A Framework to Guide Defining an Upper Threshold of Crystalline Vitamin B12 in Foods and Food Supplements

Abstract

Purpose of review To defne an intake threshold of vitamin B12 from food supplements that is sufcient to maintain normal body functions, but it does not cause pharmacological efects. Recent fndings We used studies on the amount of B12 absorbed following oral B12 application and non-comparative case-series studies to synthesize evidence on pharmacological efects of oral B12 (between<10 µg and 3000 µg) in people with manifested defciency. There is a dose-dependent intestinal absorption of B12 and in the same time efects on body metabolism and functions. Food supplements providing≤20 µg B12 daily are unlikely to cause pharmacological efects, while 50 µg might correct abnormal biochemical markers in some defcient patients. Foods for special medical purposes for people who cannot absorb B12 may contain 100 µg to 150 µg B12. This dose may ensure 1–4 µg of the vitamin reaching the circulation on a daily basis independent of intrinsic factor. Dosages≥200 µg/d should be considered as drugs that can correct anemia, metabolic markers and clinical symptoms. Summary The content of vitamin B12 in food supplements should not exceed 20 µg. In addition, people with defciency should receive appropriate medical treatment with high dose B12.