Oranges, leafy green vegetables and folic acid supplements could help prevent people developing Alzheimer’s, a new study has found.

Research from the University of California has shown that the folates or B-vitamin nutrients found in these sources are more effective in limiting the risk of Alzheimer’s than antioxidants and other nutrients.

A team from the university’s Irvine’s Institute for Brain Aging and Dementia discovered the advantages after analysing the diets of non-demented men and women aged 60 and older.

They compared the food nutrient and supplement intake of those who later developed Alzheimer’s disease to the intake of those who did not develop the disease.

Between 1984 and 1991, study volunteers provided detailed dietary diaries, which included supplement intake and calorie amounts, for a typical seven-day period.

Ultimately, 57 of the original 579 participants developed Alzheimer’s disease. But the researchers found that those with higher intake of folates vitamin E and vitamin B6 shared lower comparative rates of the disease.

And when the three vitamins were analysed together, only folates were associated with a significantly decreased risk.

Dr Maria Corrada, research team leader, said: “The participants who had intakes at or above the 400-microgram recommended dietary allowance of folates had a 55-percent reduction in risk of developing Alzheimer’s.

“But most people who reached that level did so by taking folic acid supplements, which suggests that many people do not get the recommended amounts of folates in their diets.

“Although folates appear to be more beneficial than other nutrients, the primary message should be that, overall, healthy diets seem to have an impact on limiting Alzheimer’s disease risk,” she added.