220 THE CHINA STUDYlevels of vitamin C and selenium, both of which reduce free radical ac-
tivity.65 Vitamins E and C are antioxidants found almost exclusively in
plant foods, while selenium is found in both animal-and plant-based
foods.
In a study of 260 elderly people aged sixty-five to ninety years, it was
reported that: "A diet with less fat, saturated fat and cholesterol, and
more carbohydrate, fiber, vitamins (especially folate, vitamins C and E
and beta-carotenes) and minerals (iron and zinc) may be advisable not
only to improve the general health of the elderly but also to improve
cognitive function."66 This conclusion advocates plant-based foods and
condemns animal-based foods for optimal brain function. Yet another
study on several hundred older people found that scores on mental tests
were higher among those people who consumed the most vitamin C
and beta-carotene.^67 Other studies have also found that a low level of
vitamin C in the blood is linked to poorer cognitive performance in old
age,68,69 and some have found that B vitamins,69 including beta-caro-
tene,1° are linked to better cognitive function.
The seven studies mentioned above all show that one or more nutri-
ents found almost exclusively in plants are associated with a lower risk
of cognitive decline in old age. Experimental animal studies have not
only confirmed that plant foods are good for the brain, but they show
the mechanisms by which these foods work. 71, 72 Although there are
important variations in some of these study findings-for example, one
study only finds an association for vitamin C, and another only finds
an association for beta-carotene and not vitamin C-we shouldn't miss
the forest by focusing on one or two trees. No study has ever found that
consuming more dietary antioxidants increases memory loss. When as-
sociations are observed, it is always the other way around. Furthermore,
the association appears to be Significant, although more substantial re-
search must be done before we can know exactly how much cognitive
impairment is due to diet.
What about the more serious dementia caused by strokes (vascular
dementia) and Alzheimer's? How does diet affect these diseases? The de-
mentia that is caused by the same vascular problems that lead to stroke
is clearly affected by diet. In a publication from the famous Framingham
Study, researchers conclude that for every three additional servings of
fruits and vegetables a day, the risk of stroke will be reduced by 22%.73
Three servings of fruits and vegetables is less than you might think. The
following examples count as one serving in this study: 112 cup peaches,