Researchers at INSERM, the French National Institute for Health and Medical Research, in Bordeaux, France, examined the diets of 8,085 men and women over the age of 65 who did not have dementia at the beginning of the study.
Over four years of follow-up, 183 of the participants developed Alzheimer's disease and 98 developed another type of dementia, ScienceDaily reports.
They also found people who regularly consumed omega-3 rich oils, such as canola oil, flaxseed oil and walnut oil, reduced their risk of dementia by 60 percent compared to people who did not regularly consume such oils.
People who ate fruits and vegetables daily also reduced their risk of dementia by 30 percent compared to those who didn't regularly eat fruits and vegetables.
They also found people who ate fish at least once a week had a 35-percent lower risk of Alzheimer's disease and 40-percent lower risk of dementia, but only if they did not carry the gene that increases the risk of Alzheimer's, called apolipoprotein E4, or ApoE4.
