American diets abundant in foods rich in either vegetable oil or animal fat are suspects for contributing to the body’s inflammatory response, cardiac disease, arthritis, and Alzheimer’s disease. Now vegetable oil and animal fat have been linked to Parkinson’s disease.

Researchers Frederic Calon and Francesca Cicchetti, Université Laval, Quebec, believe that a diet rich in omega-3’s docosahexaenoic acid (DHA) may counteract the effect of omega-6 that is found in vegetable oil and animal fat. Calon and Cicchetti fed one group of mice an omega-3 rich diet and a control group a regular diet. The mice were then given MPTP—a toxic compound that causes the same damage to the brain as Parkinson’s disease, but works faster than the disease.

When the control group was injected with MPTP they showed symptoms characteristic of the disease; a 31% drop in dopamine-producing neurons and a 50% decrease in dopamine levels. The omega-3 rich diet mice appeared to be protected from the MPTP injection and showed no signs of the disease’s symptoms.

The researchers suspect that the omega-3 fatty acids—in particular the DHA—had replaced the omega-6 fatty acids already present in the brain, preventing the disease symptoms.

A balanced diet has a ratio between omega-6 and omega-3 fatty acids of 4 to 1. However, the average Western diet contains 10 to 20 times more omega-6’s than omega-3’s. In North America, the average intake of DHA is between 60 to 80 mg a day, while experts recommend a daily minimum of 250 mg. The researchers believe the results of their study suggest that a DHA deficiency is a risk factor of developing Parkinson’s disease.