A diet rich in fruit, vegetables, and nuts appears to lower the risk of several non-motor symptoms that tend to be associated with a later finding of Parkinson’s disease, a study reported.
The study, “Diet pattern and prodromal features of Parkinson’s disease,” was published in the journal Neurology.
A team of Harvard University researchers looked at how diet might associate with symptoms that often precede Parkinson’s, such as constipation, daytime sleepiness and depression, and for patterns that might arise.
Such symptoms can precede a Parkinson’s diagnosis by 10 years or more.
The Nurses’ Health Study began in 1976 and evaluates risk factors for major chronic diseases in women. The Health Professionals Follow-up Study, launched in 1986, looks for links between nutrition and men’s health.
The Harvard team found 47,679 records of people who had provided information about their diet every four years since 1986, when they were middle-aged.
Participants responded to questions in 2012 regarding constipation and a sleep disorder called rapid eye movement (REM) sleep behavior disorder. This disorder involves movements that appear to act out dreams, such as flailing arms, and shouting or screaming. Many people with REM sleep behavior disorder eventually develop Parkinson’s.
A few years later, between 2014 and 2015, the investigators examined the 17,400 people who had replied to the 2012 questionnaire, checking for five additional pre-Parkinson’s symptoms. These were loss of smell (anosmia), troubled color vision, excessive daytime sleepiness, body pain, and depression.
“We need to emphasize that, while these symptoms are associated with an increased risk of Parkinson’s disease, especially in combination, experiencing any or several of these symptoms does not necessarily mean that a person will eventually develop Parkinson’s disease,” Samantha Molsberry, PhD, the study’s lead author, said in a press release.
A comparison of participants’ symptoms and their diets found that adherence to two diets in particular was linked to fewer symptoms that can precede Parkinson’s.
These were the alternate Mediterranean diet (aMED) and the Alternative Healthy Eating Index (AHEI), both of which feature fruit, vegetables, whole grains, nuts and legumes, and discourage eating red meat. Similar to the Mediterranean diet, the aMED includes only whole grains and avoids dairy.
The researchers found that better adherence to these diets correlated with fewer of the pre-Parkinson’s risk factors.
After adjusting for other factors that might influence a person’s health risks, such as smoking and obesity, they found that people who best adhered to the Mediterranean diet were 33% less likely to have three or more symptoms than those who adhered least.
A similarly strong relationship between eating choices and three or more symptoms was seen among those following the AHEI diet.
Out of 29,899 women in the study, 37% of least-adherent people reported problems with constipation, compared to 32% of those who were most adherent.
This difference was wider among the 17,770 men in the study, with constipation troubling 22% of those least adherent, and 12% of those most adherent.
Among the 11,493 women with measures for all five non-motor symptoms, 13% of those who best stuck to the diet had body pain, compared to 15% of the those who followed the diet least.
In these same women, depression was a problem for 14% of those with high good diet adherence and 17% of those with low adherence.
Among the 5,907 men with information across symptoms, body pain was reported in 14% of the least adherent and 16% of the most adherent; depression in 13% of those with poorer diets relative to 12% of those sticking best to the perceived healthy diets.
Eating more vegetables, nuts, legumes (like beans and lentils) and consuming moderate amounts of alcohol — defined here as no more than one drink a day for women and two drinks a day for men — was associated with a lowered risk for three or more of these prodromal symptoms.
“While this study does not show cause and effect, it certainly provides yet another reason for getting more vegetables, nuts and legumes in your diet,” Molsberry added.