Increased Lung Cancer Risk with Supplements? Reasons to Be Cautious with B12 and Antioxidant Vitamins

The German newspaper Augsburger Allgemeine (September 30, 2025) warned that excessive intake of vitamins, particularly high-dose supplementation, could increase the risk of lung cancer. This warning is based on two main points: (1) epidemiological studies suggesting that high-dose supplements of vitamins B12 and B6 have increased lung cancer in men, especially smokers, and (2) basic research indicating that antioxidant vitamins (such as A, C, and E) activate the "BACH1" pathway, which promotes the formation of new blood vessels in tumors and aids tumor growth. On the other hand, an analysis has shown that vitamin D, when administered "daily," can reduce cancer mortality by about 12%, highlighting differences based on dosage, frequency, and target population. On social media, extreme opinions such as "cancer prevention through supplements is a myth" and "pharmaceutical conspiracy theories" are circulating, alongside more measured discussions pointing out dosage issues. The conclusion is simple: vitamins should primarily come from diet, and supplements should be taken only in cases of deficiency or under medical advice. High doses of B vitamins should be avoided by smokers, and indiscriminate high intake of "antioxidants" should be approached with caution.