For years, experts have recommended low-fat dairy products over the full-fat versions, which are higher in calories and contain more saturated fat. Recent research, however, indicates that full-fat dairy may actually be healthier than its reputation suggests, and that people who eat full-fat dairy are not more likely to develop cardiovascular disease and type 2 diabetes than people who consume low-fat dairy. They may even be less likely to gain weight.
Now, new research published Tuesday in
, adds to that body of evidence.
The research suggests that eating dairy products of all kinds is associated with a lower risk of premature death, cardiovascular disease and stroke. “About three servings of dairy a day is associated with a lower risk of mortality and cardiovascular disease,” says study co-author Mahshid Dehghan, a nutrition epidemiology researcher at the Population Health Research Institute in Canada. “We are suggesting that dairy is healthy, and people should be encouraged to consume dairy.”
The Dietary Guidelines for Americans also recommend consuming about three servings of dairy per day, but specify that these foods should be fat-free or low-fat. The new research, however, suggests that full-fat dairy can also be part of a healthy diet. While there was stronger data for milk and yogurt consumption than butter and cheese, dairy eaters in the study consumed more full-fat than low-fat products, suggesting that these results apply particularly strongly to whole-fat dairy foods.
The observational study was based on data from about 136,000 adults who took part in the Prospective Urban Rural Epidemiology (PURE) study, which collected diet and health information from people in 21 countries on five continents. (The United States was not among them, but Canada was.) None of the people included in the study had a history of cardiovascular disease, and all of them completed a detailed dietary survey, which included questions about type and frequency of dairy intake. Over about nine years of follow-up, roughly 10,500 people either died or had a major cardiovascular issue, such as a heart attack or stroke.
Dairy consumption, the researchers found, was associated with a lower risk of both outcomes. Compared to people who didn’t eat dairy, those who consumed more than two servings per day had lower total mortality rates (3.4% versus 5.6%) and cardiovascular mortality rates (0.9% versus 1.6%). They also had lower rates of major cardiovascular disease (3.5% versus 4.9%) and stroke (1.2% versus 2.9%).
And among people who ate only full-fat dairy, those who consumed about three servings per day had lower mortality rates than people who ate less than 0.5 servings per day (3.3% versus 4.4%).
That finding suggests that vilifying whole-fat dairy solely because of its higher saturated fat content — even though plenty of research does link saturated fat to heart disease — may not capture the whole picture, Dehghan says.
“Focusing on low-fat is predominantly based on the assumption that saturated fat increases LDL cholesterol,” she says. “But dairy contains many other components [which may be healthy] — amino acids, vitamin K, calcium, magnesium. They can be fermented and have probiotics. We should not focus on a single nutrient.” And the rest of the diet matters, too; eating dairy is likely better than loading up refined carbohydrates, according to recent research.
The new research has several limitations. The study participants only completed one diet survey at the beginning of the research period, so the results did not capture changes in eating patterns over time. The follow-up period of nine years was also relatively short, in terms of measuring long-term health outcomes like cardiovascular disease. And observational studies can never prove cause and effect, only point out patterns and associations.
Plus, while patterns were consistent across regions, many of the countries in the PURE study are low- or middle-income. Residents of these nations tend to eat less dairy than people in wealthy countries, which may mean they stand to benefit more from increasing consumption than people in the U.S. and other developed areas. There also was not much data for people eating more than three servings of dairy per day, which means it wasn’t possible to say how very heavy consumption affects health.
Pharmaceutical companies including Boehringer Ingelheim and GlaxoSmithKline also helped fund the research, though they were not involved in the study’s design or production. GlaxoSmithKline makes Horlicks, a milk-based nutritional beverage, while Boehringer Ingelheim’s animal health division makes medications for dairy cows.
An accompanying editorial written by Jimmy Chun Yu Louie, from the University of Hong Kong, and Anna Rangan, from the University of Sydney — both of whom have ties to Dairy Australia — says the study should not be treated as “the ultimate seal of approval for recommending whole-fat dairy over its low-fat or skimmed counterparts. Readers should be cautious and should treat this study only as yet another piece of evidence (albeit a large one) in the literature.”
Dehghan takes a similarly measured approach to the results, adding that the study is important in part because it broadens nutrition research beyond its traditionally North American and European epicenters.
No one ever had fun visiting the cardiologist. Regardless of how good the doc might be, it’s always a little scary thinking about the health of something as fundamental as the heart. But there are ways to take greater control—to ensure that your own heart health is the best it can be—even if you have a family history of cardiovascular disease.
Although 50% of cardiovascular-disease risk is genetic, the other 50% can be modified by how you live your life, according to Dr. Eugenia Gianos, director of Women’s Heart Health at Lenox Hill Hospital in New York City. “This means you can greatly reduce a high genetic risk or greatly worsen a low genetic risk,” she says. “Your fate really lies largely in your hands.”
Having that kind of control over your heart health is particularly welcome news right now, with cardiovascular disease remaining the number-one killer of both men and women. A recent CDC report revealed that “largely preventable” heart problems killed around 415,000 Americans in 2016. Under its Million Hearts campaign—which aims to prevent 1 million heart attacks and strokes by 2022—the CDC identified approximately 2.2 million hospitalizations and 415,000 deaths from heart attacks, strokes, heart failure and related conditions in 2016 that likely could have been avoided.
“Many of these cardiovascular events are happening to middle-aged adults—who we wouldn’t normally consider to be at risk,” CDC principal deputy director Dr. Anne Schuchat said in a statement. “Most of these events can be prevented through daily actions to help lower risk and better manage medical conditions.”
Beyond remembering to go easy on the cheeseburgers, what else can you do to protect your heart? We all know the broad strokes—eat well, work out and find ways to relax—but science is learning more about the specifics that make a real difference. Consider this your daily planner for heart health.
1. Add more plants to your menu
The more vegetables you eat, the better your cardiac future looks. Research shows that people who eat plant-based diets are less likely to develop heart disease. And the more plants, the greater the benefits, Gianos notes.
Fruits and vegetables work their magic in several ways. First, they provide heart-healthy nutrients, including fiber, antioxidants, potassium, B vitamins, and vitamins A and C, explains Cynthia Sass, a registered dietitian in private practice in Los Angeles and New York. And nonstarchy vegetables—from spinach to broccoli to peppers—are low in calories and carbohydrates too, helping keep weight under control. Not to mention, veggies supply prebiotics, nondigestible carbs that serve as food for beneficial probiotic bacteria.
“This is key because we’re learning more about the role of a healthy gut microbiome in disease prevention,” Sass says. Veggies also help reduce chronic, low-level inflammation, which has been linked to heart disease.
Rather than dwelling on cutting back on red meat, think of what you’re adding to your plate. “Focus on what to eat as much as what to avoid,” Sass notes, “and be open to experimenting.” Aim big: five cups of fruits and vegetables a day. It sounds like a daunting number, but by working in a cup at breakfast (with eggs, in a smoothie or mixed into overnight oats), two at lunch and two at dinner, you can get your fill.
When doing meal prep, flip your thinking. “Build meals around veggies, so they’re never an afterthought,” Sass advises. Instead of having the typical pasta primavera that is a mound of spaghetti with a few shavings of carrots and a couple of broccoli florets on top, reverse it so that you fill your plate with steamed or sautéed veggies over a modest portion of pasta—or better yet, farro or quinoa. “It may feel less satisfying at first,” Sass concedes, “but the rewards, like more energy, sustainable weight loss and better digestive health, can drastically improve your everyday quality of life.”
2. Watch animal fat
Heard the buzz about how butter is good for you? Don’t believe it, warns Gianos: “Animal fats and even animal proteins are definitely linked to elevated cholesterol and elevated heart risk. It’s so important that this message is clear so we can reverse the increase in heart disease–related death.”
Monounsaturated fats, on the other hand—the ones in olive oil, avocado and many nuts—along with polyunsaturated fats from fish like wild salmon and sardines, are great for heart health. Part of the confusion about the risks and benefits of fats stems from the fact that saturated fats, like those from animals, may in fact be neutral for some people, Sass explains. But that doesn’t mean they’re safe for everyone.
Nobody pretends that we’re going to live in a meatless world anytime soon, but moderation can make a big difference. If you do eat meat, keep your portions small, go easy on sugar, processed carbs and butter, and help yourself to plenty of vegetables and fruits. Also keep in mind that the quality of the animal fat matters, Sass says. “Grass-fed and organic dairy and meats provide some beneficial fats that are not in conventionally produced animal foods.”
3. Slash added sugar
In a study in JAMA Internal Medicine, researchers reported that people who ate the most sugar had a higher risk of death from heart disease, even if they weren’t overweight. Another study found that spending just three months on a sugar-heavy diet changed fat metabolism in healthy men, causing them to develop non-alcoholic fatty-liver disease, which boosts the risk of cardiovascular disease.
While the American Heart Association (AHA) recommends that women have no more than six teaspoons worth of added sugar daily and men stick to nine, the average intake for all Americans is now the equivalent of 22 teaspoons per day, Sass says. (Four grams of sugar is one teaspoon’s worth.)
What is added sugar, anyway? It refers to sugar that is not found naturally in food. Honey in your tea is added sugar. The sugar in a banana is not. Some foods like yogurts and fruit bars may have both natural and added sugars, and it’s usually unclear from labels what the ratios of each are. But the FDA’s new food labels—which must be adopted by Jan. 1, 2020—will require companies to spell out the amount of “added sugar,” making it much easier to track your sugar load.
4. Don’t smoke. And if you do, stop
Do you smoke even a little? If so, know this: “Smoking even a single cigarette can induce changes that lead to a heart attack,” Gianos says. Lighting up increases your risk of atherosclerosis, raises your chances of blood clots, reduces blood flow and puts you at increased risk for stroke. But it’s never too late to quit and start reversing the damage. “Heart disease risk goes down 50% in the first year [after quitting] and becomes equivalent to a nonsmoker after 10 years,” Gianos says.
5. Drink in moderation
Heavy drinking does the body no favors. It can lead to weakened heart muscle and irregular heart rhythms, as well as dementia, cancer and stroke. But could drinking just a little be heart healthy? The science is unsettled. While some research suggests that moderate drinking (up to a drink a day for women and up to two for men) is linked with lower rates of cardiovascular disease, the research does not prove cause and effect, Gianos cautions. For example, it could be that people who drink regularly take time to relax with loved ones, and that may be what is providing the heart benefit.
6. Exercise often
There’s no doubt that exercise is essential for a strong heart. One 2018 study published in the journal
found that physical activity can even counteract a genetic risk for heart disease. The researchers looked at 500,000 men and women in the U.K. and found that those at the highest risk of heart troubles who had high levels of physical fitness had a 49% lower risk of coronary heart disease. While the AHA recommends 150 minutes of moderate activity a week, Gianos urges 30 to 60 minutes every day. Overall the goal is to move daily, but don’t feel you have to run 20 miles a day. “Extreme exercise has not been noted to be protective,” Gianos says, “and it may add some harm.”
7. … And stand up for your health
Prolonged sitting is terrible for our bodies. It has been linked to heart disease, diabetes and early death. If you have a desk job, make sure to get up and move frequently even if you have to set your alarm on your smartphone to sound every hour to remind you. “Ten-minute spurts of exercise throughout the day can counteract that risk,” says Gianos.
8. Watch weight gain
Obesity is a risk factor for high blood pressure, heart attack and stroke. Being overweight but not obese still puts you at risk for insulin resistance, which is linked to heart disease. The more fat a person carries around the abdomen in particular, the higher the risk.
Gianos recommends following the Mediterranean diet and the DASH (Dietary Approaches to Stop Hypertension) diet. Both are rich in plants, with an emphasis on leafy greens, whole foods and plant fats like olive oil. Your eating schedule matters too. “Sticking to three balanced meals and one snack works well for optimizing energy, blood sugar and insulin regulation, digestive health and weight,” Sass says. “Time your carbs for early in the day, before your most active hours.”
9. Tame stress
Believe it or not, “stress can increase your risk of heart disease 2.5-fold—similar to smoking and diabetes,” says Gianos. That’s because chronic stress puts the body into constant fight-or-flight mode, triggering inflammation, high blood pressure and other unhealthy changes. But mindfulness can be a powerful antidote to that modern state of overload. By focusing on our thoughts and sensations, we can learn to control our body’s response to stress.
Practices like meditation, deep breathing and yoga have been shown to dial down the stress response. In 2017, the AHA endorsed seated meditation as a “reasonable intervention” along with other strategies for maintaining cardiac health. Research also shows that yoga improves circulation and blood pressure and may lower heart disease risk as much as brisk walking.
10. Nurture close relationships
Could good interpersonal ties bolster the cardiovascular system? One study found that people who were socially isolated and lonely were more likely to have a heart attack or stroke than people with strong social networks. Being in a supportive marriage also cuts your risk heart disease, according to a 2018 study. Your relationships may actually matter more to your lifelong health than your cholesterol readings, suggest findings from the 80-year-old, ongoing Harvard Study of Adult Development. The researchers have discovered that the people who were most satisfied with their relationships at 50 were the healthiest at 80. Love, it seems, really is good for the heart.
Your body doesn’t like things to be too easy. Challenging it from time to time—with exercise, with the elements, and even with short periods of going without food—is often associated with better health outcomes.
The same is true of your gut and the foods it digests. Foods that break down and slip through too quickly (namely, refined starches and sugars) tend to promote overeating, out-of-control blood sugar surges, and other disease-linked side effects. Meanwhile, foods that put up a bit of a fight against digestion are often the best ones for you. That’s certainly true in the case of fiber, which is the edible part of a plant that resists breakdown and absorption in your small intestine.
“The evidence from prospective studies is remarkably consistent that a higher intake of fiber is related to lower risk of type 2 diabetes, cardiovascular disease and weight gain,” says Dr. Walter Willett, a professor of nutrition and epidemiology at Harvard School of Public Health.
Almost every year, a new long-term review paper reaffirms the links between dietary fiber and lower rates of disease and death. Earlier this year, a review published in the American Journal of Clinical Nutrition found that the consumption of dietary fiber was “convincingly” associated with lower risks for pancreatic cancer, heart disease-related death, and death from any cause.
But not all fiber is equal.
“Our FDA now allows purified and synthetic fibers to be included on the fiber line on [a food label’s] Nutrition Facts,” Willett says. For example, polydextrose is a synthetic fiber added to many packaged foods in order to boost the food’s fiber content and cut down its levels of sugar, fat and calories. Synthetic fibers also tend to pop up in nutrition bars or drinks, some breakfast cereals, and other ready-to-eat products. While the FDA has collected some evidence that suggests replacing unhealthy sugars and refined starches with poly dextrose may lead to lower blood-sugar spikes and reduced appetite, Willett says synthetic fibers do not contain the minerals, vitamins and phyto chemicalsfound in natural sources of fiber—and so aren’t nearly as good for you.
Fiber can be broken down into two subtypes: soluble and insoluble. Soluble fiber dissolves in water, and the healthiest varieties of it tend to become viscous or “gel-like” during digestion, says Nicola McKeown, a fiber researcher and associate professor at Tufts University’s School of Nutrition Science and Policy. McKeown says soluble, viscous fiber is associated with lower blood cholesterol and better control of blood sugar levels.
Insoluble fibers, on the other hand, do not dissolve in water and so tend to pass through the digestive system largely intact. This is a good thing. “Insoluble fiber acts like little scrubbies on the inside of your colon to remove old and damaged cells, thus reducing risk for colon cancer,” says Dr. Robert Lustig, a metabolism researcher and professor emeritus of pediatrics at the University of California, San Francisco. Lustig says insoluble fiber also slows digestion and helps support the health of the microbiome.
These are just a handful of the many ways fiber is good for you. Unfortunately, most people aren’t getting nearly enough of the stuff. While the average American eats about 15 grams of fiber each day, the Institute of Medicine recommends that adult men eat 38 grams of fiber each day while women should aim for 25 grams. “I would say 25 is the bare minimum, actually,” says Wendy Dahl, an associate professor of food science and human nutrition at the University of Florida. As long as it comes from whole foods or whole grains, “there is no upper limit on fiber—you can’t get too much.”
The best foods to eat to up your fiber intake are those that naturally include both soluble and insoluble fiber. “That’s everything that comes out of the ground and is not processed,” Lustig says. Think whole fruits, vegetables, seed sand legumes (beans and peanuts). Beans in particular are a cheap, eco-friendly and plentiful source of dietary fiber, Dahl says: “We should all eat more beans.”
Whole grains, too, are a particularly good source of fiber. If the inclusion of whole grains surprises you, you’re not alone. Many popular low-carbohydrate diets call for the elimination of whole grains and other fiber-rich foods. Willett says this is a concern. “We have no long-term studies of these diets,” he says. Meanwhile, “the evidence of benefits for dietary fiber, especially from grains, is strong. If we really consume our grains as whole grains, we can have a relatively low carbohydrate intake and still get plenty of fiber.”
The healthiest whole-grain foods are the ones that can be eaten more or less intact, such as brown rice, wheat berries or steel-cut oats. Other experts add barley, rye and popcorn to his list.
But while whole grains are great, “fiber from a variety of sources is desirable to minimize the chance of missing something important,” Willett says. For example, a breakfast of unsweetened oatmeal and berries is one healthy, fiber-rich way to start your day. (A cup of oatmeal and half a cup of berries include roughly 15 grams of fiber.) But eating other fruits and whole grains—as well as legumes, seeds, nuts and other fiber-packed plant foods—is optimal.
“A variety of plant-based foods ensures the fiber you get in your diet is not exclusively soluble or insoluble, so you can reap the benefits of both,” McKeown adds.
For most Americans with weight issues, the problem is carrying around too much, not too little. While obesity rates have surged in North America since the 1970s, the proportion of underweight people has remained low—less than 5% of the population, according to a study in
These bodyweight trends mean that most health experts are focused on helping people lose weight to avoid disease. But there are also some potentially serious health consequences associated with being clinically underweight, which is usually defined as having a body mass index (BMI) of 18.5 or below.
“There are many epidemiologic studies that indicate that underweight in adults and older people is associated with higher risk of death or mortality,” says Kay-Tee Khaw, a professor of clinical gerontology at the University of Cambridge in the UK. There are a range of possible explanations why. For some, a low BMI coupled with unexplained weight loss may be an indication of an underlying medical condition such as cancer.
Also, bone and muscle (not just fat) contribute to body weight and BMI. Being underweight may be an indicator of loss of bone and muscle mass—and therefore frailty—particularly in older adults, Khaw says. Frailty can increase a person’s risks for weakness, falls, broken bones and other health problems.
It’s important to point out that being skinny is not the same as being clinically underweight. A 5’10” man who weighs 140 pounds has a BMI of 20—still within the range of normal and healthy. The same is true of a woman who is 5-foot-3 and weighs 113 pounds.
But let’s say you’re intent on gaining weight—either because you just feel too slim, your BMI is below 18.5 or you’re an older adult who’s worried about becoming frail. How should you go about it?
Start by adding more healthy, nutrient-dense foods to your diet, says Eric Ravussin, a professor and chair in diabetes and metabolism at Louisiana State University’s Pennington Biomedical Research Center. High-fat foods like olive oil, avocados, nuts and nut butters, seeds, and fatty fish are all great options. Replacing low-fat dairy products with full-fat dairy, like whole milk, cheese and Greek yogurt, is another way to squeeze more healthy fat into your diet, he says.
If you’ve read about the recent studies tying consumption of these healthy and fatty foods to lower body weights, you may be confused by Ravussin’s advice. How could the same foods help people both gain and lose weight? In the context of a typical Western diet, swapping these fatty foods in for low-fat, heavily processed and sugary foods may help people feel more full and consume fewer total calories throughout the day, which can aid weight loss, says Alicia Romano, a clinical registered dietitian at the Frances Stern Nutrition Center at Tufts Medical Center. But these foods are still calorie-dense, so if you eat enough of them, they can help you add healthy weight. “Fatty foods have the most calories per gram—an average of nine, compared to about half that for protein or carbohydrates,” Romano explains.
To fit more of these foods into your diet, Ravussin recommends eating three large meals and adding a few 300-calorie snacks in the morning and afternoon. “With obesity, we recommend that people don’t snack,” he says, “but if you’re trying to gain weight, more frequent eating is a winning situation.” Your meals shouldn’t be composed solely of fats; you’ll want to eat a healthy range of foods, including plenty of vegetables, whole grains, legumes and protein, to avoid any nutritional deficiencies.
“Take a bag of almonds or walnuts and measure out a cup,” Romano advises. “One cup is about 800 calories.” You can eat some of these nuts as a snack and sprinkle more of them onto salads at mealtimes to inflate your calorie intake. Drizzling olive oil onto everything is another way to pump up your calorie total in a healthy way, she says.
Eggs should be limited to fewer than about four a week, the report says. Dairy foods should be about a serving a day, or less.
The report from a panel of nutrition, agriculture and environmental experts recommends a plant-based diet, based on previously published studies that have linked red meat to increased risk of health problems. It also comes amid recent studies of how eating habits affect the environment. Producing red meat takes up land and feed to raise cattle, which also emit the greenhouse gas methane.
John Ioannidis, chair of disease prevention at Stanford University, said he welcomed the growing attention to how diets affect the environment, but that the report’s recommendations do not reflect the level of scientific uncertainties around nutrition and health.
“The evidence is not as strong as it seems to be,” Ioannidis said.
The report was organized by EAT, a Stockholm-based nonprofit seeking to improve the food system, and published Wednesday by the medical journal Lancet. The panel of experts who wrote it says a “Great Food Transformation” is urgently needed by 2050, and that the optimal diet they outline is flexible enough to accommodate food cultures around the world.
Overall, the diet encourages whole grains, beans, fruits and most vegetables, and says to limit added sugars, refined grains such as white rice and starches like potatoes and cassava. It says red meat consumption on average needs to be slashed by half globally, though the necessary changes vary by region and reductions would need to be more dramatic in richer countries like the United States.
Convincing people to limit meat, cheese and eggs won’t be easy, however, particularly in places where those foods are a notable part of culture.
In Sao Paulo, Brazil, systems analyst Cleberson Bernardes said as he was leaving a barbecue restaurant that limiting himself to just one serving of red meat a week would be “ridiculous.” In Berlin, Germany, craftsman Erik Langguth said there are better ways to reduce greenhouse gas emissions, and dismissed the suggestion that the world needs to cut back on meat.
“If it hasn’t got meat, it’s not a proper meal,” said Langguth, who is from a region known for its bratwurst sausages.
Before even factoring in the environmental implications, the report sought to sketch out what the healthiest diet for people would look like, said Walter Willett, one of its authors and a nutrition researcher at Harvard University. While eggs are no longer thought to increase risk of heart disease, Willett said the report recommends limiting them because studies indicate a breakfast of whole grains, nuts and fruit would be healthier.
He said everybody doesn’t need to become a vegan, and that many are already limiting how much meat they eat.
“Think of it like lobster — something that I really like, but have a few times a year,” Willett said.
Advice to limit red meat is not new, and is tied to its saturated fat content, which is also found in cheese, milk, nuts and packaged foods with coconut and palm kernel oils. The report notes most evidence on diet and health is from Europe and the United States. In Asian countries, a large analysis found eating poultry and red meat (mostly pork) was associated with improved lifespans. That might be in part because people might eat smaller amounts of meat in those countries, the report says.
Ioannidis of Stanford noted nutrition research is often based on observational links between diet and health, and that some past associations have not been validated. Dietary cholesterol, for example, is no longer believed to be strongly linked to blood cholesterol.
The meat and dairy industries also dispute the report’s recommendations, saying their products deliver important nutrients and can be part of healthy diets.
Andrew Mente, a nutrition epidemiology researcher at McMaster University, urged caution before making widespread dietary recommendations, which he said could have unintended consequences.
Still, the EAT-Lancet report’s authors say the overall body of evidence strongly supports reducing red meat for optimal health and shifting toward plant-based diets. They note the recommendations are compatible with the U.S. dietary guidelines, which say to limit saturated fat to 10 percent of calories.
While people in some poorer counties may benefit from getting more of the nutrients in meat and dairy products, the report says they shouldn’t follow the path of richer countries in how much of those foods they eat in coming years.
Though estimates vary, a report by the United Nations said livestock is responsible for about 15 percent of the world’s gas emissions that warm the climate.
Robbie Andrew, a senior researcher at CICERO Center for International Climate Research in Norway, said farming practices that make animals grow faster and bigger may help limit emissions. But he said cows and other ruminant animals nevertheless produce a lot of methane, a powerful greenhouse gas.
“It’s very difficult to get down these natural emissions that are part of their biology,” Andrew said.
The environmental benefits of giving up red meat depend on what people eat in its place. Chicken and pork produce far fewer emissions than beef, Andrew said, adding that plants in general have among the smallest carbon footprints.
Brent Loken, an author of the EAT-Lancet report, said the report lays out the parameters of an optimal diet, but acknowledged the challenge in figuring out how to work with policy makers, food companies and others in tailoring and implementing it in different regions.
Growing data suggests that exposing young children to too much time in front of a TV or computer can have negative effects on their development, including issues with memory, attention and language skills.
In the latest look at the topic, researchers report in JAMA Pediatrics that more screen time is linked to poorer progress on key developmental measures such as communication skills, problem solving and social interactions among young kids over time.
Sheri Madigan, an assistant professor of psychology at University of Calgary in Canada, and her colleagues studied 2,441 mothers and children enrolled in the All Our Families study, which followed young children from ages two to five. Mothers reported on how much time their children spent in front of a television or computer screen on a typical day, and also reported on developmental measures by answering questions about their children’s communication skills, behavior and social interactions. The data were collected at the start of the study, when the children were two years old, then again when they were three and five.
Many studies have looked at the connection between screen time and developmental issues at one point in time, but by following the children over many years, Madigan and her team could learn more about how screen time and development interact. For example, while some studies suggested that increased screen time might contribute to slower development, it was also possible that parents with children with behavioral issues and developmental delays might be more likely to use movies, TV or video games to calm or quiet their child.
Madigan found that on average, the children in the study were spending about 2-3 hours a day in front of a screen. (The American Academy of Pediatrics currently recommends that toddlers and young children spend no more than one hour a day watching quality educational programming.)
The researchers found that over time, children who spent more time using TV or computers did indeed show poorer performance on the developmental measures. But they did not find evidence that the opposite was occurring; it did not seem that children with developmental issues were more likely to spend time in front of a screen. The links remained strong even after they accounted for other factors that can influence developmental milestones, including parents’ education, how physically active the children were and whether parents read to their children regularly. “The results show that there is a lasting influence of screen time, especially when children are two to five years old, when their brains are undergoing a period of tremendous development,” Madigan says.
That strongly supports expert guidelines that recommend limiting screen time for young children, when the brain is rapidly developing new connections and learning from every cue it receives. “What too much screen time leads to is a variety of missed opportunities for learning and development,” says Madigan. “When a child is watching a screen, he or she is missing out on the opportunity for walking, talking and interacting with others.”
Not all screen time is detrimental, she says, and her study did not delve into the quality of programming the children were watching. The way in which children are using TV or computers is also important. Watching with parents or caregivers, for example, can make the experience more engaging and less passive, and can even provide opportunities for learning and social development. “Families can develop healthy media habits,” she says. “When parents watch with their children, they can point out interesting things and contribute to language skills and learning.”
“We have been researching aging and metabolism for many years and decided to search for unknown health effects in human fasting,” said Dr. Takayuki Teruya, first author of the paper and a technician in the OIST G0 Cell Unit, led by Prof. Mitsuhiro Yanagida. “Contrary to the original expectation, it turned out that fasting induced metabolic activation rather actively.”
In previous research, the G0 Cell Unit identified various metabolites whose quantities decline with age, including three known as leucine, isoleucine, and ophthalmic acid. In fasting individuals, these metabolites increase in level, suggesting a mechanism by which fasting could help increase longevity.
“These are very important metabolites for maintenance of muscle and antioxidant activity, respectively,” said Teruya. “This result suggests the possibility of a rejuvenating effect by fasting, which was not known until now.”
Metabolites Give Clues to Mechanism and Health Effects
The human body tends to utilize carbohydrates for quick energy — when they’re available. When starved of carbs, the body begins looting its alternate energy stores. The act of “energy substitution” leaves a trail of evidence, namely metabolites known as butyrates, carnitines, and branched-chain amino acids. These well-known markers of energy substitution have been shown to accumulate during fasting.
But fasting appears to elicit effects far beyond energy substitution. In their comprehensive analysis of human blood, the researchers noted both established fasting markers and many more. For example, they found a global increase in substances produced by the citric acid cycle, a process by which organisms release energy stored in the chemical bonds of carbohydrates, proteins and lipids. The marked increase suggests that, during fasting, the tiny powerhouses running every cell are thrown into overdrive.
Fasting also appeared to enhance the metabolism of purine and pyrimidine, chemical substances which play key roles in gene expression and protein synthesis. The finding suggests fasting may reprogram which proteins cells build at what time, thus altering their function. The change may promote homeostasis in cells, or serve to edit their gene expression in response to environmental influences.
When metabolized, purine and pyrimidine also boost the body’s production of antioxidants. Several antioxidants, such as ergothioneine and carnosine, were found to increase significantly over the 58-hour study period. Antioxidants serve to protect cells from free radicals produced during metabolism. Products of a metabolic pathway called the “pentose phosphate pathway” also stay the harmful effects of oxidation, and were similarly seen to increase during fasting, but only in plasma.
Newfound Health Benefits of Fasting?
The authors suggest that these antioxidative effects may stand as the body’s principal response to fasting, as starvation can foster a dangerously oxidative internal environment. Their exploratory study provides the first evidence of antioxidants as a fasting marker. In addition, the study introduces the novel notion that fasting might boost production of several age-related metabolites, abundant in young people, but depleted in old.
“Recent aging studies have shown that caloric restriction and fasting have a prolonging effect on lifespan in model animals…but the detailed mechanism has remained a mystery,” said Teruya. “It might be possible to verify the anti-aging effect from various viewpoints by developing exercise programs or drugs capable of causing the metabolic reaction similar to fasting.”
The findings expand on established ideas of what fasting could do for human health. The next step would be to replicate these results in a larger study, or investigate how the metabolic changes might be triggered by other means.
“People are interested in whether human beings can enjoy the effects of prevention of metabolic diseases and prolonging life span by fasting or caloric restriction, as with model animals,” said Teruya. “Understanding the metabolic changes caused by fasting is expected to give us wisdom for maintaining health.”
After performing experiments in both humans and mice, the researchers found that exercise training causes dramatic changes to fat. Additionally, they discovered that this “trained” fat releases factors into the bloodstream that can have positive effects on health.
It’s known that fat cells secrete proteins called adipokines, and that many adipokines increase with obesity, having harmful effects on metabolism and health.
“In contrast to the negative effects of many adipokines, our study identified transforming growth factor beta 2 (TGF-beta 2) as an adipokine released from adipose tissue (fat) in response to exercise that actually improves glucose tolerance,” says Laurie J. Goodyear, PhD, Head of Joslin’s Section on Integrative Physiology and Metabolism and study co-author.
Not only did exercise-stimulated TGF-beta 2 improve glucose tolerance, treating obese mice with TGF beta 2 lowered blood lipid levels and improved many other aspects of metabolism.
“The fact that a single protein has such important and dramatic effects was quite impressive,” says Goodyear, Professor of Medicine at Harvard Medical School.
Two years ago, the international research team first demonstrated that adipose tissue offers beneficial metabolic effects in response to exercise.
“Our hypothesis was that exercise is changing the fat, and as a result of that change, the fat releases these beneficial proteins into the bloodstream,” says Goodyear. “Before this discovery, we always just focused on the positive effects of muscle.”
Building on this insight, Joslin researchers sought to identify the adipokines released from fat in exercise. To do so, they ran a series of molecular experiments in both humans and mice. They identified levels of adipokines in men before and after a cycle of exercise. They also studied exercising mice.
Their analysis identified TGF beta 2 as one of the proteins upregulated in exercise in humans and mice. Additional investigation confirmed that levels of this one adipokine actually increased in the fat tissue as well as in the bloodstream with exercise, in both cases.
To find out if the protein promoted beneficial metabolic effects, they treated the mice with TGF beta 2. The experiment showed a number of positive metabolic effects in the mice, including improved glucose tolerance and increased fatty acid uptake.
Next, they fed the mice a high fat diet, causing the animals to develop diabetes. To know if TGF beta 2 was actually responsible for the metabolic effects, they treated the diabetic mice with TGF beta 2. This reversed the negative metabolic effects of the high fat diet, similar to what happens with exercise.
“Our results are important because it’s really the first demonstration of an exercise-released adipokine that can have beneficial metabolic effects on the body,” says Goodyear.
Another significant finding was that lactic acid, which is released during exercise, serves as an integral part of the process. Lactate is released by the muscles during exercise then travels to the fat where it triggers the release of TGF beta 2.
“This research really revolutionizes the way we think about exercise, and the many metabolic effects of exercise. And, importantly, that fat is actually playing an important role in the way exercise works,” says Goodyear.
These findings suggest that TGF beta 2 may be a potential therapy for treatment of high blood sugar, and eventually a potential therapy for type 2 diabetes. Long-term studies will be needed to determine the safety of TGF beta 2 treatment.
Researchers at the Westmead Institute for Medical Research interviewed more than 2,000 Australian adults aged over 49 and followed them over a 15-year period.
The research showed that people who ate between 100 to 142 mgs of vegetable nitrates each day had a 35% lower risk of developing early AMD than people who ate less than 69mgs of vegetable nitrates each day.
Lead Researcher Associate Professor Bamini Gopinath from the Westmead Institute and the University of Sydney said the link between vegetable nitrates and macular degeneration could have important implications.
“This is the first time the effects of dietary nitrates on macular degeneration risk has been measured.
“Essentially we found that people who ate 100 to 142 mgs of vegetable nitrates every day had a reduced risk of developing early signs of macular degeneration compared with people who ate fewer nitrates.
“If our findings are confirmed, incorporating a range of foods rich in dietary nitrates — like green leafy vegetables and beetroot — could be a simple strategy to reduce the risk of early macular degeneration,” Associate Professor Gopinath said.
Spinach has approximately 20mg of nitrate per 100g, while beetroot has nearly 15mg of nitrate per 100g.
The research did not show any additional benefits for people who exceeded 142mgs of dietary nitrate each day. It also did not show any significant connections between vegetable nitrates and late stage AMD, or between non-vegetable nitrates and AMD risk.
One in seven Australians over 50 have some signs of macular degeneration.
Age is the strongest known risk factor and the disease is more likely to occur after the age of 50.
The research compiled data from the Blue Mountains Eye Study, a benchmark population-based study that started in 1992.
It is one of the world’s largest epidemiology studies, measuring diet and lifestyle factors against health outcomes and a range of chronic diseases.
“Our research aims to understand why eye diseases occur, as well as the genetic and environmental conditions that may threaten vision,” Associate Professor Gopinath concluded.
The study found that increased cardiorespiratory fitness was directly associated with reduced long-term mortality, with no limit on the positive effects of aerobic fitness. Extreme aerobic fitness was associated with the greatest benefit, particularly in older patients (70 and older) and in those with hypertension.
“Aerobic fitness is something that most patients can control. And we found in our study there is no limit to how much exercise is too much,” said Wael Jaber, M.D., Cleveland Clinic cardiologist and senior author of the study. “Everyone should be encouraged to achieve and maintain high fitness levels.”
The risk associated with poor cardiorespiratory fitness was comparable to or even exceeded that of traditional clinical risk factors, such as cardiovascular disease, diabetes and smoking.
The study’s findings emphasize the long-term benefits of exercise and fitness, even to extreme levels, regardless of age or coexistent cardiovascular disease.
Several recent studies have suggested associations between extreme exercise and certain adverse cardiovascular findings, such as atrial fibrillation and coronary artery disease. However, the newly published study from Cleveland Clinic found that extreme fitness provided additional survival benefit over more modest levels of fitness, and that extremely fit patients lived the longest.
“We were particularly interested in the relationship between extremely high fitness and mortality” said Kyle Mandsager, M.D., an electrophysiology fellow at Cleveland Clinic and the lead author of the study. “This relationship has never been looked at using objectively measured fitness, and on such a large scale.”
All patients had previously undergone stress tests at Cleveland Clinic, and were broken up into five performance groups — elite, high, above average, below average and low. Elite performers were defined as having aerobic fitness in the top two and half percent by age and gender, and demonstrated fitness levels comparable to endurance athletes. Long-term survival was adjusted for a patient’s age, sex, height, weight, BMI, medications and comorbidities.
When the subgroups were analyzed by age, the survival benefit of elite versus high performance was most notable in older patients. In those over the age of 70, elite performers had a nearly 30 percent reduced risk of mortality compared to high performers. In younger age groups there was no statistical difference in outcomes between elite and high performers.
When the subgroups were analyzed by comorbidities, all-cause mortality inversely related to cardiorespiratory fitness and was lowest in the elite performers. For those patients with hypertension, the elite performers again showed a nearly 30 percent reduction in all-cause mortality compared to high performers. For all other comorbidity subgroups there was no statistical difference in survival rates between the elite and high performers.
It is important to note that the study analyzed findings over a large population, and individual patients should always check with their healthcare provider before starting an exercise program.