Everyone knows that drinking milk is good for your bones, but a new study may indicate that it’s not great for your brain—as researchers have now linked milk consumption to signs of Parkinson’s disease.
“The link between dairy products and Parkinson’s disease has been found in other studies,” explained study author R. D. Abbott, PhD, with the Shiga University of Medical Science in Otsu, Japan, in a statement. “Our study looked specifically at milk and the signs of Parkinson’s in the brain.”
According to the paper, which is published in Neurology, Abbott and his team followed 449 Japanese-American men who were participating in the Honolulu-Asia Aging Study. These men were an average of 54 years old, and were followed usually for 30 or more years until death. Then, they were autopsied, with the focus being on the substantia nigra region of the brain—which plays a key role in Parkinson’s. Loss of cells in this area leads to the tremors associated with the disease.
The team also measured the amount of a pesticide called heptachlor epoxide in 116 of the brains—which was found to be in very high concentrations in the milk supply of Hawaii in the early 1980s. At the time, it was a popular agent for protecting pineapples against insects, but was quickly removed from use in the US. It may still exist in significant concentrations in certain water supplies.
Two cups of milk per day could lead to fewer brain cells
The researchers discovered that nonsmokers who drank more than two cups of milk per day had 40 percent fewer brain cells in the substantia nigra than the people who drank less. Interestingly, smokers exhibited no connection between milk consumption and reduction in brain cells—which ties into previous studies which showed that people who smoke have a lower risk of developing Parkinson’s. (Not that that should be a reason to take up smoking.)
Moreover, traces of the pesticide heptachlor epoxide were found in 90 percent of the men who drank the largest amount of milk daily, whereas it was found in only 63 percent of men who did not drink any milk.
The researchers stressed, however, that they cannot definitively show that the milk consumed contained the pesticide, merely that there seems to be a link between the two. Further, the study does not show that the pesticide or milk intake directly causes Parkinson’s disease, but suggests there is an association between them.
“There are several possible explanations for the association, including chance,” said Honglei Chen, MD, PhD, with the National Institute of Environmental Health Sciences and a member of the American Academy of Neurology, who wrote a corresponding editorial. “Also, milk consumption was measured only once at the start of the study, and we have to assume that this measurement represented participants’ dietary habits over time.”
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Feature Image: Thinkstock
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