A significant reduction in precancerous lung cells among heavy cigarette smokers was achieved with large doses of two members of the Vitamin B family, according to a team of University of Alabama researchers.
The preliminary findings indicate that folate and Vitamin B-12 may join the growing list of dietary factors that appear to provide some protection against cancer, Dr. Douglas Heimburger reported in Friday`s Journal of the American Medical Association.
Although the findings are encouraging, Heimburger cautioned that they should not be used by people as a reason to self-medicate with high doses of the nutrients.
``The results should not be construed as pointing to a potential way of preventing lung cancer in individuals who continue to smoke or as supporting self-medication with large doses of folate or B-12 by smokers,`` he said.
In the four-month study, 36 smokers were given the nutrient supplements and 37 smokers served as controls, receiving only a placebo.
Pathologists examining lung cells from sputum samples found a significant reduction in the number of squamous metaplasia cells among the subjects receiving the vitamin supplements. Squamous metaplasia cells are generally regarded as precancerous cells that eventually could evolve into malignant tumors.
Heimburger said he decided to try the vitamin combination because smoking decreases levels of both folate and B-12 in cells lining the lungs. These cells then may become more vulnerable to damage from cancer-causing chemicals in cigarette smoke, he said.
Other researchers are testing the same vitamins to see if they can reduce the risk of other cancers.
Folate is naturally found in vegetables and fruits such as asparagus, broccoli, lima beans, spinach, potatoes, lemons, bananas, strawberries and cantaloupes, as well as liver, eggs and peanut butter. Vitamin B-12 is found in meat, such as liver, and in oysters, tuna, milk, eggs and cheese.
Recent research suggests that diet may play an important role in protecting people against cancer. Among the nutrients in food that have shown this promise are Vitamins A, E and C, carotene and selnium.
Heimburger said the levels of vitamins used in the experiment were much higher than what could be obtained from the diet. The dose of B-12 used was 167 times higher than the recommended daily allowance and the dose of folate was 25 times greater than the recommended daily allowance.