MANY people have been making the case that
Americans and the rest of the world have grown fat because they eat too much
starch and sugar, and not enough meat, fat and eggs. Recently, the Dietary
Guidelines Advisory Committee lifted recommendations that consumption of
dietary cholesterol should be
restricted, citing research that dietary cholesterol does not have a major
effect on blood cholesterol levels. The predictable headlines followed: “Back
to Eggs and Bacon?”
But, alas, bacon and egg yolks are not health foods.
Although people have been told for decades to
eat less meat and fat, Americans actually consumed 67 percent more added fat,
39 percent more sugar, and 41 percent more meat in 2000 than they had in 1950
and 24.5 percent more calories than they had in 1970, according to the Agriculture Department. Not
surprisingly, we are fatter and unhealthier.
The debate is not as simple as low-fat versus
low-carb. Research shows that animal protein may significantly increase the
risk of premature mortality from all causes,
among them cardiovascular disease, cancer and Type 2 diabetes. Heavy consumption of saturated fat and trans fats may double the risk of
developing Alzheimer’s disease.
A study published last March found a 75 percent increase in premature deaths from all causes,
and a 400 percent increase in deaths from cancer and Type 2 diabetes, among
heavy consumers of animal protein under the age of 65 — those who got 20
percent or more of their calories from animal protein.
Low-carb, high-animal-protein diets promote
heart disease via mechanisms other than just their
effects on cholesterol levels. Arterial blockages may be caused by
animal-protein-induced elevations in free fatty acids and insulin levels and
decreased production of endothelial progenitor cells (which help keep arteries
clean). Egg yolks and red meat appear to
significantly increase the risk of coronary heart disease and cancer due to increased production of
trimethylamine N-oxide, or TMAO, a metabolite of meat and egg yolks linked to
the clogging of arteries. (Egg whites have neither cholesterol nor TMAO.)
Animal protein increases IGF-1, an insulin-like growth hormone, and chronic
inflammation, an underlying factor in many chronic diseases. Also, red meat is
high in Neu5Gc, a tumor-forming
sugar that is linked to chronic inflammation and an increased risk of cancer. A
plant-based diet may prolong life by blocking the mTOR protein, which is linked
to aging. When fat calories were carefully
controlled, patients lost 67 percent more body fat than when carbohydrates were
controlled. An optimal diet for preventing disease is a whole-foods,
plant-based diet that is naturally low in animal protein, harmful fats and
refined carbohydrates. What that means in practice is little or no red meat;
mostly vegetables, fruits, whole grains, legumes and soy products in their
natural forms; very few simple and refined carbohydrates such as sugar and
white flour; and sufficient “good fats” such as fish oil or flax oil, seeds and
nuts. A healthful diet should be low in “bad fats,” meaning trans fats,
saturated fats and hydrogenated fats. Finally, we need more quality and less
quantity.
My colleagues and I at the nonprofit Preventive
Medicine Research Institute and the University of California, San
Francisco, have conducted clinical research proving the many benefits of a
whole-foods, plant-based diet on reversing chronic diseases, not just on
reducing risk factors such as cholesterol. Our interventions also included stress management
techniques, moderate exercise like walking and social support.
We showed in randomized, controlled trials that these diet
and lifestyle changes can reverse the progression of
even severe coronary heart disease. Episodes of chest pain decreased by 91
percent after only a few weeks. After five years there were 2.5 times fewer cardiac events. Blood flow to
the heart improved by over 300
percent.
Other physicians, including
Dr. Kim A. Williams, the
president of the American College of Cardiology, are also finding that these
diet and lifestyle changes can reduce the need for a lifetime of medications
and transform people’s lives. These changes may also slow, stop or even reverse the progression of early-stage prostate cancer,
judging from results in a randomized controlled trial.
These changes may also alter your genes, turning
on genes that keep you healthy, and turning off genes that promote disease.
They may even lengthen telomeres, the
ends of our chromosomes that control aging.
The more people adhered to these
recommendations (including reducing the amount of fat and cholesterol they
consumed), the more improvement we measured — at any age. But for reversing
disease, a whole-foods, plant-based diet seems to be necessary.
In addition, what’s good for you is good for
our planet. Livestock production causes more disruption of the climate than all
forms of transportation combined. And because it takes as much as 10 times more
grain to produce the same amount of calories through livestock as through
direct grain consumption, eating a plant-based diet could free up resources for
the hungry.
What you gain is so much more than what you
give up.
Dean Ornish is a clinical professor of medicine
at the University of California, San Francisco and the founder of the
Preventive Medicine Research Institute
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