Researchers from the Harvard T.H. Chan School of Public Health in Boston, MA, analyzed data from a study that had followed 27,842 men for 26 years.
The men had all filled in detailed surveys about their food and drink intake at the start of the study in 1986 — when they were aged 51 years, on average — and then every 4 years until 2002.
The follow-up lasted until 2012, by which time their average age was in the mid- to late-70s.
During the last few years of the follow-up, they had also completed short tests to find out whether they had noticed any decline in their own ability to think and remember things.
The analysis showed that consuming higher amounts of certain foods and drinks was tied to lower risk of decline in memory and thinking skills.
The foods that most strongly showed this effect were leafy greens, red and dark orange vegetables, berry fruits, and orange juice.
The journal Neurology recently published a paper about the study and its findings.
“Our studies,” says first author Dr. Changzheng Yuan, who works in the school’s departments of nutrition and epidemiology, “provide further evidence [that] dietary choices can be important to maintain your brain health.”
Subjective cognitive function test
The purpose of the subjective cognitive function (SCF) tests that the men completed was to discern changes in memory and thinking abilities that they had noticed themselves.
The SCF test contains six items, and the study authors note that its “validity was supported by strong associations” with a gene that is linked to Alzheimer’s disease.
Consumption of fruits and vegetables
The team split the men into five groups according to their fruit and vegetable intake. The results showed that the group that ate the most vegetables consumed about 6 servings per day, and that the group that ate the least consumed 2.
The daily consumption of fruit ranged from 3 servings for the group that ate the most to half a serving for the group that ate the least.
A comparison of the vegetable consumption against the SCF scores revealed that:
- The men who ate the most vegetables were 34 percent less likely to report having experienced a reduction in memory function.
- Of the men who ate the most vegetables, 6.6 percent scored poor on the SCF, compared with 7.9 percent of those who ate the least.
The results also showed a 47 percent less chance of having a poor SCF score among the men who drank orange juice every day compared with those who only drank it once per month. The link was most relevant for older men who drank orange juice every day.
In addition, men who ate the most fruit each day were the least likely to have a poor SCF score, but this link lost its strength after the team considered the effect of other foods.
The team also found that high levels of fruit and vegetable consumption near the start of the study period was linked to a lower chance of having a poor SCF score some 20 years later.