A study following nearly 28,000 older men for 20 years has found that regular consumption of leafy greens, dark orange and red vegetables and berry fruits, and orange juice, was associated with a lower risk of memory loss.
The study looked at 27,842 male health professionals, who were an average age of 51 in 1986, when the study began. Participants filled out questionnaires about how many servings of fruits, vegetables and other foods they had each day, at the beginning of the study and then every four years.
- those who consumed the most vegetables (around six servings a day) were 34% less likely to develop poor thinking skills than the men who consumed the least amount of vegetables (around two servings)
- 6.6% of men who consumed the most vegetables developed poor cognitive function, compared to 7.9% of men who consumed the least
- those who drank orange juice every day were 47% less likely to develop poor thinking skills than those who drank less than one serving per month
- 6.9% of men who drank orange juice every day developed poor cognitive function, compared to 8.4 % of men who drank orange juice less than once a month
Interestingly, those who ate larger amounts of fruits and vegetables 20 years earlier were less likely to develop cognitive problems, whether or not they kept eating larger amounts of fruits and vegetables about six years before the memory test.
Cognition was not, however, assessed objectively, nor was it tested at baseline. In 2008 and 2012, participants were given a short cognitive test to assess their subjective judgments of their memory and cognition. The brief test included such questions as:
- "Do you have more trouble than usual remembering a short list of items, such as a shopping list?"
- "Do you have more trouble than usual following a group conversation or a plot in a TV program due to your memory?"
Just over half the participants (55%) had good thinking and memory skills, 38% had moderate skills, and 7% had poor thinking and memory skills.
Changzheng Yuan et al. 2019. Long-term intake of vegetables and fruits and subjective cognitive function in US men. Neurology, 92 (1) e63-e75.