There's plenty of evidence around to suggest that Parkinson's disease can be slowed, certainly in its early stages. High doses of vitamins C and E have both been proven to be beneficial - but we do mean high doses if they are going to have an effect, and way beyond the levels being dreamed of by the EU regulators. To have an effect, you'd need to take 3,000 mg a day of vitamin C and 3,200 IU a day of vitamin E.
Another supplement that may slow Parkinson's is the coenzyme Q10. It was tested at a daily dose of 300, 600 and 1,200 mg against a placebo and, perhaps not surprisingly, the highest dose was the most effective at slowing the disease.
Those in the placebo group saw their disease worsen by 12 points, as measured on a rating scale, over 16 months, while those taking 300 mg of Q10 saw their score worsen by 8.8 points, the 600 mg group by 10.8 points, but the 1,200 mg group by just 6.7 points, nearly half that of the placebo group.
It would be interesting to see the effect of combining Q10 with vitamins C and E - provided we can buy the potency.
(Source: Archives of Neurology, 2002; 59: 1541-50).