Dr. David Heber recommends a diet with fruits and vegetables across the spectrum of color.
Heber, author of "What Color is Your Diet?" and director of the UCLA Center for Human Nutrition, says Americans do not receive enough fruits and vegetables in their diets. He believes a category system he created would make it easier to consume the proper amount and types of vitamins needed in diets.
Nearly all fruits and vegetables are low-fat and contain fiber and natural chemicals known as phytonutrients that can help protect against heart disease, cancer and age-related cognitive decline, cataracts and macular degeneration.
Government health experts say that people should get a minimum five servings a day of fresh produce. Currently it's estimated about a third of the population fulfils that requirement, and it may be as high as 80% that do not get enough servings. As many as 50 percent of Americans don't eat a piece of fruit all day long. Nine servings are optimal for health maintenance.
"What Color Is Your Diet?" provides a color guide to fruits and vegetables and their benefits, as well as recipes to encourage an increased intake of produce. Heber says that counting servings may not be adequate if you are missing out on one or more major color categories. Not all members of the fruit and vegetable group are alike.
They have unique properties that provide combinations of substances with unique effects on human biology. Therefore, simply eating five servings a day of fruits and vegetables will not guarantee that you are eating enough of the different substances needed to stimulate the metabolic pathways of genes in the different organs where fruits and vegetables have their beneficial effects.
The colors represent 25,000 chemicals that are beneficial. There is evidence that interaction between the colors provides benefits, so it's important to have a diverse diet and eat different foods. We normally eat three color groups on average in this country. Heber believes in evolutionary terms, man started out on a plant-based diet.
Fruits and vegetables are historically and biologically important. Our ancestors the hunter-gatherers ate over 800 varieties. The different colors represent families of compounds, and we have even selectively bred the colors we eat into an even narrower range. There are red carrots in India, we eat orange ones. There are 150 varieties of sweet peas, but only a few are available to us. We need to make an extra effort to eat many different foods to get the full range of benefits, he says
Heber groups produce into seven color categories:
(tomatoes, can of V8 juice, pink grapefruit, watermelon)
These contain the carotenoid lycopene, which helps rid the body of free radicals that damage genes. Lycopene seems to protect against prostate cancer as well as heart and lung disease. Processed juices contain a lot of the beneficial ingredients. One glass of tomato juice gives you 50 percent of the recommended lycopene.
(spinach greens, collard greens, mustard greens, turnip greens, yellow corn, green peas, avocado, honeydew melon)
These are sources of the carotenoids lutein and zeaxanthin. These are believed to reduce the risk of cataracts and age-related macular degeneration. Lutein is a yellow-green substance that concentrates in the back of your eye. It may also reduce atherosclerosis.
(carrots, mangos, apricots, cantaloupes, pumpkin, acorn squash, winter squash, sweet potatoes)
These contain alpha carotene, which protects against cancer. They also contain beta-carotene, which the body converts to vitamin A.
It protects the skin against free-radical damage and helps repair damaged DNA. Beta-carotene is also good for night vision. It's important to note that these beneficial nutrients can be received from other foods, too. For instance vitamin is found in dairy products and meat. But it's not as beneficial because you get high calories and fat along with it.
(pineapple, orange juice, oranges, tangerines, peaches, papayas, nectarines)
These contain beta cryptothanxin, which helps cells in the body communicate and may help prevent heart disease. Also, an orange contains 170 percent of the recommended daily vitamin C. It's interesting to note that the skin of an orange is high in a protective fat that has been found to kill cancer cells in humans and animals, which highlights the fact that two-thirds of all drugs come from the plant world.
(beets, eggplant, purple grapes, red wine, grape juice, prunes, cranberries, blueberries, blackberries, strawberries, red apples)
These are loaded with powerful antioxidants called anthocyanins believed to protect against heart disease by preventing blood clots. They may also delay the aging of cells in the body. There is some evidence they may help delay the onset of Alzheimer's disease.
(broccoli, brussels sprouts, cabbage, Chinese cabbage or bok choi, kale)
These contain the chemicals sulforaphane and isocyanate and they also contain indoles, all of which help ward off cancer by inhibiting carcinogens. It's a fact that ten percent of the population - like George Bush Sr. - doesn't like broccoli. But it is important in diets because of the beneficial chemicals it contains.
(leeks, scallions, garlic, onions, celery, pears, white wine, endive, chives)
The onion family contains allicin, which has antitumor properties. Other foods in this group contain antioxidant flavonoids like quercetin and kaempferol.