The final common
mechanism believed to mediate the effects of different diets on cancer
and aging is the oxidation of the genome and other cellular and subcellular
structures. Mutations induced by oxidative damage may then lead to increased
cellular proliferation, reduced apoptosis or both. Therefore, genes
confer susceptibility to oxidative damage through absence or malfunction
of the extensive antioxidant defense and DNA repair mechanisms, while
the diet can affect whether and to what extent that oxidative damage
In aging, oxidative
damage is increased and aging is the predominant risk factor for cancer.
The demonstration of the effects of nutrition on cancer requires using
age-adjusted incidences. Furthermore, dietary restriction with vitamin
and antioxidant supplementation can extend maximum lifespan significantly
in rodents. In epidemiologic studies in humans, the intake of 400 to
600 grams per day of fruits and vegetables is associated with a reduced
risk of gastric and other cancers. The most common cancers in developed
societies are breast, prostate and colon cancer. Obesity, high fat diets,
and reduced intake of fiber from cereals, grains, fruits and vegetables
comprise a high risk dietary pattern. For each of the most common cancers,
there is extensive evidence of a variation in incidence as individuals
move from low risk to high risk countries. For prostate cancer, there
is an equal incidence of latent prostate cancer in the U.S. and Japan,
but clinical cancer is five times more frequent in the U.S. In animal
experiments, nutrition affects the growth, progression and metastasis
of established tumors as well as the incidence of new tumors.
"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
(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