Korean University researchers say drinking a glass or two of milk a day may increase the risk of Parkinson's disease in middle-aged men, but the apparent link is unlikely to be due to milk's main nutritional ingredient, calcium.
But whether another ingredient, or a contaminant is responsible for the possible raised risk of Parkinson's - which still remains low is unclear.
Parkinson's, a degenerative disease of the nervous system, is associated with trembling of the arms and legs, stiffness and rigidity of the muscles and slowness of movement, and previous research has also suggested a link between high consumption of dairy products and a raised risk of Parkinson's in men - but not women.
The latest study, over 30-years, focused on 7,504 men aged 45 to 68, who were enrolled in a heart study in Hawaii, and during the course of the study, 128 developed Parkinson's.
The researchers found those men who consumed more than 16oz (454g) of milk a day were 2.3 times more likely to develop Parkinson's than those who drank no milk at all, but overall, the risk of Parkinson's - even among men who drank a lot of milk was low.
In each 12 month period, 6.9 cases of Parkinson's could be expected per 10,000 people who drank no milk, and among those who drank more than 16ozs a day the figure was 14.9 per 10,000, but they found no evidence of a link between calcium consumption and Parkinson's.