A new study from Harvard University suggests that eating a healthy diet in middle age may be linked to having fewer of the early, non-motor symptoms of Parkinson’s disease.

The study involved around 47,000 people who were asked about their diet every four years – starting in the 1980s when they were middle-aged.

The researchers looked at how closely people’s diets followed either the alternate 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 eating fruit, vegetables, whole grains, nuts and legumes and discourage eating red meat.

The study found that the people with the highest adherence to the diets were less likely to have three or more symptoms that precede Parkinson’s disease than the people with the lowest adherence. Those in the high group for adherence to the alternate Mediterranean diet were 33% less likely to have three or more symptoms than those in the low adherence group.

When looking at individual food groups, the researchers found that eating more vegetables, nuts, legumes and consuming a moderate amount of alcohol were all associated with a lower risk of having three or more of the preceding symptoms. Moderate alcohol consumption was considered no more than one drink per day for women and no more than two drinks per day for men.