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Diet Therapy

By Steven Novella, MD, Assistant Professor of Neurology, Yale University School of Medicine

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Diet therapy, a biologically based practice, uses specialized dietary regimens (eg, Gerson therapy, macrobiotic diets, Pritikin diet) to

  • Treat or prevent a specific disorder (eg, cancer, cardiovascular disorders)

  • Generally promote wellness

  • Detoxify the body (ie, neutralize or eliminate toxins from the body)

Some diets (eg, Mediterranean diet) are widely accepted and encouraged in traditional western medicine.

Diet therapy usually takes months or years for its maximal effects to occur and is more likely to have effects if started at a young age.

Ornish diet

This very low-fat vegetarian diet aims to help reverse arterial blockages that cause coronary artery disease and may help prevent or slow the progression of prostate and other cancers. However, its efficacy is not yet clear because definitive clinical trials have not been done.

Gerson diet

This diet involves consuming the equivalent of 15 to 20 lb of fruits and vegetables (in solid food and juices) each day, plus taking supplements and using coffee enemas. Proponents claim that this protocol is effective for treating cancer, heart disease, arthritis, autoimmune disorders, and diabetes; however, there are no rigorous clinical trials to support any of these claims. Also, claims of detoxification are not based on identification and measurement of any specific toxin.

One risk with this therapy is that its unsubstantiated claims for efficacy (eg, against cancer) can delay treatment with efficacious conventional therapies and worsen outcome.

Macrobiotic diet

This diet consists mainly of vegetables, whole grains, fruits, and cereals. Some proponents claim that this diet can prevent and treat cancer and other chronic disorders; however, no evidence supports efficacy of a macrobiotic diet for treatment of cancer.

Risks include inadequate nutrition if the diet is not followed carefully.

Paleo diet

This diet consists of types of food allegedly consumed during the Paleolithic era, when food was hunted or gathered (ie, animals and wild plants). Thus, the diet includes

  • Increased protein intake

  • Decreased carbohydrate intake (with intake consisting mainly of nonstarchy fresh fruits and vegetables)

  • Increased fiber intake

  • A moderate to higher fat intake (with intake mainly of monounsaturated and polyunsaturated fats)

Foods thought not to be available during the Paleolithic era (eg, dairy products, grains, legumes, processed oils, refined sugar, salt, coffee) are avoided. Proponents claim that human metabolism has not adapted to handle many of these foods.

Proponents of the Paleo diet claim that it reduces the risk of coronary artery disease, type 2 diabetes, and many chronic degenerative disorders. They also claim it promotes weight loss in overweight people, improves athletic performance, enhances sleep, and improves mental function. However, there is no good-quality evidence concerning the efficacy of this diet.

Risks include inadequate nutrition (due to decreased intake of whole grains and dairy) and possibly an increased risk of coronary artery disease (due to increased intake of fat and protein).

Knowledge of what was eaten in the Paleolithic era is limited; however, some evidence suggests that the diet of the Paleolithic era was not as limited as the modern Paleo diet.