A Mediterranean-style diet may slow memory loss, even if adopted late in life

Whenever the fictional character Popeye the Sailor Man managed to down a can of spinach, the results were almost instantaneous: he gained superhuman strength. Devouring any solid object similarly did the trick for one of the X-Men. As we age and begin to struggle with memory problems, many of us would love to reach for an edible mental fix. Sadly, such supernatural effects remain fantastical. Yet making the right food choices may well yield more modest gains.
A growing body of evidence suggests that adopting the Mediterranean diet, or one much like it, can help slow memory loss as people age. The diet's hallmarks include lots of fruits and vegetables and whole grains (as opposed to ultrarefined ones) and a moderate intake of fish, poultry and red wine. Dining mainly on single ingredients, such as pumpkin seeds or blueberries, however, will not do the trick.
What is more, this diet approach appears to reap brain benefits even when adopted later in life—sometimes aiding cognition in as little as two years. “You will not be Superman or Superwoman,” says Miguel A. Martínez González, chair of the department of preventive medicine at the University of Navarra in Barcelona. “You can keep your cognitive abilities or even improve them slightly, but diet is not magic.” Those small gains, however, can be meaningful in day-to-day life.
From Fork to Brain
Scientists long believed that altering diet could not improve memory. But evidence to the contrary started to emerge about 10 years ago. For example, Nikolaos Scarmeas of Columbia University and his colleagues collected information about the dietary habits and health status of about 2,000 Medicare-eligible New Yorkers—typically in their mid-70s—over the course of four years on average. In 2006 the investigators reported that tighter adherence to a Mediterranean diet, which had previously been linked to a lower risk of cardiovascular disease, was associated with slower cognitive decline and a lower likelihood of acquiring Alzheimer's disease. Because the researchers merely observed dietary patterns and did not control them—as would be the case in a clinical trial—doubts lingered, however. It was still possible that the apparent brain benefit was the result of chance or some other trait common to folks who consistently follow a Mediterranean diet in the U.S., such as educational achievement or particular life choices.
Seven years later researchers pinned down some answers. In 2013 Martínez González and his colleagues published findings on their massive PREDIMED study, an experiment that included almost 7,500 people in Spain. (PREDIMED stands for Prevention with Mediterranean Diet.) The investigators randomly assigned study subjects to one of two experimental groups. In the first, participants followed the Mediterranean diet with an additional helping of mixed nuts; in the second, they also adhered to the Mediterranean diet but were given additional extra virgin olive oil. (Researchers felt that providing extra nuts and oils at no cost to participants would guarantee that certain healthy fats were eaten in quantities large enough to have measurable effects on the study's outcomes.) The control group, against which the results of the experimental groups would be compared, was instructed generally on how to lose weight. Its members were given advice on eating vegetables, meat and high-fat dairy products that jibed with the Mediterranean diet, but they were discouraged from using olive oil for cooking and from consuming nuts.
As expected, the results showed that either of the experimental Mediterranean diet options led to significantly better cardiovascular outcomes. But when the scientists tested cognition in a subset of study members, they also discovered that individuals in either of the Mediterranean diet groups performed better than the weight-instruction group in a battery of widely accepted cognitive tests. “This is surprising, of course,” Martínez González says.
As intriguing as these findings are, they are still not conclusive; the researchers had not gathered any cognitive information at the beginning of the study. Therefore, the possibility remains that there was something different between the two experimental groups and the control group—beyond their diet interventions—that could account for the findings.
Martínez González sought to quiet such criticisms with a new study his team published in July in JAMA Internal Medicine. Drawing from a group of more than 300 participants who were also part of PREDIMED but at a specific site with more financial resources, the researchers conducted baseline cognitive measurements and compared them with that same group's results four years later. On average, people were 67 years old at the start of the study. The newest findings, Martínez González says, are consistent with what he found in his earlier studies. These results are also not definitive, however, because this substudy was relatively small. Yet, he notes, it is the first time scientists have seen improvements in cognitive function from a randomized trial of the Mediterranean diet.