Our dietary habits are one of the most important influences relative to our health. Most of the diseases associated with aging have their roots in our food choices. The leading causes of mortality in our country are heart attacks, cancer and strokes, and all have been shown to be modifiable with diet. We often hear warnings about reducing the amounts of certain things in our diets, such as cholesterol, saturated fats and sugars. While the moderation of these is essential to a healthy body, it is also important to increase our intake of foods that have advantageous properties in order to reap their nutritional benefits.

Studies that look at the health of populations routinely reveal that people with diets based on fruits, vegetables, whole grains, nuts, seeds, beans and fish live longer and have significantly less cancer, heart disease and strokes. For example, Okinawa, Japan, where the aforementioned foods represent the average diet, has the largest population of centenarians in the world. The old adage “we are what we eat” is absolutely true.

According to a study published in the European Journal of Cancer Prevention, “A large body of evidence indicates that a high intake of fruits and vegetables is associated with a reduced risk of cancer at several sites .”¹ A higher intake of fruits and vegetables directly correlates to a lower risk of cancers, especially of the digestive and respiratory tracks. While it is important to reduce the consumption of certain foods, a diet rich in antioxidants, fiber and omega-3 fatty acids is essential to good health.

Antioxidants

Abundant in many fruits and vegetables, antioxidants are a vital component to a healthy diet because they stabilize free radicals. Free radicals are unstable electrons formed during the process of oxidation (a natural process associated with aging and metabolizing foods), as well as from drinking alcohol, exposure to pollution and radiation, smoking, iron overload and extreme exercise. During oxidation, a free radical takes an electron from another source in order to become stable. This process can, in turn, form new free radicals, cause DNA to become unstable and turn a cell cancerous or cause oxidation of the bad form of cholesterol, which makes it stickier and creates cholesterol plaques in the arteries. This oxidation process leads to Alzheimer’s disease, cardiovascular disease, cancer, cataracts, arthritis, macular degeneration and immune dysfunction, just to name a few.

Antioxidants can donate an electron to free radicals while still maintaining their own stability. The free radicals are then stabilized, hopefully before much damage has been done. Antioxidants are plentiful in colorful fruits and vegetablesthe more colorful, the better. The antioxidant chemicals are usually found in the pigment, and are much more plentiful in organic produce.² Interestingly, antioxidants are produced by the plant as a natural insecticide. If the plant is exposed to chemical insecticides, it gradually loses the need to produce antioxidants for survival.

There are many different kinds of antioxidants, and each offer particular benefits. Lycopene, a powerful antioxidant, is a pigment that gives some fruits and vegetables their red color. It is found in tomatoes (and found in higher concentrations in cooked tomatoes), pink and red grapefruit, guava and watermelon. The lycopene content of tomato products may account for the benefits seen in 57 out of 72 studies recently reviewed by Giovannucci at Harvard Medical School. “The evidence for a benefit was strongest for cancers of the prostate, lung and stomach…and suggestive of a benefit for cancers of the pancreas, colon, rectum, esophagus, oral cavity, breast and cervix.”³ With our top cancer killers in the United States being in the lung, colon and breast, diets high in tomatoes seem more than prudent.

Polyphenols, another class of antioxidants, have also been “associated with a lower risk of some diseases, including cancer.”⁴ These compounds, which are in high concentration in green tea, are also found in fruits and vegetables. Tea polyphenols have been shown to lower LDL (bad) cholesterol and lower the risk of specific types of cancer. They detoxify the metabolites of cancer, decrease cell replication and therefore cancer growth, and improve the ratio of good versus bad bacteria in the gut.⁵

Phytoestrogens, a category of compounds that fall within the polyphenol class, is also showing promise in the fight against cancer. Studies have shown that eating a diet high in these plant estrogens (e.g. soy, hops and black cohosh) may decrease the risk of developing breast cancer⁶ and prostate cancer.⁷ However, the benefit of these plants remains controversial for a person who has been diagnosed with an estrogen receptor positive breast cancer.⁸

Fiber

Diets high in fiber are helpful in bowel regulation and seem to be protective against colon cancer. “Populations that have a very low intake of fiber have high rates of colon cancer and vice-versa.”⁹ Fiber supplements do not confer the same level of protection against cancer. In almost all studies performed to date, getting nutrients from food supplements in general does not provide the same benefit as obtaining them from the food or plant (as in tea). This is likely because the compounds in the whole food work together in ways that cannot be replicated by a supplement taken out of context.

Fats

Fats are metabolized into products that can be categorized as either pro-inflammatory or anti-inflammatory. Animal fats and trans fats (such as partially hydrogenated vegetable oils) produce pro-inflammatory cytokines, which can lead to chronic illnesses. These fats are found in red meat, poultry, dairy products, margarines and almost all packaged foods. Interestingly, free-range meat (animals eating grass and allowed to exercise) has a higher percentage of omega-3 fatty acids and lower saturated fat than meat subjected to standard animal husbandry techniques (animals fed grains and remains of other animals, and also not allowed to move).

Omega-3 fatty acids are in the category of essential fatty acids, meaning that we must get these from foods because our bodies cannot produce them. Omega-6 fatty acids, found in many vegetable oils, are also considered essential, but we currently have an overabundance in our standard American diet. The ratio of omega-6 to omega-3 is important. In an ideal situation, the ratio is 3:1, but in our diets it is closer to 20:1. Fish, flaxseed and walnuts are excellent sources of omega-3 fatty acids, which have been shown to help reduce heart attacks, arrhythmias (irregular heart beats), strokes, Alzheimer’s disease, and reduce inflammation in a whole host of autoimmune disorders such as rheumatoid arthritis, lupus and sarcoidosis.¹⁰

Maitake mushrooms have significant immunostimulant properties by activating natural killer cells, cytotoxic T-cells, interleukin-1, superoxide anions and macrophages. In animal studies, they show marked inhibitory activity against sarcomas.¹¹ “In combination with chemotherapy, they increase the effectiveness of lower doses of Western drugs, while protecting the immune system from toxic damage .”¹²

Watch What you Eat

A healthy diet also requires monitoring and elimination (or at least a reduction) of foods that can be harmful. Recent reports regarding polychlorinated biphenyl (PCB) contamination in 70% of the farm-raised fish studied are also concerning. These should be avoided.¹³ Mercury is also a concern for many lake and ocean fish, while herring, sardines and canned chunk light tuna are very low in mercury. Alaskan salmon (fresh or canned) is also safe, but tuna steaks, halibut and mackerel have been shown to have elevated mercury levels.¹⁴ Studies using fish oil supplementation show a benefit when at least 2,000 mg are used. These do not appear to be a significant source of mercury or PCBs.¹⁵

In order to create and maintain good health, it is important to eat a healthy, well-balanced diet that includes a variety of fruits and vegetables. Sometimes, Moms really do know best!

¹ LaVecchia C, Tavani A, Fruit and vegetables and human cancer. Eur J Cancer Prev. 1998 Feb;7(1):3-8.
² Asami DK et al: J Agric Food Chem, 51:1237-1241, 2003.
³ Giovannucci E, Tomatoes, tomato-based products, lycopene, and cancer: a review of the epidemiologic literature. J Natl Cancer Inst. 1999 Feb 17;91(4):317-31.
⁴ Ahmad N, Mukhtar H, Green tea polyphenols and cancer: biologic mechanisms. Nutr Rev. 1999 Mar;57(3):78-83.
⁵ Weisburger JH, Tea and health: the underlying mechanisms. Proc Soc Exp Biol Med. 1999 Apr;220(4):271-5.
⁶ Grant KL, McDermott JH, Alternative Medicine in Nutrition Support. Pharmacotherapy Self Assessment Program (PSAP) 3rd ed. 1999.
⁷ Weil A, Spontaneous Healing, 1995, Alfred A. Knopf, Inc.
⁸ Grant KL, McDermott JH, Alternative Medicine in Nutrition Support. 1999.
⁹ Ahmad N, Mukhtar H Nutr Rev. 1999 Mar.
¹⁰ Monograph: Fish Oil; Alternative Medicine Review. 2000 Dec. 5(6):576-80.
¹¹ Grant KL, McDermott JH, Alternative Medicine in Nutrition Support. 1999.
¹² Weil A, Spontaneous Healing, 1995, Alfred A. Knopf, Inc.
¹³ Environmental Working Group: PCBs in Farmed Salmon 7/30/03.
¹⁴ Mercury Levels in Commercial Fish and Shellfish http://www.cfsan.fda.gov/~frf/sea-mehg.html.
¹⁵ Environmental Working Group: PCBs in Farmed Salmon 7/30/03.

This article was originally published in Balanced Living Magazine, May – June, 2005.

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Last Reviewed: Oct 31, 2005

Tanya I Edwards, MD, MEd Associate Professor Medical Director, Center for Integrative Medicine Cleveland Clinic Foundation School of Medicine Case Western Reserve University