Parkinson's Disease Has Been Linked to Drinking Milk

Proving once and for all that environmental factors are and will continue to be an important, if not crucial, factor in your health, a study has found that a pesticide widely used in the early 80s—and which found its way into our nation's supply of cow's milk—may be the cause of Parkinson's disease emerging in people today.

Researchers have long speculated that contaminants and chemicals found in milk—especially milk produced in the early- to mid-80s—directly contributed to the spread of Parkinson's, yet little to no evidence actually existed. That is, until Robert Abbott and the rest of his team at Japan's Shiga University of Medical Science began thinking about an environmental scandal that took place in Hawaii during that time period. And it involved pineapples.

Here's what went down: A pesticide called heptachlor epoxide was used for insect control by the pineapple industry back then. The pesticide found its way into cow feed and then into the cows' milk. Abbott and his team were able to take advantage of data that was collected for a study of heart disease in Japanese-American men living in Hawaii at that time. The study followed the men from mid-life to death, providing all kinds of information about them, including what they ate. Some of the men even agreed to donate their brains upon their death for research purposes. Abbott looked at 449 of these brains.

What he found was that the men who drank more than two cups of milk a day had 40 percent fewer brain cells in an area of their brains related to Parkinson's disease. In addition, residue of the pesticide was also found in the brains of 90 percent of the men who drank the most milk—compared to just 63 percent of those who didn't drink any milk at all. Ipso facto: pretty clear correlation between pesticide and Parkinson's.

The good news is that the commercial sale of this particular pesticide in agriculture was banned in the United States by 1988. But, of course, there's bad news: a similar compound is used today for controlling fire ants in electrical grid machinery.

Although there are no longer any samples of the milk around for researchers to test, the scientists are convinced that the pesticides in the milk are what led to the increased rates of Parkinson's. Abbott said that they "just have no other explanation for how heptachlor epoxide found its way into the brains of men who consumed milk." The study, published this week in the journal Neurology, is important because it quite clearly ties a pesticide to a detrimental brain change—not always the easiest connection to prove.

As usual, the researchers don't want you to be alarmed: "The vast majority of milk consumers do not get Parkinson's disease," Abbott told Live Science. He did say, however, that people should be careful about eating food that may contain pesticides. And if you're feeling a little sketchy about milk after hearing this, consider some good news that just came out about milk of late: A new study says that milk collected from cows at night can be used to treat both anxiety and insomnia, thanks to significantly higher levels of tryptophan and melatonin found in the milk of these sleepy cows.

So the next time you're in the supermarket, instead of buying low-fat, calcium-enriched milk with DHA-omega 3, look for the milk from the sleepy cow that lived a pristine life with no pesticide exposure. That's the milk you want.