ads for this drug — or any drug ad, for that matter.

While I’m not sure whether Veozah will prove to be a wonder drug, one thing’s for sure: that song sure holds up well.

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

Concussion is one of the most common injuries to the brain, affecting about two million children and teens every year. It is a particular kind of injury that happens when a blow to the head or somewhere else on the body makes the brain move back and forth within the skull.

It’s possible to get a concussion after what might seem like a minor injury, like a forceful push from behind, or a collision between two players in a football or soccer game.

What are the signs and symptoms of concussion?

Because the injury may not seem that significant from the outside, it’s important to know the symptoms of a concussion. There are many different possible symptoms, including

• passing out (this could be a sign of a more serious brain injury)
• headache
• dizziness
• changes in vision
• feeling bothered by light or noise
• confusion or feeling disoriented
• memory problems (such as difficulty remembering details of the injury) or difficulty concentrating
• balance or coordination problems
• mood changes.

Some of these are visible to others and some are felt by the person with the concussion. That’s why it’s important to know the signs and to ask all the right questions of a child who has had an injury.

Sometimes the symptoms might not be apparent right away, but show up in the days following the injury. The CDC’s Heads Up website has lots of great information about how to recognize a concussion.

How can further harm to the brain be avoided?

The main reason it’s important to recognize a possible concussion early is that the worst thing you can do after getting a concussion is get another one. The brain is vulnerable after a concussion; if it is injured again, the symptoms can be longer lasting — or even permanent, as in cases of chronic traumatic encephalopathy (CTE), a condition that has been seen in football players and others who have repeated head injuries.

If there is a chance that a child has had a concussion during a sports competition, they must stop playing — and get medical attention. It’s important to get medical attention any time there is concern about a possible concussion, both to be sure there isn’t a more serious brain injury, and to do a good assessment of the symptoms, so that they can be monitored over time. There are some screening questionnaires that are used by doctors that can be used again in the days and weeks after the concussion to see how the child is improving.

What helps children recover after a concussion?

Experts have struggled with figuring out how to protect the brain after a concussion. For a long time, the recommendation was to rest and do very little at all. This meant not doing any exercise, not going to school, not even reading or watching television. As symptoms improved, the restrictions were lifted gradually.

Over time, though, research showed that not only was this much rest not necessary, it was counterproductive. It turns out that getting kids back into their daily lives, and back into being active, is safe and leads to quicker recovery. Experts still recommend rest and then moving gradually back into activities, but the guidelines are no longer as strict as they once were.

One important note: A medical professional should guide decisions to move from rest to light activity, and then gradually from there to moderate and then regular activities based on how the child is doing. This step-by-step process may extend for days, weeks, or longer, depending on what the child needs. Parents, coaches, and schools can help support a child or teen as they return to school and return to activities and sports.

Some children will be able to get back into regular activities quickly. But for others it can take weeks or even months. Schools and sports trainers should work with children to support them in their recovery. Some children develop post-concussive syndromes with headache, fatigue, and other symptoms. This is rare but can be very disabling.

How can parents help prevent concussions?

It's not always possible to prevent concussions, but there are things that parents can do:

• Be sure that children use seat belts and other appropriate restraints in the car.
• Have clear safety rules and supervise children when they are playing, especially if they are riding bikes or climbing in trees or on play structures.
• Since at least half of concussions happen during sports, it’s important that teams and coaches follow safety rules. Coaches should teach techniques and skills to avoid dangerous collisions and other injuries. Talk to your child’s coaches about what they are doing to keep players safe. While helmets can prevent many head injuries, they don’t prevent concussions.

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

If the eyes are the windows to the soul, then consider the tongue a sort of check-engine light for the body. The tongue’s appearance gives doctors an idea about certain aspects of your health, and its color is an important clue.

What should your tongue look like?

The tongue should have a rounded, symmetrical shape. It’s generally light pink, though it may have a little purple or brown pigmentation in African, Asian, and Mediterranean populations. It can also have a hint of white coating.

“The coating comes from a tough protein called keratin, which helps keep your tongue from being scratched when you eat,” says Dr. Tien Jiang, a prosthodontist in the Department of Oral Health Policy and Epidemiology at the Harvard School of Dental Medicine.

Up close, you might be able to see that your tongue is covered in tiny bumps (papillae) that serve several purposes:

• They sense temperature and touch.
• They contain taste buds that enable you to detect if food is sweet, salty, sour, bitter, or savory.
• They create friction to help you form a little ball of food (bolus) that you can swallow.

Can diet affect tongue color?

Yes. Sometimes diet may be partly to blame for a shift away from your usual tongue tone. That’s because the papillae can absorb the colors and residues of foods and drinks you consume. For example, that blue popsicle or candy you ate as a kid probably turned your tongue an exciting shade of azure. Coffee, tea, and many types of foods, such as curried dishes with lots of yellow turmeric, can also leave their marks.

Discoloration is usually just temporary, however. Drinking plenty of water and maintaining good oral hygiene will wash away food and dyes that cling to the tongue.

A dark or bright tongue, white patches, and other causes for concern

Some tongue colors and appearances are signs of health issues. Check with your doctor if you notice any of the following:

• A brown or black tongue signals a condition called “black hairy tongue.” This occurs when papillae get too long. These tiny bumps don’t usually get much chance to grow because they are shed regularly with all the activity in your mouth. If they do grow, they can trap bacteria and a mix of food colors, leading to the brown or black tinge. Risk factors include taking antibiotics or antihistamines, smoking, dry mouth, drinking excessive amounts of coffee or black tea, or poor oral hygiene.
• Thick white patches or white sores on the tongue probably mean you have an overgrowth of yeast in the mouth (thrush). Thrush can be triggered by conditions such as diabetes or HIV, side effects of antibiotics or cancer treatment, wearing dentures, smoking, dry mouth, or using steroid inhalers. In rare cases, white patches or sores are symptoms of oral cancer.
• If your tongue has painful red or yellow sores, you might be dealing with canker sores (irritated tissues), thrush (which can sometimes appear as red patches), or (in rare cases) oral cancer.
• A bright red tongue can indicate that you have a vitamin B12 deficiency or an infection called scarlet fever — a Streptococcus bacteria infection in the throat (strep throat) accompanied by a red body rash. If you have bright red patches that don’t hurt and seem to migrate from one place on the tongue to another, you might have a harmless, incurable condition called “geographic tongue.”

Should you brush your tongue or use a tongue scraper?

Good oral hygiene requires that you floss your teeth at least once a day and brush them at least twice a day. Take a few seconds to use the brush on your tongue.

“Stick out your tongue and swipe your toothbrush from the back of your tongue to the front: one swipe down the middle, one swipe down the left side, and one swipe down the right side. That helps remove bacteria and debris that collect in papillae,” Dr. Jiang says.

Some people swear by using a tongue scraper to clean the tongue. Dr. Jiang isn’t a fan, but doesn’t have a problem with someone using the tool, which is pulled forward on the tongue in a similar fashion to brushing the tongue. “The data about tongue scraper effectiveness are mixed,” she says. “It just comes down to what you’re willing to do daily to keep your tongue, teeth, mouth, and gums as healthy as possible.”

Worried about your tongue? What to do

If you’re worried about anything wrong with your tongue — especially if you also have a fever, a very sore throat, sores that won’t go away, or other new symptoms — call your primary care doctor or dentist.

Your doctor or dentist can

• assess your condition
• prescribe or suggest treatments to relieve discomfort, such as medicated mouthwashes or warm-water rinses
• urge you to stay hydrated and step up your oral hygiene.

If necessary, your doctor can refer you to a specialist for further evaluation.

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

You probably know that you have a thyroid gland. Perhaps you or someone you know has had thyroid tests or a thyroid disorder such as hypothyroidism.

But did you know you also have a parathyroid gland? It’s true — in fact, most people have four of them, even though one would suffice.

Where are the parathyroid glands?

From the name, you might assume the role of the parathyroid glands is related to that of the thyroid gland. Well, you’d be wrong. The name comes solely from their location: they sit just behind the thyroid gland: two on the right side, two on the left.

The parathyroid glands are small (the size of peas), and can weigh less than a thousandth of an ounce each. Although it’s normal to have four parathyroid glands, about 13% of people have fewer and 5% have more. And some people have parathyroid glands in other locations, such as alongside the esophagus or in the chest. This variation rarely matters, unless surgery is necessary to remove one or more of them.

What do the parathyroid glands do?

Logically enough, parathyroid glands make parathyroid hormone (PTH). And what does PTH do? It has several functions, including:

• Regulating calcium: Calcium is a mineral with many essential roles throughout the body, such as maintaining bone strength, allowing nerves and muscles to function normally, and making sure blood clots as it should. Higher levels of PTH lead to higher calcium levels in the blood through actions on the kidneys and bones.
• Regulating phosphorus: Among other roles, this mineral is a key component of our DNA, bones, and teeth. Phosphorus activates essential enzymes throughout the body, including enzymes necessary for cell reproduction and survival. It also helps with nerve and muscle function.
• Regulating vitamin D: This vitamin is actually a hormone that helps maintain normal levels of calcium throughout the body, by controlling how much gets absorbed from food in the intestinal tract and how much is lost by the kidneys in your urine. Remember PTH? Well, PTH regulates production of the enzyme that converts inactive vitamin D to an active form that helps your gut absorb calcium and reduces the loss of calcium in urine.

PTH released by the parathyroid glands helps keep each of these nutrients in balance. For example, if your blood calcium level falls, your parathyroid glands make more PTH. Higher amounts of PTH prompt bones to release stored calcium into the bloodstream, and also signal the kidneys to pull back on the amount of calcium lost through urine.

What if your blood calcium level rises? Then the parathyroid glands make less PTH, which helps to correct the blood calcium level.

Which diseases involve the parathyroid glands?

The most common are:

• Hyperparathyroidism: This is a condition in which the parathyroid glands make more than the normal amount of PTH. This can be due to a benign or cancerous tumor on a single gland, or due to multiple glands becoming overactive. Or it may be due to some other trigger, such as a low level of calcium in the blood, inadequate vitamin D levels, or kidney failure. When there’s too much PTH, blood calcium levels can become dangerously high and phosphorus levels fall. Surgery may be recommended to remove the overactive gland or glands.
• Hypoparathyroidism: This rare condition is diagnosed when less than the normal amount of PTH is produced. The most common causes are prior neck surgery or radiation, autoimmune disease, or low magnesium levels.
• Parathyroid cancer: Risk factors for parathyroid cancer include certain genetic diseases and prior radiation to the neck.

Why do we rarely hear about the parathyroid glands?

The reason is that most of the time they do their job without fuss or fanfare. Although disorders of the parathyroid glands are not rare, they are just uncommon enough that most people will never hear about them. I think of the parathyroid glands as one of many parts of our bodies that play a huge role in our health, but go unappreciated because they are so good at what they do.

Many other quiet heroes, including the thymus gland, serve as testaments to the remarkable design and function of the human body. Then again, I can think of a few body parts that could be considered expendable.

The bottom line

I hope it’s comforting to know that your amazing parathyroid glands are keeping tabs on your calcium levels and helping your bones, nerves, muscles, and other organs to function normally.

Ounce for ounce, the parathyroid glands may be the most important glands you’d never heard of. Until now.

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

Colon cancer is the second-deadliest form of cancer after lung cancer. If recent messages about colon cancer screening have left you a little confused, that's understandable. In August, the American College of Physicians (ACP) released updated guidance for colon cancer screening that differs from other major organizations, including recommendations from the American Cancer Society (ACS) and the US Preventive Services Task force (USPSTF).

So, what do you need to know?

How does the advice differ?

First, please note that this advice applies only to people at average risk without a family history of colon cancer. If you have family history, or if other health issues put you at higher-than-average risk for colorectal cancer, talk to your doctor about the best course of action for you.

The main point of disagreement relates to the age at which people should start getting screened. The new ACP guidance says 50, while the other two organizations recommend 45. That earlier age is endorsed by the U.S. Multisociety Task Force on Colorectal Cancer. It's also endorsed by many physicians, including Harvard Medical School professor Dr. Andrew T. Chan, a gastroenterologist and director of epidemiology at Massachusetts General Hospital Cancer Center, who helps explain key facts below.

Why do experts suggest starting screening earlier?

"We're facing an unexplained and alarming increase in the incidence of colon cancer in people younger than 50," says Dr. Chan.

Overall, deaths from colon cancer dropped by 2% per year from 2011 to 2020. But that's not the case among people younger than 50. In that age group, deaths from colon cancer rose between 0.5% and 3% during the same time period, according to statistics published in 2023.

The rising rates of colon cancer in younger people are occurring in all racial and ethnic groups, with the steepest rises seen among Alaskan Natives and Native Americans. Overall, Blacks and African Americans are more likely to get and die from colon cancer than whites, and early-onset cases are higher in Black individuals than whites.

Efforts to encourage colon cancer screening began in the mid-1990s. Today, about 60% of adults over 50 follow the advice to receive a colonoscopy (described below) on a regular basis. This track record, while not perfect, likely explains the decline in deaths from colon cancer in older adults.

"I think that promoting earlier screening will help stem the rise in early-onset cases, at least for those in their 40s. We've also seen that earlier colonoscopies may be associated with lowering incidence of colon cancer even later in life, "says Dr. Chan.

What are the different screening tests for colon cancer?

The two most widely used screening tests are a standard colonoscopy and various stool-based tests.

Colonoscopy. For this test, a gastroenterologist or surgeon snakes a long, flexible tube with a camera on the end through your rectum and beyond to inspect the entire length of your colon. Considered the gold-standard test, this procedure can detect precancerous polyps called adenomas, and allow for their removal.

The test requires taking laxatives and drinking lots of fluids beforehand to clean all the fecal material (stool) out of your colon. Serious complications, which include perforation or bleeding, are rare, occurring in about three in 1,000 procedures. If no polyps are found, a repeat colonoscopy isn't recommended for another 10 years. If you have polyps, or your risk or symptoms change, this interval will be shorter.

Stool tests. The more worrisome colon polyps (adenomas) often shed tiny amounts of blood and abnormal DNA into the stool. This can be detected from samples you collect yourself at home.

• Two tests, the fecal occult blood test (FOBT) and fecal immunochemical test (FIT), check for blood. They require small stool samples that you put on a card or in a tube that's then mailed to a lab. These tests should be done every year.
• A third option, the FIT-DNA test, checks for both blood and abnormal DNA; it's usually repeated every three years.

Additionally, the guidelines from the American College of Physicians suggest another option: flexible sigmoidoscopy, which inspects only the lower part of the colon, once every 10 years, combined with a fecal FIT testing every two years. However, doctors in the United States rarely order sigmoidoscopy today.

If flexible sigmoidoscopy or any of these stool tests show evidence of a problem, a colonoscopy is needed to check for adenomas or cancer.

Why might stool-based screening make sense for younger adults?

Colonoscopy isn't necessarily the best initial screening test for everyone, says Dr. Chan. That's especially true for younger people, mainly because it's time-consuming and inconvenient.

"Maybe you just can't find time in your schedule or are worried about having a colonoscopy," he says. If that's the case, a stool-based test — which is noninvasive and takes very little time — is an appropriate option.

"The worst option is not doing anything, because early detection and treatment can prevent deaths," he says.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

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

When preschoolers are melting down or teens are slamming doors, parents face two difficult tasks: keeping themselves composed and supporting their kids’ ability to self-soothe while building skills to handle future challenges.

These abilities are at the heart of co-regulation, a parenting tool that requires patience and practice. But what exactly is involved, and how does it help support children and teens wrestling with big emotions?

What is co-regulation?

“Co-regulation is a supportive, interactive, and dynamic process,” says Lauren Marchette, a child, adolescent, and family psychologist and a lecturer in psychiatry at Harvard Medical School.

Through warm and responsive interactions, caregivers help young people learn better ways to regulate their emotions during the inevitable upsets and challenges of life. “At its heart, co-regulation is connecting with a child who’s in distress and being able to evaluate what that child needs in the moment to help calm themselves.”

But before a parent or trusted adult can help a child, they need to understand — and possibly expand — their own emotional skills and limitations. Emotions are often contagious, whether a person is upset or sharing a sense of calm.

“The tricky part of co-regulation is that adults have to recognize how they’re feeling and be able to regulate their own emotions in difficult moments so they can help children to gain these same skills,” Marchette says. “But this will be so important for kids to develop healthy relationships over time, and affects how people do in school, work, and life in general.”

How does building emotional skills help children and teens?

As children grow up, they learn different skills — how to build a block tower, play a sport, or solve a math equation. They also learn emotional skills: how to recognize and handle feelings of anger or anxiety, for example.

Known as self-regulation, such emotional skills are truly the basis of wellness in life, Marchette says. By consistently practicing co-regulation, parents and other trusted adults foster self-regulation skills in kids.

The list of self-regulation skills is wide-ranging, involving

• emotional awareness and literacy, including the ability to identify emotions
• emotional regulation skills such as self-soothing
• perspective-taking, or the ability to "walk in another’s shoes”
• social skills such as taking turns and practicing patience
• paying attention and remaining focused when needed
• problem-solving
• thinking flexibly
• time management skills
• goal-setting.

What are the potential benefits of co-regulation?

Co-regulation enables kids to eventually learn to

• handle stress
• resist immediate gratification
• avoid hasty, ill-informed decisions
• make and stick to plans
• solve problems
• adapt to challenges
• take healthy risks.

Some research suggests that having better self-regulation skills is linked to more positive outcomes in life, such as higher income and lower rates of substance use and violence.

Who might especially benefit from co-regulation?

Everyone wins when kids are better able to navigate frustrations and manage their reactions to their thoughts and feelings. Parents, teachers, coaches, guidance counselors, mentors, and other adults who interact closely with children also stand to benefit.

As for kids themselves, it’s hard to think of any whose lives won’t be improved by adults who have invested themselves in practicing co-regulation, Marchette says.

But practicing co-regulation skills with certain children and adolescents — including those whose families are experiencing economic hardship, substance abuse, divorce, or other distressing situations — can be especially important.

Is there evidence that co-regulation works?

“While co-regulation is built upon a solid theoretical framework, not many studies have delved into its effectiveness — at least across all age groups,” Marchette says. “Research that does focuses mainly on infants and preschoolers.”

“Much less is known about how co-regulation interventions work for older youth,” she says. “The research is trying to catch up to what we know from years of clinical experience.”

How can a parent coach a child through co-regulation?

Co-regulation doesn’t stand alone as a skill. It relies on fostering a warm, responsive relationship with children, providing structure, and setting limits. “Children benefit from consistent, predictable routines with clear expectations and consequences,” Marchette says.

When a child begins experiencing big emotions, a co-regulation response will look different depending on the child and circumstances. But the steps to take are similar.

“First, the parent needs to pause and self-regulate their own emotions, such as by taking a deep breath,” Marchette explains. “The next steps are validating the child’s feelings, observing the child’s response, and then deciding how to respond next, including verbally and nonverbally, such as with a touch.”

Marchette offers an example based on her own practice: 12-year-old “Eric” is tackling a writing assignment in his bedroom when his mother suddenly hears loud noises. She walks to his door and finds him throwing a stapler, notebook, and container of pens off his desk. “What’s wrong with me?” he yells. “I suck at writing and I hate school!” Then Eric puts his head down on his desk.

The sixth grader’s mom knows he needs help calming down, so she pauses and takes a deep breath. Then she walks over and whispers his name, placing her hand on his shoulder. After more silence, Eric gradually starts sitting up in his chair. “I can tell how frustrated you are with this assignment,” she says to him, validating his feelings. “It must be a really challenging one.”

Eric’s mother knows he needs a break after he mutters, “I can’t do it.” She suggests a getting a glass of ice-cold water, and Eric glumly follows her to the kitchen. After the break, they can re-evaluate if Eric is ready to return to his homework or needs further coping strategies — like a walk outside or a round of jumping jacks — to get his frustration out.

What resources can help parents practice co-regulation?

The Administration for Children and Families offers a free Co-Regulation in Action video series. And some therapists — especially those who specialize in behavioral parent training or cognitive behavioral therapy — can help parents who feel their skills need a boost.

It’s worth noting that it can be hard to have sufficient resources — emotional, financial, and other supports — to practice co-regulation consistently. Those who wish to try should give themselves some grace as they learn the process. “Even parents who are thinking their own self-regulation skills aren’t where they want them to be should realize this is a muscle they can strengthen,” Marchette says. “It’s important to have that growth mindset.”

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