Q. Could a low-fat diet contribute to memory problems?

A. “Since the brain and body cells need fat to survive and thrive, depriving them of certain types of brain-healthy fats may be detrimental to your memory,” said Dr. Richard Isaacson, the director of the Alzheimer’s Prevention Clinic at Weill Cornell Medicine and NewYork-Presbyterian.

The key issue, Dr. Isaacson said, is the type of fat, with fats being an integral part of a healthy diet. Generally, he said, there are good fats, bad fats and fats on which more research is needed to be certain. Certain fats are indeed essential to protect against memory loss, specifically polyunsaturated fats and monounsaturated fats, he said, while trans fats are certainly harmful, and conflicting data exists for saturated fats.

How brain-healthy a fat is tends to vary by individual, depending on precision nutrition. Despite some differences in data on effectiveness in treating a person already given a diagnosis of Alzheimer’s disease, Dr. Isaacson said, studies suggest that diets containing healthy levels of unsaturated fats may help protect against its development.