A group of researchers examined the association between long-term use of supplemental B vitamins and lung cancer risk. They discovered that vitamin B supplements are not chemopreventive for lung cancer and may be harmful. This was published recently in the Journal of Clinical Oncology.
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism. These vitamins ( thiamine, riboflavin, niacin, pantothenic acid, B-6, biotin, B-12 and folate or folic acid.) are chemically distinct vitamins that often coexist in the same foods.
Dietary supplements (multivitamins) containing all eight are referred to as a vitamin B complex. These multivitamins are used to give vitamins that are not taken in through the diet. Multivitamins are also used to treat vitamin deficiencies (lack of vitamins) caused by illness, pregnancy, poor nutrition, digestive disorders, and many other conditions.
As important as B vitamins to human health, this is not the first time they have been associated with cancer. In 2009, researchers reported in the Journal of the American Medical Association that treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes in Norway.
In the recent study, the B vitamin-cancer connection was related to vitamin source and user’s gender. The researchers studied a total of 77,118 participants of the VITAL cohort ranging from 50 to 76 years of age, which were recruited between October 2000 and December 2002. The 10-year average daily dose from individual and multivitamin supplements were the exposures of primary interest.
The researchers reported that the use of supplemental vitamins B6, folate, and B12 though not associated with lung cancer risk among women, the use of vitamin B6 and B12 from individual supplement sources (not from multivitamins) is associated with a 30% to 40% increase in lung cancer risk among men, which is even higher among men who are smoking at baseline.