In “The New Normal,” Dr. Jennifer Ashton explores the mental health repercussions of the pandemic and ways to rebuild our overall health.As the chief medical correspondent for ABC News, Dr. Jennifer Ashton has spent the past year helping to make sense of the pandemic for the network’s millions of viewers.But another aspect of the pandemic that she deals with is the toll it has taken on our nation’s mental health, which she sees on a daily basis at her medical practice in New Jersey, where Dr. Ashton is an obstetrician-gynecologist. In the past year, she says, patient after patient has opened up to her about the crippling stress and uncertainty caused by Covid-19 and their struggles with fear, anxiety, loneliness, frustration and depression.“I have patients ranging in age from teenagers to women in their 70s and 80s, and they all say this to me,” Dr. Ashton said. “They express it to me almost with this tone that they think there’s something wrong with it. The first thing that I do is I help them recognize that it’s appropriate and it’s OK. Everyone is having these feelings.”HarperCollins publishersDr. Ashton explores the psychological toll of the pandemic in her new book, “The New Normal,” which shows us how thinking like a doctor may help us to build resilience and strengthen our overall health. We recently caught up with Dr. Ashton to discuss her thoughts on how the pandemic is affecting our mental health, why it’s essential that we practice self-care during these stressful times, and one of the best hacks she found to improve her diet. Here are edited excerpts from our conversation.Q. How do you define the “new normal”?This past year has been filled with so much uncertainty and unfamiliarity. Nothing that we are doing today or have lived through in the last year is normal. The approach that I’ve taken to covering this pandemic has been that of viewing the country as one big patient, and the first step in healing or recovery from any illness is accepting the current situation.It’s like taking care of a patient who has recently undergone an amputation. The goal of rehabilitation is to get that person walking again or using a prosthetic device. That is their new normal. If they keep thinking of what they did before the amputation, it just hinders their progress. But when you stop looking back and start focusing on the present and the future, you can have an incredible healing and recovery.Q. You write that a lot of people have developed signs of post-traumatic stress this past year, even if they didn’t develop Covid-19. Can you explain?I divide it up into different subsets of the population. First, you have to address the frontline health care workers, and not just doctors and nurses. The transporters, technicians, clinical clerks — there are so many people who work in hospitals that never get recognized. And yet every death due to Covid affects them in the same way. To be in a hospital setting where you are losing a patient every hour for months on end takes a massive psychological toll.And for everyone else, I’ve spoken to many mental health professionals over the last year, and every single one has said that the social isolation and persistence of this pandemic has affected all of us. Human beings are social creatures. If you think about how many of us have been isolated for so long, it’s easy to see how entire elements of our society will have post-traumatic stress disorder because of that.Q. You say that it’s essential for people to practice self-care right now. What are some of the best ways to do that?How you eat, sleep and move is what I call the trifecta of good health and wellness. But I realized after the first stay-at-home period in New York, when I was working 15-hour days from my small New York apartment, that I had let all of those things fall by the wayside, and it had a massive impact on how my brain and my body felt. I had to turn the doctor lens on myself and say, ‘How would you talk to you, if you were your own patient?’I said it’s time to go back to the basics: Stop eating this comfort food that you never ate before the pandemic. Make sure that you get outside and exercise every day. I recommitted to getting eight hours of sleep and doing my meditation practice every day, and it was incredibly transformative. It made a huge difference in how I felt.Q. In the book you talk about how the pandemic has changed the way we eat, and mostly for the worse. What is one of your top rules for eating right?For those of us who are lucky, one of the blessings of this pandemic was that by necessity we started cooking from home. I could not cook a single meal before this pandemic. But I learned to cook and no one was more shocked than my children, who couldn’t believe what they were seeing. So, I would say my first rule is don’t be afraid to fail safely and quickly when it comes to trying new things with food, whether that’s with cooking or a new diet. Now is the time to be curious and experiment. I had to quarantine three different times in the last year because of exposure to positive cases. The last time I quarantined, I experimented with being completely vegan. In only 10 days, my LDL cholesterol dropped from 111 to 85. I had never considered going vegan before, but there are certain parts of it that I’m going to continue forever.Q. You’re a busy doctor and journalist. What do you do for exercise, and what advice do you have for our readers?Exercise is my stress release. I like a combination of resistance training and all kinds of cardio. Sometimes I do what I call low and slow, which is when I’m barely sweating but it’s something I can do while I’m on my device or watching TV. I do a lot of work with resistance bands because it never gets easy. You can work your entire body. You can do it anywhere, and they’re cheap. I keep them in my office and in my apartment. That’s my default.Q. What is one thing you do every day for your mental health?I’m a big believer in meditation. I do 20 minutes of it every day, and it’s life changing. I try to start my day with it because then I know that I’ll get it in. As the saying goes, I don’t find the time, I make the time. It’s helped me immensely during this pandemic.

Many Americans increased their alcohol intake during the pandemic, with women and parents of young children disproportionately affected.For most of her life, Andrea Carbone, a 51-year-old paralegal living in Florida, wasn’t a big drinker. But when the pandemic struck, she worried constantly about her job, her health and the safety of her children.While many people were able to work from home last year, Ms. Carbone, was required to go into the office. Some mornings she would cry in her car as she drove along deserted roads and highways to get to her office in downtown Tampa, which looked, she said, “like a ghost town.”As her stress levels soared, so did her alcohol intake. Before the pandemic, Ms. Carbone would have a glass of red wine with dinner most nights. But by May, her intake had climbed substantially. “I noticed I was having a glass of wine as soon as I got home, then a glass with dinner, then we’d sit down to watch TV and I’d have another glass or two,” she said. “By the end of the night I was drinking a bottle.”Ms. Carbone is far from alone. The widespread fear, frustration and social isolation surrounding the tumultuous events of the past year — the pandemic, civil unrest, political upheaval — caused stress levels to skyrocket, with many people increasing their alcohol intake. Women and parents of young children seem to have been hit particularly hard. A nationwide survey commissioned by the American Psychological Association in February found that one in four adults reported drinking more this past year to manage their stress. That rate more than doubled among those who had children between the ages of 5 and 7.Another study published in JAMA Network Open in October found that Americans increased the frequency of their alcohol consumption by 14 percent compared to a year earlier. But the same study found a 41 percent increase in the number of days on which women drank heavily, defined as having four or more drinks in a couple of hours.“Women have disproportionately left the labor force entirely compared to men; they have disproportionately taken on the work around the house, the child care, and the child’s education,” said Michael S. Pollard, the lead author of the JAMA study and a senior sociologist at the RAND Corporation. “So, it stands to reason that women would increase their alcohol use disproportionately as well.”The psychological damage from the past year has caused sharp declines in physical health, including widespread weight gain and disruptions in sleep. Hospitals around the country have reported an increase in admissions for hepatitis, cirrhosis, liver failure and other forms of alcohol-related diseases. Almost no group has been spared.Driftwood Recovery, an addiction and mental health rehabilitation center in Texas, has had so many requests for treatment this past year that it has a two-month waiting list. Vanessa Kennedy, Driftwood’s director of psychology, said that many of her clients are parents who started drinking heavily as they struggled to balance their day jobs with home-schooling and other parental responsibilities.“They’re used to having their kids go off happily to school and having an experienced teacher teach their children while they go to work and focus on performing well and providing financial support for their family,” said Dr. Kennedy. “Their work roles are conflicting with their parenting roles, and it’s been difficult for them to create space and do those things well.”Dr. Kennedy has treated a wide range of patients who turned to excessive drinking this past year. Some lost their jobs or shuttered their businesses, which left them without daily structure and the means to provide for their families. Others were college students who felt socially disconnected when they were sent home to do virtual schooling, or older adults who drank because they were depressed that they could not see their loved ones or hug their grandchildren.Before last year, Gordon Mueller, a retiree who lives in Rochester, N.Y., rarely consumed more than one or two drinks a day. But when the pandemic struck and the economy and stock market stumbled, Mr. Mueller was consumed by anxiety as he followed the news and worried about his retirement account. As Mr. Mueller sheltered in place at home with his wife, his alcohol intake escalated to seven drinks a day: vodka cocktails in the afternoon, wine with dinner, and a whisky nightcap before bed. “We had no idea if we were going to financially get through this thing, let alone get sick and potentially die,” he said. “It was just a lot of fear and boredom. Those were the two emotions.”Ms. Carbone now uses an app to track her alcohol intake and has at least two “dry” days a week.Zack Wittman for The New York TimesBut many people have found novel ways to rein in their drinking. In December, Mr. Mueller turned to Moderation Management, an online community that helps people who want to cut back on their drinking but not necessarily abstain. He started attending Zoom calls with other members and using the organization’s private Facebook group to learn tips and advice to reduce his drinking. Then, in January, he decided to give up alcohol for a while to see how he would feel.“I’m happy to say that I haven’t had a drink this year, and I feel a lot better: I sleep better, and I can get more things done,” he said. “The nice thing about this moderation group is that it’s not an all-or-nothing ‘You can never drink again or you’re a failed alcoholic’ approach.”In Tampa, Ms. Carbone started using a popular app called Cutback Coach, which helps people track their alcohol intake and set goals and reminders so they can develop healthier drinking habits. Using the app, Ms. Carbone makes a plan for how much she will drink each week. The app tracks her daily intake, sends her notifications about her goals, and updates her on her progress, including all the calories she avoided and the money she saved by drinking less. She now has at least two “dry” days per week and has cut her drinking in half.“Seeing the progress that I’ve made makes me feel good and makes me keep doing it,” she said. “I sleep a lot better. I wake up less at night. I wake up feeling less sluggish, less tired, and I’ve been going to the gym more regularly, whereas before I couldn’t drag myself there.”For people who want to reduce their drinking, here are some simple tips that might help.Try PrecommitmentRather than relying on willpower alone, make a plan every Sunday to limit your drinking to a specific amount each day of the week and stick to it. This is a tactic known as precommitment, which Cutback Coach uses to help its thousands of members. The idea behind it is that you increase your chances of success by committing to a plan and restricting your ability to back out later on. Some other examples of precommitment are deciding not to keep junk food in your house and encouraging yourself to exercise by scheduling a workout with a friend. Studies show that precommitment is an effective way to change behavior.Find Social SupportTalk to your spouse, a friend or a family member about your plan to drink less. They can hold you accountable and help you find healthier ways to manage your stress. Make a plan to go for a walk with your friend or partner at the end of the day, for example, instead of opening a bottle. “You might find that you have a buddy who says, ‘why don’t we go play tennis or do something else to unwind after work,’” said Dr. Kennedy. “There are a lot of benefits to trying healthy activities instead of the wine.”Create ObstaclesSet up rules to slow your drinking. Mary Reid, the executive director of Moderation Management, follows a simple rule that helps her avoid drinking heavily: Each glass of wine she drinks has to last at least one hour. “My strongest tool is timing my drinks,” she said. “We always tell new members that we do have stop buttons, but we just ignore them.” Dr. Kennedy at Driftwood employs a similar rule. She tells people to alternate every alcoholic drink they have with a glass of water.Change Your RoutineSome people drink more out of habit than an actual desire for alcohol. Try substituting sparkling water or another beverage for your usual drink. Mr. Mueller used to have a cocktail every night while watching the evening news. But when he cut back on alcohol, he switched to drinking a cup of tea or nonalcoholic beer while watching the news and realized he just needed a beverage to sip. “Now I still have a glass in my hand but it doesn’t have alcohol,” he said. “It’s almost like having a glass in your hand is the habit and not the alcohol.”

Teenagers are more likely to get hooked on marijuana, stimulants and other recreational drugs than college-aged or older adults.Adolescents and teenagers who experiment with marijuana and prescription drugs are more likely to get hooked on them than young people who try these drugs for the first time when they are college-aged or older, according to a new analysis of federal data.The research suggests that young people may be particularly vulnerable to the intoxicating effects of certain drugs, and that early exposure might prime their brains to desire them. The findings have implications for public health policymakers, who in recent years have called for increased screening and preventive measures to reverse a sharp rise in marijuana vaping among teenagers.The new study, published in JAMA Pediatrics and led by a team of scientists at the National Institute on Drug Abuse, sought to gain a better understanding of how adolescent brains respond to a variety of recreational drugs. Previous research suggested that early exposure to marijuana, nicotine and alcohol might lead to faster development of substance use disorders. But the new analysis cast a wider net, looking at the effects of nine different drugs, including opioid painkillers, stimulants, marijuana, alcohol, cigarettes, cocaine, heroin, methamphetamine and tranquilizers.The researchers used data from the government’s National Survey on Drug Use and Health, a closely watched annual study that tracks substance use and mental health issues among Americans. The new research focused on two age groups: adolescents between the ages of 12 and 17, and young adults aged 18 to 25. Alcohol was by far the most commonly used substance in both groups: A quarter of adolescents and 80 percent of young adults said they had used it. About half of young adults said they had tried cannabis or tobacco. But among adolescents, that number was smaller: Roughly 15 percent said they had experimented with cannabis, and 13 percent said they had tried tobacco.Most troubling to the authors of the new study was how many people went on to develop a substance use disorder, indicating that their experimentation had spiraled into an addiction. The researchers found that within a year of first trying marijuana, 11 percent of adolescents had become addicted to it, compared to 6.4 percent of young adults. Even more striking was that within three years of first trying the drug, 20 percent of adolescents became dependent on it, almost double the number of young adults.Adolescents who tried prescription drugs were also more likely to become addicted. About 14 percent of adolescents who took prescription stimulants for recreational use went on to develop a substance use disorder within one year, compared to just 4 percent of young adults. And while 7 percent of young adults who tried opioid painkillers became addicted soon after taking them, that figure rose to 11.2 percent among younger users.For alcohol and tobacco, however, there was not much of a difference between the two age groups: Both older and younger youth had a similar rate of developing a substance use disorder. And for illicit drugs such as cocaine and heroin, the number of adolescents using them was too small for the researchers to draw any meaningful conclusions.One possible explanation for the findings is that young people who have a greater predisposition to developing an addiction may be more likely to seek out illicit drugs at an earlier age. But Dr. Nora Volkow, a senior author of the new study and the director of NIDA, said it is known that cannabis and other drugs can have a potent effect on adolescent brains because they are still developing. Younger brains exhibit greater plasticity, or ability to change, than the relatively static brains of older individuals. As a result, drugs like cannabis are more likely to alter synaptic connections in younger brains, leading to stronger memories of pleasure and reward.“It’s a learning process when you become addicted,” said Dr. Volkow. “It’s a type of memory that gets hard-wired into your brain. That occurs much faster in an adolescent brain.”Studies show that regularly using marijuana can affect cognition in adolescents, leading to impairments in parts of the brain that are involved in learning, reasoning and paying attention. Yet in recent years the booming popularity of e-cigarettes has led to a sharp increase in the number of adolescents who vape nicotine and marijuana, a trend that has alarmed public health officials. Some studies suggest that adolescents may also be more likely to try marijuana as more and more states legalize its recreational use.Dr. Volkow said that as states implement new marijuana regulations, policymakers should work on measures aimed at protecting adolescents. She stressed that pediatricians and dentists should screen for drug use in their young patients by asking them about it. And she cautioned parents not to dismiss marijuana use in teens and adolescents as something that is harmless.“As it relates to marijuana, the drugs that were available when parents today were teenagers are very different from the drugs that are available now,” she said. “The content of THC is much higher, and the higher the THC content, the greater the risk of adverse effects.”

In “Hooked,” Michael Moss explores how no addictive drug can fire up the reward circuitry in our brains as rapidly as our favorite foods.In a legal proceeding two decades ago, Michael Szymanczyk, the chief executive of the tobacco giant Philip Morris, was asked to define addiction. “My definition of addiction is a repetitive behavior that some people find difficult to quit,” he responded.Mr. Szymanczyk was speaking in the context of smoking. But a fascinating new book by Michael Moss, an investigative journalist and best-selling author, argues that the tobacco executive’s definition of addiction could apply to our relationship with another group of products that Philip Morris sold and manufactured for decades: highly processed foods.In his new book, “Hooked,” Mr. Moss explores the science behind addiction and builds a case that food companies have painstakingly engineered processed foods to hijack the reward circuitry in our brains, causing us to overeat and helping to fuel a global epidemic of obesity and chronic disease. Mr. Moss suggests that processed foods like cheeseburgers, potato chips and ice cream are not only addictive, but that they can be even more addictive than alcohol, tobacco and drugs. The book draws on internal industry documents and interviews with industry insiders to argue that some food companies in the past couple of decades became aware of the addictive nature of their products and took drastic steps to avoid accountability, such as shutting down important research into sugary foods and spearheading laws preventing people from suing food companies for damages.PenguinRandomHouseIn another cynical move, Mr. Moss writes, food companies beginning in the late 1970s started buying a slew of popular diet companies, allowing them to profit off our attempts to lose the weight we gained from eating their products. Heinz, the processed food giant, bought Weight Watchers in 1978 for $72 million. Unilever, which sells Klondike bars and Ben & Jerry’s ice cream, paid $2.3 billion for SlimFast in 2000. Nestle, which makes chocolate bars and Hot Pockets, purchased Jenny Craig in 2006 for $600 million. And in 2010 the private equity firm that owns Cinnabon and Carvel ice cream purchased Atkins Nutritionals, the company that sells low-carb bars, shakes and snacks. Most of these diet brands were later sold to other parent companies.“The food industry blocked us in the courts from filing lawsuits claiming addiction; they started controlling the science in problematic ways, and they took control of the diet industry,” Mr. Moss said in an interview. “I’ve been crawling through the underbelly of the processed food industry for 10 years and I continue to be stunned by the depths of the deviousness of their strategy to not just tap into our basic instincts, but to exploit our attempts to gain control of our habits.”A former reporter for The New York Times and recipient of the Pulitzer Prize, Mr. Moss first delved into the world of the processed food industry in 2013 with the publication of “Salt Sugar Fat.” The book explained how companies formulate junk foods to achieve a “bliss point” that makes them irresistible and market those products using tactics borrowed from the tobacco industry. Yet after writing the book, Mr. Moss was not convinced that processed foods could be addictive.“I had tried to avoid the word addiction when I was writing ‘Salt Sugar Fat,’” he said. “I thought it was totally ludicrous. How anyone could compare Twinkies to crack cocaine was beyond me.”But as he dug into the science that shows how processed foods affect the brain, he was swayed. One crucial element that influences the addictive nature of a substance and whether or not we consume it compulsively is how quickly it excites the brain. The faster it hits our reward circuitry, the stronger its impact. That is why smoking crack cocaine is more powerful than ingesting cocaine through the nose, and smoking cigarettes produces greater feelings of reward than wearing a nicotine patch: Smoking reduces the time it takes for drugs to hit the brain.But no addictive drug can fire up the reward circuitry in our brains as rapidly as our favorite foods, Mr. Moss writes. “The smoke from cigarettes takes 10 seconds to stir the brain, but a touch of sugar on the tongue will do so in a little more than a half second, or six hundred milliseconds, to be precise,” he writes. “That’s nearly 20 times faster than cigarettes.”This puts the term “fast food” in a new light. “Measured in milliseconds, and the power to addict, nothing is faster than processed food in rousing the brain,” he added.Mr. Moss explains that even people in the tobacco industry took note of the powerful lure of processed foods. In the 1980s, Philip Morris acquired Kraft and General Foods, making it the largest manufacturer of processed foods in the country, with products like Kool-Aid, Cocoa Pebbles, Capri Sun and Oreo cookies. But the company’s former general counsel and vice president, Steven C. Parrish, confided that he found it troubling that it was easier for him to quit the company’s cigarettes than its chocolate cookies. “I’m dangerous around a bag of chips or Doritos or Oreos,” he told Mr. Moss. “I’d avoid even opening a bag of Oreos because instead of eating one or two, I would eat half the bag.”As litigation against tobacco companies gained ground in the 1990s, one of the industry’s defenses was that cigarettes were no more addictive than Twinkies. It may have been on to something. Philip Morris routinely surveyed the public to gather legal and marketing intelligence, Mr. Moss writes, and one particular survey in 1988 asked people to name things that they thought were addictive and then rate them on a scale of 1 to 10, with 10 being the most addictive.“Smoking was given an 8.5, nearly on par with heroin,” Mr. Moss writes. “But overeating, at 7.3, was not far behind, scoring higher than beer, tranquilizers and sleeping pills. This statistic was used to buttress the company’s argument that cigarettes might not be exactly innocent, but they were a vice on the order of potato chips and, as such, were manageable.”But processed foods are not tobacco, and many people, including some experts, dismiss the notion that they are addictive. Mr. Moss suggests that this reluctance is in part a result of misconceptions about what addiction entails. For one, a substance does not have to hook everyone for it to be addictive. Studies show that most people who drink or use cocaine do not become dependent. Nor does everyone who smokes or uses painkillers become addicted. It is also the case that the symptoms of addiction can vary from one person to the next and from one drug to another. Painful withdrawals were once considered hallmarks of addiction. But some drugs that we know to be addictive, such as cocaine, would fail to meet that definition because they do not provoke “the body-wrenching havoc” that withdrawal from barbiturates and other addictive drugs can cause.The American Psychiatric Association now lists 11 criteria that are used to diagnose what it calls a substance use disorder, which can range from mild to severe, depending on how many symptoms a person exhibits. Among those symptoms are cravings, an inability to cut back despite wanting to, and continuing to use the substance despite it causing harm. Mr. Moss said that people who struggle with processed food can try simple strategies to conquer routine cravings, like going for a walk, calling a friend or snacking on healthy alternatives like a handful of nuts. But for some people, more extreme measures may be necessary.“It depends where you are on the spectrum,” he said. “I know people who can’t touch a grain of sugar without losing control. They would drive to the supermarket and by the time they got home their car would be littered with empty wrappers. For them, complete abstention is the solution.”

People whose gut bacteria transformed over the decades tended to be healthier and live longer.The secret to successful aging may lie in part in your gut, according to a new report. The study found that it may be possible to predict your likelihood of living a long and healthy life by analyzing the trillions of bacteria, viruses and fungi that inhabit your intestinal tract.The new research, published in the journal Nature Metabolism, found that as people get older, the composition of this complex community of microbes, collectively known as the gut microbiome, tends to change. And the greater the change, the better, it appears.In healthy people, the kinds of microbes that dominate the gut in early adulthood make up a smaller and smaller proportion of the microbiome over the ensuing decades, while the percentage of other, less prevalent species rises. But in people who are less healthy, the study found, the opposite occurs: The composition of their microbiomes remains relatively static and they tend to die earlier.The new findings suggest that a gut microbiome that continually transforms as you get older is a sign of healthy aging, said a co-author of the study, Sean Gibbons, a microbiome specialist and assistant professor at the Institute for Systems Biology in Seattle, a nonprofit biomedical research organization.“A lot of aging research is obsessed with returning people to a younger state or turning back the clock,” he said. “But here the conclusion is very different. Maybe a microbiome that’s healthy for a 20-year-old is not at all healthy for an 80-year-old. It seems that it’s good to have a changing microbiome when you’re old. It means that the bugs that are in your system are adjusting appropriately to an aging body.”The researchers could not be certain whether changes in the gut microbiome helped to drive healthy aging or vice versa. But they did see signs that what happens in people’s guts may directly improve their health. They found, for example, that people whose microbiomes shifted toward a unique profile as they aged also had higher levels of health-promoting compounds in their blood, including compounds produced by gut microbes that fight chronic disease.Scientists have suspected for some time that the microbiome plays a role in aging. Studies have found, for example, that people 65 and older who are relatively lean and physically active have a higher abundance of certain microbes in their guts compared to seniors who are less fit and healthy. People who develop early signs of frailty also have less microbial diversity in their guts. By studying the microbiomes of people of all ages, scientists have found patterns that extend across the entire life span. The microbiome undergoes rapid changes as it develops in the first three years of life. Then it remains relatively stable for decades, before gradually undergoing changes in its makeup as people reach midlife, which accelerates into old age in those who are healthy but slows or remains static in people who are less healthy.Although no two microbiomes are identical, people on average share about 30 percent of their gut bacterial species. A few species that are particularly common and abundant make up a “core” set of gut microbes in all of us, along with smaller amounts of a wide variety of other species that are found in different combinations in every person.To get a better understanding of what happens in the gut as people age, Dr. Gibbons and his colleagues, including Dr. Tomasz Wilmanski, the lead author of the new study, looked at data on over 9,000 adults who had their microbiomes sequenced. They ranged in age from 18 to 101.About 900 of these people were seniors who underwent regular checkups at medical clinics to assess their health. Dr. Gibbons and his colleagues found that in midlife, starting at around age 40, people started to show distinct changes in their microbiomes. The strains that were most dominant in their guts tended to decline, while other, less common strains became more prevalent, causing their microbiomes to diverge and look more and more different from others in the population.“What we found is that over the different decades of life, individuals drift apart — their microbiomes become more and more unique from one another,” said Dr. Gibbons.People who had the most changes in their microbial compositions tended to have better health and longer life spans. They had higher vitamin D levels and lower levels of LDL cholesterol and triglycerides, a type of fat in the blood. They needed fewer medications, and they had better physical health, with faster walking speeds and greater mobility.The researchers found that these “unique” individuals also had higher levels of several metabolites in their blood that are produced by gut microbes, including indoles, which have been shown to reduce inflammation and maintain the integrity of the barrier that lines and protects the gut. In some studies, scientists have found that giving indoles to mice and other animals helps them stay youthful, allowing them to be more physically active, mobile and resistant to sickness, injuries and other stresses in old age. Another one of the metabolites identified in the new study was phenylacetylglutamine. It is not clear exactly what this compound does. But some experts believe it promotes longevity because research has shown that centenarians in northern Italy tend to have very high levels of it.Dr. Wilmanski found that people whose gut microbiomes did not undergo much change as they got older were in poorer health. They had higher cholesterol and triglycerides and lower levels of vitamin D. They were less active and could not walk as fast. They used more medications, and they were nearly twice as likely to die during the study period.The researchers speculated that some gut bugs that might be innocuous or perhaps even beneficial in early adulthood could turn harmful in old age. The study found, for example, that in healthy people who saw the most dramatic shifts in their microbiome compositions there was a steep decline in the prevalence of bacteria called Bacteroides, which are more common in developed countries where people eat a lot of processed foods full of fat, sugar and salt, and less prevalent in developing countries where people tend to eat a higher-fiber diet. When fiber is not available, Dr. Gibbons said, Bacteroides like to “munch on mucus,” including the protective mucus layer that lines the gut.“Maybe that’s good when you’re 20 or 30 and producing a lot of mucus in your gut,” he said. “But as we get older, our mucus layer thins, and maybe we may need to suppress these bugs.”If those microbes chew through the barrier that keeps them safely in the gut, it is possible they could trigger an immune system response.“When that happens, the immune system goes nuts,” Dr. Gibbons said. “Having that mucus layer is like having a barrier that maintains a détente that allows us to live happily with our gut microbes, and if that goes away it starts a war” and could set off chronic inflammation. Increasingly, chronic inflammation is thought to underlie a wide range of age-related ailments, from heart disease and diabetes to cancer and arthritis.One way to prevent these microbes from destroying the lining of the gut is to give them something else to snack on, such as fiber from nutritious whole foods like beans, nuts and seeds and fruits and vegetables.Other studies have shown that diet can have a substantial impact on the composition of the microbiome. While the new research did not look closely at the impact of different foods on changes in the microbiome as we age, Dr. Gibbons said he hopes to examine that in a future study.“It may be possible to preserve the aging mucus layer in the gut by increasing the amount of fiber in the diet,” Dr. Gibbons said. “Or we might identify other ways to reduce Bacteroides abundance or increase indole production through diet. These are not-too-distant future interventions that we hope to test.”In the meantime, he said, his advice for people is to try to stay physically active, which can have a beneficial effect on the gut microbiome, and eat more fiber and fish and fewer highly processed foods.“I have started eating a lot more fiber since I began studying the microbiome,” he said. “Whole foods like fresh fruits and veggies have all the complex carbohydrates that our microbes like to eat. So, when you’re feeding yourself, think about your microbes too.”