The Role of Vitamins, Specific Nutrients and the Development of Cancer
- Nutrients in fruits and vegetables protect the body against
oxygen-induced damage that occurs constantly as a result of normal
metabolism. Such damage is associated with increased cancer risk.
Accordingly, these nutrients are thought to protect against cancer.
This protective effect is seen only when these nutrients are taken
as whole foods. Antioxidant supplements have not shown a reduction
in cancer risk.
- Artificial Sweeteners
- No increase in the risk of cancer development has been shown
from either saccharin or Aspartane.
- Betacarotene is an antioxidant and is found in fruits and vegetables.
As a supplement, it has been shown ineffective in reducing cancer risk.
Two studies have shown a higher risk of lung cancer in cigarette smokers
taking betacarotene supplements.
- There is no proven relationship between the amount of calcium in
the diet and a reduction in cancer risk. Calcium is important to
reduce the risk of osteoporosis and is found in low fat and nonfat
dairy products. It is also present in leafy vegetables and beans.
- Carotenoids are the pigments found in fruits and vegetables
which have been shown to reduce the risk of cancer.
- Cholesterol in the diet is found only in meat, dairy products,
eggs, and fats. There is no evidence as to whether cholesterol
itself is responsible for an increase in cancer risk.
- Although coffee was at one time thought to increase the risk
of cancer of the pancreas and breast, current studies have failed
to confirm this relationship.
- Cruciferous Vegetables
- Vegetables which belong to the cabbage family and include
broccoli, cauliflower, and brussel sprouts are thought to reduce
the risk of colorectal cancer.
- Fiber is found in beans, vegetables, whole grains, and fruits.
It is thought to reduce the risk of colorectal cancer; however,
the way in which fiber acts is poorly understood.
- Fish Oil
- There is no evidence for a protective effect from fish oil in humans.
As is the case with all fats, fish oils are high calorie foods.
- Fluoride in toothpaste, the public water supply, and foods has
not been shown to increase the risk of cancer.
- Folic Acid
- Folic acid is one of the B vitamins and is found in vegetables,
beans, fruits, and whole grains. Supplements are recommended for
women who are pregnant and have been shown to reduce the risk of
spina bifida and other neural tube defects in their infants. To
reduce the risk of cancer, folic acid should be consumed together
with other nutrients found in whole foods.
- Food Additives
- There is no evidence at present that substances added to foods
to preserve them and enhance color, flavor, or texture increase
the risk of cancer in humans.
- Although numerous studies are ongoing, there is no specific
role for this vegetable in cancer prevention at present.
- Nitrites are not a significant cause of cancer. They are,
however, found in lunch meats, ham, and hot dogs which are not
considered healthful in large quantities.
- Olestra is a synthetic fat substitute and, as such, can
reduce fat intake. It also reduces the absorption of fat soluable
vitamins and other protective phytochemicals from fruits and
vegetables. The effect of this fat substitute on the risk of
cancer is unknown.
- Olive Oil
- The consumption of olive oil does not increase or decrease
the risk of cancer.
- There is no benefit from taking phytochemicals as supplements.
They are, however, present in large quantities in fruits, vegetables,
beans, and grains.
- Moderate intake of salt is not associated with an increased
risk of cancer.
- Selenium supplements are not recommended. Grains are the best
source of natural selenium.
- Soybeans appear to have a beneficial effect on hormone-dependent
cancers in animals. Their effect in humans is unclear. They are,
however, an excellent protein source and a good alternative to meat.
- As of yet, supplements are not recommended in lieu of whole
foods. The complex relationship between nutrition and cancer risk
is shown by the failure of many studies to demonstrate a positive
influence of vitamin or mineral supplements on the development of
- No beneficial effect of tea on the risk of developing cancer
has been proven in humans.
- Vitamin A
- Supplements of vitamin A have not been shown to reduce the risk
- Vitamin C
- Although vitamin C is found in many fruits and vegetables which
are considered beneficial, supplements of vitamin C have not consistently
been shown to reduce the risk of cancer.
- Vitamin E
- Vitamin E has not been shown to reduce the risk of cancer. It can,
however, reduce the risk of coronary artery disease.
The precise role of diet and physical activity in the reduction of
cancer risk remains to be defined. The interaction of various nutrients
in different food groups is complex. It is clear, however, that a high
fat diet, obesity, and a sedantery lifestyle do predispose to the
development of cancer, as well as to coronary artery disease.