New research from Karolinska Institutet in suggests that there is a link between dietary cadmium and breast cancer. The results, which are presented online in Cancer Research, are based on data from over 55,000 women.
"It's been known for some time that cadmium is toxic and, in certain forms, carcinogenic," says Bettina Julin, doctoral student at Karolinska Institutet's Institute of Environmental Medicine. "Our point of inquiry was whether there was some connection between dietary cadmium and, specifically, breast cancer. At the same time, we must remember that cadmium concentrations in our food are generally quite low and that there are several other scientifically established causes of breast cancer."
The study is based on a survey of the dietary habits of 55,987 women in Uppsala and Västmanland carried out in 1987. The researchers estimated how much cadmium the women had ingested with their food on the basis of the cadmium content of every single food item that they ate. Over the 12-year follow-up period, they were able to note 2,112 cases of breast cancer occurring post-menopause.
The researchers divided the participants into three groups depending on their dietary cadmium intake. Doing this, they found that the group with the highest cadmium intake had a 21 per cent greater risk of developing breast cancer than the group with the lowest. They also discovered, importantly, that the women who ate mostly wholegrain products (e.g. wholemeal bread) and vegetables were less likely to develop breast cancer than women who had been exposed to cadmium through other sorts of food. The researchers also note, however, that bread and vegetables are the most common sources of dietary cadmium, a fact that complicates the interpretation of the results of their work.
"We certainly cannot advise women against eating a certain kind of food; indeed, it seems as if wholegrain products and vegetables even provide a degree of protection against cancer," says lead investigator Agneta Åkesson, docent at the Institute of Environmental Medicine. "On the other hand, these findings are interesting given the current debate on what levels of cadmium we're to accept in our environment, bearing in mind the health hazards it poses."
Dietary Cadmium Exposure and Risk of Postmenopausal Breast Cancer: A Population-Based Prospective Cohort Study. Bettina Julin, Alicja Wolk, Leif Bergkvist, Matteo Bottai & Agneta Åkesson. Cancer Research, online 15 March 2012