you place people on a low-fat diet, but they do not follow the diet and do
not substantially reduce their fat intake, there will be few health
Thus, it would have
been more accurate for the newspapers to proclaim: "When people don't
follow low-fat diets, health benefits are few." That is quite different
than what the newspapers announced.
Dr. Jay Cohen
The results of the 3 studies were irrelevant
for other reasons. First, the low-fat diet used in the studies made no
distinction between healthful and unhealthful fats. The low-fat diet
discouraged all types of oils. Olive oil was discouraged the same as
lard and trans fats with their known health toxicities. A reduction in
healthful oils would have negated any benefit from reducing unhealthful oils,
and no overall benefits would be expected. This was another key flaw of
A second problem with
these studies was how calories were counted. According to Dr. Marion
Nestle, a highly regarded expert on nutrition at New York University, there
may have been problems with the food-intake questionnaire with which the women
reported their food consumption. Based on the numbers provided, Dr.
Nestle questioned the accuracy of the women's reporting1. I
would add that it has long been known that food diaries kept by subjects are
often inaccurate in the types and especially in the amounts of food consumed.
criticized the study because 8 years was not a sufficient time frame to
demonstrate significant effects on heart disease or canc.
The 3 Studies
Demonstrated Important Low-Fat Benefits
The negative headlines were also misleading
because the studies, despite their flaws, suggested important benefits for
people on low-fat diets.
Women who consumed the most fats at the
beginning of the study and then had the greatest reduction in fat intake
demonstrated the lowest risk of breast canc.
The lowest risk of heart disease was seen in
women who reduced fat intake to the lowest levels.
Women who substantially reduced fat intake
also had a lower incidence of polyps of the colon, which often precede colon
These are not minor
findings. Thus, the headlines should have read: "Low-fat diets
suggest major benefits on risks of heart disease and canc."
on Fats and Diet
Last year, when I published my new book on
statin medications and natural alternatives for reducing cholesterol and other
cardiac risks, I included a long chapter on diet. Here are a few
excerpts from the book7:
research on the heart-healthy Mediterranean diet demonstrates the same
thing: cholesterol problems are not due to the amount of fats people
eat, but the types of fats. Italians and Greeks eat as much
fat as Americans, but theirs is primarily olive oil, which provides large
amounts of heart-healthy monounsaturated fats. Olive oil also contains
phenols that are similar to those found in green tea and red wine that
inhibit LDL-C oxidation. Thus, a 2003 study in the New England
Journal of Medicine reported: "Greater adherence to the
traditional Mediterranean diet is associated with a significant reduction in
The diet of the
people of Okinawa, who have the longest lifespans on the planet, contains
high amounts of fat (from fish and soy) and carbohydrates (from vegetables
and rice), but is low in saturated fats. Eskimos live on very high-fat
foods, but Eskimos have low incidences of heart disease and arthritis
because the fats they eat are very rich in omega-3 fatty acids.
The lesson is that
Atkins, who said "All fats are good," was wrong.
are good, and bad fats are bad. Americans consume large quantities of
bad fats -- saturated fats and hydrogenated oils -- that elevate cholesterol
levels and cause cardiovascular disease. Indeed, every society that
has adopted western dietary habits has suffered major increases in heart
attacks and strokes. People from diet-healthy societies who come here
and adopt our ways of eating get all of our diseases.
Advocates of low-fat
diets with moderate amounts of protein and high-quality complex
carbohydrates have plenty of evidence supporting their perspective. Studies repeatedly show that when people stick with low-fat diets,
incidences of coronary disorders, heart attacks, and cardiac deaths
plummet. Dr. Caldwell Esselstyn of the Cleveland Clinic reminds us
that "although coronary artery disease is the leading killer of men and
women in the USA, it is rarely encountered in cultures that base their
nutrition primarily on grains, legumes, lentils, vegetables, and fruit10."
In other words, the doctor is advocating a low-fat, moderate-protein -- high
quality -- diet based on natural foods. Dr. Dean Ornish has clearly
demonstrated that for people with advanced coronary disease, strict
restriction of fat, especially saturated and hydrogenated fat, can halt and
sometimes reverse atherosclerosis10,11.
high-quality diet does not mean going crazy on carbohydrates. It does
not mean you can eat unlimited amounts of "low-fat" foods filled
with sugars and calories. It does not mean breads and pastries made
from refined white flour or loaded with sugar. Bad carbohydrates are
just as bad as bad fats. You must select your carbohydrates just as
carefully as you select fats.
In the book, I also
explain that low-fat diets work for some people and low-carb diets work for
others because of genetically-determined metabolic differences. I
explain how people can learn which metabolic type they are and how to adjust
their diets accordingly. Metabolic differences explain why the widely
differing diets of Drs. Dean Ornish and Robert Atkins are right for some
people and not others.
The Bottom Line
The 3 low-fat studies published in JAMA were
performed by very good people. Many of these researchers have produced
excellent work in the field of health and nutrition. However, these 3
studies add little to our current knowledge, and instead serve to confuse a
picture that has become quite clear about healthful nutrition:
Good nutrition means
a diet based on vegetables and fruits, with a healthful diversity of complex
carbohydrates, low-fat protein, and healthful fats. A healthful
lifestyle also means not smoking, a moderate degree of regular exercise, and
avoidance of prolonged excessive stress.
1. Maugh TH, Chong JR. Eating lean doesn't cut
risk. Los Angeles Times, Feb. 8, 2006:A-1.
2. Low-fat diet cuts health risks? Fat chance. San Diego
Union-Tribune, Feb. 8, 2006:A-1.
3. Kolata G. Low-fat diet does not cut health risks, study
finds. New York Times, Feb. 8, 2006:www.nytimes.com.
4. Howard BV, et al. Low-fat dietary pattern and risk of
cardiovascular disease. JAMA, Feb. 8, 2006;295:655-666.
5. Prentice RL, et al. Low-fat dietary pattern and risk of
invasive breast canc. JAMA, Feb. 8, 2006;295:629-642.
6. Beresford SA, et al. Low-fat dietary pattern and risk of
colorectal canc. JAMA, Feb. 8, 2006;295:643-654.
7. Cohen, JS. What You Need to Know about Statin Drugs and Their
Natural Alternatives. Square One Publishers, New York: January 2005.
8. Trichopoulou, A, Costacou, T, Bamia, C, Trichopoulos, D. Adherence to a Mediterranean Diet and Survival in a Greek Population.
New England Journal of Medicine 2003;348:2599?]2608.
9. Esselstyn, CB. Becoming Heart Attack Proof. Cleveland
10. Ornish, D, Scherwitz, LW, Billings, JH, et al. Intensive
lifestyle changes for reversal of coronary heart disease. JAMA
11. Ornish D. Avoiding revascularization with lifestyle changes:
The Multicenter Lifestyle Demonstration Project. American Journal of
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Copyright 2006, Jay S. Cohen,
M.D. All rights reserved.