A common belief held by many health professionals, including dietitians, is that weight loss occurs when a person burns more calories than they take in. While I know from my own personal experience and that of hundreds of others that calories do count in terms of weight balance, there are many other factors in play as well. Several hormones (including insulin, leptin, cortisol, estrogen, and T3) have a substantial influence on caloric intake and/or weight, although the exact mechanisms are not universally agreed upon. And in recent years, the effect of various chemicals on weight has also been investigated. Most notable among these is bisphenol A (BPA), an organic compound extremely common in the modern world.
Recent animal studies have found that BPA disrupts hormonal activity, resulting in insulin resistance and fat accumulation. Research also suggests that BPA may cause neurological and thyroid problems and increase the risk for breast cancer, prostate cancer, and many other health conditions, particularly in pregnant women and infants. To say that BPA has the potential for harm is likely an understatement.
All the more concerning, then, that BPA is virtually ominpresent in our society. From plastic water bottles to canned foods to grocery store receipts, we are exposed to this chemical multiple times a day. While the Bisphenol A website
contains links to studies meant to assure us that its use is absolutely safe, at this point I'd prefer to limit my exposure as much as possible based on several animal studies that suggest otherwise, as well the Environmental Working Group's assertion that the compound is toxic even at low levels.
There are several ways to do this, including carrying a thermos instead of bottled water, never heating foods in plastic, reducing consumption of canned foods, and purchasing BPA-free containers and bakeware. While I don't use a lot of canned items, I do eat a fair amount of canned fish. As of now, Trader Joe's states that while most of its salmon is packaged in BPA-free cans, sardines (my favorite), are not, although the chain hopes to remedy this by the end of the year. Treehugger.com has a nice list of companies that use BPA-free cans., and the Inspiration Green site has additional useful information.
Does BPA exposure cause weight gain, insulin resistance, and other health problems in humans? While further research needs to be done to determine the extent of risk posed by BPA, it's disturbing that the manufacturer's site states the product causes no harmful effects despite significant evidence to the contrary. Because it's impossible to completely avoid this chemical, I recommend we do our best to limit exposure as much as we can for the time being.
1. Soriano S, et al. Rapid Insulinotropic Action of Low Doses of Bisphenol-A on Mouse and Human Islets of Langerhans: Role of Estrogen Receptor β. PLoS One 2012; 7(2): e31109
2. Masuno H, et al. Bisphenol A in combination with insulin can accelerate the conversion of 3T3-L1 fibroblasts to adipocytes. J Lipid Res. May 2002. 43:676-684
3. Masuno H, et al. Bisphenol A accelerates terminal differentiation of 3T3-L1 cells into adipocytes through the phosphatidylinositol 3-kinase pathway.Toxicol Sci. Apr 2005; 84(2):319-27
4. Brisken C. Endocrine disruptors and breast cancer. CHIMIA Int National J Chem 2008 62(5) 406-409
5.Ho S-M, et al.Developmental exposure to estradiol or bisphenol A increases susceptibility to prostate carcinogenesis and epigenetically regulates phosphodiesterase Type 4 variant 4. Cancer Res. June 2006;66:5624–5632
Franziska Spritzler, RD, CDE