After tracking 7504 men for thirty years, researchers in the US identified a two fold "excess" of Parkinson's Disease in those men with the highest intake, more than 16oz a day, compared to those who consumed no milk.
While the scientists are unclear as to which ingredient or compound could influence the onset of this degenerative disease, they suggest it is not calcium.
"Whether observed effects are mediated through nutrients other than calcium or through neurotoxic contaminants warrants further study," they report in the April issue of Neurology.
Parkinson's disease is a degenerative condition affecting movement and balance in more than one million Americans each year: its prevalence is slated to rise in ageing populations.
For the current study 7504 men enrolled in the Honolulu Heart Program between 45 and 68 years of age were followed for thirty years for the development of Parkinson's disease. Dietary intake for all subjects was recorded when the study began in the late 1960s.
A total of 128 participants developed Parkinson's disease and according to the statistics, the risk of Parkinson's disease increased as the amount of milk consumed each day rose. Heavy milk drinkers, more than 16 oz a day, were 2.3-times more likely to develop Parkinson's disease than non-milk drinkers.
But the risk was slight: even among the high intake groups.
The researchers calculated that in the course of a year, 6.9 cases of the disease would be expected among 10,000 people who drank no milk each day. By contrast, 14.9 cases would be expected if each of those 10,000 people drank more than 16 ounces per day.