Home Original News Skin Cancer: Green leafy vegetables decreases risk; dairy increases risk
Skin Cancer: Green leafy vegetables decreases risk; dairy increases risk PDF Print E-mail
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Written by Roman Bystrianyk   
Sunday, 04 June 2006 00:00

According to the Centers for Disease Control (CDC) the number of skin cancer cases has increased in the United States with more than 1 million cases of basal cell or squamous cell cancer being diagnosed annually. This number has greatly increased from 400,000 in 1980 and 600,000 in 1990. Squamous cell carcinoma (SCC) is the most common skin cancer in white-skinned people and accounts for 20% of all deaths from skin cancer. 

Exposure to the ultraviolet (UV) rays from the sun is widely considered to be the most important environmental factor in developing skin cancer. UV radiation causes direct damage to the DNA and to the immune system. UV radiation also causes indirect damage through the formation of free radicals. 

There has been evidence that diet could modify the risk SCC and other cancers of the skin. Animal studies have shown that amount and type of dietary fats promote skin cancer by altering the body’s immune system response to UV radiation. Other studies have shown that intake of antioxidants such as selenium, vitamin C, vitamin E, and B-carotene may provide protection against oxidative damage in the skin by neutralizing free radicals formed by UV radiation. 

Green leafy vegetables such as kale, spinach, and collard greens, are known to contain a variety of vitamins and minerals and other bioactive substances that may protect against cancer. These substances include lutein, vitamins C and E, flavonoids, folic acid, and fiber. Dark green leafy vegetables are rich in folic acid, which plays a key role in DNA synthesis and repair.

A recent study in the International Journal of Cancer, examined the association between food intake and the risk of SCC. The authors studied over 1,000 adults living in Australia over an 11-year period. Study participants were followed from February 1992 until December of 2002. Participants were provided full-body skin examinations as well as detailed dietary food frequency questionnaire. 

After adjusting for a variety of factors the authors found that increasing intakes of green leafy vegetables were associated with a significant decrease risk of SCC. “The highest tertile [one third of a study participants] of intake of green leafy vegetables was associated with a 41% decreased risk.” However, intake of “unmodified” dairy (for example, full-cream milk and cheese) was associated with an 84% increased risk for SCC, although the results were considered non-significant. 

The authors also examined diet if any participant previously had skin cancer. They found an even more substantial relationship. People who previously had skin cancer had a 55% decrease in SCC with increasing intakes of green leafy vegetables. Conversely, dairy showed a significant 153% increased SCC risk. “Increased intake of unmodified dairy products increased SCC risk by more than 2-fold.” 

The authors also found a non-significant protective effect in drinkers of black tea in people who had no previous skin cancer. A previous study had shown a significant protective effect of black tea consumption on SCC risk. “Black tea contains theaflavins that have been shown to scavenge oxygen species and inhibit UV-induced oxidative DNA damage.” 

The authors conclude, “our findings show that higher intakes of green leafy vegetables may help prevent SCC tumours among people who have prior skin cancers, and that a high intake of unmodified dairy, such as whole milk, cheese, and yogurt, may increase SCC risk in susceptible individuals.”


Source: International Journal of Cancer, May 2006
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Last Updated on Wednesday, 09 September 2009 02:10