Diet: why variety matters

Philip J. Goscienski, M.D.

May 2008

How many different kinds of vegetables are you likely to find in the produce section of your local supermarket? Forty? How about fruits? Even in the summer the number is likely to be fewer than 25 different kinds.

Some grocery chains have been trying to introduce exotics such as starfruit and Asian pear but these are not usually bargain buys. Mangos, papayas and kiwis have been around for decades but have never become staples in American homes. If old-time vegetables such as rutabaga, kohlrabi and parsnips have a small following, the chances that jicama, endive or mung beans will ever become commonplace are pretty remote.

Mainstream America is in a dietary rut. Native Americans could hunt dozens of big game animals, scores of smaller ones and hundreds of bird species. Just think of the variety of eggs they could collect! If you went to the market today you probably found three types of "large game": cow, pig and sheep. Instead of hundreds of kinds of fowl we have only two: chicken and turkey. How dull! Eggs are the most uniform and boring of all; they vary a little in size and they come in only two colors. (In case you wondered, the color of the shell has nothing to do with nutritional value.)

To be sure, gourmet food magazines introduce us to exotic ingredients but there are few takers. Pick up a copy of Food and Wine or Cooking Light magazine and I'll bet that you'll find a couple of recipes that call for veggies that have never crossed your pantry threshold.

There's a reason why humans need a variety of plant foods. Over millions of years all living things have been exposed to the damaging effects of free radicals generated by radiation and chemical reactions. The species that survived were the ones with the most effective defenses, collectively known as antioxidants. They neutralize free radicals and thus prevent damage to genes and other critical components of plants. In all there are well over 4,000 phytonutrients; there are probably thousands more that we haven't discovered yet. Animals make only a few of their own antioxidants and they rely on plant sources.

Back in the Stone Age our ancestors ate hundreds of different plant species. The few hunter-gatherer populations that still exist in temperate climates do, too. Australian Aborigines are known to eat several hundred different kinds of plant foods even though they have been pushed to the fringe of what used to be their original habitat.

Fruits and vegetables provide us with the best nutrition but they continue to give way to convenience foods that are mostly grain-based. A high intake of green leafy vegetables, nuts and fruits is associated with lower rates of heart disease, cancer and diabetes, as well as osteoporosis, macular degeneration and Alzheimer's disease.

Variety isn't just the spice of life. It could mean years more of healthy living.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.