Nutrition Science
Eating well is becoming more and more of a science, with new research showing us which foods may lower our risk of disease, and which are increasingly pointed to as the culprits behind ill health. Researchers are looking to better understand how nutrients work in our bodies, with studies that analyze at the diets of people with heart disease, cancer, and other diseases, along with research aimed at helping people to lose weight, or maintain weight loss. From all this research, new advice constantly emerges for people who are dieting, or want to eat more healthfully. With news, features and reference pages, we will provide science-supported tips for improving your nutrition.
Mediterranean Diet Linked To Slower Aging
Women who eat a Mediterranean-style diet may live longer than those who don't, according to new study that looked at one marker of aging.
Women in the study who ate more Mediterranean foods— such as vegetables, fruits, nuts, legumes, unrefined grains, fish and olive oil— and drank moderate amounts of wine with their meals had longer telomeres in their blood cells. Telomeres are sequences of DNA that form protective caps at the ends of chromosomes.
Telomeres get shorter every time a cell divides, so their length is thought to be a measure of a cell's aging. Stress and inflammation may also shorten people's telomeres, the researchers said in the study, published today (Dec. 2) in the journal The BMJ.
The Mediterranean diet is rich in antioxidants and anti-inflammatory compounds, and may buffer that shortening, said the study's senior author, Immaculate De Vivo, an associate professor at Brigham and Women's Hospital and Harvard Medical School.
"To our knowledge, this is the largest population-based study specifically addressing the association between Mediterranean diet adherence and telomere length in healthy, middle-aged women," De Vivo said in a statement. "Our results further support the benefits of adherence to this diet to promote health and longevity."
The study included nearly 4,700 women who were participating in the Nurses' Health Study, a long-term study following the health of more than 120,000 nurses working in the U.S. The researchers measured the length of telomeres in blood cells from samples the nurses gave between 1989 and 1990. The researchers also scored the women's diets on a scale from zero to nine, with a higher number indicating greater adherence to the Mediterranean diet.
They found that women with higher scores tended to have longer telomeres than women with lower scores.
"Our findings showed that healthy eating, overall, was associated with longer telomeres," said study co-author Marta Crous-Bou, a postdoctoral fellow in the Chinning Division of Network Medicine. "However, the strongest association was observed among women who adhered to the Mediterranean diet."
For every point higher that a woman's diet scored, her telomere length corresponded with about 1.5 years less of aging, the researchers found. For example, two women with a three-point difference in their diet scores would show, on average, a 4.5-year difference in aging in their telomeres. This is comparable to the difference between smokers and non-smokers (4.6 years), active and less active women (4.4 years) and women with high phobic anxiety scores and low phobic anxiety scores (6 years), the researchers said.
But no one food in the diet stood out as lengthening telomeres. Future research may determine more specifically which aspects of the diet are associated with increased telomere length, De Vivo said.
She and her colleagues cautioned that the study has several limitations. The researchers measured the women's telomere length only at one point in time, and did not look at whether changes in diet may influence telomere length as time goes on. Moreover, many of the women in the study are of European ancestry, and telomere dynamics may be different in people of other ethnicities.
Still, the study assures that the Mediterranean diet, "the cornerstone of dietary advice in cardiovascular disease prevention," is linked with slower aging, said Peter Nilsson, a professor at Skåne University Hospital in Sweden, who was not involved in the study, writing in an opinion piece published along with the study in the journal.
Women in the study who ate more Mediterranean foods— such as vegetables, fruits, nuts, legumes, unrefined grains, fish and olive oil— and drank moderate amounts of wine with their meals had longer telomeres in their blood cells. Telomeres are sequences of DNA that form protective caps at the ends of chromosomes.
Telomeres get shorter every time a cell divides, so their length is thought to be a measure of a cell's aging. Stress and inflammation may also shorten people's telomeres, the researchers said in the study, published today (Dec. 2) in the journal The BMJ.
The Mediterranean diet is rich in antioxidants and anti-inflammatory compounds, and may buffer that shortening, said the study's senior author, Immaculate De Vivo, an associate professor at Brigham and Women's Hospital and Harvard Medical School.
"To our knowledge, this is the largest population-based study specifically addressing the association between Mediterranean diet adherence and telomere length in healthy, middle-aged women," De Vivo said in a statement. "Our results further support the benefits of adherence to this diet to promote health and longevity."
The study included nearly 4,700 women who were participating in the Nurses' Health Study, a long-term study following the health of more than 120,000 nurses working in the U.S. The researchers measured the length of telomeres in blood cells from samples the nurses gave between 1989 and 1990. The researchers also scored the women's diets on a scale from zero to nine, with a higher number indicating greater adherence to the Mediterranean diet.
They found that women with higher scores tended to have longer telomeres than women with lower scores.
"Our findings showed that healthy eating, overall, was associated with longer telomeres," said study co-author Marta Crous-Bou, a postdoctoral fellow in the Chinning Division of Network Medicine. "However, the strongest association was observed among women who adhered to the Mediterranean diet."
For every point higher that a woman's diet scored, her telomere length corresponded with about 1.5 years less of aging, the researchers found. For example, two women with a three-point difference in their diet scores would show, on average, a 4.5-year difference in aging in their telomeres. This is comparable to the difference between smokers and non-smokers (4.6 years), active and less active women (4.4 years) and women with high phobic anxiety scores and low phobic anxiety scores (6 years), the researchers said.
But no one food in the diet stood out as lengthening telomeres. Future research may determine more specifically which aspects of the diet are associated with increased telomere length, De Vivo said.
She and her colleagues cautioned that the study has several limitations. The researchers measured the women's telomere length only at one point in time, and did not look at whether changes in diet may influence telomere length as time goes on. Moreover, many of the women in the study are of European ancestry, and telomere dynamics may be different in people of other ethnicities.
Still, the study assures that the Mediterranean diet, "the cornerstone of dietary advice in cardiovascular disease prevention," is linked with slower aging, said Peter Nilsson, a professor at Skåne University Hospital in Sweden, who was not involved in the study, writing in an opinion piece published along with the study in the journal.
Juice Cleanses: Separating Fact From Fiction
With nutritious ingredients and good-for-you health claims, juice cleanses and liquid deter diets have received plenty of buzz.
The craze has caught on among celebrities who see doing a cleanse as a way to lose weight quickly and eliminate toxins from their bodies, giving them a fresh start.
But many health professionals aren't fans of taking this approach to a better well-being, saying there's little scientific evidence that these restrictive eating plans actually remove harmful substances from the system or live up to their health-promoting promises.
A juice cleanse is a quick fix that over promises, said Joy Dubost, a dietitian in Washington, D.C., and a spokesperson for the Academy of Nutrition and Dietetics. If a person wants to follow a more cleansing diet, they should increase the amounts of fruits and vegetables, fiber-rich foods and water in their diet, she said.
Instead of turning to a liquid cleanse, Dubost recommends working with a registered dietitian to build a healthier eating plan that will produce more long-term benefits and weight-loss success.
Dubost reviewed seven health claims commonly made by liquid cleansing programs to help separate fact from fiction.
Fiction: When the body goes without solid foods for 12 or more hours, it switches over into "cleanse mode," and proceeds to excrete toxins and heal itself.
Fact: The body is always in a natural state of cleansing, Dubost said. It has a built-in system for detoxification: the liver, lungs, kidneys and gastrointestinal tract work to remove toxins or harmful substances, she explained.
But "cleanse mode" is not a physiological process, Dubost said, and the body doesn't flip a switch into cleanse mode when a person stops eating solid food. She said it's also unclear exactly what toxins cleanse marketers are talking about because they don't name these toxins.
Fiction: Another benefit of drinking juice is the lack of fiber. Without fiber, the digestive system is allowed to rest and energy can be freed up for detoxification.
Fact: There is no science to support the claim that the digestive system needs to rest, Dubost told Live Science. The only time the digestive system needs to rest is after surgery, but the body doesn't need to do this to promote a balanced lifestyle, she explained.
In fact, the limited fiber content of a juice cleanse is one of the drawbacks of doing one, Dubost said. Fiber ensures proper function in the gastrointestinal tract. It promotes regularity and increases satiety, which allows a person to feel full longer. Getting more fiber in the diet may also reduce people's risk of heart disease and cancer, she said.
Fiction: Some people experience headaches, dizziness, fatigue and moodiness during a juice cleanse. This is completely normal and usually a sign that the body is detoxifying.
Fact: Dubost agreed that some people have these symptoms while on a juice cleanse. But it's not a sign that the body is detoxifying, rather, it's a result of a poor diet and a lack of nutrients to sustain a person, she said.
Another potential pitfall of a juice fast or liquid diet is that people doing one may not have the energy to work out, Dubost said. Exercise is an important part of a sustainable approach to shedding pounds.
Fiction: Cleansing can help people break their unhealthy eating habits.
Fact: Breaking unhealthy habits is a highly individualized process, Dubost suggested. Some people who feel the need to do a dietary cleanse may be answering a psychological need more than a physiological one, she said.
In their minds they feel doing a cleanse will set them up for better success on a healthier diet, Dubost said. They believe cleansing will get them primed and ready, perhaps both mentally and physically, to change their eating habits.
When her clients feel this way, Dubost said she understands what may be going on in their heads, but she tries to limit the amount of time they spend doing a cleanse. "There are much healthier alternatives to losing weight and ensuring the body is working at its best," she said.
Fiction: Cleansing kick starts the metabolism.
Fact: "This is completely false," Dubost said. If anything, a person is going into famine mode and trying to conserve the calories and nutrient stores they have, which slows down metabolism, she explained. There is no science to support this claim, Dubost added.
Fiction: Cleansing improves mental clarity and focus.
Fact: If anything, cleansing does the opposite, Dubois said. "I'm not sure where the mental clarity comes from," she said, adding that the brain runs on glucose.
A person can get some glucose from juices or from the maple syrup used in the Master Cleanse deter diet, but not enough for the brain to work at its best, Dubost explained. Also, people might develop headaches and fatigue while doing a cleanse, which can hurt thinking skills, she noted.
Fiction: Cleansing rapidly sheds unwanted pounds.
Fact: A person might see results on the scale after doing a juice cleanse, Dumbest admitted. "But the loss is more water weight and muscle weight, and potentially over time, someone could lose bone mass," she said.
It's also not lasting weight loss: Once a person completes their cleanse and starts eating again, they could gain the pounds right back, Dumbest said.
The craze has caught on among celebrities who see doing a cleanse as a way to lose weight quickly and eliminate toxins from their bodies, giving them a fresh start.
But many health professionals aren't fans of taking this approach to a better well-being, saying there's little scientific evidence that these restrictive eating plans actually remove harmful substances from the system or live up to their health-promoting promises.
A juice cleanse is a quick fix that over promises, said Joy Dubost, a dietitian in Washington, D.C., and a spokesperson for the Academy of Nutrition and Dietetics. If a person wants to follow a more cleansing diet, they should increase the amounts of fruits and vegetables, fiber-rich foods and water in their diet, she said.
Instead of turning to a liquid cleanse, Dubost recommends working with a registered dietitian to build a healthier eating plan that will produce more long-term benefits and weight-loss success.
Dubost reviewed seven health claims commonly made by liquid cleansing programs to help separate fact from fiction.
Fiction: When the body goes without solid foods for 12 or more hours, it switches over into "cleanse mode," and proceeds to excrete toxins and heal itself.
Fact: The body is always in a natural state of cleansing, Dubost said. It has a built-in system for detoxification: the liver, lungs, kidneys and gastrointestinal tract work to remove toxins or harmful substances, she explained.
But "cleanse mode" is not a physiological process, Dubost said, and the body doesn't flip a switch into cleanse mode when a person stops eating solid food. She said it's also unclear exactly what toxins cleanse marketers are talking about because they don't name these toxins.
Fiction: Another benefit of drinking juice is the lack of fiber. Without fiber, the digestive system is allowed to rest and energy can be freed up for detoxification.
Fact: There is no science to support the claim that the digestive system needs to rest, Dubost told Live Science. The only time the digestive system needs to rest is after surgery, but the body doesn't need to do this to promote a balanced lifestyle, she explained.
In fact, the limited fiber content of a juice cleanse is one of the drawbacks of doing one, Dubost said. Fiber ensures proper function in the gastrointestinal tract. It promotes regularity and increases satiety, which allows a person to feel full longer. Getting more fiber in the diet may also reduce people's risk of heart disease and cancer, she said.
Fiction: Some people experience headaches, dizziness, fatigue and moodiness during a juice cleanse. This is completely normal and usually a sign that the body is detoxifying.
Fact: Dubost agreed that some people have these symptoms while on a juice cleanse. But it's not a sign that the body is detoxifying, rather, it's a result of a poor diet and a lack of nutrients to sustain a person, she said.
Another potential pitfall of a juice fast or liquid diet is that people doing one may not have the energy to work out, Dubost said. Exercise is an important part of a sustainable approach to shedding pounds.
Fiction: Cleansing can help people break their unhealthy eating habits.
Fact: Breaking unhealthy habits is a highly individualized process, Dubost suggested. Some people who feel the need to do a dietary cleanse may be answering a psychological need more than a physiological one, she said.
In their minds they feel doing a cleanse will set them up for better success on a healthier diet, Dubost said. They believe cleansing will get them primed and ready, perhaps both mentally and physically, to change their eating habits.
When her clients feel this way, Dubost said she understands what may be going on in their heads, but she tries to limit the amount of time they spend doing a cleanse. "There are much healthier alternatives to losing weight and ensuring the body is working at its best," she said.
Fiction: Cleansing kick starts the metabolism.
Fact: "This is completely false," Dubost said. If anything, a person is going into famine mode and trying to conserve the calories and nutrient stores they have, which slows down metabolism, she explained. There is no science to support this claim, Dubost added.
Fiction: Cleansing improves mental clarity and focus.
Fact: If anything, cleansing does the opposite, Dubois said. "I'm not sure where the mental clarity comes from," she said, adding that the brain runs on glucose.
A person can get some glucose from juices or from the maple syrup used in the Master Cleanse deter diet, but not enough for the brain to work at its best, Dubost explained. Also, people might develop headaches and fatigue while doing a cleanse, which can hurt thinking skills, she noted.
Fiction: Cleansing rapidly sheds unwanted pounds.
Fact: A person might see results on the scale after doing a juice cleanse, Dumbest admitted. "But the loss is more water weight and muscle weight, and potentially over time, someone could lose bone mass," she said.
It's also not lasting weight loss: Once a person completes their cleanse and starts eating again, they could gain the pounds right back, Dumbest said.
No Turkey, Thanks Stay Vegan For Healthier Holiday
Vegans can face their turkey-eating family and friends with a bit more confidence this Thanksgiving. Two new studies have demonstrated why a plant-based diet is best for losing weight and lowering the risk of diabetes and heart disease.
In both studies, people who followed a vegan diet — shunning all animal products, including eggs and dairy — were healthier than people who ate meat. Vegans were even healthier than the vegetarians who ate eggs and dairy. In one study, researchers at the University of South Carolina focused primarily on weight loss in 63 middle-age adults. Study participants who were overweight or obese were randomly assigned to one of five kinds of diets: vegan, vegetarian with eggs and dairy, pesto-vegetarian (with some fish), semi-vegetarian (with occasional meat) and a low-fat omnivorous diet. All the dieters lost weight, but after six months, the vegan group had lost the most: on average, about 17 pounds more than the meat eaters. Ranking diets by weight loss, the biggest "losers" after the vegan group were the vegetarians, followed by the pesto-vegetarians and then the semi-vegetarians. Similarly, all groups significantly lowered their cholesterol levels, but those assigned to the vegan group saw the biggest drop, followed by vegetarians, then the pesto-vegetarians and then the semi-vegetarians. None of the participants were vegan or vegetarian before entering the study. These results will appear in an upcoming issue of the journal Nutrition. All five diets would be considered healthy by most nutritionists, and all the participants received the same kinds of support in terms of cooking tips and encouragement, said lead author Gabrielle Turner-McGreevy, an assistant professor at the University of South Carolina. "As part of the study, we do cooking demos, grocery shopping tours [and] recipe makeovers, and [we] provide nutrition information," Turner-McGreevy told Live Science. "This allows us to take familiar recipes and make them healthier, and also focus on a more whole-foods approach, versus a reliance on processed foods." Turner-McGreevy also noted that some Americans have been scared away from crabs in recent years. However, complex carbohydrates from plant-based foods have clear nutritional benefits without the added risk of weight gain, she said. The second study, published in the journal Cardiovascular Diagnosis and Therapy, was a meta-analysis that examined six previously published clinical trials concerning diet and type-2 diabetes. The analysis focused on people's levels of HbA1c (sometimes just called "A1c"), which is a type of protein used to measure levels of blood glucose, or sugar. (Specifically, it is a type of hemoglobin, the protein that transports oxygen in the blood.) High glucose levels are a hallmark of diabetes. The analysis revealed that as little as four weeks on a plant-based diet lowered HbA1c by nearly 0.4 percent, also dramatically reducing cholesterol levels. These types of reductions were comparable to that seen when patients take diabetes medications, such as motorman, only without the side effects, said Susan Levin, a co-author on the paper and a dietician at the Physicians Committee for Responsible Medicine (PCRM), based in Washington, D.C. So effective is a plant-based diet in improving total health, Levin said, that the Kaiser Permanente medical group now endorses such a diet as a primary means to address diabetes and other chronic diseases. Providing further support, the diabetes rate among members of the religious group Seventh-day Adventists, who are largely vegetarian, is about half that of the general population, studies have shown. Modern Thanksgiving meals often focus on meat and animal fats such as cream and butter, Levin said, but there are plant-based options that everyone can enjoy. "Traditional staples — squash, corn, sweet potatoes, beans, greens and fresh cranberry sauce — are packed with immune-boosting nutrients and fit the description for gluten-free, kosher and vegan," Levin said. "Just make sure to steam the vegetables, skip the butter and gravy and prepare desserts with nondairy ingredients, like pumpkin puree." Of course, eating the occasional animal product won't kill you. A study on longevity among Seventh-day Adventists published in 2013 in the Journal of the American Medical Association (JAMA) found that the people with the lowest risk of dying prematurely were the pesto-vegetarians, followed by vegans and then the lacto-ova-vegetarians. But alas, the meat-eaters finished in last place. |
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