A higher dietary intake of vitamin B6 may decrease the risk of Parkinson’s disease, a study suggests.

Among more than 5,000 people, Dutch researchers found those who reported taking in the most vitamin B6 were about half as likely as those who consumed the least to develop Parkinson’s disease.

Vitamin B6 is essential for metabolism of protein and proper immune and nervous system function, and is found in both meat and vegetables.

There is evidence that high levels of the amino acid homocysteine could cause damage to brain cells. To see whether higher intake of folate and vitamins B6 and B12, which can reduce homocysteine levels, would also reduce Parkinson’s risk, researchers followed 5,289 men and women aged 55 and older who were free of the disease at the study’s outset.

During nearly 10 years of follow up, 72 people developed Parkinson’s disease, Dr. Monique M. B. Breteler of Erasmus Medical Center in Rotterdam and colleagues report in the journal Neurology.

The researchers found no association between consumption of B12 or folic acid and risk of developing the disease. However, the more B6 people consumed, the lower their risk.

Those in the highest third of vitamin B6 intake were 54 percent less likely to develop the disease compared to those in the lowest third. A closer look suggested that this relationship was only statistically significant for smokers.

The findings suggest that the nutrient could lower Parkinson’s disease risk not by affecting homocysteine levels but by protecting brain cells from damage caused by harmful by-products of metabolism known as free radicals, Breteler and her team propose. They note that several studies have shown that smoking actually cuts Parkinson’s risk, possibly due to brain-cell-protecting properties of nicotine.

The study doesn’t rule out the possibility that B12 and folate could also be protective, the researchers point out. To provide a more definitive answer, they add, studies must be conducted that look at levels of the nutrients in the blood, which is a more sensitive indicator of their effects.

SOURCE: Neurology, July 2006.