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Nutrients - How Vitamin C Helps Protect
Against Cancer
Vitamin C is most famous for fighting colds, but its key role is in the formation of
collagen, the most abundant protein in the human body, which is present in all types of
connective tissue such as bones, cartilage, ligaments, and tendons. A lack of vitamin C
can result in scurvy, a disease that causes bleeding, swollen gums and loose teeth
resulting from the weakening of bones and connective tissue. Vitamin C is also extremely
important for fighting cancer.1
Vitamin C, like some of the other nutrients, carotenoids
and vitamin E, is an antioxidant that helps
destroy cancer-causing free radicals in the body. The difference
is that while vitamin E and carotenoids are fat-soluble, lodging
themselves in the fatty layer of each cell membrane, vitamin C is
water-soluble, protecting against oxidation in the watery areas
such as blood and inside cells. It also helps to recycle vitamin
E to keep it actively fighting free radicals. The protective effect
of vitamin C has been shown for cancers of the esophagus, larynx,
mouth, pancreas, stomach, colon, and breast.2,3
Food Sources
Humans, guinea pigs, the Indian fruit bat, and a handful of other species are the only
mammals who cannot make their own vitamin C. These species are missing the enzyme
necessary to produce the vitamin out of glucose found in the body. So we must be mindful
to get it from food sources. Fortunately, that's easy to do. As long as you eat a variety
of fruits and vegetables everyday, you should have no problem getting more than enough
vitamin C. To achieve protection against cancer, vitamin C supplements are probably
unnecessary. In fact, some studies have shown that excess vitamin C may cause kidney
stones in individuals who are at risk.4
Here are some vitamin C-rich foods:
| Food |
Vitamin
C (mg/serving) |
Broccoli, 1 cup raw, chopped |
82 |
| Cabbage, red, 1 cup, shredded |
40 |
Cauliflower, 1 cup raw |
46 |
| Grapefruit, 1 pink or red |
84 |
| Guava, 1 medium |
165 |
| Kale, 1 cup cooked |
68 |
| Lemon, 1 medium |
31 |
| Orange, 1 medium |
75 |
| Pepper, hot chili, 1 |
109 |
| Pepper, red sweet, 1 cup raw |
90 |
| Potato, 1 medium |
26 |
| Strawberries, 1 cup raw |
84 |
| Sweet Potato, 1 medium |
28 |
| Tomato, 1 medium |
23 |
| Source: Pennington, JAT. Bowes and Church's Food Values
of Portions Commonly Used, 17th edition,
Lippincott-Raven, 1998. |
Tips for Increasing Vitamin C in Your Diet
- Have a piece of citrus fruit for dessert. Just one orange takes care of a day's
requirement for vitamin C.
- Toss some peaches and berries into your cereal or pancakes.
- Do not store your produce for too long. Vitamin C is one of the more unstable vitamins,
and the longer you wait to eat your fruits and vegetables, the more it degrades and the
more cancer-fighting power it loses.
- Store produce at low temperatures.
- Minimize cooking time. Cooking reduces the amount of vitamin C in most foods, with the
possible exception of broccoli.2
- Because vitamin C is water-soluble, steaming your vegetables or cooking them quickly in
a small amount of liquid (instead of boiling them for longer periods of time) will
minimize vitamin loss.
References
1. Luben R, Khaw KT, Welch A, et al. Plasma vitamin C in the EPIC-Norfolk cohort.
Abstract from the European Conference on Nutrition and Cancer, Lyon, France, June 21-24,
2001: 35, www.nutrition-cancer2001.com.
2. Combs GF. The Vitamins, Fundamental Aspects in Nutrition and Health. 2nd ed. San Diego, CA: Academic Press, 2001:245-272.
3. Block G. Vitamin C and cancer prevention: the epidemiological evidence. Am J
Clin Nutr 1991;53:270s-82s.
4. Rivers JM. Safety of high-level vitamin C ingestion. In: Elevated Dosages of
Vitamins, Walter P, Stahelin H, and Brubacher G, eds. Lewiston, New York: Hans Huber
Publications, 1989: 95-102.
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