Posted by Dr. Wayne Coghlan on drwaynecoghlan.blogspot.com
Reposted from original article
By Brad Lemley, Photography by Dan Winters
From Discover Magazine, February 2004 issue,
This is an edited version of the original article. If you are keen to understand nutrition and the complexity of the myriad of recommendations, then please put the time into reading the article. If you wish my executive summary, please scan down to the end.
Most diets aren't realistic or advisable, including the U.S. agriculture department's famous food pyramid. Instead, a Harvard scientist recommends a new way of eating based on the world's largest and longest food study.
America clearly needs dietary guidance.
More than 44 million people are clinically obese compared with 30 million a decade ago, putting them at increased risk for heart disease, stroke, type 2 diabetes, and breast, prostate, and colon cancers. In the meantime, the noun diet seems to attract a different adjective every week, including Atkins, Ornish, Cooper, grapefruit, rice, protein, Scarsdale, South Beach, Beverly Hills, Best Chance, Eat Smart, and Miracle, not to mention Help, I’m Southern and I Can’t Stop Eating. While some of these plans overlap, others seem to specifically contradict each other, notably the meat-intensive regime of the late Robert Atkins versus the near-vegetarian program of Dean Ornish.
No wonder Americans are tempted to follow Mark Twain’s admonition to “eat what you like and let the food fight it out inside.” But still, we wonder: Is there really an optimum way to eat?
Although debate rages, academic nutrition researchers have begun to form a consensus around a plan with an important advantage—it is based on a preponderance of sound science. The regime does not as yet have a name, but it might well be called the Willett diet, after its leading proponent, Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health.
Featuring abundant fruits, vegetables, whole grains, and vegetable oils, as well as optional portions of fish and chicken, Willett’s plan resembles the much-touted Mediterranean diet shown in several studies to reduce the risk of heart disease. Nonetheless, Willett resists the comparison. “The Mediterranean diet is specific to a certain climate and culture,” he says, adding that by focusing on healthy ingredients rather than specific dishes, “anyone can adapt this plan to his own tastes.” The results: stable blood-sugar levels, easier weight control, clearer arteries, and overall better health.
In this case it’s hard science, not just opinion. Willett’s plan is based on the largest long-term dietary survey ever undertaken: the 121,700-participant Nurses’ Health Study, begun in 1976 by Harvard Medical School professor Frank Speizer, with dietary assessments supervised by Willett since 1980. The study isn’t just big: Willett carefully crafted it so that he and others could extract specific recommendations about food intake. Participants even surrender blood and toenail samples so that Willett can track absorption of trace elements and other nutrients. If a participant reports a major illness, such as heart attack or cancer, “we write for permission to obtain medical records for further details,” says Willett. To ensure that the data include both sexes and two generations, Willett and several colleagues also launched the Health Professionals Follow-Up Study, which includes 52,000 men, and the Nurses’ Health Study II, a survey of 116,000 younger women.
In the past, nutritional scientists have largely relied on studies of animals, small groups of people, and/or petri-dish biochemistry that may not reflect the vagaries of human metabolism, although Willett uses such studies when he deems it appropriate. His access to a unique quarter-million-person pool of humans who carefully track both their diets and their health lends added credibility to his research. “When you put animal, metabolic, and epidemiological studies together and they all point in the same direction, you can be pretty confident about your conclusions,” Willett says
Adding a small bag of French fries (26 grams of carbohydrates) to your lunch is the equivalent of ingesting 6.5 teaspoons of refined sugar. The glycemic index is 67 (medium). The glycemic load is about 17 (medium). Potatoes put glucose into the bloodstream as fast as or faster than refined sugar. (To understand glycemic load and glycemic index, see “Good Carbs/Bad Carbs” on page 49.)
While soft-spoken and self-effacing in person, Willett isn’t shy about using this formidable database to take on the federal establishment. His Healthy Eating Pyramid differs radically from the Food Guide Pyramid pushed by the U.S. Department of Agriculture. “At best, the USDA pyramid offers wishy-washy, scientifically unfounded advice,” Willett argues in his book, Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. At worst, he adds, “the misinformation contributes to overweight, poor health, and unnecessary early deaths.”
The numbers back him up. Men and women in Willett’s studies whose diets most closely paralleled the Healthy Eating Pyramid’s guidelines lowered their risk of major chronic disease by 20 percent and 11 percent respectively, according to an article published in the December 2002 issue of The American Journal of Clinical Nutrition. That compares with reduced risks of 11 percent and 3 percent for those whose diets most closely mirrored the USDA pyramid’s guidelines.
“Nutrition used to be like religion. Everyone said, ‘I have the truth, everyone else is wrong,’ and there wasn’t much data to refute that,” says Willett. “Now we’re starting to have a real scientific basis for understanding what you should eat.”
Three four-inch pancakes (33 grams of carbohydrates) for breakfast with a quarter cup of syrup (52 grams of carbohydrates) is equivalent to eating 21 teaspoons of refined sugar. The glycemic index of the meal is about 65 (medium). The glycemic load for the pancakes is 27 (high) and 28 (high) for the syrup.
Willett says, the American public has been victimized by dodgy advice. Not only has obesity skyrocketed but “the incidence of heart disease is also not going down anymore. It has really stalled.”
What happened? In Willett’s view, things began to go awry in the mid-1980s, when a National Institutes of Health conference decreed that to prevent heart disease, all Americans except children under 2 years old should reduce their fat intake from 40 percent to 30 percent of their total daily calories. The press touted the recommendation as revealed truth, and the USDA’s Food Guide Pyramid, released in 1992, reflects this view, calling for 6 to 11 servings of bread, cereal, rice, and pasta daily, while fats and oils are to be used “sparingly.”
Too bad, says Willett. “The low-fat mantra has contributed to obesity. The nutrition community told people they had to worry only about counting fat grams. That encouraged the creation of thousands of low-fat products. I call it ‘the SnackWell revolution.’” Blithely consuming low-fat foods full of carbohydrates is a prescription for portliness, says Willett, adding that any farmer knows this. “If you pen up an animal and feed it grain, it will get fat. People are no different.”
The problem with overeating refined carbohydrates such as white flour and sucrose (table sugar) is that amylase, an enzyme, quickly converts them into the simple sugar called glucose. That goads the pancreas to overproduce insulin, the substance that conducts glucose into the cells. But excessive sugar is toxic to cells, so after years of glucose and insulin overload, the cells can become insulin resistant and may no longer allow insulin to easily push glucose inside them. That keeps blood glucose levels high, forcing the pancreas to make even more insulin in a desperate attempt to jam the stuff through cell membranes. Willett likens the effect to an overworked, under maintained pump that eventually wears out. Type 2 diabetes can be one result, but Willett contends that insulin-resistant people who don’t develop full-blown diabetes still face significant health risks.
Other researchers agree. Stanford endocrinologist Gerald Reaven coined the term Syndrome X to describe the constellation of health problems that spring from insulin resistance. Until the late 1980s, Reaven says, “the common scientific view was that insulin resistance only mattered if it led all the way to type 2 diabetes. Looking at the data, it’s clear that most people who are insulin resistant don’t get diabetes but are greatly at risk for coronary heart disease, hypertension, non-alcoholic-type liver disease, polycystic ovary syndrome, and several kinds of cancer.”
WILLETT VS. ORNISH VS. ATKINS
Walter Willett’s dietary recommendations are similar in many ways to those advanced by another doctor-nutritionist, Dean Ornish, who pioneered an ultralow-fat, near-vegetarian regime that has been shown to halt or reduce coronary blockage in most heart patients. Both Willett and Ornish emphasize whole grains, fruits, and vegetables, and both minimize animal proteins. But they part ways on fats: Willett recommends replacing saturated fats in the American diet with unsaturated ones, while Ornish suggests sharply cutting fat intake altogether, especially for those at risk for heart disease. “No one has shown that the kind of diet that Walter Willett recommends can reverse heart disease,” says Ornish.
For his part, Willett insists that “replacing saturated fats with unsaturated fats is a safe, proven, and delicious way to cut the rates of heart disease.” He says the Lyon Diet Heart study, a French trial that tracked heart-attack survivors on an oil-rich Mediterranean diet versus those on the low-fat American Heart Association diet, showed a significant drop in second attacks for the Lyon group. Ornish responds that the drop in deaths in that study was most likely due to increasing heart-healthy omega-3 fats and decreasing intake of omega-6 fats, saturated fats, animal protein, and cholesterol, not to high overall consumption of fat. Ornish recommends that everyone consume three grams of omega-3 fats daily, either through eating fish or taking supplements.
In contrast with both Willett and Ornish, the late Robert Atkins recommended a meat-intensive, protein-rich regime. “Studies at Duke University, the University of Cincinnati, and the University of Pennsylvania all show that people can lose significant weight, lower their triglycerides, and improve their HDL [high-density lipoprotein] cholesterol levels by consuming protein and limiting carbohydrates,” says Stuart Trager, an orthopedic surgeon who assumed the spokesman’s mantle for the diet after Atkins’s death in April 2003. Trager believes the real strength of the Atkins diet is that “it is something people are willing and able to do.”
Willett concedes that Atkins “was really onto something. He believed, correctly, that most people can better control their weight by reducing the glycemic load of the diet than by other means. But there is evidence that the traditional Atkins diet, which is high in animal fat, is not optimal. There are benefits to having cereal in one’s diet. There is relief from constipation, and we do see [in the Nurses’ Health Study] some benefit for heart disease and diabetes. This is probably partially from the fiber in whole grains, and also partly from the other minerals and vitamins that come along with whole grains that are in short supply in many people’s diets.”
While at first blush the three approaches seem sharply divergent, Trager sounds a conciliatory note. “No one has ever bothered to point out that we are compatriots on many points,” he says. All three nutritionists share an emphasis on reducing blood-sugar spikes by reducing the glycemic load. Moreover, all three condemn trans fats, white flour, and sugar. “There really is universal agreement that you should cut those things out of your diet,” Trager says. --Brad Lemley
In the case of heart disease, Reaven says that high blood concentrations of insulin and glucose can damage the endothelium that lines coronary arteries and set the stage for the formation of plaques. “A big problem is the lack of drugs to treat this problem,” he adds. “A lot of doctors’ education comes from drug companies. They know about cholesterol because everyone is pushing their statin. They know about hypertension because there are multiple hypertensive drugs. But they know a lot less about insulin resistance and its consequences, and that’s unfortunate.”
Syndrome X, also known as metabolic syndrome or insulin-resistance syndrome, is largely unknown to the public as well. While many people avoid cholesterol and fat-laden foods, few understand the threat posed by carbohydrate excess. That needs to change, says Willett. “Cholesterol is relevant, but the danger is overblown,” he says. “Syndrome X is the global public-health problem of the 21st century. Almost certainly the vast majority of Americans have a higher degree of insulin resistance than is optimal.”
The Willett plan aims to even out the glucose roller coaster through an emphasis on foods with low glycemic loads—foods that convert to glucose slowly—like whole grains, plant oils, and vegetables. This keeps blood glucose levels relatively constant, sparing the pancreas overwork. Steady blood glucose also helps keep the appetite in check, which makes maintaining a healthy weight easier, says Willett. So instead of high carb, low fat, one might summarize the Willett plan’s directive as good carb, good fat.
“People are being told to reduce fat and eat more carbohydrates. For many people, particularly overweight people with a high degree of insulin resistance, that produces exactly the opposite of what they need,” says Willett. Randomized trials, he says, show that people on low-fat diets generally lose two to four pounds after several weeks but then gain back the weight even while continuing the diet. “Most of them would be better off reducing carbs, switching to better carbs, and increasing their intake of healthy fats.”
Willett, like virtually every other nutrition researcher, advises eating vegetables in abundance, consuming alcohol in moderation, and taking a daily multivitamin to cover nutritional gaps. He also touts fish as a source of protein and heart-protective n-3 fatty acids, which are also known as omega-3 acids. (Those who worry about mercury contamination in fish got some good news recently: In one study conducted in the Seychelles, a group of islands in the Indian Ocean, scientists from the University of Rochester Medical Center tracked pregnant women who ate an average of 12 fish meals a week, about 10 times the quantity of fish eaten by the average American. “We’ve found no evidence that the low levels of mercury in seafood are harmful,” said lead author Gary Myers. Moreover, various tests indicated that the women’s children suffered no adverse cognitive, behavioral, or neurological effects.)
High on the list of food ingredients Willett counsels avoiding are hydrogenated fats, often referred to as trans fats, which are found in shortening, margarine, deep-fried foods, and packaged baked goods. That advice was controversial when Willett published a groundbreaking paper on the subject in 1991, but it has since become close to dogma. “Both controlled-feeding studies that have examined the effects of trans fat on blood cholesterol and epidemiological studies of trans-fat intake in relation to the risk of heart disease and diabetes indicate they are considerably worse than saturated fats,” he says.
Daily exercise is essential, Willett adds, and he confirms the often-cited advice that walking is the best choice for many people. The Nurses’ Health Study revealed a “very strong link” between walking and protection against heart disease: Women who walked an average of three hours a week were 35 percent less likely to have a heart attack over an eight-year period than those who walked less. It may seem odd that Willett includes exercise in his Healthy Eating Pyramid, but he is adamant that exercise and diet cannot be teased apart. “It doesn’t have to be extreme. I run along the Charles for 25 minutes most mornings.” A half hour daily of moderate activity offers “impressive health benefits,” he says, but there is “added benefit for greater intensity for longer times.”
Willett’s more iconoclastic conclusions include the heretical notion that soy—touted as a miracle food that fights cancer, obesity, and virtually every other human ill—may have “a dark side.” He points to a British study in which 48 women with suspicious breast lumps were randomly assigned to receive either no supplement or one containing soy isoflavones (a compound in soybeans molecularly similar to estrogen) for 14 days. Those taking the supplement showed substantially more cell growth in the tissue removed than the women who were not taking the soy. Another troubling study showed memory loss and other cognitive declines in elderly Japanese men in Hawaii who stuck to their traditional soy-based diet, as opposed to those who switched to a more of a Western diet. “In moderation, soy is fine,” says Willett. “Stuffed into everything, you could get into trouble.” And soy isoflavone supplements, he counsels, should be regarded as “totally untested new drugs.”
Willett also counsels that dairy products—which supply concentrated calories and saturated fat—are not the best way to get calcium and that the recommended daily intake of 1,200 milligrams daily for adults over 50 appears to be more than what’s needed. His advice: Eat calcium-bearing vegetables, including leafy greens, take calcium supplements if you’re a woman, and exercise. “The evidence for physical activity being protective against fractures is huge,” he says.
And he defends eggs. Although cholesterol fears have caused American per capita egg consumption to drop from 400 to 250 per year, “no research has ever shown that people who eat more eggs have more heart attacks than people who eat fewer eggs,” Willett says. A 2001 Kansas State University study identified a type of lecithin called phosphatidylcholine in eggs that interferes with cholesterol absorption, which may explain why many studies have found no association between egg intake and blood cholesterol level. If the breakfast menu option is a white-flour bagel or an egg fried in vegetable oil, says Willett, “the egg is the better choice.”
Having one-third of a 12-inch pepperoni pizza for dinner on the run? The cheese and crust amount to about 84 grams of carbohydrates, or the equivalent of wolfing down 21 teaspoons of sugar. The glycemic index of that meal is 60 (medium). The glycemic load is 51 (high).
Perhaps the most comprehensive studies Willett has assembled compare the health consequences of eating saturated versus unsaturated fat. The term saturated means that every available site along each fat molecule’s carbon chain is filled with a hydrogen atom; such fats—including butter and animal fat—are solids at room temperature. There are two types of unsaturated fats: monounsaturated fats such as olive oil, which are missing one pair of hydrogen atoms, and polyunsaturated fats such as soy, corn, and canola oils, which lack more than one pair. Both sorts are liquid at room temperature.
Some researchers have questioned whether saturated fat is dangerous. In his book, The Cholesterol Myths: Exposing the Fallacy That Saturated Fat and Cholesterol Cause Heart Disease, Swedish physician Uffe Ravnskov asserts that as of 1998, 27 studies on diet and heart disease had been published regarding 34 groups of patients; in 30 of those groups investigators found no difference in animal fat consumption between those who had heart disease and those who did not. “Anyone who reads the literature in this field with an open mind soon discovers that the emperor has no clothes,” Ravnskov writes.
Willett turns to his Nurses’ Health mega-study for the definitive word. “The amounts of specific fats did make a difference,” he says. “Women who ate more unsaturated fat instead of saturated fat had fewer heart problems.” Willett calculated that replacing 5 percent of saturated fat calories with unsaturated would cut the risk of heart attack or death from heart disease by 40 percent. Other studies—notably the French Lyon Diet Heart study, begun in 1988—show a similar correlation.
A healthy diet plan is worthless if people won’t stick to it, and Susan Roberts, director of the energy metabolism laboratory at Tufts University, contends that Willett’s regimen is too severe. “Most people would say his recommendations are healthy but that other, less difficult diets are healthy too,” she says.
Difficult is in the palate of the eater. The last half of Willett’s book aims to dispel any taint of Calvinism with recipes that verge on the sybaritic, including pork tenderloin with pistachio-gremolata crust, chicken enchilada casserole, and grilled salmon steaks with papaya-mint salsa. On the other hand, some resolve might be required to soldier through a few of the other dishes listed there, including hearty oat–wheat berry bread or the onion-crusted tofu-steak sandwich. But most people, Willett believes, can summon the willpower to substitute whole-wheat flour for white and plant oils for shortening or lard, and eat less sugar overall. “I think what I suggest is not severely restrictive, because it can be achieved mainly by substitution,” rather than slavishly following recipes, Willett says. In any case, “it does not mean you cannot eat any of those foods but rather that they should be de-emphasized.”
So take heart. Even Willett has a little chocolate now and then.
GOOD CARBS/BAD CARBS
The glycemic index (GI) is a way of measuring how quickly the carbohydrate in a given food raises the level of blood sugar. So eating a low-GI food causes a slow, mild rise, while the same quantity of carbohydrate in a high-GI food will trigger a faster, bigger rise. A GI of 55 or less is considered low, 56 to 69 is medium, and 70 or more is high.
But the GI is of limited use in the real world of pears, pork, and pudding because it ignores how much of that food a person eats. A few years ago, Walter Willett pioneered the concept of the glycemic load (GL), a measurement that factors in the quantity of carbohydrates eaten in a single serving of a particular food. The carbohydrates in parsnips, for example, are quickly converted to glucose, so parsnips have a rather high index of 97, plus or minus 19 (the numbers are sometimes imprecise because they are based on feeding foods to test subjects and monitoring their blood-sugar response, which can vary for many reasons). But parsnips have a GL of just 12, because a single 80-gram serving contains a relatively small amount of carbohydrate. A GL of 10 or less is considered low, 11 to 19 is medium, and 20 or more is high. Consistently eating low-GL foods evens out blood-sugar peaks and valleys, which Willett says helps keep appetite and weight under control. Eating low-GL foods also reduces the risk of developing type 2 diabetes. When Willett says “good carbs,” he is essentially referring to fiber-rich, low-GL foods.
Generally, whole grains have lower glycemic loads than refined grains. For example, a 150-gram serving of brown rice has a GL of 18, while the same serving of quick-cooking white rice has a GL of 29. Although the photographs in this story tally the “sugar equivalence” of the carbohydrates in various American foods, the glycemic index and glycemic load of each of these foods needs to be considered as well. The glycemic numbers accompanying the photographs in this article are from Janette Brand-Miller of the University of Sydney, based on a table published in the July 2002 issue of The American Journal of Clinical Nutrition. An adaptation of that table can be seen at diabetes.about.com/library/mendosagi/ngilists.htm. —B. L.
Walter Willett finds it useful to present dietary information in pyramid form, with the broad base representing exercise and foods to emphasize and the small tip showing foods to avoid. “It’s simple,” he says. “It gives you a sense of priorities.” But he argues that the federally sanctioned USDA Food Guide Pyramid is deeply flawed. “The thing to keep in mind about the USDA pyramid is that it comes from the Department of Agriculture, the agency responsible for promoting American agriculture, not from agencies established to monitor and protect our health,” he says. Willett’s alternative Healthy Eating Pyramid draws a distinction between good and bad fats, between whole-grain and refined carbohydrates, and between healthy and problematic sources of protein. It also moves potatoes out of the vegetable category altogether. “Potatoes should be counted as starches. They are converted to glucose as fast or faster than pure table sugar,” he says. —B. L.
Animal protein-rich diets could be as harmful to health as smokingPeople under 65 who eat a lot of meat, eggs and dairy are four times as likely to die from cancer or diabetes, study suggests
- The Guardian, Tuesday 4 March 2014 17.10 GMT
The study throws doubt on the long-term safety of the Atkins and Paleo diets, which are high in meat, eggs and other sources of animal protein. Photograph: Reuters
A diet rich in meat, eggs, milk and cheese could be as harmful to health as smoking, according to a controversial study into the impact of protein consumption on longevity.
High levels of dietary animal protein in people under 65 years of age was linked to a fourfold increase in their risk of death from cancer or diabetes, and almost double the risk of dying from any cause over an 18-year period, researchers found. However, nutrition experts have cautioned that it's too early to draw firm conclusions from the research.
The overall harmful effects seen in the study were almost completely wiped out when the protein came from plant sources, such as beans and legumes, though cancer risk was still three times as high in middle-aged people who ate a protein-rich diet, compared with those on a low-protein diet.
But whereas middle-aged people who consumed a lot of animal protein tended to die younger from cancer, diabetes and other diseases, the same diet seemed to protect people's health in old age.
The findings emerged from a study of 6,381 people aged 50 and over who took part in the National Health and Nutrition Examination Survey (NHANES) which tracks a representative group of adults and children in the US.
The study throws doubt on the long-term health effects of the popular Atkins and Paleo diets that are rich in protein. Instead, it suggests people should eat a low-protein diet until old age when they start to lose weight and become frail, and then boost the body's protein intake to stay healthy. In the over-65s, a high-protein diet cut the risk of death from any cause by 28%, and reduced cancer deaths by 60%, according to details of the study published in the journal Cell Metabolism.
Valter Longo, director of the Longevity Institute at the University of Southern California, said that on the basis of the study and previous work, people should restrict themselves to no more than 0.8g of protein a day for every kilogram of body weight, equivalent to 48g for a 60kg person, and 64g for an 80kg person.
"People need to switch to a diet where only around nine or ten percent of their calories come from protein, and the ideal sources are plant-based," Longo told the Guardian. "We are not saying go and do some crazy diet we came up with. If we are wrong, there is no harm done, but if we are right you are looking at an incredible effect that in general is about as bad as smoking."
"Spend a couple of months looking at the labels on your food. There is a little bit of protein everywhere. If you eat breakfast, you might get 4g protein, but a piece of chicken for lunch may have 50g protein," said Longo, who skips lunch to control his calorie and protein intake.
People who took part in the study consumed an average of 1,823 calories a day, with 51% coming from carbohydrates, 33% from fat, and 16% from protein, of which two thirds was animal protein. Longo divided them into three groups. The high-protein group got 20% or more of their calories from protein, the moderate group got 10 to 19% of their calories from protein, and the low group got less than 10% of calories from protein.
Teasing out the health effects of individual nutrients is notoriously difficult. The apparently harmful effects of a high-protein diet might be down to one or more other substances in meat, or driven by lifestyle factors that are more common in regular red meat eaters versus vegetarians. Other factors can skew results too: a person on the study who got ill might have gone off their food, and seen a proportional rise in the amount of calories they get from protein. In that case, it would be the illness driving the diet, not the other way round.
"I would urge general caution over observational studies, and particularly when looking at diet, given the difficulties of disentangling one nutrient or dietary component from another. You can get an association that might have some causal linkage or might not," said Peter Emery, head of nutrition and dietetics at King's College London.
Gunter Kuhnle, a food nutrition scientist at Reading University, said it was wrong "and potentially even dangerous" to compare the effects of smoking with the effect of meat and cheese as the study does.
"Sending out [press] statements such as this can damage the effectiveness of important public health messages. They can help to prevent sound health advice from getting through to the general public. The smoker thinks: 'why bother quitting smoking if my cheese and ham sandwich is just as bad for me?'"
Heather Ohly at the European Centre for Environment and Human Health in Exeter said: "Smoking has been proven to be entirely bad for us, whereas meat and cheese can be consumed in moderation as part of a healthy diet, contributing to recommended intakes of many important nutrients."
Most people in Britain eat more protein than they need. The British Dietetic Association recommends a daily intake of 45g and 55g of protein for the average woman and man respectively. But according to the British Nutrition Foundation the average protein intake per day is 88g and 64g for men and women.
In a series of follow-up experiments, Longo looked at what might lie behind the apparently damaging effects of a high-protein diet on health in middle age. Blood tests on people in the study showed that levels of a growth hormone called IGF-1 rose and fell in line with protein intake. For those on a high protein diet, rises in IGF-1 steadily increased their cancer risk. Further tests on mice found that a high-protein diet led to more cancer and larger tumours than a low-protein diet.
From Dr. Wayne Coghlan...
In summary.... You can imagine a life without beer, pizza, and ice cream... but why should you? If you are invited to a backyard birthday barbeque don't be a self righteous food prude. Just generally eat such things sparingly. For the most part, eat more* fruits, veggies (in abundance), and whole grains. Eat less* meat (less red meat), dairy, and egg. Live culture yogurt is good. A daily vitamin is a good idea. Alcohol, if at all, in moderation. Be more active and less sedentary. Invigorating exercise regularly. What does more* mean? More than you are now. What does less* mean? Less than you are now. The Mediterranean Diet gets it pretty close.
Please feel free to contact me firstname.lastname@example.org, and www.drwaynecoghlan.com
Mediterranean Eating Habits Prove Good for the Brain A Mediterranean-style diet may slow memory loss, even if adopted late in life
By Dina Fine Maron | Aug 18, 2015
Aleks Sennwald Whenever the fictional character Popeye the Sailor Man managed to down a can of spinach, the results were almost instantaneous: he gained superhuman strength. Devouring any solid object similarly did the trick for one of the X-Men. As we age and begin to struggle with memory problems, many of us would love to reach for an edible mental fix. Sadly, such supernatural effects remain fantastical. Yet making the right food choices may well yield more modest gains.
A growing body of evidence suggests that adopting the Mediterranean diet, or one much like it, can help slow memory loss as people age. The diet's hallmarks include lots of fruits and vegetables and whole grains (as opposed to ultrarefined ones) and a moderate intake of fish, poultry and red wine. Dining mainly on single ingredients, such as pumpkin seeds or blueberries, however, will not do the trick.
What is more, this diet approach appears to reap brain benefits even when adopted later in life—sometimes aiding cognition in as little as two years. “You will not be Superman or Superwoman,” says Miguel A. Martínez González, chair of the department of preventive medicine at the University of Navarra in Barcelona. “You can keep your cognitive abilities or even improve them slightly, but diet is not magic.” Those small gains, however, can be meaningful in day-to-day life.
From Fork to Brain
Scientists long believed that altering diet could not improve memory. But evidence to the contrary started to emerge about 10 years ago. For example, Nikolaos Scarmeas of Columbia University and his colleagues collected information about the dietary habits and health status of about 2,000 Medicare-eligible New Yorkers—typically in their mid-70s—over the course of four years on average. In 2006 the investigators reported that tighter adherence to a Mediterranean diet, which had previously been linked to a lower risk of cardiovascular disease, was associated with slower cognitive decline and a lower likelihood of acquiring Alzheimer's disease. Because the researchers merely observed dietary patterns and did not control them—as would be the case in a clinical trial—doubts lingered, however. It was still possible that the apparent brain benefit was the result of chance or some other trait common to folks who consistently follow a Mediterranean diet in the U.S., such as educational achievement or particular life choices.
Seven years later researchers pinned down some answers. In 2013 Martínez González and his colleagues published findings on their massive PREDIMED study, an experiment that included almost 7,500 people in Spain. (PREDIMED stands for Prevention with Mediterranean Diet.) The investigators randomly assigned study subjects to one of two experimental groups. In the first, participants followed the Mediterranean diet with an additional helping of mixed nuts; in the second, they also adhered to the Mediterranean diet but were given additional extra virgin olive oil. (Researchers felt that providing extra nuts and oils at no cost to participants would guarantee that certain healthy fats were eaten in quantities large enough to have measurable effects on the study's outcomes.) The control group, against which the results of the experimental groups would be compared, was instructed generally on how to lose weight. Its members were given advice on eating vegetables, meat and high-fat dairy products that jibed with the Mediterranean diet, but they were discouraged from using olive oil for cooking and from consuming nuts.
As expected, the results showed that either of the experimental Mediterranean diet options led to significantly better cardiovascular outcomes. But when the scientists tested cognition in a subset of study members, they also discovered that individuals in either of the Mediterranean diet groups performed better than the weight-instruction group in a battery of widely accepted cognitive tests. “This is surprising, of course,” Martínez González says.
As intriguing as these findings are, they are still not conclusive; the researchers had not gathered any cognitive information at the beginning of the study. Therefore, the possibility remains that there was something different between the two experimental groups and the control group—beyond their diet interventions—that could account for the findings.
Martínez González sought to quiet such criticisms with a new study his team published in July in JAMA Internal Medicine. Drawing from a group of more than 300 participants who were also part of PREDIMED but at a specific site with more financial resources, the researchers conducted baseline cognitive measurements and compared them with that same group's results four years later. On average, people were 67 years old at the start of the study. The newest findings, Martínez González says, are consistent with what he found in his earlier studies. These results are also not definitive, however, because this substudy was relatively small. Yet, he notes, it is the first time scientists have seen improvements in cognitive function from a randomized trial of the Mediterranean diet.
Can Americans, whose standard diet and way of life are often substantially different from that of adults living in Spain, benefit from the approach? That remains to be seen. The normal diet of the people in the study's control group was still closer to a Mediterranean diet than that of most Americans, so they already had years of relatively healthy eating under their belts, which could have helped their overall health. But Martínez González believes that the diet might provide even greater benefits for Americans because they have so much more room for improvement. Still, nutrition expert Martha Morris of Rush University says, only a randomized trial in the U.S. can truly answer the question—something she hopes to spearhead in the coming years.
Proving that a particular cuisine affects cognitive health is one thing. Getting a lot of Americans to eat more fruits, vegetables, fish and olive oil is another matter altogether. Two major obstacles are cost and ingrained habits. For PREDIMED, study participants were supplied with expensive extra virgin olive oil and told how to prepare meals. “To transfer this knowledge to the American population, you can't just show them food items,” Martínez González says. “You have to show them how to shop for them, cook with them and prepare them to keep all the nutrients in line with the traditional Mediterranean diet.” The first step in the right direction, he says, would be for Americans to slash their consumption of red meats and use poultry instead. But that still leaves a lot of other steps to go before they are eating a Mediterranean diet.
Adhering to the exact diet laid out in PREDIMED may not be the only way to gain cognitive benefits from food. In February, Morris and her colleagues published online a study recommending a modified diet largely consistent with the Mediterranean diet but one cheaper to adopt in the U.S. Morris's so-called MIND diet emphasizes green, leafy plant and whole grain consumption. Its staples include two veggie servings a day, two berry servings a week and, instead of the almost daily fish consumption required in the Mediterranean diet, fish only once a week.
Morris found that even moderate adherence to the MIND diet for an average of 4.5 years appeared to reduce Alzheimer's risk compared with the Mediterranean and another diet. She and her colleagues judged that outcome by counting the number of cases of clinically diagnosed Alzheimer's among each group during the study period. (The comparison diets required stricter adherence to get the same cognitive benefit.) Better yet, the MIND diet may be more achievable for the average person's wallet and for American culture. In the bigger picture, this finding suggests that “people improving their diet can make a difference for their memory,” says Francine Grodstein, a professor focusing on healthy aging at Brigham and Women's Hospital in Boston and Harvard Medical School, who was not involved with the work.
Why certain food choices might help the brain function better remains unclear. Perhaps these regimens' known cardiovascular benefits, which promote a good flow of blood and oxygen to the brain, are key. But other factors may be at work. Of course, questions about when these dietary changes need to happen or how diet stacks up against other factors, such as physical activity, sleep patterns and genetics also remain unanswered.
Recently some researchers have begun broadening their focus beyond food alone. In the European Union, a multicountry randomized trial beginning this year is designed to provide further insights into how diet, exercise and better control of blood pressure could work together to promote brain health. (Hypertension is a leading cause of stroke, which can seriously harm mental processing.) Although the study will not allow scientists to pinpoint which factor offers the greatest benefit, it should give them a better understanding of how significant a role life changes can play.
There is reason to be hopeful. A pilot study published in June in the Lancet found that making changes in diet and habits later in life can slow the course of cognitive decline. Scandinavian researchers divided a group of 1,260 people in Finland either to receive standard nutrition and diet advice or to follow a specified exercise plan and eat a modified Mediterranean diet—all while their blood pressure and other health indicators were monitored and, if necessary, treated. Subjects in the experimental group ended up doing significantly better on standard tests of cognition. “We could really see that [the intervention] can protect against or at least delay cognitive impairments,” says lead study author Miia Kivipelto, director of research and education at the geriatric clinic at the Karolinska Institute in Stockholm. Unexpectedly, she says, those changes were visible within just two years. And best of all, superpowers are not required.
ABOUT THE AUTHOR(S) Dina Fine Maron is an associate editor at Scientific American. She focuses on medicine and health.
This article was originally published with the title "Brain Food."
Not all vegan or plant-based diets are equally healthy
By HENA PATEL and KIM ALLAN WILLIAMS SR.
AUGUST 22, 2017
Move over, low-fat diets. More and more experts are recommending plant-based diets to reduce the risk of heart disease and other chronic conditions such as diabetes and cancer. But are all plant-based diets equally beneficial? And must they be all-or-none eating strategies, or is there a role for a semi-vegetarian or “flexitarian” approach?
The term plant-based diet often conjures up images of vegetarian or vegan fare. But it really means a diet that emphasizes foods from plants — vegetables, fruits, grains, nuts, seeds, and the like — not one that necessarily excludes non-plant foods.
The results of studies on the health effects of plant-based diets have varied widely, largely due to how these diets were defined. Some focused on vegetarian or vegan eating habits, others included some foods from animals. Notably, these studies tended to treat all plant foods equally, even though eating certain foods from plants, such as refined grains and sugar-sweetened beverages, is associated with a higher risk of developing diabetes or having a heart attack or stroke, while eating whole grains and produce are associated with lower risks.
That’s why we were so interested to see the results of a recently published study performed by researchers at the Harvard T.H. Chan School of Public Health. Led by Ambika Satija, the team catalogued the diets of nearly 210,000 nurses and other health professionals based on their answers to food frequency questionnaires every two years for an average of 23 years. From these data, the researchers defined three versions of a plant-based diet: an overall plant-based diet that emphasizes the consumption of all plant foods and reduced the intake of animal foods; a healthful plant-based diet that emphasizes the intake of healthy whole grains, fruits, and vegetables; and an unhealthful plant-based diet that emphasizes the intake of less-healthy plant foods, such as refined grains.
In addition to detailing their food choices, the study participants also recorded other lifestyle choices, health behaviors, and their medical histories.
Over the course of the study, 8,631 participants developed coronary heart disease, which the researchers defined as a nonfatal heart attack or dying of heart disease. Those who followed an overall plant-based diet were slightly less likely (an 8 percent reduction) to have developed coronary heart disease than those who didn’t.
But here’s where things get interesting. Those who followed a healthful plant-based diet had a substantial 25 percent lower risk of coronary heart disease, while those who followed an unhealthful plant-based diet had a substantial 32 percent increased risk.
This study is certainly not the last word on the subject. As an observational study, it can’t prove cause and effect like a randomized trial can. And the diet data came from self reports, which aren’t always accurate at measuring an individual’s diet. However, these diet assessments were validated against multiple-week diet records and biomarkers. Overall, this work adds to the substantial evidence that a predominately plant-based diet reduces the risk of developing heart disease.
It has two important take-home messages. One is that a plant-based diet is good for long-term health. The other is that not all plant-based diets are equally healthy. The kind that deserves to be highlighted in dietary recommendations is rich in fruits and vegetables, whole grains, and unsaturated fats, and contains minimal animal protein, refined carbohydrates, and harmful saturated and trans fats.
In practice, this translates into eating mostly vegetables, fruits, whole grains, legumes, and soy products in their natural forms; sufficient “good fats,” such as those in fish or flax seeds, nuts, and other seeds; very few simple and refined carbohydrates; and little or no red meat, poultry, fish, eggs, and dairy. It also means choosing quality over quantity.
Click here for a link to a description of the Mediterranean Diet.