Environmental Toxin May Thwart a Healthy Diet and Lead to Breast Cancer
Eating a plant-based diet rich in grains, fruits and vegetables is considered a very positive step in reducing the risk of many types of cancers. However, a toxic chemical that is widely dispersed in the environment and affects our food and water supply may make our agriculture crops less healthful. Cadmium, a component of many farm fertilizers, has been linked to an increased risk of breast cancer, according to the latest research from the American Association for Cancer Research.
Although cadmium is a naturally occurring component of the earth’s crust and waters, and is present everywhere in our environment, exposure to certain forms of the mineral is known to produce toxic effects on humans. Higher concentrations of cadmium over what occurs naturally are due mainly to atmospheric deposition and the use of fertilizers which leads to higher uptake in plants.
Another aspect of cadmium ingested from the diet is that it can have some estrogen-like activity and affect estrogen receptor signaling. Environmental pollutants that mimic the effects of estrogen are suggested to contribute to the high incidence of hormone-related cancers, such as breast cancer or endometrial cancer.
Agneta Akesson PhD, an associate professor at Karolinska Institutet in Sweden, has studied the effects of dietary cadmium on both breast and endometrial cancers. The latest research findings are based on data from nearly 56,000 women who were followed for more than 12 years. Dietary cadmium exposure was estimated using a food frequency questionnaire.
Overall, there were 2,112 incidences of breast cancer, including 1,626 estrogen receptor-positive and 290 estrogen receptor-negative cases. Those women who had the highest exposure to cadmium through the diet had a 21% increased risk of development breast cancer.
Unfortunately, the foods that are considered most healthy are those which have the highest levels of the chemical. “Because of a high accumulation in agricultural crops, the main sources of dietary cadmium are bread and other cereals, potatoes, root crops and vegetables (especially leafy greens),” said Dr Åkesson. Cadmium is also found in shellfish due to contaminated sea water and in the meats of animals that eat cadmium-containing plants.
In Dr. Akesson’s previous work, published also in the journal Cancer Research in 2008, average intake of dietary cadmium based on data from the Swedish Mammography Cohort, is about 15 micrograms per day, with 80% of that coming from cereals and vegetables. The World Health Organization sets the maximum tolerable intake at 25 micrograms per kilogram of body weight.
So does this mean that a healthful diet can fall by the wayside? No, says Dr. Akesson. Women who consumed higher amounts of whole grains (versus refined grains) and vegetables had a lower risk of breast cancer compared to women exposed to dietary cadmium through other foods.
“It’s possible that this healthy diet to some extent can counteract the negative effect of cadmium, but our findings need to be confirmed with further studies,” said Åkesson. “It is, however, important that the exposure to cadmium from all food is low.” A healthy and varied diet full of vegetables, fruits, whole grains and beans can protect against a range of other types of cancers, including those of the mouth, esophagus, stomach, lung, pancreas, and prostate. Plus, poor nutrition actually increases the uptake of the chemical in the body.
Cigarette smoking is a much greater risk, as the chemical is present in tobacco.
The American Association for Cancer Research (AACR)
Agneta Åkesson et al. Dietary Cadmium Exposure and Risk of Postmenopausal Breast Cancer: A Population-Based Prospective Cohort Study. doi: 10.1158/0008-5472.CAN-11-0735 Cancer Res March 15, 2012 72;1459
Agneta Åkesson et al. Long-term Dietary Cadmium Intake and Postmenopausal Endometrial Cancer Incidence: A Population-Based Prospective Cohort Study. doi: 10.1158/0008-5472.CAN-08-0329 Cancer Res August 1, 2008 68;6435
American Institute for Cancer Research
This page is updated on Sept, 29, 2013.