Michael Greger MD

Michael Greger MD

Posted August 5, 2010

Published in Health

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Vegans "Significantly Less Polluted"

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Every five years, the U.S. government measures the amount of toxic waste in our food supply. Dioxins are a class of industrial pollutants spewed into the atmosphere that "accumulates in the fatty tissues of humans and food animals consumed by humans. It is generally believed that the most significant exposure to DLCs [dioxin-like compounds such as PCBs] by humans is from the dietary intake of animal and fish products." But which animal products pose the greatest risk?

According to recent data from the Environmental Protection Agency, second only to fish in terms of PCB levels: eggs. This may help explain the findings of a recent study that found that egg consumption "was associated with in increased odds of cancers of the oral cavity and pharynx, esophagus, upper aerodigestive tract (includes oral cavity, pharynx, esophagus, larynx), colon and colon and rectum combined, lung, breast, prostate, bladder, and all cancers combined."

Of all the cancers, egg consumption was most tightly correlated with breast cancer risk. Those eating more than a half an egg a day were found to have nearly 3 times the odds of breast cancer compared to those that stayed away from eggs entirely.

The industrial toxins found in animal products don't just contribute to cancer risk. According to a recent commentary in the journal Reproductive Toxicology, "increasing evidence suggests that maternal exposure to toxic chemical compounds may be associated with various congenital [birth] defects, pediatric problems, skewed gender ratios, lethal cancers in children and teens, psychosexual challenges, as well as reproductive and endocrine [hormonal] dysfunction in later life." The author concludes: "I anticipate that future generations of scientists will look back with disbelief at a medical culture that permitted poisoning of reproductive aged women and ignored ramifications to unborn children."

What if one chooses not to eat meat, fish, dairy, or eggs, though? A study entitled "Impact of Adopting a Vegan Diet...on Plasma Organochlorine Concentrations" was recently published by an international team of scientists. Organochlorines "are chemical products that were widely used after World War II as insecticides and in industry. In the 1960s, their adverse effects for the environment and human health began to be known, and in the 1970s their use was banned in most industrialized countries [including the United States]. However, because they are so resistant to degradation...[they] continue to be present in most food chains worldwide....Being at the top of the food chain, man is contaminated via food, in infancy from breast milk and later from animal products such as fish, meat and dairy products."

The investigators note that studies have shown that organochlorine concentrations in the breast milk and fat tissue of vegetarians is lower than in omnivores, but no studies of "real vegans" had been undertaken. Until now. Testing a wide range of carcinogenic industrial toxins and pesticides, the researchers  "found that vegans, were significantly less polluted, then omnivores...."

What surprised the research team was that vegans had as much toxic exposure as they did. The scientists offered a number of explanations. For example, the vegans "may have been breast-fed as infants, and might thus have been exposed to OC accumulated by the mother, and which are transferred to her baby at the time of lactation. Moreover, becoming vegetarian or vegan is often a decision made in adulthood." That was another problem they noted: most vegans aren't vegan from birth. "Thus, the omnivore diet followed during childhood and adolescence results in a contamination by OC that is still detectable in adults....In addition, vegans may, on rare occasions, depart from their diet and eat some animal products."

To decrease our exposure to industrial toxins in our increasingly polluted world, we need to eat as low as possible on the food chain as soon as possible: a plant-based diet.

This is excerpted from Dr. Greger's Latest in Clinical Nutrition vol. 4 DVD (July 2010), all proceeds of which go to benefit the Humane Society of the United States.