Everyday food compound associated with stronger memory in older adults

Older adults who consumed more lecithin, a nutrient found in eggs and soybeans, generally performed better on thinking tests.

Eggs at breakfast, beans at lunch and meat at dinner can all supply lecithin, a blend of fatty compounds present in many foods.

Lecithin is often promoted as a memory booster, though the scientific evidence has been limited.

In a Chinese study, older adults with higher dietary lecithin intake showed slightly better memory and cognitive scores.

They were also less likely to have mild cognitive impairment, a condition involving thinking difficulties that go beyond normal aging but do not amount to dementia.

Because the researchers assessed participants only once, the study offers a snapshot of diet and cognition and cannot show that lecithin caused the differences.

The first authors were Xiaoying Li and Chengyan Qi, two hospital researchers in Beijing. Both hospitals are affiliated with Capital Medical University, where coauthor Yuandi Xi, a public health professor, studies nutrition, memory and muscle loss in older adults.

Why study lecithin?

Cells rely on lecithin in the thin membranes that enclose them. When lecithin is digested, it also provides choline, which the body uses to produce a chemical messenger that helps nerve cells communicate.

That gives scientists a reason to examine lecithin and memory together.

A Finnish study of 2,497 middle-aged men linked higher dietary phosphatidylcholine intake with a lower risk of dementia.

But lecithin has not fared as well as a dementia treatment. A review of randomized trials published in 2003 found no support for using it that way.

Li and Qi’s group wanted to examine the years before dementia develops. Could getting more lecithin from ordinary meals be tied to better memory and thinking?

Examining everyday diets

The study included 1,917 people from three Chinese cities: Beijing, Jincheng and Linyi.

Participants were recruited from census or village records and were all 60 or older and had lived locally for at least a year.

In face-to-face interviews, researchers asked about health and food intake. A questionnaire captured how often different foods were eaten.

Using those responses and China’s food composition database, the team estimated each person’s daily lecithin intake.

About 88 milligrams was the midpoint, so the main comparison was between people who consumed more and those who consumed less.

Testing memory and thinking

The researchers used the 30-point Montreal Cognitive Assessment to screen for memory and thinking problems. A low score meant different things depending on education level.

A score of 13 or below suggested possible trouble for someone who could not read. For people with at least seven years of schooling, the cutoff was 24 or below.

Neurologists evaluated everyone flagged by the screening and used criteria from the U.S. National Institute on Aging and the Alzheimer’s Association to determine who had mild cognitive impairment.

Overall, 1,023 of the 1,917 participants were diagnosed with the condition, a little more than half the group.

How the groups compared

The two intake groups differed by about half a point, with the higher score going to those consuming more than 88 milligrams a day.

That result accounted for age, sex, education, calorie intake, blood fats, body composition and seven chronic diseases, including diabetes and stroke.

Half a point was a small difference on this test. The typical score was 23 among people without mild cognitive impairment and 19 among those with it.

The higher-intake group had roughly 20% lower odds of receiving a diagnosis. When participants were divided into thirds by intake, the pattern was similar: the top third had about 27% lower odds than the bottom third.

Food sources of choline

The researchers described the findings as epidemiological evidence, meaning they identified a health pattern across a population.

“This study provides important epidemiological evidence that ensuring adequate lecithin intake through a balanced diet could be a feasible approach to support cognitive health in the elderly,” the team wrote.

The authors noted China’s daily reference intake for choline: 450 milligrams for men and 380 for women. Those are choline targets and should not be confused with the lecithin amounts measured in the study.

According to the researchers, a balanced diet that includes eggs, legumes and lean meats can easily meet those choline goals.

They also pointed out that earlier research has linked dietary patterns such as the Mediterranean diet with better thinking later in life.

Schooling made a difference

The strongest association appeared among people with the least education. Of the participants, 1,025 had no schooling beyond primary school, including 387 who could not read.

Among this group, those who ate more lecithin scored nearly one point higher. For the other 892 participants, who had reached junior high school or beyond, there was barely any difference.

The pattern did not consistently vary by age, sex or the chronic illnesses examined by the team. Education stood out, and the authors suggested cognitive reserve might help explain the difference.

Schooling and mental activity may give the brain more ways to compensate for damage.

Someone with less of that reserve could be more affected by dietary differences, although the study cannot show whether changing meals would help.

A closer look at blood cells

Red blood cell membranes provided another way to compare the groups, since they can reflect fats consumed over time.

For this analysis, the team randomly selected 15 people with mild cognitive impairment and 15 without it, then studied their blood samples.

People with impairment had less lecithin in their cell membranes. The lecithin they did have also differed in composition: less of it carried polyunsaturated fatty acids, while more carried saturated fatty acids.

One member of the polyunsaturated family is DHA, a fat found in high amounts in nerve cells.

A form of lecithin containing linoleic acid, another polyunsaturated fat, was one of six membrane fats that best separated the groups.

It was a very small comparison, involving only 30 people. The analysis also could not isolate lecithin carrying DHA.

What the study cannot prove

One unresolved question is the direction of the association. Because diet and cognition were measured at the same time, it is possible that memory problems had already changed eating habits.

The researchers had no information on household income or household size, both of which can affect diet and brain health. Participants also had to recall what they ate, which leaves room for error.

All participants were from three cities in China, and diagnoses were made without a full battery of memory tests.

Studies in other places could find a different result.

The authors suggested that asking about lecithin intake might one day serve as a low-cost first step in community memory screening.

A model that combined intake with age, sex, education, calories and several health measures distinguished the two groups reasonably well.

For now, the study does not show whether eating more lecithin slows memory decline. To answer that, the authors called for long-term research that follows older adults over time and tracks both diet and cognition.

The study was published in the journal Chinese Medical Journal.