New, small study finds slight rise in blood pressure after drinking soy milk. Was it from BPA?

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bpaResearchers from South Korea s Seoul University College of Medicine and its Department of Environmental Health did a double-blind, crossover study of 60 older people to detect an effect of bisphenol-A (BPA) on blood pressure. Their results gave them a basis for asserting a causal relationship between drinking soy milk from a can lined with a BPA-containing polymer, and a 4.5 mm rise in systolic blood pressure (SBP).

The changes in SBP were compared with controls the same subjects who were given soy milk from glass bottles. The several-week-long study was conducted among seniors (over-60) at a community center, and the subjects were all matched at baseline for other parameters. The urine levels of BPA were measured two hours after milk consumption, and BPs were measured just before, and then twice, two hours after consumption. The difference between the before and (the mean of the two readings) after beverage consumption was the key parameter measured. They also did those same measurements with another arm of the study: a group which was given one glass container and one can: thus, there were three arms compared: a 2-glass bottle group (GG), a 2-can group (CC), and a mixed group (CG). SBPs and DBPs (diastolic blood pressure) were compared, and the differences as well. Of course, all participants served as their own controls.

The authors publication found in the AHA s journal Hypertension found that there was indeed a 16-fold increase in urine BPA levels after consumption of the soy milk served in cans, as compared with those measurements in the bottle-fed subjects. They also determined that SBP increased by 4.5 mm among those who had consumed the soy milk from cans vs. those measurements made on the same subjects after they had consumed bottle-contained milk. Their statistical analysis proclaimed this elevation statistically significant.

The authors and the AHA s press release concurred, deeming this study as showing a cause-and-effect relationship between can-derived BPA and an acute rise in SBP, and then going so far as to advise the American (and we imagine) the Korean public to eat fresh foods or glass-bottle contained foods rather than canned foods ¦. Even the New York Times Anahad O Connor s Well column went uncharacteristically hyperbolic over this study, referring to BPA as an endocrine disruptor and, after referring to BPA s being associated with heart effects, cancer, and the all-purpose other health problems, went so far as to cite the American Chemistry Council s retort: BPA is safe.

ACSH s Dr. Gil Ross had a bit more to say in lending perspective to the guilty as charged media circus: No one commenting on this study in the public arena seems to recall that every scientific body in the world, including our FDA and even the EPA, has deemed BPA safe in consumer products, including food and packaging. The scattered bans are based on the precautionary principle: consumer concerns. This particular study is rife with confounding and confusing fudge factors: soy is replete with estrogenic substances, some of which may impact BP itself. The CG group had no significant change in any BP measurement, thus bespeaking the lack of a dose-response. The DBP also had no differences among any of the study arms. And what in reality would a 4.5 mm increase in SBP mean in the real world of clinical medicine, even if it were caused by BPA? This is truly another BPA-mountain constructed out of molehills by the AHA and these authors.