Having been approached by a GP about a rising interest of high dose vitamin D therapy (that a German website praises as a panacea for all kind of diseases) it took me some time to recall a recent IARC monograph.
Sure, it’s all about the correct dose, while excess vitamin supplementation may even kill people. Here is what the IARC says about 100,000 IU vitamin D daily:
Since 1928, it has been known that excessive daily vitamin D ingestion (200,000 â€“ 300,000 IU, i.e., 5,000 â€“ 7,500 Âµg) produces toxic effects in humans […] Acute vitamin D intoxication with hypercalcemia may clinically evoke a myocardial infarction […]. Hypercalcemia could also lead to an increased calcium excretion into urine. Prolonged hypercalcemia can cause kidney damage (kidney stones and renal dysfunction), calcification of soft tissues, including kidney, blood vessels, heart and lungs. […] Second, recently published results from prospective cohort studies in the USA, one from the Third National Health and Nutrition Examination Survey (NHANES III), and one from the Framingham Offspring Study suggest that low as well as high 25-hydroxyvitamin D could be associated with increased all-cause mortality (Melamed et al., 2008) and incidence of cardiovascular diseases (Wang et al., 2008). Risks are more pronounced for low 25-hydroxyvitamin D, but figures 5.1, 5.2 and 12.2 suggest that individuals with high 25-hydroxyvitamin D levels over the long term could also be at higher risk of death, from cancer or from a cardiovascular event. In the NHANES III study (Figures 5.1 and 12.2) higher mortality risk was observed for subjects with unusually high 25-hydroxyvitamin D above 49 ng/mL […]