What we eat and drink can profoundly affect our disease risk as we age. A recent study found that consuming just 1.5 teaspoons of olive oil daily can reduce the risk of death from dementia by 28%, even among APOE4 carriers, a potent genetic risk factor for dementia.

Researchers asked more than 92,000 healthy, middle-aged adults about their olive oil consumption over a 28-year period. They conducted genetic analyses to determine whether the participants carried the APOE4 gene. Then, using national death records, they ascertained which of the participants died of dementia.

They found that more than 4,700 of the participants died of dementia during the study period. People who carried one APOE4 allele were roughly twice as likely to die from dementia; those with two APOE4 alleles were five to nine times more likely. However, people who consumed 7 grams or more of olive oil daily—roughly 1.5 teaspoons—were 28% less likely to die of dementia than those who didn’t consume olive oil, regardless of their APOE4 status. Replacing 5 grams (about a teaspoon) of margarine or mayonnaise with an equivalent amount of olive oil reduced the risk of death from dementia by as much as 14%.

These findings suggest that eating olive oil markedly reduces the risk of death from dementia. Olive oil contains healthy fats and polyphenols—bioactive compounds with potent antioxidant and anti-inflammatory properties. Learn more about polyphenols in our overview article.