Not all that long ago, most of us thought we understood nutrition pretty well. There was protein, fat, and carbohydrates, plus vitamins and minerals. Oh – and fiber. That was pretty much it.

Then “they” started finding out that fruits and vegetables don’t have all their pretty colors just for show. Those pigments are actually vitamin-like substances that help the body fight many so-called signs of aging which are caused by oxidation ("rusting," if you will) in the body.

I own a copy of a 1983 book entitled Gardening for Maximum Nutrition, by Jerry Minnich. As you might guess, it rates fruits and vegetables according to their nutritional content, to help you make efficient use of your garden space. The book is well-written, and the layout makes it easy to discover, for example, that the blueberry’s only dietary contribution is “modest amounts of Vitamin C.” Unfortunately, Mr. Minnich wrote this book before “they” discovered anthocyanins, the flavonoids that give blueberries their color, their name, and their current rating as one of the most nutritious fruits available.

Both the Blood Type Diet and the GenoType Diet offer long lists of foods for each Type. As a “Teacher” GenoType, for example, my recommended foods include beet roots, squash, and raspberries. The lists say nothing about color, but beets come in red, yellow, or white. Winter squash flesh ranges from pale yellow to deep gold. Raspberries can be purplish-black, red, yellow, or white. I figure I’m making the best use of my grocery dollar or my garden space by choosing the darkest and most brightly colored varieties available.

The color differences aren't always obvious. I used to buy organic Thompson raisins from the natural-foods market. For some reason, it never fully sank in that the dark-brown blobs were made from those bland pale-green Thompson seedless grapes. Raisins aren’t on my “Teacher” list, but if they were, I’d buy Zante “currants,” which are actually small raisins made from dark purple, nearly black grapes. (By the way, red or black currants, which are on my “Teacher” list, are related to gooseberries, and are generally sold fresh, frozen, or as jam, rather than dried. They're no relation at all to Zante “currants.”)

In general, though, it’s easy to choose the most antioxidant-rich fruits and vegetables. Just look for deep, bright colors – red cabbage, rainbow chard, orange-fleshed nectarines. You get the idea.