Older people do seem to be much more vulnerable to deficits in thinking and remembering caused by poor diet.
Low levels of B-12 and folic acid in particular, appear to be involved in age-related cognitive decline.
Green leafy vegetables, citrus fruits and juices, whole wheat bread and dry beans are good sources of folate. Fruit and vegetables, whole grains, beans and other protein sources (nuts, meat, fish) are good sources of the B vitamins.
Experiments with rats suggest sunflower seeds (and other seeds high in linoleic acid) may help against cognitive decline caused by hypertension.
Fruits and vegetables high in antioxidants (for example, spinach, blueberries) may reduce and even reverse age-related impairment to neuron function.
Experiments in rats suggest that two chemicals normally found in the body's cells and available as dietary supplements may also improve memory function and increase energy in older people. One of these substances is found in meat and vegetables, the other in green leafy vegetables.
Carbohydrates, fat, and protein, all seem to have positive effects - different effects - on thinking and remembering. It has been shown that having breakfast has a positive effect on memory in older adults; perhaps low energy intake in general is partly responsible for cognitive decline in some older people.