The new pyramid attempts to provide individualize advice based on a person ‘s age, gender and horizontal surface of physical natural process. It focuses on the consumption of grains, kernel and beans, milk, vegetables, fruit, and oils .
The 2005 pyramid replaced a 1992 USDA pyramid that differed from it in several respects. The modern pyramid provides more emphasis on solid grains and physical natural process. It does not, however, solve all the problems associated with its predecessor, because it still places excessively much vehemence on grains and milk and does not sufficiently emphasize the adverse effects of some types of fat. Unlike the old pyramid ‘s graphic representation, which showed the proportions of diverse foods that should be consumed as stack layers of different sizes, the 2005 pyramid conveys no information about nutriment ; it plainly shows a calculate ascending a rainbow-colored stairway [ see box on page 17 ] .
We have drawn up a revised pyramid that better reflects the stream evidence regarding the relation between diet and health. Studies indicate that adhesiveness to the recommendations in our revised pyramid can importantly reduce the gamble of cardiovascular disease for both men and women.
Reading: Rebuilding the Food Pyramid
The Old Food Pyramid
THE USE OF IMAGES to promote dietary advice goes back closely a century in the U.S. The recommendations embodied in the 1992 pyramid were wide adopted, and the picture became an icon. The basic advice was that people should minimize their consumption of fats and oils but should eat six to 11 servings a day of foods rich in complex carbohydrates — bread, grain, rice, pasta and thus on. The food pyramid besides recommended generous amounts of vegetables ( including potatoes, another bountiful beginning of complex carbohydrates ), fruit and dairy products, and at least two servings a day from the kernel and beans group, which lumped together red kernel with poultry, fish, nuts, legumes and eggs .
even when the pyramid was being developed, though, nutritionists had long known that some types of fat are all-important to health and can reduce the risk of cardiovascular disease. furthermore, scientists had found little evidence that a eminent inhalation of carbohydrates is beneficial. After 1992 more and more research showed that the USDA pyramid was grossly flawed. By promoting the consumption of all complex carbohydrates and eschewing all fats and oils, the pyramid provided misinform guidance. In short, not all fats are bad for you, and by no means are all complex carbohydrates good for you .
How did the original USDA pyramid go then faulty ? In region, nutritionists fell victim to a desire to simplify their dietary recommendations. Researchers had known for decades that saturated fat — found in abundance in red kernel and dairy products — raises cholesterol levels in the blood. High cholesterol levels, in turn, are associated with a high gear risk of coronary heart disease ( center attacks and early ailments caused by the obstruction of the arteries to the affection ). In the 1960s controlled feeding studies, in which the participants ate cautiously prescribed diets for several weeks, substantiated that saturated fat increases cholesterol levels. But the studies besides showed that polyunsaturated fatty — found in vegetable oils and pisces — reduces cholesterol. thus, dietary advice during the 1960s and 1970s emphasized the successor of impregnate fat with polyunsaturated fat, not total adipose tissue decrease .
The impression that fat in general is to be avoided stems chiefly from observations that feeder western countries have both high intakes of adipose tissue and high rates of coronary thrombosis kernel disease. This correlation coefficient, however, is limited to saturated fatness. Societies in which people eat relatively large portions of monounsaturated and polyunsaturated fat tend to have lower rates of center disease [ see box on page 21 ] .
On the Greek island of Crete, for exercise, the traditional diet contained much olive petroleum ( a full-bodied reference of monounsaturated fat ) and pisces ( a source of polyunsaturated fat ). Although fat constituted 40 percentage of the calories in this diet, the rate of affection disease for those who followed it was lower than the rate for those who followed the traditional diet of Japan, in which fat made up only 8 to 10 percentage of the calories. Furthermore, international comparisons can be mislead : many negative influences on health, such as smoke, physical inactiveness and high amounts of body fatten, are besides correlated with western affluence .
unfortunately, many nutritionists decided it would be besides unmanageable to educate the public about these subtleties. alternatively they put out a clear up, simple message : “ Fat is bad. ” Because saturated fat represents about 40 percentage of all fat consumed in the U.S., the rationale of the USDA was that advocating a low-fat diet would naturally reduce the inhalation of saturated fat. This recommendation was soon reinforced by the food industry, which began selling cookies, chips and other products that were depleted in fatty but often high in sweeteners such as sucrose and high-fructose corn syrup .
When the original food pyramid was being developed, the typical American got approximately 40 percentage of his or her calories from fatten, about 15 percentage from protein and about 45 percentage from carbohydrates. Nutritionists did not want to suggest eating more protein, because many sources of protein ( red kernel, for example ) are besides fleshy in saturate fatness. So the “ Fat is bad ” mantra led to the corollary “ Carbs are thoroughly. ” dietary guidelines from the American Heart Association and early groups recommended that people get at least half their calories from carbohydrates and no more than 30 percentage from fatness. This 30 percentage limit has become indeed entrenched among nutritionists that evening the advanced perceiver could be forgiven for thinking that many studies must show that individuals with that level of fat intake enjoy better health than those with higher levels. But no sketch has demonstrated long-run health benefits that can be directly attributed to a low-fat diet. The 30 percentage limit on fat was basically drawn from dilute air .
The wisdom of solomon of this guidance became even more questionable after researchers found that the two independent cholesterol-carrying chemicals — low-density lipoprotein ( LDL ), popularly known as bad cholesterol, and high-density lipoprotein ( HDL ), known as good cholesterol — have very different effects on the hazard of coronary thrombosis heart disease. Increasing the ratio of LDL to HDL in the blood raises the hazard, whereas decreasing the ratio lowers it. By the early 1990s controlled fertilize studies had shown that when a person replaces calories from saturated fat with an equal amount of calories from carbohydrates the levels of LDL and full cholesterol fall, but the degree of HDL besides falls. Because the proportion of LDL to HDL does not change, there is merely a small reduction in the person ‘s risk of heart disease. furthermore, the throw to carbohydrates boosts the rake levels of triglycerides, the component molecules of fat, probably because of effects on the torso ‘s hormone system. gamey triglyceride levels are besides associated with a high risk of heart disease .
The effects are more grievous when a person switches from either monounsaturated or polyunsaturated fat to carbohydrates. LDL levels wax and HDL levels drop, making the cholesterol ratio worse. In contrast, replacing saturated fatten with either monounsaturated or polyunsaturated adipose tissue improves this proportion and would be expected to reduce heart disease. The only fats that are significantly more deleterious than carbohydrates are the trans-unsaturated fatso acids ; these are produced by the fond hydrogenation of liquid vegetable oil, which causes it to solidify. Found in many margarines, baked goods and fry foods, trans fats are uniquely bad for you because they raise LDL and triglycerides while reducing HDL .
The New Food Pyramid
THE 2005 PYRAMID provided a singular opportunity to draw on more than a twelve years of advances in nutritional science. Although the fresh pyramid improved on the 1992 version in respective ways, overall it was a major disappointment to many nutriment experts. A big change is that the basic image nobelium longer conveys any data about diet — the calculate climbing the pyramid promotes physical action, but to get any dietary advice, one must visit the Web site www.mypyramid.gov and make selections for senesce, gender and stream flat of physical action. thus, a marvelous opportunity to provide compendious dietary advice to consumers was squandered, and the impact of the fresh pyramid on diet most likely will be modest compared with what it might have been .
The dietary advice that accompanies the pyramid, for those who navigate the Web web site, represents some clear improvements over the 1992 version. whole grains are emphasized more ; the distinction between types of fats is clearer ; and healthier choices for protein sources are emphasized. But these are only incremental changes and do not fully reflect the best dietary advice available today .
The Big Picture
TO EVALUATE FULLY the health effects of diet, one must look beyond cholesterol ratios and triglyceride levels. The foods we eat can cause kernel disease through many other pathways, including raising blood atmospheric pressure or boosting the inclination of lineage to clot. And other foods can prevent affection disease in surprise ways ; for exemplify, omega-3 fatty acid fatty acids ( found in fish and some plant oils ) can reduce the likelihood of ventricular fibrillation, a heart rhythm noise that causes sudden end .
The ideal method acting for assessing all these adverse and beneficial effects would be to conduct large-scale trials in which individuals are randomly assigned to one diet or another and followed for many years. Because of virtual constraints and price, few such studies have been conducted, and most of these have focused on patients who already suffer from affection disease. Though restrict, these studies have supported the benefits of replacing saturated fat with polyunsaturated adipose tissue, but not with carbohydrates. In the most expensive study always conducted — the Women ‘s Health Initiative — closely 50,000 women were randomly assigned to either a low-fat diet or their common diet. The results, reported in early 2006 after approximately eight years, showed no dispute in health between the two groups .
The best alternative is to conduct large epidemiologic studies in which the diets of many people are sporadically assessed and the participants are monitored for the exploitation of heart disease and early conditions. One of the best-known examples of this inquiry is the Nurses ‘ Health Study, which was begun in 1976 to evaluate the effects of oral contraceptives but was soon extended to nutrition a well. Our group at Harvard University has followed closely 90,000 women in this survey who beginning completed detailed questionnaires on diet in 1980, a well as more than 50,000 men who were enrolled in the Health Professionals Follow-Up Study in 1986 .
After adjusting the psychoanalysis to account for smoke, physical bodily process and early recognized gamble factors, we found that a participant ‘s risk of affection disease was powerfully influenced by the type of dietary fatty consumed. Eating trans adipose tissue increased the risk substantially, and eating saturated fatty increased it slightly. In contrast, eating monounsaturated and polyunsaturated fats decreased the gamble — just as the see feed studies predicted. Because these two effects counterbalanced each early, higher overall consumption of fat did not lead to higher rates of coronary thrombosis heart disease. This find reinforced a 1989 report by the National Academy of Sciences that concluded that the type of fat, but not the percentage of calories from sum fat, is an important component in the growth of affection disease risk .
But what about illnesses besides coronary heart disease ? high rates of breast, colon and prostate cancers in affluent western countries have led to the impression that the consumption of fatty, particularly animal fat, may be a risk component. But boastfully epidemiologic studies have shown little evidence that entire fat pulmonary tuberculosis or intakes of specific types of fat during midlife affect the risks of breast or colon cancer. Some studies have indicated that prostate cancer and the consumption of animal fat may be associated, but reassuringly there is no suggestion that vegetable oils increase any cancer risk. indeed, some studies have suggested that vegetable oils may slightly reduce such risks .
last, one must consider the impact of fatty consumption on fleshiness, the most unplayful nutritional problem in the U.S. Obesity is a major hazard divisor for respective diseases, including type 2 diabetes ( besides called adult-onset diabetes ), coronary thrombosis heart disease, and cancers of the front, colon, kidney and esophagus. many nutritionists believe that eating fatness can contribute to weight reach because adipose tissue contains more calories per gram than protein or carbohydrates. besides, the process of storing dietary fat in the torso may be more efficient than the conversion of carbohydrates to body fat. But recent controlled feeding studies have shown that these considerations are not practically significant. The best way to avoid fleshiness is to limit your total calories, not equitable the adipose tissue calories. So the critical emergence is whether the fatness composition of a diet can influence one ‘s ability to control calorie inhalation. In other words, does eating fat leave you more or less athirst than eating protein or carbohydrates ? There are assorted theories about why one diet should be better than another, but few long-run studies have been done. In randomize trials, individuals assigned to low-fat diets tend to lose a few pounds during the first months but then regain the burden. In studies lasting a year or longer, low-fat diets have systematically not led to greater weight loss .
The text accompanying the new pyramid provides some improvement over the 1992 interpretation in recognizing that some fats ( trans and saturated ) are worse than others ( poly and monounsaturated ). unfortunately, it treats trans and saturated fats the same way, flush though trans fat from hydrogenated vegetable oils is at least twice a harmful, on a gram-for-gram footing. And unlike saturated fat, it can potentially be eliminated from the diet. besides, the new pyramid largely ignores the positive benefits of sanitary oils .
NOW LET ‘S LOOK at the health effects of carbohydrates. Complex carbohydrates dwell of long chains of sugar units such as glucose and fructose ; sugars contain only one or two units. Because of concerns that sugars offer nothing but “ evacuate calories ” — that is, no vitamins, minerals or other nutrients — complex carbohydrates form the infrastructure of the USDA food pyramid. But polished carbohydrates, such as white boodle and white rice, can be very cursorily broken down to glucose, the primary fuel for the body. The refine process produces an well absorb form of starch — which is defined as glucose molecules bound in concert — and besides removes many vitamins and minerals and fiber. thus, these carbohydrates increase glucose levels in the blood more than whole grains do. ( whole grains have not been milled into ticket flour. )
Read more: The Best Foods to Eat When You Are Sick
Or consider potatoes. Eating a boiled potato raises lineage carbohydrate levels higher than eating the same sum of calories from table sugar. Because potatoes are by and large starch, they can be quickly metabolized to glucose. In contrast, mesa sugar ( sucrose ) is a disaccharide dwell of one molecule of glucose and one molecule of fructose. Fructose takes longer to convert to glucose, hence the slower rise in blood glucose levels .
A rapid increase in blood sugar stimulates a large release of insulin, the hormone that directs glucose to the muscles and liver-colored. As a result, blood sugar plummets, sometimes even going below the baseline. high levels of glucose and insulin can have negative effects on cardiovascular health, raising triglycerides and lowering HDL ( the good cholesterol ). The abrupt decline in glucose can besides lead to more starve after a carbohydrate-rich meal and thus contribute to overeating and fleshiness .
In our epidemiologic studies, we have found that a high intake of starch from refined grains and potatoes is associated with a high risk of type 2 diabetes and coronary heart disease. conversely, a greater inhalation of roughage is related to a lower risk of these illnesses. Interestingly, though, the consumption of character did not lower the risk of colon cancer, as had been hypothesized earlier .
Overweight, passive people can become immune to insulin ‘s effects and therefore require more of the hormone to regulate their lineage carbohydrate. recent evidence indicates that the adverse metabolic reception to carbohydrates is well worse among people who already have insulin resistance. This recover may account for the ability of peasant farmers in Asia and elsewhere, who are extremely lean and active voice, to consume large amounts of refine carbohydrates without experiencing diabetes or heart disease, whereas the same diet in a more sedentary population can have crushing effects .
The new pyramid appropriately provides more vehemence on hale grains, but it even implies that getting one-half of your grains as refined starch is desirable, whereas these carbohydrate sources should be used meagerly. Further, the new pyramid gives insufficient care to total sugars and sugar voiced drinks, which constitute about 8 percentage of all calories consumed in the U.S. — more than any other food detail .
Eat Your Veggies
HIGH INTAKE OF FRUITS and vegetables is possibly the least controversial aspect of the 1992 food pyramid, and the 2005 pyramid gives them even greater emphasis than before.A decrease in cancer risk has been a widely promoted profit. But most of the evidence for this benefit has come from case-control studies, in which patients with cancer and selected restraint subjects are asked about their earlier diets. These retrospective studies are susceptible to numerous biases, and holocene findings from large prospective studies ( including our own ) have tended to show little relation between overall fruit and vegetable consumption and cancer incidence. ( specific nutrients in fruits and vegetables may offer benefits, though ; for example, the folic acid in fleeceable leafy vegetables may reduce the hazard of colon cancer, and the lycopene found in tomatoes may lower the risk of prostate gland cancer. )
The real rate of eating fruits and vegetables may be in reducing the risk of cardiovascular disease. Folic acid and potassium appear to contribute to this effect, which has been seen in several epidemiologic studies. Inadequate consumption of folic acid is creditworthy for higher risks of dangerous birth defects vitamin a well, and moo intake of xanthophyll, a pigment in greens leafy vegetables, has been associated with greater risks of cataracts and degeneration of the retina. Fruits and vegetables are besides the basal source of many vitamins needed for good health. therefore, there are good reasons to consume the recommend five servings a day, even if doing so has little impact on cancer risk. The inclusion of potatoes as a vegetable in the USDA pyramid has small justification, however ; being chiefly starch, potatoes do not confer the benefits seen for other vegetables .
Another defect in both the previous and new versions of the USDA pyramid is its failure to recognize the important health differences between red meat ( gripe, pork barrel and lamb ) and the other foods in the kernel and beans group ( poultry, fish, legumes, nuts and eggs ). high consumption of red meat has been associated with an increased risk of coronary thrombosis center disease, probably because of its high contentedness of saturate adipose tissue and cholesterol. Red kernel besides raises the risk of type 2 diabetes and colon cancer. The lift hazard of colon cancer may be related in part to the carcinogens produced during cooking and the chemicals found in processed meats such as salami and bologna .
domestic fowl and pisces, in contrast, contain less saturated fat and more unsaturated fatten than crimson kernel does. Fish is a rich source of the essential omega-3 fatty acid fatty acids adenine well. not amazingly, studies have shown that people who replace bolshevik kernel with chicken and fish have a lower gamble of coronary heart disease and colon cancer. Eggs are high in cholesterol, but pulmonary tuberculosis of up to one a sidereal day does not appear to have adverse effects on heart disease hazard ( except among diabetics ), probably because the effects of a slightly higher cholesterol level are counterbalanced by early nutritional benefits .
many people have avoided nuts because of their high fat capacity, but the fat in nuts, including peanuts, is chiefly unsaturated, and walnuts in particular are a good informant of omega-3 fatty acid fatty acids. Controlled feeding studies show that nuts improve blood cholesterol ratios, and epidemiologic studies indicate that they lower the risk of heart disease and diabetes. besides, people who eat nuts are actually less likely to be corpulent ; possibly because nuts are more hearty to the appetite, eating them seems to have the consequence of significantly reducing the intake of other foods .
yet another concern regarding both versions of the USDA pyramid is that they promote overconsumption of dairy products, recommending the equivalent of three glasses of milk a day for most individuals. This advice is normally justified by dairy ‘s calcium contented, which is believed to prevent osteoporosis and bone fractures. But the highest rates of fractures are found in countries with high dairy consumption, and boastfully prospective studies have not shown a lower risk of fractures among those who eat batch of dairy products. calcium is an essential alimentary, but the requirements for bone health have probably been overstated. What is more, we can not assume that high dairy pulmonary tuberculosis is safe : in several studies, men who consumed large amounts of dairy products experienced an increased risk of prostate gland cancer, and in some studies, women with high intakes had elevated rates of ovarian cancer. Although fat was initially assumed to be the responsible factor, this has not been supported in more detailed analyses. high calcium intake itself seemed most clearly related to the risk of prostate cancer .
More inquiry is needed to determine the health effects of dairy products, but at the moment it seems imprudent to recommend high consumption. Most adults who are following a good overall diet can get the necessary come of calcium by consuming the equivalent of one glass of milk a day. Under certain circumstances, such as after menopause, women may need more calcium, but it can be obtained at lower cost and without saturated fat or calories by taking a append .
A Healthier Pyramid
ALTHOUGH THE USDA ‘S food pyramid has become an icon of nutriment over the past decade, until recently no studies had evaluated the health of individuals who followed its guidelines. It very likely has some benefits, particularly from a high consumption of fruits and vegetables. And a decrease in total fat inhalation would tend to reduce the pulmonary tuberculosis of harmful saturated and trans fats. But the pyramid could besides lead people to eat fewer of the healthy unsaturated fats and more starches, so the benefits might be negated by the damage .
To evaluate the overall impact, we used the Healthy Eating Index ( HEI ), a score developed by the USDA to measure adhesiveness to the 1992 pyramid and its accompanying dietary guidelines in federal nutriment programs. From the data collected in our big epidemiologic studies, we calculated each player ‘s HEI grade and then examined the relation of these scores to subsequent hazard of major chronic disease ( defined as center attack, stroke, cancer or nontraumatic death from any cause ). When we compared people in the lapp senesce groups, women and men with the highest HEI scores did have a lower gamble of major chronic disease. But these individuals besides smoked less, exercised more and had broadly healthier lifestyles than the other participants. After adjusting for these variables, we found that participants with the highest HEI scores did not experience significantly better overall health outcomes. As predicted, the 1992 pyramid ‘s harms counterbalanced its benefits. The modern pyramid has yet to be evaluated in this manner, but because its basic advice is similar to that given by the earlier pyramid, the effect on health outcomes will credibly be similar as well .
The best feature of the new pyramid is its net vehemence on forcible bodily process. This is applaudable but does not help people choose what to eat. The modern pyramid provides “ custom-make ” dietary advice based on sex and long time but regardless of torso size — so a six-foot-six-inch-tall, 330-pound world gets the like advice as a 5-foot-3-inch-tall world weighing 120 pounds .
Because the goal of the USDA pyramids was a desirable one — to encourage healthy dietary choices — we have tried to develop an option derived from the best available cognition. Our revised pyramid [ see box on page 18 ] emphasizes weight dominance through exercising daily and avoiding an excessive entire consumption of calories. This pyramid recommends that the majority of one ‘s diet should consist of healthy fats ( liquid vegetable oils such as olive, canola oil, soy, corn, sunflower and peanut ) and healthy carbohydrates ( whole grain foods such as unharmed wheat boodle, oatmeal and brown rice ) .
If both the fats and carbohydrates in your diet are healthy, you credibly do not have to worry besides much about the percentages of total calories coming from each. Fruits and vegetables should besides be eaten in abundance. moderate amounts of healthy sources of protein ( nuts, legumes, fish, domestic fowl and eggs ) are encouraged, but dairy consumption should be limited to one to two servings a day. The revised pyramid recommends minimizing the pulmonary tuberculosis of red kernel, butter, refined grains ( including white bread, white rice and white pasta ), potatoes and boodle .
Trans fat does not appear at all in the pyramid, because it has no place in a healthy diet. A multiple vitamin is suggested for most people, and centrist alcohol consumption can be a worthwhile option ( if not contraindicated by specific health conditions or medications ). This last recommendation comes with a caution : drink no alcohol is clearly better than drinking besides a lot. But more and more studies are showing the benefits of moderate alcohol pulmonary tuberculosis ( in any phase : wine, beer or spirits ) to the cardiovascular system .
Can we show that our pyramid is healthier than the USDA ‘s ? We devised a raw Healthy Eating Index that measured how closely a person ‘s diet followed our recommendations. Applying this revised index to our epidemiologic studies, we found that men and women who were eating in accordance with the modern pyramid had a lower risk of major chronic disease [ see box on opposite page ]. This benefit resulted about entirely from significant reductions in the hazard of cardiovascular disease — up to 30 percentage for women and 40 percentage for men. Following the new pyramid ‘s guidelines did not, however, lower the risk of cancer. Weight master and physical activity, rather than specific food choices, are associated with a reduce risk of many cancers.
Of course, uncertainties still cloud our sympathy of the relative between diet and health. More research is needed to examine the role of dairy products, the health effects of particular fruits and vegetables, the risks and benefits of vitamin supplements, and the long-run effects of diet during childhood and early adult life. The interaction of dietary factors with genetic sensitivity should besides be investigated, although its importance remains to be determined .
Another challenge will be to ensure that the data about nutriment given to the populace is based rigorously on scientific attest. The USDA may not be the best politics means to develop objective nutritional guidelines, because it may be excessively close linked to the agricultural industry. The food pyramid should be rebuilt in a fix that is well insulated from political and economic interests .
WALTER C. WILLETT and MEIR J. STAMPFER are professors of epidemiology and nutrition at the Harvard School of Public Health. Willett chairs the school ‘s department of nutrition, and Stampfer heads the department of epidemiology. Willett and Stampfer are besides professors of medicine at Harvard Medical School. Both of them commit what they preach by eating well and exercising regularly .