The results of a study that will be reported at the American Academy of Neurology's 63rd Annual Meeting this year suggest that eating more foods containing high amounts of flavonoids could help protect against the development of Parkinson's disease. Flavonoids are a class of compounds that include flavanones, anthocyanins, flavan-3-ols, flavonols, flavones, and polymers, and are abundant in chocolate, tea and other plant foods.
Xiang Gao, MD, PhD of the Harvard School of Public Health and colleagues evaluated data from 49,281 men enrolled in the Health Professional Follow-up Study and 80,336 women who participated in the Nurses' Health Study. Dietary questionnaires completed upon enrollment were analyzed for the intake of flavonoids and five sources of flavonoid-rich food, including tea, berries, apples, red wine, and orange or orange juice.
Over two decades of follow-up, 805 subjects were diagnosed with Parkinson's disease. Men whose intake of flavonoids was among the top 20 percent of participants had a 40 percent lower risk of developing Parkinson's disease compared to men whose intake was among the lowest 20 percent. While no significant association with total flavonoid intake was observed for women, a lower risk of developing Parkinson's disease was observed in association with the intake of anthocyanins and anthocyanin rich foods (apples and berries) among both women and men.
"This is the first study in humans to examine the association between flavonoids and risk of developing Parkinson's disease," Dr Gao announced. "Our findings suggest that flavonoids, specifically a group called anthocyanins, may have neuroprotective effects. If confirmed, flavonoids may be a natural and healthy way to reduce your risk of developing Parkinson's disease."
During Parkinson’s, cells in the parts of the brain that control movement and regulate mood are gradually destroyed. The primary defect in Parkinson’s is a loss of dopaminergic neurons (such as dopamine-producing neurons) in a part of the brain called the substantia nigra. Dopamine is a neurotransmitter that modulates movement (Purves D et al 2001). In Parkinson’s disease, the dopamine-producing nerve cells are destroyed by high levels of oxidative damage (Atasoy HT et al 2004; Ross GW et al 2004). There is evidence that this oxidative damage is, in turn, caused by defects in the cells’ mitochondria, or power-generating centers.
Vitamin C may relieve the symptoms of Parkinson’s disease by neutralizing dopamine free radicals (Sakagami H et al 1998) and toxic quinones released from dopamine metabolism (Pardo B et al 1995), thereby protecting brain cells from levodopa-induced damage (Mytilineou C et al 1993). In the laboratory, bathing nerve cells in vitamin C enhanced dopamine synthesis (Seitz G et al 1998).
Bioflavonoids, which provide the red, pink, and purple colors in fruits and vegetables, are even stronger antioxidants than vitamin C. Most are water soluble and easily penetrate the brain. Suggested antioxidant supplements include grape seed extract. The herbal compound Ginkgo biloba contains numerous antioxidants, including proanthocyanins and flavonoids, which help maintain healthy brain function, circulation, and metabolism.
Polyphenols are antioxidants found in green tea, which are being investigated for their potential to protect against Parkinson’s disease (Weinreb O et al 2004). Polyphenols are also found in extracts of grape seeds and other plants. Like the bioflavonoids, they are powerful antioxidants. They may also inhibit the nerve cell damage in diseases such as Parkinson’s and Alzheimer’s