The World's Healthiest Foods

Folate Deficiency Linked to Parkinson's Disease

Parkinson's disease is a progressive disorder marked by hand and facial tremors, stiffness in the limbs and slow movement. In Parkinson's disease, the brain cells that produce the neurotransmitter, dopamine, slowly become dysfunctional, degenerate and die. Although the cause of Parkinson's disease is still unknown, a good deal of epidemiological data suggests that environmental factors, especially nutrient deficiencies in an individual's diet, may greatly increase the susceptibility of dopamine-producing brain cells to dysfunction and death.

In this study, researchers tested the hypothesis that inadequate consumption of foods rich in the B-vitamin folate affects the vulnerability of dopamine-producing brain cells. They found that when mice were given a folate-deficient diet, their dopamine-producing cells were much more susceptible to damage and death, in part because their blood levels of a very damaging molecule called homocysteine rose significantly.

Normally, homocysteine, an intermediate product created during a cellular process called the methylation cycle, is immediately converted with the help of folate into the harmless amino acid, cysteine. When folate levels are low, however, this conversion cannot take place, so homocysteine accumulates. Homocysteine promotes atherosclerosis by directly damaging blood vessel walls and by interfering with the formation of collagen (the main protein in connective tissue). A good deal of research has already shown that high levels of homocysteine are a significant risk factor for cardiovascular disease. Now, this study suggests that homocysteine is also involved in the development of Parkinson's disease.

When the researchers infused homocysteine directly into either the substantia nigra or striatum, the parts of the brain where dopamine-producing cells are found, the rate at which the mice's dopamine-producing cells deteriorated and their Parkinson's-like motor dysfunction dramatically increased.

Researchers then exposed human dopamine-producing brain cells to homocysteine and the pesticide rotenone, a double whammy that resulted in the brain cells' rapid deterioration and death. The researchers concluded that folate deficiency, which leads to elevated homocysteine levels, renders dopamine-producing brain cells more susceptible to damage from environmental toxins, thus significantly increasing the risk for Parkinson's disease.

Previous studies have shown that levels of homocysteine are elevated in people with Parkinson's disease, but the precise role of homocysteine in the development of the disease was unclear. This study strongly suggests that elevated homocysteine levels can indeed render neurons vulnerable to Parkinson's disease and shows that a diet with low folic acid levels increases homocysteine levels, which, in turn, renders neurons in the brain vulnerable to dysfunction and death.

Want to increase your consumption of foods rich in folate? Not surprisingly, the richest sources of folate are found among the World's Healthiest Foods. Excellent sources of folate include spinach, asparagus, turnip and mustard greens, beef liver, broccoli, cauliflower, beets, celery, cabbage, zucchini, lentils, and brussels sprouts. Very good sources include squash, cucumber, black beans, pinto beans, and garbanzo beans.

To learn more about these folate-rich foods, including quick and easy cooking and serving ideas, simply click on the highlighted name of the food in the above list. To learn more about this important B vitamin, click folate

For some truly exceptional recipes that will help you enjoy folate-rich foods more frequently as part of your healthy way of eating, take a look at the World's Healthiest Foods' Recipes containing of these foods. Simply, click on the Recipe Assistant, select the foods for which you'd like some recipes from the Healthy Foods List, and click on the Submit button. A list containing links to all our recipes containing the foods chosen will appear immediately below.

Reference:Duan W, Ladenheim B, Cutler RG, Kruman II, Cadet JL, Mattson MP. Dietary folate deficiency and elevated homocysteine levels endanger dopaminergic neurons in models of Parkinson's disease. J Neurochem 2002 Jan;80(1):101-10.