<html>
<head>
<title>Jay's World of Abstracts 00027: Rebuilding the Food Pyramid</title>
<meta name="keywords"
content="mcch, nutrition, cancer, heart, prevention, intervention">
<meta name="description"
content="An abstract of an article with changes to be made to the USDA Food Pyramid that are based on research.">
</head>
<body>
<h2 align="right">Jay's World of Abstracts 00027</h2><hr>
<div align="center"><h1>Rebuilding the Food Pyramid</h1>
by Walter C. Willett and Meir J. Stampfer<br>
ScientificAmerican.com -- December 17, 2002</div>
<hr>
<i>[Standard disclaimer: The nature of abstracts are that they are pieces of something larger. Not everyone is going to be happy with my choice of abstracts from any larger work, so if you are dissatisfied, I would refer you to the original document, which should be able to be found on the Internet. I encourage others to make their own abstracts to satisfy their needs. I would be happy to publish them here.</i>
<h3>Jay's Introduction</h3>
<p>Since the time I was the area WIC nutritionist (1995-1997), the Food Guide Pyramid put out by the USDA was considered the most sensible exposition on nutritional needs, oft copied by nations around the world. There were always certain problems with it, often because of the need to keep it simple enough for "regular" people to understand and use.</p>
<p>There is a growing desire to update the Pyramid or do away with it in favor of recommendations that are based more strongly on nutritional research. This article is another proposal for how new nutritional guidelines should look.</p>
<i>I produced this abstract using time paid for by the Quay County Maternal Child and Community Health Council with funds from the New Mexico Department of Health.</i>
<hr>
<h3>Abstracts</h3>
<p>In 1992 the U.S. Department of Agriculture
officially released the Food Guide Pyramid, which was intended to help the
American public make dietary choices that would maintain good health and
reduce the risk of chronic disease. The recommendations embodied in the
pyramid soon became well known: 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, cereal, rice, pasta and so on. The food
pyramid also recommended generous amounts of vegetables (including
potatoes, another plentiful source of complex carbohydrates), fruit and
dairy products, and at least two servings a day from the meat and beans
group, which lumped together red meat with poultry, fish, nuts, legumes
and eggs.</p>
<i>[...]</i>
<P>Unfortunately, many nutritionists decided it would be too difficult to
educate the public about these subtleties <i>[saturated vs. unsaturated fats; red meat vs. poultry/fish]</i>. Instead they put out a clear,
simple message: "Fat is bad." Because saturated fat represents about 40
percent of all fat consumed in the U.S., the rationale of the USDA was
that advocating a low-fat diet would naturally reduce the intake of
saturated fat. This recommendation was soon reinforced by the food
industry, which began selling cookies, chips and other products that were
low in fat but often high in sweeteners such as high-fructose corn syrup.
<P>When the food pyramid was being developed, the typical American got
about 40 percent of his or her calories from fat, about 15 percent from
protein and about 45 percent from carbohydrates. Nutritionists did not
want to suggest eating more protein, because many sources of protein (red
meat, for example) are also heavy in saturated fat. So the "Fat is bad"
mantra led to the corollary "Carbs are good." Dietary guidelines from the
American Heart Association and other groups recommended that people get at
least half their calories from carbohydrates and no more than 30 percent
from fat. This 30 percent limit has become so entrenched among
nutritionists that even the sophisticated observer could be forgiven for
thinking that many studies must show that individuals with that level of
fat intake enjoyed better health than those with higher levels. But no
study has demonstrated long-term health benefits that can be directly
attributed to a low-fat diet. The 30 percent limit on fat was essentially
drawn from thin air. </p>
<i>[...]</i>
<P>Finally, one must consider the impact of fat consumption on obesity,
the most serious nutritional problem in the U.S. Obesity is a major risk
factor for several diseases, including type 2 diabetes (also called
adult-onset diabetes), coronary heart disease, and cancers of the breast,
colon, kidney and esophagus. Many nutritionists believe that eating fat
can contribute to weight gain because fat contains more calories per gram
than protein or carbohydrates. Also, the process of storing dietary fat in
the body 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 important. The best way to avoid
obesity is to limit your total calories, not just the fat calories. So the
critical issue is whether the fat composition of a diet can influence
one's ability to control caloric intake. In other words, does eating fat
leave you more or less hungry than eating protein or carbohydrates? There
are various theories about why one diet should be better than another, but
few long-term studies have been done. In randomized trials, individuals
assigned to low-fat diets tend to lose a few pounds during the first
months but then regain the weight. In studies lasting a year or longer,
low-fat diets have consistently not led to greater weight loss. </p>
<P><B>Carbo-Loading</B><BR>Now let's look at the health effects of
carbohydrates. Complex carbohydrates consist 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 "empty calories"--that
is, no vitamins, minerals or other nutrients--complex carbohydrates form
the base of the USDA food pyramid. But refined carbohydrates, such as
white bread and white rice, can be very quickly broken down to glucose,
the primary fuel for the body. The refining process produces an easily
absorbed form of starch--which is defined as glucose molecules bound
together--and also 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 fine flour.)
<P>Or consider potatoes. Eating a boiled potato raises blood sugar levels
higher than eating the same amount of calories from table sugar. Because
potatoes are mostly starch, they can be rapidly metabolized to glucose. In
contrast, table sugar (sucrose) is a disaccharide consisting 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. </p>
<i>[...]</i>
<P>In our epidemiological 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 intake
of fiber is related to a lower risk of these illnesses. Interestingly,
though, the consumption of fiber did not lower the risk of colon cancer,
as had been hypothesized earlier. </p>
<i>[...]</i>
<P>Poultry and fish, in contrast<i>[to red meats]</i>, contain less saturated fat and more
unsaturated fat than red meat does. Fish is a rich source of the essential
omega-3 fatty acids as well. Not surprisingly, studies have shown that
people who replace red meat with chicken and fish have a lower risk of
coronary heart disease and colon cancer. Eggs are high in cholesterol, but
consumption of up to one a day does not appear to have adverse effects on
heart disease risk (except among diabetics), probably because the effects
of a slightly higher cholesterol level are counterbalanced by other
nutritional benefits. Many people have avoided nuts because of their high
fat content, but the fat in nuts, including peanuts, is mainly
unsaturated, and walnuts in particular are a good source of omega-3 fatty
acids. Controlled feeding studies show that nuts improve blood cholesterol
ratios, and epidemiological studies indicate that they lower the risk of
heart disease and diabetes. Also, people who eat nuts are actually less
likely to be obese; perhaps because nuts are more satisfying to the
appetite, eating them seems to have the effect of significantly reducing
the intake of other foods.
<P>Yet another concern regarding the USDA pyramid is that it promotes
overconsumption of dairy products, recommending the equivalent of two or
three glasses of milk a day. This advice is usually justified by dairy's
calcium content, which is believed to prevent osteoporosis and bone
fractures. But the highest rates of fractures are found in countries with
high dairy consumption, and large prospective studies have not shown a
lower risk of fractures among those who eat plenty of dairy products.
Calcium is an essential nutrient, but the requirements for bone health
have probably been overstated. What is more, we cannot assume that high
dairy consumption is safe: in several studies, men who consumed large
amounts of dairy products experienced an increased risk of prostate
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.
<P>More research 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 amount of calcium by consuming the equivalent of one glass of
milk a day. Under certain circumstances, such as after menopause, people
may need more calcium than usual, but it can be obtained at lower cost and
without saturated fat or calories by taking a supplement.</p>
<i>[...]</i>
<P>Can we show that our pyramid is healthier than the USDA's? We created a
new Healthy Eating Index that measured how closely a person's diet
followed our recommendations. Applying this revised index to our
epidemiological studies, we found that men and women who were eating in
accordance with the new pyramid had a lower risk of major chronic disease.
This benefit resulted almost entirely from significant reductions in the
risk of cardiovascular disease--up to 30 percent for women and 40 percent
for men. Following the new pyramid's guidelines did not, however, lower
the risk of cancer. Weight control and physical activity, rather than
specific food choices, are associated with a reduced risk of many cancers.
<P>Of course, uncertainties still cloud our understanding of the relation
between diet and health. More research is needed to examine the role of
dairy products, the health effects of specific fruits and vegetables, the
risks and benefits of vitamin supplements, and the long-term effects of
diet during childhood and early adult life. The interaction of dietary
factors with genetic predisposition should also be investigated, although
its importance remains to be determined.
<P>Another challenge will be to ensure that the information about
nutrition given to the public is based strictly on scientific evidence.
The USDA may not be the best government agency to develop objective
nutritional guidelines, because it may be too closely linked to the
agricultural industry. The food pyramid should be rebuilt in a setting
that is well insulated from political and economic interests. </p>
</body>
</html>
