Yep there was some hype about 100 years ago, soon after the discovery of vitamin D by Windaus – where vitamin D / cod liver oil was used to treat tuberculosis.
Also vitamin A (also contained in high doses in cod liver oil) was used in the pre-antibiotic era as anti-infective therapy while it has lost its role being used only as some supportive add-on after during measles infection. Reliable prevention of measles by vaccination should not be confused with uncertain supportive therapy.
But what about vitamin D supplementation and cancer? A new study in the Annals last week show
7% reduction in cancer mortality was observed after a median cumulative follow-up of 22.3 years (1817 vs. 1943 deaths; hazard ratio [HR], 0.93 [95% CI, 0.87 to 0.99]), along with a 6% increase in CVD mortality (2621 vs. 2420 deaths; HR, 1.06 [CI, 1.01 to 1.12]).
As both risks are of borderline significance and we don’t trust P values alone, my conclusion is: vitamin D supplementation doesn’t prevent cancer.
