(NewsNation) — A new study of data that took nearly three decades to collect appears to add more weight to the idea that olive oil is not only good for heart health but helps fight off death from dementia.

The research says those who consume at least a half-tablespoon of olive oil every day have a 28% lower risk of dying from dementia, regardless of their overall diet.

The study looked at data collected over 28 years from more than 92,000 health care professionals. A study using the same data two years ago found that higher olive oil consumption was linked to a 19% lower risk of dying from cardiovascular disease.

There have been many studies examining the benefits of the Mediterranean Diet, which favors fresh fruits, vegetables, nuts, fish, dairy and olive oil.

The conclusion comes from surveys of health care workers starting in 1990. It tracked the subjects’ diets every four years and reviewed the death certificates of those who died during the survey period.

Of the more than 92,000 participants, 4,751 died of dementia during the study period.

The study was conducted at the Harvard T.H. Chan School of Public Health and released this week in the journal JAMA Network Open.

One skeptic says the results are “very nice.” However, Mayo Clinic neurology professor David Knopman tells The Washington Post the results may just reflect the idea that health care professionals are generally more conscious of their health and diets than the general public.

In fact, the researchers noted that the people in the databases may have consumed more olive oil than most people because they used it as substitutes for mayonnaise, butter or other vegetable oils. Consuming less of those products over a lifetime could have had an effect on dementia rates.