Thanks to Nutrition Science News for the use of this article!
By Carmia Borek, Ph.D.
The problem with
aging isn't getting older. The problem is being too short of
breath to blow out all those birthday candles as the years mount.
With each passing year, an ever-larger assemblage of age-related
diseases seems to pursue the aging customers who frequent health
stores--each malady groaning and dragging its chains like a
specter. This macabre cast includes heart disease, chronic
infection, stroke, cancer, cataracts, macular degeneration and
How can your customers bring on the birthday candles but spare
themselves from such ailments? There are only two answers--good
genes and healthy living. No one can control the former, but it
is possible to affect the latter. Living well includes getting
enough relaxation, exercise, community spirit and nutritious
foods. It may also include taking vitamins. An avalanche of
research data suggests that high intakes of antioxidant-rich
fruits, vegetables and supplements lowers the risk of old-age
Antioxidants are agents that disable havoc-wreaking molecules
called free radicals. The body generates free radicals as
by-products of burning fuel for energy within the cells,
exercising, and fending off infections. Various environmental
exposures such as pollution, tobacco smoke, the sun's ultraviolet
light and radiation can also create free radicals. 
Take breathing. Without the complication of air pollution, the
life-giving oxygen we inhale goes to cells to help burn food for
energy. In the process, some oxygen molecules lose an electron.
Ideally, oxygen and other molecules keep their electrons in
pairs. Molecules containing electron-
deficient oxygen are free radicals. These free radicals stabilize
themselves by capturing an electron from any substance in their
path, damaging it in the process. This process, called oxidative
damage, underlies many chronic illnesses.
Oxidative damage to low-density lipoprotein (LDL) cholesterol,
for example, increases the risk of atherosclerosis and heart
disease. Oxidation of DNA can cause mutations that lead to
cancer. If antioxidants don't mop up free radicals, the damage
accumulates and fast-forwards aging and disease. Add in stresses
such as infection and air pollution, and the body may not be able
to supply enough antioxidants to stanch free radical damage.
Our bodies possess a defense force of free radical quenchers.
These native antioxidants come to the rescue by giving up
electrons to stabilize free radicals and halt further damage. The
body's antioxidants include enzymes, for example, superoxide
dismutase (SOD) and small molecules our cells make, such as
glutathione, as well as vitamins and minerals manufactured or
obtained from the diet. These major players from diet include
vitamins E and C, provitamin A--precursors to vitamin A such as
As free radical levels rise, so does the need for additional
antioxidants. Eventually, free radical production outpaces the
body's natural supply of antioxidants. So, the greater the
oxidative stress, the more antioxidants a person needs to add to
his or her diet. Smokers, for example, must take two to three
times as much vitamin C to achieve the same antioxidant blood
levels as nonsmokers. 
Following is an overview of numerous potent antioxidants:
Vitamin C (ascorbic acid): Epidemiological studies show
that diets high in vitamin C substantially cut the risk of most
cancers and reduce stomach cancer risk by as much as 50
percent.  It also inhibits the production of
cancer-causing nitrosamines, which are chemicals derived from
nitrites used in curing meats, and in experimental models,
protects against radiation and chemical
Equally as important, vitamin C may protect against heart
disease. Water-soluble vitamin C neutralizes free radicals that
oxidize LDL cholesterol, thereby preventing artery wall damage
that precipitates atherosclerosis. In a nationwide survey, men
who took vitamin C supplements or consumed more than 50 mg of
vitamin C from foods had reduced heart disease
Vitamin C occurs abundantly in fruits and vegetables, especially
citrus, berries, tomatoes, leafy vegetables and the cabbage
Vitamin E: Whereas vitamin C dissolves in water, making it
a good free radical scavenger in body fluids, vitamin E is fat
soluble and therefore acts in cell membranes and other
fat-containing tissues. Of the eight forms of vitamin E that
occur in nature as tocopherols and tocotrianols, it appears that
alpha-tocopherol is the main defense against the oxidation of
lipids (fats). Vitamin E also helps break free radical chain
Mounting evidence indicates that vitamin E protects against heart
disease. For example, a study of 87,000 nurses enrolled in The
Nurses' Health Study in Boston showed that an average daily
intake of 200 IU of vitamin E for more than two years cut the
risk of heart disease by 41 percent.  A study of 2,002
men at Cambridge University in England found that those with
existing heart disease who took 400-800 IU/day of vitamin E
supplements reduced their risk of nonfatal heart attacks by 77
Vitamin E supplements can also increase immunity in the
elderly,  and protect against cataracts 
and macular degeneration.  Vitamin E protects cells
from the cancerous effects of X-rays, chemicals, air pollutants
and ultraviolet light.  Similar to vitamin C, it
prevents the formation of carcinogenic nitrosamines.
Insufficient intake of vitamin E correlates with an increased
risk of lung, colon, stomach, breast and cervical cancer.
Conversely, vitamin E supplementation reduces colon cancer
risk.  A six-year clinical trial of 29,133 Finnish,
male, long-term smokers showed that, while supplements of vitamin
E and beta-carotene did not reduce lung cancer in this high-risk
group, vitamin E reduced the risk of prostate cancer by 34
The richest sources of vitamin E are oils, nuts and grains--all
high in fat. Supplements offer an effective source of vitamin E
without the calories.
Why Take Antioxidants?|
Both normal bodily processes and everyday environmental
encounters like the ones listed below generate extra free
radicals and raise the risk of cancer.
Dietary carcinogens -- Charcoal-broiled, smoked and cured
meats, and foods fried at high temperatures.
Family history of disease -- Genetics may render someone
susceptible to a disease that antioxidants can prevent.
Old age -- Antioxidant supplies dwindle with age,
particularly in postmenopausal women.
Sunlight (ultraviolet radiation)
Minerals: These essential dietary ingredients--the body
can manufacture vitamins, but not minerals--are all antioxidants.
In particular, selenium, zinc, copper, manganese and iron are
components of antioxidant enzymes.
Researchers have long known selenium, the most studied of the
minerals, is a cancer-preventive micronutrient. Selenium fed to
cells increases their levels of antioxidant enzymes and prevents
damage caused by radiation and chemical carcinogens. 
Deficiency in humans correlates with higher rates of colon,
breast, ovary, prostate, lung, bladder and skin cancer. Studies
show it can prevent cancer in both animals and
Proof of selenium's cancer-preventing power in humans came from a
recent multi-center clinical trial reported by the Arizona Cancer
Center. This five-year study followed 1,312 elderly people with a
history of skin cancer. Half took daily supplements of 200 mg
selenium (about five times the average American's intake); half
took a placebo. Compared to placebo, selenium supplementation
slashed the occurrence of overall cancer by 42 percent and
significantly reduced the occurrence of lung, colon and prostate
cancers. Selenium did not protect against the recurrence of skin
cancers, indicating that antioxidants function primarily as
preventive agents. 
Selenium occurs naturally in many plants, notably garlic,
asparagus and grains, but the levels depend on regional soil
contents. Other sources include sea foods and meats.
A number of chemicals found in plants--phytochemicals--protect
against free radical damage, LDL cholesterol oxidation, blood
vessel fragility, dementia, macular degeneration and cancer. Most
of the information on phytochemical protection comes from cell
and animal studies, although researchers are beginning to test
the effects of these plant properties on humans. The most studied
phytochemical groups include the carotenoids and the flavonoids.
Following is a rundown on the major attributes of some plant
Carotenoids: These potent phytochemicals are the
fat-soluble pigments abundant in yellow, orange, red and green
fruits and vegetables. Of the 600 known carotenoids, 50 can
convert to vitamin A, a vitamin essential for normal metabolism
and health. Carotenoids, however, exert far more antioxidant
activity than vitamin A.
The provitamin-A carotenoid receiving the most research attention
is beta-carotene. Special controls in our body limit how much
beta-carotene becomes vitamin A, leaving the remainder to act as
an antioxidant. It can disarm reactive oxygen molecules generated
by sunlight and air pollution and prevent free radical damage to
skin, eyes and lungs. 
Like vitamin E, beta-carotene breaks free radical chain reactions
and prevents LDL cholesterol oxidation, thereby providing
protection against heart disease and stroke. 
Although beta-carotene acts as a strong antioxidant in laboratory
experiments, clinical trial results are conflicting. Here are
highlights of the research:
Healthy humans who eat fruits and vegetables high in
beta-carotene show reduced cancer risk in many sites including
the breast. 
A study of 29,584 adults in Linxian, China, found that combined
supplementation with beta-carotene (14 mg), alpha-tocopherol (30
mg) and selenium (50 mcg) lowered stomach cancer rates by 21
percent and esophageal cancer by 42 percent. 
Although a small study found that beta-carotene supplementation
in men with angina halved the rate of heart attacks, a more
recent, 12-year clinical trial of 22,071 men (both smokers and
nonsmokers) who took 50 mg of beta-carotene every second day
failed to find protection against heart disease or
Although important because of its efficient convertibility to
vitamin A, beta-carotene is not the most powerful antioxidant.
For instance, lycopene, the red pigment abundant in tomatoes, has
at least 10 times more antioxidant capability. Studies show it
protects against prostate cancer.  Lutein and
zeaxanthin, abundant in spinach, protect the eye from free
radical induced macular degeneration, a disease that causes
vision loss. 
Antioxidants affect each other, sometimes creating a
synergistic action, other times influencing intestinal absorption
or rescuing different antioxidants from oxidation. Here's how the
primary antioxidants found in most multivitamins interact.
Vitamin C maintains vitamin E (alpha tocopherol) in its
antioxidant state, at least in vitro.
Vitamin E storage and transport depends on selenium. Its
absorption may be reduced if there are high levels of vitamin A
and beta-carotene in the body.
Selenium is synergistic with vitamin E.
Beta-carotene in high levels may interfere with the
absorption of other carotenoids.
Flavonoids: This large family is the biggest group of
antioxidant phytochemicals studied. Whereas the carotenoids are
fat-soluble plant pigments, flavonoids form the water-soluble
colors of vegetables, fruit, grain, seeds, leaves and bark.
Some plants contain higher concentrations of certain flavonoids.
Grapes, and the juices and wines made from them, are rich in
flavonoids called catechins and resveratrol. Red grapes and their
products contain an additional antioxidant, anthocyanin, that
gives them their intense red-purple color. Recent animal studies
on resveratrol show that it protects against carcinogenesis in
skin and inhibits the body's production of chemicals that
increase inflammation. 
Flavonoids in grapes may account for the so-called French
Paradox. Despite eating large amounts of fatty foods, the French
have a relatively low rate of heart disease. Their secret?
Washing down those artery-clogging foods with red
Like grapes, green and black teas contain large amounts of
catechin flavonoids. Catechins extracted from tea protect against
oxidation of lipids such as LDL cholesterol and suppress the
growth of many types of cancers induced by chemicals or
radiation. Population studies support tea's cancer-preventing
effects. For instance, high consumption of green tea may explain
why Japanese men who smoke more than American men have lower lung
cancer rates. A Dutch study of 62,573 women and 58,279 men found
that drinking one to five cups of black tea a day significantly
reduced the rate of stomach and lung cancer. The tea drinkers,
however, also smoked less and ate more fruits and
Another typically Asian food, soybeans, contains isoflavones.
This type of flavonoid has weak estrogenic activity and can
compete with the body's own estrogen. This may partly explain why
the Japanese, who eat a diet low in fat and rich in soy and green
tea, have lower rates of breast, prostate and colorectal cancer
than Westerners. Soy extracts of genistein, one of the most
abundant isoflavones in soy, inhibit growth of a wide range of
tumors in animals, including mammary tumors. Most epidemiological
studies show that a high intake of soy is associated with reduced
cancer risk, including breast cancer.  For more
information on soy and cancer, please see related article on p.
Onions: The onion family--garlic, onions, shallots and
leeks--contains flavonoids, vitamin C, selenium and
sulfur-containing substances. In experimental models, garlic
extracts protect against free radical damage and inhibit LDL
oxidation. Garlic extracts also protect against cancer at several
sites, probably because of a combined effect of antioxidant
action and the ability of sulfur compounds to help cells dispose
of chemical carcinogens. Epidemiological observations in Italy
and China show an association between high consumption of garlic
and onions and low rates of stomach cancer. 
Cruciferous Vegetables: Like the onion family, vegetables
such as cabbage, broccoli and brussels sprouts have antioxidant
capabilities because of their high vitamin C and flavonoid
content. They also contain plant chemicals called indols and
isocyanates that help cells detoxify chemical carcinogens.
Indeed, epidemiological and experimental studies consistently
show that eating cruciferous vegetables protects against several
forms of cancer including colon cancer. 
Ginkgo: As mentioned earlier, some phytochemical
antioxidants appear to strengthen blood vessels and improve
circulation. The best examples of this class include ginkgo
(Ginkgo biloba) extracts and anthocyanin extracts from
bilberry (Vaccinium myrtillus).
For thousands of years, the Chinese have known the virtues of
ginkgo. Modern research focuses on using ginkgo tree leaf
extracts to improve brain function. Ginkgo contains quercetin and
ginkgolides, two flavonoids that prevent oxidative damage to LDL
cholesterol and blood vessels.
In a recent multicenter trial, more than 200 severely demented
patients, some with Alzheimer's disease, received daily
supplements with either placebo or 120 mg of a ginkgo extract.
The study lasted 52 weeks. Compared to the placebo group,
patients receiving ginkgo significantly improved cognitive
performance and social functioning. The benefits of ginkgo lasted
six months to a year. The authors suggested that ginkgo's action
partly stems from constituents that protect cell membranes and
fight oxidative stress. 
Start Supplementing Early
How can your customers ensure they're getting enough antioxidants
in their diets? First of all, they should eat a lot of
antioxidant-rich fruits and vegetables. Unfortunately, many
Americans don't eat enough of these foods. And it's not just what
you eat, but how the food is prepared. For example, beta-carotene
in raw carrots is less bioavailable than in cooked carrots.
A second questions is, can people get all the antioxidants they
need from food alone? That depends on each person's oxidative
load. (See sidebar on increased antioxidant needs.) For many
people, supplements are an important part of an overall health
program, along with eating antioxidant-rich foods and avoiding
free radical generating stresses.
Because free radical damage accumulates with age, people should
start supplementing with antioxidants early to achieve long-term
benefits. Think of antioxidants as weapons for combating free
radicals. By preventing free radical induced damage, people may
live not just longer, but healthier lives. Who knows, they may
remain robust enough to blow out 100 birthday candles. NSN
Carmia Borek, Ph.D., is a research professor at Tufts
University School of Medicine in Boston. She studies the role of
antioxidants and phytochemicals in disease prevention.
1. Borek, C. Maximize Your
Health-Span with Antioxidants: The Baby-Boomer's Guide: 1-98.
New Canaan, Conn.: Keats Publishing, 1995.
2. Borek, C. "Molecular mechanisms in cancer induction and
prevention." Environ Health Perspectives, 101 (suppl 3):
3. Borek C. "Antioxidants and Cancer." Science and
Medicine, 4: 51-61, 1997.
4. Block, G., et al. "Fruit, vegetables and cancer
prevention: A review of the epidemiological evidence." Nutr
Cancer, 18: 1-29, 1992.
5. Block, G. "Vitamin C and cancer prevention: The
epidemiologic evidence, " Am J Clin Nutr, 53: 270S-82S,
6. Enstrom, J.E., et al. "Vitamin C intake and mortality
among a sample of the United States population."
Epidemiology, 3: 194-202, 1992.
7. Stampfer, M., et al. "Vitamin E consumption and the
risk of coronary disease in women." New Engl J Med, 328:
8. Stephens, N.G., & Parsons, A. "Randomized control
trial of vitamin E in patients with coronary disease: Cambridge
Heart Antioxidant Study (CHAOS)." Lancet, 374: 781-86,
9. Meydani, S.N., et al. "Vitamin E supplementation and in
vivo immune response in healthy subjects." JAMA, 227:
10. Robertson, J., et al. "A possible role for vitamins C
and E in cataract prevention." Am J Clin Nutr, suppl 53:
11. Snodderly, D.M. "Evidence for protection against
age-related macular degeneration by carotenoids and antioxidant
vitamins." Am J Clin Nutr, 62: 148S-1461S, 1995.
12. Borek, C. Environ Health Perspectives, 1993, loc.
13. Bostick, R.M. "Reduced risk of colon cancer with high
intake of vitamin E: The Iowa Women's Health Study." Cancer
Res, 53: 4230-37, 1993.
14. Albanes, D., et al. "Tocopherol, beta-carotene cancer
preventive study: effects of baseline statistics and study
compliance." J Nat Cancer Inst, 88: 1560-70, 1996.
15. Borek, C. Environ Health Perspectives, 1993, loc.
16. Borek, C. Maximize Your Health-Span with
Antioxidants: The Baby-Boomer's Guide, 1995, loc. cit.
17. Clark, L., et al. "Effects of selenium supplementation
for cancer prevention in patients with carcinoma of the skin."
JAMA, 276: 1957-63, 1996.
18. Krinsky, N.I. "Antioxidant function of carotenoids."
Free Rad Biol Med, 7: 627-35, 1989.
19. Jialal, I., & Grundy, S.M. "Effect of dietary
supplementation with alpha-tocopherol on the oxidative
modification of low density lipoprotein. " J Lipid Res,
33: 899-905, 1992.
20. Ziegler, R.G. "Vegetables and fruit and carotenoids and
the risk of cancer." Am J Clin Nutr, 53: 251S-59S, 1991.
21. Blot, W.J., et al. "Nutrition intervention trials in
Linxian, China: Supplementation with specific vitamin/mineral
combinations, cancer incidence and disease specific mortality in
the general population." J Nat Cancer Inst, 85: 1483-92,
22. Hennekens, H.H., et al. "Lack of effect of long term
supplementation with beta carotene on the incidence of malignant
neoplasms and cardiovascular disease." New Engl J Med,
334: 1145-49, 1996.
23. Givannucci, E., et al. "Intake of Carotenoids and
retinol in relation to risk of prostate cancer." J Nat Cancer
Inst, 87: 1767-76, 1995.
24. Seddon, M., et al. "Dietary carotenoids, vitamins A, C,
and E and age-related macular degeneration." Eye Disease Case
Control Study Group, JAMA, 272: 1413-20, 1994.
25. Borek, C. Science and Medicine, 1997, loc. cit.
26. Criqui, M.H. "Does diet or alcohol explain the French
Paradox?" Lancet, 344: 1719-23, 1994.
27. Goldbohn, A., et al. "Consumption of black tea and
cancer risk: A protective cohort study." J Nat Cancer
Inst, 88: 93-99, 1966.
28. Messina, M. & Barnes, S. "The role of soy products
in reducing risk of cancer." J Nat Cancer Inst, 83:
29. Buiatti, E., et al. "A case control study of gastric
cancer and diet in Italy." Intern J Cancer, 44: 611-16,
30. Graham, S., et al. "Diet in the epidemiology of cancer
of the colon." J Nat Cancer Inst, 61: 709-14, 1978.
31. Le Bars, P.L., et al. "A placebo-controlled,
double-blind, randomized trial of an extract of Ginkgo biloba
for dementia." JAMA, 278: 1327-32, 1997
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