Not only may the variety of fruit and vegetable consumption decrease disease risk, independent from quantity of consumption; sometimes variety may even be more important. Check this out. No difference in inflammation — C-reactive protein levels — between those eating six servings of vegetables a day, and those eating two servings. But those eating the more variety — even if they didn't necessarily eat greater overall quantities — had significantly less inflammation.

"Cabbage, cauliflower, broccoli, and Brussels sprouts are associated with lower risk of colon cancer in the middle and right side of our body, whereas risk of colon cancer further down on the left side of our body appears to be lowered by carrots, pumpkins, and apples. So, different fruits and vegetables may confer different risks for cancer of different parts of even the same organ."

If you have two groups of people eating approximately the same amount of fruits and vegetables, but one group ate a relatively low biological diversity diet, where they ate tons of really healthy foods, but just less variety than smaller servings of a high-diversity diet, which group would win in terms of protecting their DNA from free radical damage? The high-diversity group. This suggests that “smaller amounts of many phytochemicals may have a greater potential to exert beneficial effects than larger amounts of fewer phytochemicals.”

Same result for inflammation. Greater variety in fruit and vegetable intake is associated with lower inflammation, even if you eat the same number of servings. Same with improving cognitive function. “[G]reater variety in fruit and vegetable intake was associated with a better [mental status], executive function, attention, [and] memory function [in some cases]—even after adjustment for total quantity.”

So, if you have two people eating the same number of servings of healthy foods, the one eating a greater variety may do better.

And perhaps the most interesting finding: different foods seemed to boost different areas of the brain. For example, total vegetable consumption had the strongest positive associations with executive function, perceptual speed, global cognition, and semantic, or fact-based memory, whereas total fruit intake was more consistently associated with visuospatial skills and autobiographical memory.

So, yes, while carrots and cruciferous cabbage-family vegetables seemed to win out above the rest, we have to eat a variety of whole healthy plant foods, because they each tend to shore up different cognitive domains.