A new study suggests that eating a healthy diet in middle age may be associated with having fewer of the symptoms that precede the onset of Parkinson's by up to 10 years, primarily non-motor symptoms, according to the online edition of Neurology, the medical journal of the American Academy of Neurology.
While this study does not show cause and effect, it certainly provides one more reason to include more vegetables, nuts, and legumes in your diet, said study author Samantha Molsberry of Harvard University. More research is needed to determine if a healthy diet could delay or even prevent the development of Parkinson's disease among people who already have these earlier symptoms.
The study involved 47,679 people who were asked about their diet every four years starting in the 1980s when they were middle-aged. Then, in 2012, the people were asked if they had two conditions that are common in people who are later diagnosed with Parkinson's disease: constipation and a sleep disorder called rapid eye movement sleep behavior disorder, which involves acting out dreams during sleep through movements such as waving arms or screaming.
In 2014-2015, 17,400 of the participants were asked about five more symptoms that may precede Parkinson's disease: loss of sense of smell, altered color vision, excessive daytime sleepiness, body pain, and depression.
The researchers examined the extent to which the people's diets followed the alternative Mediterranean diet, which is similar to the Mediterranean diet but includes only whole grains and does not consider dairy, or the Alternative Healthy Eating Index. Both diets encourage consumption of fruits, vegetables, whole grains, nuts and legumes and discourage consumption of red meat. They divided participants into five groups based on how closely they followed the diets.
The study found that people with the highest adherence to the diets were less likely to have three or more symptoms preceding Parkinson's disease than people with the lowest adherence. Those in the high adherence group to the Mediterranean diet were 33% less likely to have three or more symptoms than those in the low adherence group. These results were found after the researchers adjusted for other factors that might affect the risk of developing these earlier symptoms, such as physical activity, smoking, and body mass index (BMI).
Looking at the individual food groups, the researchers found that eating more vegetables, nuts, legumes, and consuming a moderate amount of alcohol were associated with a lower risk of having three or more of the above symptoms. Moderate alcohol consumption was considered to be no more than one drink per day for women and no more than two drinks per day for men.
"We need to emphasize that while these symptoms are associated with an increased risk of Parkinson's disease, especially in combination, experiencing one or more of these symptoms does not necessarily mean that a person will eventually develop Parkinson's disease," Molsberry said.