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Vol. 12 Issue 3, Summer 2007
By Jennifer L. Wilkins, Ph.D., R.D., Senior Extension Associate, Division of Nutritional Sciences, Cornell University
When many people choose to eat a nutritious diet – one with plenty of fruits, vegetables, and whole grains, and limited added sugars, saturated and trans fats – feeling good and living a long and healthy life are key motivators. But in this paper, Using Nutrition for Intervention and Prevention against Environmental Chemical Toxicity and Associated Diseases, the researchers offer yet another good reason for getting your “five-a-day”: the potential for wise food choices to protect against diseases that are associated with exposure to toxic chemicals and other environmental pollutants.
We know from research that exposure to environmental chemicals and pollutants is a contributing factor in poor health and the development of many diseases. In today’s world it’s difficult to avoid toxic chemicals and other pollutants. In the United States poorly managed hazardous waste sites and the use and accumulation of chemical pollutants represent a growing challenge to environmental quality and to public health. Many pollutants, such as heavy metals and persistent organics, concentrate in our bodies. So far eliminating pollutants from the environment, or preventing them from getting there in the first place, has proven either too difficult or too costly to avoid completely. Thus, making lifestyle choices to minimize their health impacts makes sense. What diet one follows is one of these important choices.
Despite decades of research that has lead to a sophisticated understanding of the connection between nutrition and health, diet-related chronic diseases remain the single largest cause of death and illness among Americans. Diet is among several factors – including environmental exposures and genetic disposition – that contribute to the development and progression of age-related chronic diseases.
The research paper reviewed here provides compelling argument for further exploration into the interactions between environmental exposure, nutrition, and disease risk and the need for better tools to evaluate these interactions. Diet appears to play at least two important roles in the outcome, and indeed incidence of these interactions.
First, depending on the specific foods eaten, one’s diet can actually be a source of exposure to environmental toxic pollutants. Because many pollutants are fat soluble, foods high in fat – such as some meats, dairy products and certain species of fish – can contain higher levels of persistent organics than “plant foods” – vegetables, fruits, and grains.
The second way diet plays a role is in its influence on an individual’s nutritional status which determines one’s lipid profile, oxidative stress, and antioxidant levels within cells. Such alterations at the cellular level can negatively impact biological processes, and in turn, magnify the potential for environmental pollutants to cause disease or dysfunction.
The authors cite several studies suggesting how diet and nutrition ameliorate (or exacerbate, in some cases) the impact toxic pollutants can have on human health.
Some studies reveal that toxic effects of dioxin and similar compounds stem from their activation of the aryl hydrocarbon receptor (AhR). Interestingly, some dietary components also activate AhR but do not lead to a toxic effect. Why? Research suggests that when dioxin and its cousins turn AhR on, it stays active leading to toxic effects. Components in the diet, however, have a short-lived affect on AhR. This temporary activation, research suggests, might avoid toxic effects while promoting health benefits.
Other studies provide evidence that various nutrients and phytochemicals – healthful chemical compounds found in plant foods – are strong antioxidants with anti-inflammatory effects. Since inflammation is known to be an underlying factor in diet-related diseases – including cardiovascular disease, diabetes, arthritis, osteoporosis, and cancer – diets rich in phytochemicals (such as flavonoids) can provide protection against environmental toxicants that diminish antioxident levels in the body.
Herbal remedies and nutraceuticals may also play an important role in the nutrition, diet, environmental toxin effects relationship. For example, polyphenols, especially catechins found in green tea, can inhibit intestinal absorption of lipids and lipid-soluble compounds (such as persistent organic pollutants) and enhance their elimination from the body.
Even very familiar nutrients, such as calcium, have been shown to be important in this regard. Calcium has been found to be an effective treatment for moderately high cumulative lifetime exposure to environmental lead pollution. Research conducted on pregnant and lactating woman in Mexico showed an association between calcium supplementation and decreased maternal blood lead levels. It would be interesting to learn if calcium obtained through food – both dairy and non-dairy sources – confers the same effect.
The authors present a strong case for further research into the many ways that diet and nutrition can either reduce exposure to environmental toxins or help reduce the likelihood they will induce age-related chronic diseases. This is an important area of research since human consumptive behavior results in a wide range of pollutants. Globally, as more countries gain economic power, the environment will sustain an even greater burden and overall exposure will increase. Learning how to better arm ourselves against the resulting pollutants through changes in diet seems a wise and necessary approach. The health effects associated with exposure to polychlorinated biphenyls, for one example, may increase as a result of ingestion of certain dietary fats, but eating more fruits and vegetables, rich in antioxidant and anti-inflammatory nutrients or bioactive compounds, may prove to be protective.
Adoption of such practices for the sake of self-preservation will ultimately fail, however, without efforts pursued in tandem – and with greater inter-governmental cooperation – to protect and restore the health and vitality of the ecosystem. After all, the foods that make up the diets we hope will enhance our health and reduce chronic disease risk depend on continuing availability of viable, sustainable, and non-toxic natural resources. Further elucidation of dietary approaches that can ameliorate the effects of pollutants should not make us complacent about their sources and the need to reduce them. In order to keep producing crops that are healthful, raising animals that are healthy, and catching fish that are safe and abundant, environmental stewardship and conservation need to remain a top priority.
Dr. Jennifer Wilkins is a Senior Extension Associate in the Division of Nutritional Sciences at Cornell, where her work focuses on the linkages between human, environmental, and community health through sustainable food systems. Dr. Wilkins conceptualized and developed the first regional food guide in the United States, the Northeast Regional Food Guide, which promotes health, sustainability, and local food systems. She directs the Cornell Farm to School and the Farmers Market Nutrition Program. Dr. Wilkins writes a column called “The Food Citizen” which appears in the Albany Times Union the first Sunday of every month.
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