Parkinson's disease is a neurodegenerative disorder that affects dopamine-producing neurons in the brain. It develops slowly over years, and leads to symptoms including tremors, balance issues, and rigid limbs. In a new study published in the journal Neurology, researchers found that high intake of dietary antioxidants like vitamins C and E is associated with a lower risk of Parkinson disease (PD).
Parkinson’s is relatively common. Approximately 1 in 500 people have the condition. It becomes more common with older age groups, and it is believed 1% of people above the age of 60 have Parkinson’s. The average age at diagnosis is 59.
It’s the lifestyle piece that is of interest to nutrition researchers, who’ve been investigating the link between certain dietary patterns, nutrients, and PD.
Researchers are also currently looking at how both the Mediterranean diet and the ketogenic diet can be used for prevention and treatment of PD.
Other researchers are drilling down to see how specific vitamins, minerals or antioxidants affect PD risk, and have seen inconsistent findings. An earlier meta-analysis of six studies showed that vitamin E intake lowered PD risk, while vitamin C and beta carotene did not.
This prospective cohort study conducted in Sweden looked at 43,865 men and women, age 18-94, who were part of the Swedish National March Cohort.
The participants filled out a 36-page lifestyle, health, and diet questionnaire. Participants were asked to report on how often and how much they eat, based on a long list of foods.
By looking at these food frequency questions, researchers were able to determine the average intake of vitamin E, vitamin C, and beta-carotene of study participants.
Researchers then followed up on participants through national demographic and health registries, including the Statistic Sweden’s Register of the Total Population and the National Board of Health and Welfare, to find diagnoses of Parkinson’s disease between 1997-2016.
After 17 years of follow-up, there were 465 incident cases of PD identified, and the mean age of diagnosis was 74.6.
The researchers found that participants who had the highest intake of vitamin E had a 32% lower risk of PD, compared to those who consumed fewer foods containing vitamin E.
The same was found for vitamin C: 32% lower risk of PD for those consuming the most vitamin C. Even better, participants who consumed the most of both vitamin C and E had 38% lower risk of PD. No association was found for beta-carotene.
For both vitamins E and C, a stronger effect was noted among overweight and obese participants, while no association was observed in normal weight participants. Since this study was observational, it shows a correlation between two variables, namely vitamins and PD. But it’s important not to infer causation.
"I wasn’t surprised with the study results since vitamin C and E are antioxidants and may prevent cell damage from oxidation and inflammation."
— Lisa Young PhD, RD
While some people take vitamins and antioxidants in pill form, the research in this study was specifically looking at the link between PD and vitamin C and vitamin E from food sources, not from supplements.
Dr. Mauro Serafini, a professor at the University of Teramo in Teramo, Italy, and one of the researchers on this study, explains that they asked the question about the daily use of vitamin supplements, but only for yes/no answers.
"We have information on supplement use, but not which supplement they used, what dose and for how long," he explains.
In the study, he explains that they investigated the effect of vitamin C and E from dietary sources, which is how most people consume these vitamins.
The researchers did not rule out a role for supplements, but Serafini says, “I think that supplements can be considered negligible compared to dietary sources over time.”
Most health professionals recommend food sources of antioxidants rather than supplements where possible. That’s because supplements can’t possibly mimic the unique blend of nutrients and antioxidants that naturally occur in plant foods.
Plus, high doses of some supplements can be harmful. Research has shown that it’s close to impossible to get too much vitamin E from food, but taking too much supplemental vitamin E may increase prostate cancer risk, or have other side effects.
“I wasn’t surprised with the study results since vitamin C and E are antioxidants and may prevent cell damage from oxidation and inflammation,” says dietitian Lisa Young, adjunct professor of nutrition at New York University and author of Finally Full, Finally Slim.
“Vitamin C may also be protective of the neurological system,” says Young.
So, is there a diet that people can follow to prevent or treat PD, and do antioxidants play a role?
The Parkinson’s Foundation recommends avoiding fad diets, and focusing on the basics instead.
“While there is no specific diet for PD, it’s important that patients with the disease eat a well-balanced diet rich in vegetables, fruits, whole grains, and healthy protein-rich foods, such as fish and beans," says Young.
“It’s also advised to include healthy fats like olive oil, nuts, and fatty fish,” says Young, who adds that foods rich in antioxidants like vitamins C and E also are good for brain health.
If you want to make sure you include some of the best food sources of vitamin C in your diet, choose lots of vegetables and fruit, especially:
There is some vitamin E in tomato and kiwifruit, but it’s more concentrated in these foods:
“There’s also vitamin E in some greens, such as collards and spinach,” adds Young.
“While more research should be done, here’s some proof that a good diet can only help in the fight against disease,” says Young.
Future studies can further examine if there is a difference between vitamin C and E coming from food vs. supplements.
Since this study only assessed nutrition intake one time, it doesn’t account for dietary changes that may have taken place over the 17-year study period. Future studies should assess diet at baseline, then every few years to track changes.
One way to ward off a host of diseases, including Parkinson’s, is with a balanced eating pattern that includes vegetables, fruit, whole grains, beans, nuts and lean proteins. Ensure you choose foods that are rich in vitamin C and vitamin E daily.
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