A diet that contains inadequate amounts of the B vitamin folate may raise the risk of Parkinson's disease.

The study found that dopamine-producing cells in the brain were more susceptible to damage and death when mice consumed a folate-deficient diet. Dopamine is a brain chemical that helps regulate movement, and the cells that produce the neurotransmitter slowly degenerate in patients with Parkinson's disease.

Mice fed a folate-deficient diet also had elevated levels of homocysteine, a compound formed naturally when protein is metabolized.

When high concentrations of homocysteine were infused directly into the brain, it exacerbated the Parkinson's-like symptoms in mice. Parkinson's disease is a progressive disorder marked by hand and facial tremors, stiffness in the limbs and slow movement.

While previous studies have shown that levels of homocysteine are elevated in people with Parkinson's disease, the precise role of homocysteine in the development of the disease has remained unclear.

This study strongly suggest that elevated homocysteine levels can indeed render neurons vulnerable to Parkinson's disease.

This study establishes that a diet with low folic acid levels increases homocysteine levels and the homocysteine, in turn, renders neurons in the brain vulnerable to dysfunction and death.

Journal of January Neurochemistry 2002;80:101-110