Vegetables and Cancer Prevention
Disclaimer: All information provided should be considered as generalizations and not as specific information for any individual. Nor should this information be considered medical advice. This information needs to be considered in consultation with your family physician. Specific food allergies or medical conditions may make the provided information unsuitable for some individuals.
Summary: Recent evidence from epidemiologic studies (case-control and prospective cohort) have demonstrated reduced risk for individuals consuming higher quantities of vegetables.
"There is limited evidence to support the preventative effect of fruits and vegetables for cancer of the mouth, pharynx, esophagus, stomach, colon and rectum, larnyx, lung, ovary (vegetables only), bladder (fruit only) and kidney in humans. There is inadequate evidence for all other sites of cancer."1
Limited evidence means that several studies have been done but all have included small numbers of patients and the design of the study limited the it's ability to detect demonstrate a significant effect.
How much is increased? 350 grams per day.
Interpretation: Just as your parents
always said "eat your veggies!"
Click the image to see the 3 Minute Salad recipe
Increased cruciferous vegetable intake appears to have a anti-carcinogenic effect. Cabbage, cauliflower, broccoli, Brussels sprouts, watercress (see the Watercress and Cancer Prevention article) and mustard greens have been associated with a lower risk of certain cancers.2 These vegetables may perform this activity by alterations in metabolic enzyme activity altering the effect of dietary or environmental carcinogens, reduction of oxidative DNA damage to cells, and reduction of the negative effects of hydrogen peroxide in the body.3
Click the image to see the 3 Minute Salad recipe
Click the image to see the Watercress Mango Salad
recipe
Nutrition and cancer scientists have named the proportions of cancers that can be prevented through the modification of a risk factor (such as increasing your vegetable intake) as the Preventable Fraction. Various estimates of how large this fraction could be are published. A recent article suggested that for certain tumors in certain parts of the body 20-30% could be prevented by increased vegetable intake.
For example:
"This approach led to estimates of the proportion of cancers preventable by increasing fruit and vegetable intake from current levels to 350 g/day in the range of 8–16% for colorectal cancer and 20–30% for esophageal and gastric cancers; these estimates varied substantially in different regions of the world."4
This may be an optimistic view of the current evidence but there is likely some effect.
Dr. Lawrence Korngut, M.D.
Chief Neurology Resident
London Health Sciences Centre
London, Ontario, Canada
1Vainio H., Weiderpass, E., Fruit and vegetables in cancer prevention. Nutrition and Cancer 2006;54(1):111-142.
2Gill, C,. Haldar S., Boyd, LA. et al., Watercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adults
3ibid
4Vainio H., Weiderpass, E., Fruit and vegetables in cancer prevention. Nutrition and Cancer 2006;54(1):111-142.
