Research Shows Low Fat Diet Reduces Skin Cancer Risk

American Institute for Cancer Research
Monday, 12 July 1999

Ongoing research, funded by the American Institute for Cancer Research (AICR), has shown a high fat diet increases risk of subsequent skin cancer occurrences in skin cancer patients. Conversely, decreasing fat intake to 20 percent of total calories could be effective in preventing subsequent non-melanoma skin cancers.

This kind of cancer, usually diagnosed as basal or squamous cell carcinoma, is the most common form of cancer in the U.S. with incidence equal to the total of all other types of cancer combined. Among people who have had at least one occurrence of this kind of cancer, 28 percent are at risk to have another within two years.

Beginning in 1990, Dr. Homer Black of the Baylor College of Medicine, Houston, TX, has conducted a series of animal and clinical trials that have demonstrated the link between fat intake and skin cancer. In his clinical trial, skin cancer patients were assigned to one of two groups. In the first group no changes in eating habits were introduced, allowing patients to continue to consume about 36-40% of their total calorie intake as fat. Patients in the other group reduced their percent of calories from fat to around 20 percent.

A clear and significant difference in the number of premalignant skin lesions occurred between patients who continued to consume diets high in fat and those who switched to low fat diets. Patients consuming high levels of fat were found to be at nearly five-times greater risk of developing premalignant skin lesions than patients eating a low fat diet.

Dr. Black is currently engaged in a laboratory study to determine why the level of fat consumption influences the occurrence of this common malignancy. Tests on animals suggest that suppression of the immune system by a high fat diet is involved in the mechanism.

"With AICR support, we have experimentally shown that high levels of dietary fat exacerbate the development of tumors due to ultra violet rays. Intervention with a low fat diet can negate the exacerbating effect of high fat diets. Much of the effect of the high fat diet occurs from modulation of the immune system," says Dr. Black.

The Baylor studies also suggest that a low fat diet may inhibit skin cancer in people who have never had it before. Further research remains to be done to confirm that suggestion.

Still Wise to Stay Out of the Sun

Exposure to the sun's UV rays remains by far the most common cause of skin cancer, accounting for about 90 percent of its occurrence. It is estimated that more than half of the total lifetime dose of the sun's UV rays are received during childhood and adolescence.

Despite continuing efforts to warn the public about the dangers of excessive sun exposure, there has been a steady increase in the incidence of skin cancer over the past twenty years. This year, about 1.5 million new cases of skin cancer will be diagnosed in the U.S.

According to AICR, the best strategy for preventing skin cancer is to minimize time spent in the sun, especially during the hours of 10 a.m. to 4 p.m., when the sun's rays are strongest. Additional precautions include wearing sunscreen that has a sun protection factor (SPF) of 15 or higher, and wearing protective clothing including a wide-brimmed hat and sunglasses.

"Dr. Black's research provides skin cancer patients with a new strategy to prevent additional malignancies," explains Dr. Ritva Butrum, AICR Vice President for Research. "Reduction of fat consumption to 20 percent of total calorie intake appears to inhibit progression of the disease."

AICR recommends that everyone interested in reducing risk of cancer eat a predominantly plant-based diet, rich in a variety of vegetables, fruits, whole grains and beans, and select foods low in fat and salt. This, coupled with frequent exercise and the maintenance of a healthy body weight, could reduce overall cancer risk by 30 to 40 percent.

The American Institute for Cancer Research is the only major cancer charity focusing exclusively on the link between diet and cancer. The Institute provides a wide range of consumer education programs that have helped millions of Americans learn to make changes for lower cancer risk. AICR also supports innovative research in cancer prevention and treatment at universities, hospitals and research centers across the U.S. The Institute has provided nearly $50 million in funding for research in diet, nutrition and cancer. AICR's Internet Web address is http://www.aicr.org

For more information, or to contact American Institute for Cancer Research, see their website at: www.aicr.org