I am not surprised at the findings; there have been a number of studies in various populations indicating that significant amounts of fruits and leafy vegetables in the diet are associated with lower prevalence of dementia in those groups.

In addition, other foods recommended as “healthy” — that is, they have large amounts of the vitamins and minerals humans need, and are low in fat and have no refined sugars — have been shown in multiple studies to promote good health and especially good late-life health.

These data, collected over several years at intervals which allowed better recall by the subjects of what they had eaten in the recent past, represent more reliable data than food intake obtained when someone in their sixties or seventies is asked to recall what they ate in their late forties or early fifties. These data also emphasize that, like heart disease, the development of dementia or brain changes that would lower the threshold to develop dementia are greatly influenced by midlife health habits and diet.

Primary care physicians have a very difficult time getting done everything that they “should” when they interact with the patient. Given that a PCP’s time with patients is so short, it may well be good to use these data that strengthen the point about diet and brain health and put them into the same conversation as the role of diet in heart health. Since most people know that a good diet is associated with heart disease, and our knowledge of the role of diet in brain health is relatively new, these data may help get this information to patients without having to have an entirely separate conversation about the brain. This is an opportunity to decrease the projected cases of dementia in the future.

The reduced risk for cognitive decline noted for daily consumption of vegetables by Yuan et al, is interesting and consistent with other large surveys and thus, not surprising. Vegetables are low calorie, low sugar, high fiber, and high in phytochemicals that possess many health benefits such as better cardiovascular health and reductions in blood pressure.

The main theory on cognitive decline is the presence of chronic oxidative stress and inflammation. Vegetables possess hundreds of phytochemicals that have antioxidant and anti-inflammatory properties. Though this characteristic is unique to fruits and vegetables, fruit did not display as strong association an association with reduced risk for cognitive decline in this study. Leafy green vegetables (eg, spinach and kale) and carotenoid-rich vegetables (eg, tomatoes, tomato juice, tomato sauce, carrots, yams/sweet potatoes, squash, kale, spinach) were the vegetable types most related to the cognition benefit.

Thus, physicians should stress the health benefits of vegetable consumption, particularly leafy greens, tomatoes and carrots. Yuan and colleagues suggest five servings per day. This can easily be incorporated into a salad daily. One-half cup of vegetable juice or most raw vegetables equals one serving. For raw leafy greens such as lettuce and spinach, one full cup makes a serving. Cooked vegetables, even the greens, have a serving size of half a cup. Hence a leafy salad measuring two cups plus a chopped carrot, and one tomato would be about four servings of vegetables. One cup cooked vegetables with one-half cup salsa would equal three servings. Snacking on carrots, cherry tomatoes or baked sweet potato fries would add servings to the daily intake.