Eat, Drink, and Be Healthy
Walter C. Willett
FUTURECASTS online magazine
Vol. 4, No. 11, 11/1/02.
Authoritative myths from the USDA:
The USDA misinformation contributes to overweight, poor health, and unnecessary early deaths.
This Harvard Medical School Guide to Healthy Eating - "Eat, Drink, and Be Healthy" by Walter C. Willett, - co-developed with The Harvard School of Public Health - reassuringly starts with a blast at the U.S. Department of Agriculture's "Food Guide Pyramid."
In the tug of war between public health and agricultural interests, the USDA naturally favored the agricultural interests.
"Competing powerful interests, few of which had your health as a central goal," shaped the USDA Pyramid. In the tug of war between public health and agricultural interests, the USDA naturally favored the agricultural interests. Its Pyramid is actually designed to promote agricultural products.
Instead, Walter C. Willett offers a "Healthy Eating Pyramid." This is not a weight loss diet or a diet to overcome specific diseases. It is a guide - based on ordinary foods - that suggests changes that can "improve health and reduce the risk of chronic disease."
Willett candidly concedes that his Healthy Eating Pyramid may well change to reflect the scientific evidence constantly being developed. He also recommends the food guide pyramids developed by Oldways Preservation and Exchange Trust, the Asian Pyramid, the Latin Pyramid, the Mediterranean Pyramid, and the vegetarian pyramid. However, these don't take advantage of the latest research and are constrained by specific cultures so that they exclude many good foods now available from other cultures.
Willett's Healthy Eating Pyramid rests on solid scientific epidemiological research going back at least two decades.
Daily exercise and weight control
is emphasized by placing them at the broad base of the Healthy Eating Pyramid. The
next three levels include basic foods. To be employed at most meals are whole
grain foods - plant oils such as olive, canola, soy, corn, sunflower and peanut
oils - and vegetables and fruits. Just above these come nuts & legumes (one
to three times per day). Then, fish, poultry or eggs (up to twice a day).
Willett justly deplores "the pressures of modern medicine and health care [that] often make it difficult for clinicians to spend time talking about healthy food choices with their patients. (All clinical practice inevitably suffers when modern third-party-payer mass medicine restricts the time that doctors spend with patients.)
The USDA Food Guide Pyramid:
Not only is the USDA Food Guide Pyramid devoid of scientific guidance, it now determinedly ignores the growing amount of scientific evidence flowing out of modern epidemiological studies and other scientific data.
The monounsaturated and polyunsaturated fats found in vegetable oils, nuts, whole grains, and fish "are good for your heart."
Refined (white) bread and rice and baked potatoes are turned into glucose (sugar) by the body and pumped into the bloodstream "almost as fast as it delivers the sugar in a cocktail of pure glucose."
Surges of blood sugar and the insulin responses they trigger are now implicated in the processes leading to heart disease and diabetes.
Red meat comes with too much saturated fat and cholesterol.
There doesn't seem to be any relationship between calcium intake and bone loss.
A baked potato has a greater impact on blood sugar and insulin spikes "than an equal amount of calories from pure table sugar."
There have been absolutely no health benefits
shown in modern broad based epidemiological studies from following the USDA
eating guidelines, Willett points out.
There are two kinds of fats. The monounsaturated and polyunsaturated fats found in vegetable oils, nuts, whole grains, and fish "are good for your heart." It is the saturated fats and trans fats that are bad. (See, "Fats," below.)
But baked potatoes, refined (white) bread and
refined (white) rice are turned into glucose (sugar) by the body and pumped into the
bloodstream "almost as fast as it delivers the sugar in a cocktail of pure
glucose." These surges of blood sugar and the insulin responses they
trigger are now implicated in the processes leading to heart disease and
diabetes. The insulin surges ultimately cause rapid drops in blood sugar that
induce feelings of hunger, and thus play a role in the overweight conditions
that further increase the dangers of heart disease and diabetes.
But red meat comes with too much saturated fat and cholesterol. "Red meat may also give you too much iron in a form you absorb whether you need it or not." This may be harmful. (See, "Protein," below.)
But Americans get more calcium than
residents of any nation except Holland and the Scandinavian nations. There doesn't seem to be any
relationship between calcium intake and bone loss, and there are apparent
relationships between high dairy consumption and increased risks of prostate and
But potatoes are a carbohydrate - mostly starch that is easily digested. This is alright for thin people who exercise regularly or do regular manual labor, but should be consumed in modest amounts - not as a daily vegetable - by everyone else. A baked potato has a greater impact on blood sugar and insulin spikes "than an equal amount of calories from pure table sugar." Traditional French fries do the same - with "an unhealthy wallop of trans fats" added.
The Healthy Eating Pyramid:
Under Willett's Healthy Eating Pyramid:
In diet epidemiological studies, controls are always uncertain, reports are always somewhat inaccurate, knowledge of the active ingredients in foods - and how much is actually absorbed - is still evolving, differences in dietary intakes of food elements are matters of degree rather than absolutes, and the diseases studied generally have complex causes including many factors not related to diet.
Willett explains the often contradictory news about diet studies.
Dietary advice prior to recent studies was based on slim evidence, and so was naturally less reliable and
more subject to alteration or
contradiction by more rigorous work. Willett asserts that - now that some
rigorously obtained scientific evidence has been accumulated - there will be far
fewer of these apparent alterations and contradictions in the future - although
inevitably there will be some fine tuning - and sometimes more. This is the
natural course of scientific inquiry.
|Willett reviews the various types of studies generally pursued, and provides some explanation of their strengths and weaknesses and many of their results.
| Next to smoking, weight is the most significant factor
affecting health prospects. The author emphasizes the relationship between
height and weight - the size of your waist - and how much you put on after your
early twenties. He acknowledges the need for adjustments for body
In many undeveloped nations, obesity is already a greater health threat than malnutrition.
The upper boundary of the healthy range in the standard weight index is too high. The amount of weight gained after the early twenties - even if still in the healthy range - can have a major impact on health prospects. A waist that expands more than two or three inches over the years is a warning of health trouble.
Being substantially overweight is clearly related to prospects for a
Pandora's box of health evils. And obesity is a growing epidemic in the U.S. and
around the world. In many undeveloped nations, obesity is already a greater
health threat than malnutrition.
Genetic predisposition, diet, lifestyle, and the culture of
consumption all play roles in the obesity epidemic.
| Many of the popular diet fads are viewed critically by
The key is to limit calories consumed and increase calories burned through
activity until a healthy balance is reached. Increased exercise has many health
benefits besides weight control. A diet that is otherwise healthy and is
satisfying is also essential for maintenance of a healthy balance.
The "glycemic index" - long used by diabetics - is a useful tool for weight control diets.
However, foods that are rapidly absorbed cause sharp spikes in
blood sugar and insulin responses. This then causes rapid declines in blood
sugar that stimulate feelings of hunger and increase tendencies to snack between
A good brisk daily walk of at least 30 minutes is all that is needed to achieve most of the benefits of exercise. However, this has to be maintained. "The physical and physiological changes wrought by decreased muscle mass and increased weight are tough to reverse and in some cases may be irreversible."
As we age, there is a natural tendency to lose muscle and gain
fat as a result of inactivity and reductions of sex hormones. "The less
muscle you have, the less energy your body uses at rest and the easier it is to
gain weight." Indeed, the lost muscle is often replaced by fat.
| The conditions associated with fatty foods have become
increasingly prevalent despite efforts to reduce fat intake. Overweight and
diabetes keep increasing. Fat consumption in the average American
diet has been reduced from 40% to 34% of total calories without
achieving any apparent
impact on cancer rates and heart attacks from coronary artery
The real objective is an adequate intake of the good fats and reduced consumption of the bad fats rather than a total reduction of all fats.
Holding calories constant will prevent any weight gain from the increased consumption of good fats.
That's because there are good fats and bad fats, and much of
the decline in fat consumption has been in intake of good fats. The real
objective is an adequate intake of the former and reduced consumption of the
latter rather than a total reduction of all fats.
Total fat reduction diets also may reduce intake of such foods as nuts, avocadoes, salad dressings made with unsaturated oils - all of which contain beneficial fats as well as vitamin E and other valuable nutrients.
Good fats are so important, that they form part of the foundation of the Healthy Eating Pyramid.
Again, the USDA Food Guide Pyramid gets it wrong - putting good and
bad fats together at the top of the pyramid in the "use sparingly"
category. Other guidelines simplistically emphasize the need to reduce saturated
fats and to moderate intake of total fats, but omit the benefits of unsaturated
fats. The Dietary Guidelines for Americans, and dietary guidelines from the
American Heart Association, the American Cancer Society, the American Society
for Clinical Nutrition, the American Dietetic Association, the American Academy
of Pediatrics, and the National Institutes of Health all omit that "eating
unsaturated fats instead of saturated fats can improve the levels of cholesterol
and other fat particles in your blood, fortify your heart against erratic
heartbeats or help counteract a number of processes that make up
atherosclerosis, the gradual clogging and narrowing of arteries."
Trans fats are man made - and are the worst fats.
Trans fats are man-made fats such as margarine or Crisco that
may be liquid or solid and are bad for your heart. They are the worst fats.
Diet can lead to as much as a 70% decrease in risk of heart disease.
It is neither necessary nor possible to eliminate all saturated fats. Eating saturated fats "in the right proportion with unsaturated fats is perfectly fine."
The many essential functions of fats and cholesterol - and the
bad affects of LDL and high levels of triglycerides - are briefly reviewed in the
book. It is calculated from recent studies that "replacing 5 percent of
total calories as saturated fat with unsaturated fat would reduce the risk of
heart attack or death from heart disease by about 40 percent," and
"replacing just 2 percent of total calories from trans fats with the same
number of calories from unsaturated fats would cut the risk by 50 percent."
Diet can lead to as much as a 70% decrease in risk of heart disease.
Willett is especially critical of Olestra - an indigestible fat
substitute marketed by Procter & Gamble as "Olean." This substance
is designed to pass through the digestive tract without being absorbed. However,
it soaks up fat-soluble vitamins and other phytochemicals and carries them away,
too. These include vitamins A, D, E and K and beta-carotene, lycopene, "and
a host of other plant pigments and phytochemicals" which can't get into the
bloodstream except aboard fat molecules. Olestra has been banned in Canada.
The n-3 fatty acids:
The omega-3 fatty acids are essential nutrients that the body can't make from scratch.
| The n-3 polyunsaturated fatty acids - also
called omega-3 fatty acids - are essential nutrients that the body can't make
from scratch. Benefits include reduced risks for heart disease, stroke and
autoimmune problems. N-3 fatty acids are especially important for brain and
nervous system development in fetuses and babies. Cell membranes and some
hormones need n-3 fatty acids.
The n-6 fatty acids - which comprise the more numerous polyunsaturated fats in our diet - help shape healthy cholesterol levels and reduce heart disease risks.
The best sources for the n-3 fatty acids are fish, flaxseeds, walnuts,
and canola and unhydrogenated soybean oils. Most vegetable oils high in linolenic
acid are good sources. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
are other n-3 fatty acids.
| Carbohydrates are the most important constituent of
the diet. They generally provide the lions share of the calories - about
half - have the most impact on weight, and wield the greatest control over blood
sugar. As with fats, the type of carbohydrates consumed is important.
As a sedentary population cuts back on fats but eats more carbohydrates, obesity and diabetes rates soar and the decline in heart disease rates slows.
Refined carbohydrates are quickly digested and absorbed, with damaging consequences that include "higher levels of blood sugar, insulin, and triglycerides, and lower levels of HDL cholesterol."
"The low-fat, high-carbohydrate diet recommended by the National Cholesterol Education Program and the USDA Food Guide Pyramid may be among the worst eating strategies for someone who is overweight and not physically active."
Eating grains "that are as intact and unprocessed as
possible," along with fruits and vegetables, is as important for health
as consuming the right kind of fats. This fact is missed by the American Heart
Association, the American Cancer Society, the World Health Organization, - and, of
course - the USDA Food Guide Pyramid. As a sedentary population cuts back on
fats but eats more carbohydrates, obesity and diabetes rates soar and the
decline in heart disease rates slows.
Even for lean people, a switch to whole grains will provide highly
beneficial micronutrients. Fiber, antioxidants, phytoestrogens, and a variety of
minerals in bran, are some of the most important elements lost or substantially
reduced in the refining process. Adding bran and wheat germ helps, but still
doesn't prevent the rapid absorption of the starch in refined grains.
Most calories in the average U.S. diet come from sugars or highly refined grains. These are quickly absorbed, quickly increase blood sugar and thus insulin levels. The demands on the pancreas for sudden surges in insulin may lead to systemic insulin resistance, increased insulin demand, and type 2 diabetes.
Willett divides carbohydrates by their impact
on blood sugar - "the glycemic index" - and by whether they come from
whole or refined grains - rather than by whether they are
"simple" or "complex." Unfortunately, most calories in the
average U.S. diet come from sugars or highly refined grains. These are quickly
absorbed, quickly increase blood sugar and thus insulin levels. The demands on the pancreas for sudden surges
in insulin may lead to systemic insulin resistance, increased insulin demand,
and type 2 diabetes. Insulin surges rapidly reduce blood sugar levels and send hunger signals if this blood sugar roller coaster isn't modified by
slower-digested whole grains. A more drawn out process means "it may take
longer to get hungry again."
| Eating more protein from fish, chicken, and vegetable
sources like beans and nuts - and less from red meats and dairy products -
is also an important constituent of healthy eating habits.
Willett recommends leaner cuts of red meats or - better - consumption of poultry or fish instead.
However, vegetable protein is generally incomplete - lacking in
some essential amino acids. Thus, it is important for vegetarians to eat
combinations that compliment each other, such as rice and beans, peanut butter
and bread, tofu and brown rice."
Proteins leach calcium - as the body reacts to neutralize protein-related acids. So, the long run impact of high protein diets on bone loss must be considered.
High protein diets designed to reduce calorie intake from the
wrong kinds of carbohydrates do help with blood sugar problems, reduce
triglycerides, and boost HDL (good) cholesterol. There are many other claims
for and against various proteins, but most remain unproven. However, allergy
problems can be severe - especially for cows milk consumption by children. Also,
proteins leach calcium - as the body reacts to neutralize protein-related acids.
So, the long run impact of high protein diets on bone loss must be considered.
Fruits and vegetables:
| Fruits and vegetables reduce risks of
heart attacks and strokes and a variety of cancers, lower blood pressure and bad
cholesterol, help avoid diverticulitis, and cataracts and macular degeneration.
The odds are high that the benefits of fruits and vegetables emanate from many different substances found in plants and quite possibly from the interaction of these substances.
Potatoes should not be included as a vegetable.
Pills are no substitute.
Since no fruit or vegetable provides all of these substances, eating a
variety of them is important. The five servings a day recommended by the
authoritative guides should be viewed as a minimum, but potatoes should not be
included in this calculation.
| About 8 eight-ounce glasses of fluid are needed per day, but
much of this can be obtained from fruits and vegetables. Diet, physical activity
and weather conditions vary this requirement. Meat and bread, physical activity,
and hot weather and/or
low humidity increase the need for fluids. The author
advises enough fluid intake so the urine is "consistently clear or pale
yellow rather than bright or dark yellow."
Popular sodas have seven to nine teaspoons of sugar per 12 ounce can. This creates weight problems and stress for the pancreas.
But urine color or even thirst
are not always reliable guides.
The book recommends one glass of fluid with each meal and one between meals.
Milk has many problems, and is not recommended for more than occasional consumption.
In moderation, alcohol can reduce stress, improve digestion, improve emotional well being, reduce risks of heart disease and ischemic strokes, and perhaps even diabetes and gall stones. It helps raise HDL (good) cholesterol levels, and lowers risks of arterial clotting. However, even moderate consumption can disrupt sleep, interact dangerously with some medicines, and be addictive for some people.
Young men and young women gain little benefit from consumption of alcohol - and great benefit from exercise.
Fruit and vegetable juices are much better than sodas, of course, but they add calories as well as nutrients, and so are another dietary element to be used in moderation. Willett advises dilute juices if substantial volumes are consumed. Other problems and benefits of various fluids include:
Moderate consumption of alcohol is estimated as one drink per day for
women - two for men. Also, folic acid intake seems to reduce the breast and colon
cancer risk associated with moderate alcohol consumption. Even moderate
consumption, however, can disrupt sleep, interact dangerously with some
medications, and be addictive for some people.
| The appropriate level of calcium intake remains uncertain.
Low intake of calcium isn't associated with increased risks of bone fractures.
Other factors are much more important.
Low intake of calcium isn't associated with increased risks of bone fractures. Other factors are much more important.
| The current conventional
wisdom concerning dietary calcium is sharply criticized by Willett.
There is virtually no evidence that drinking two or three glasses of milk a day reduces the chances of breaking a bone.
The consumption of substantial amounts of milk or other dairy
products as a means of boosting calcium intake is especially criticized. The
author provides a page long list of foods - in addition to milk - that provide substantial amounts of calcium
and magnesium. Greens such as collards and spinach, along with
tofu and figs and oatmeal are the best sources, and don't have the problems of
milk. (Try using fresh spinach instead of lettuce for your salad. You'll like
The author favors substituting nonfat plain yogurt for other dairy products like sour cream - and recommends both yogurt and cottage cheese as good sources of vitamin B12. (However, he offers no discussion of these cultured dairy products and how they differ from other dairy products.) He concludes:
Protein digestion releases acids into the bloodstream and causes the body to draw on its calcium supplies to neutralize the acids. Animal proteins are somewhat more powerful than vegetable proteins at leaching calcium. The rate of bone fractures are higher in meat eating nations like the U.S.
Reducing consumption of proteins that trigger the leaching of
calcium out of the bones and into the bloodstream is a good place to start.
Protein digestion releases acids into the bloodstream and causes the body to
draw on its calcium supplies to neutralize the acids. Animal proteins are
somewhat more powerful than vegetable proteins at leaching calcium. The rate of
bone fractures are higher in meat eating nations like the U.S.
| The importance of food supplements for known dietary
weaknesses - and the rapidly evolving recognition of nutrients inadequately
provided by widespread dietary habits - are covered by Willett.
The book cautions that many of the benefits attributed to such vitamins as the antioxidants may be more due to the entire package of nutrients supplied by whole foods like fruits and vegetables rather than just to the identified vitamins themselves.
Taking just single antioxidants is far less effective than consuming fruits and vegetables that provide whole packages of beneficial nutrients.
However, the book cautions that many of the benefits
to such vitamins as the antioxidants may be more due to the entire package of
nutrients supplied by whole foods like fruits and vegetables rather than just to
the identified vitamins themselves.
Vegetarians and individuals with an inability to absorb natural B12 need B12 supplements. Liver, yogurt, cottage cheese and eggs are good natural sources.
B Vitamins folic acid, B6 and B12 are
required for proper metabolism of homocysteine. Poor metabolism of homocysteine
results in cholesterol-clogged arteries.
Vitamin D is more important for prevention of bone fractures due to bone loss than is calcium. Those living north of San Francisco - Denver - Philadelphia do not get enough sunlight during winter months for the production of vitamin D.
Both too little and too much potassium can cause major problems, so supplementation is risky.
Vitamin D makes sure that calcium and phosphorus are absorbed
and retained, and apparently inhibits a variety of cancer cells. Vitamin D is
more important for prevention of bone fractures due to bone loss than is
calcium. Those living north of San Francisco - Denver - Philadelphia do not get
enough sunlight during winter months for the production of vitamin D.
Salt intake for the average person need be no more than one
gram per day. Yet, the average meal provides two to five grams. Excess salt can
cause high blood pressure.
A multivitamin is good insurance, but is no substitute for a healthy diet.
The book advises taking a multivitamin as insurance against deficiencies - especially for folic acid, B6, B12, and Vitamins D and E. But it stresses that this is no substitute for a healthy diet.
Mineral supplementation is advised only in special cases, such as iron
for women of child bearing age.
The book concludes by recommending disregard for the advice embodied in the USDA Food Guide Pyramid and reliance instead on the book's Healthy Eating Pyramid. This includes, among other things,
Sources for whole grain and organic and natural foods - dietary advice - and recipes - fill about the last 90 pages of the book. The recipes cover snacks, a full week of menus, and a wide variety of specialty dishes.
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Copyright © 2002 Dan Blatt