Both types of unsaturated fatty acids are contained within neuronal cell membranes and are known to have neuroprotective, antioxidant, and anti-inflammatory properties.

The researchers involved in the new study, published in Neurology (2005;64:2040-2045), wanted to build on this knowledge by determining whether a high intake of unsaturated fatty acids might be associated with a lower risk of Parkinson's disease.

Monounsaturated (MUFAs) fatty acids have been shown to help lower LDL (bad) cholesterol when substituted for saturated fat. Sources of MUFAs include olive, canola oils, avocados, peanuts, nuts and seeds.

One of the main forms of polyunsaturated fatty acids (PUFAs) is omega-3, commonly derived from fish, which have been shown to deliver considerable benefits for cardiovascular health and cognitive function. Omega-6 is also essential for human health, found in grains, most plant-based oils, poultry, and eggs.

However the modern diet is more heavily weighted towards omega-6 consumption than omega-3, an imbalance that has led to the growing popularity of the latter in fortified and functional foods and in supplement form.

The new study may give further weight to arguments in favor of the Mediterranean diet, which typically consists of foods rich in both MUFAs and PUFAs since it is based as it is on olive oil, nuts, fresh fish, fruits and vegetables. Three separate studies published this year have highlighted the heart health benefits of this diet, in lowering cholesterol levels, lowering the risk factors for heart disease and boosting longevity.

The new prospective population-based cohort study involved 5,289 people aged 55 or over, all of whom were free of dementia and Parkinson