Metformin may reduce serum folic acid and vitamin B12 levels. These changes can lead to hyperhomocysteinemia, adding to the risk of cardiovascular disease in people with diabetes. There are also rare reports of megaloblastic anemia in people who have taken metformin for five years or more. Reduced serum levels of vitamin B12 occur in up to 30% of people taking metformin chronically. However, clinically significant deficiency is not likely to develop if dietary intake of vitamin B12 is adequate. Deficiency can be corrected with vitamin B12 supplements even if metformin is continued. The metformin-induced malabsorption of vitamin B12 is reversible by oral calcium supplementation.The general clinical significance of metformin upon B12 levels is as yet unknown.
Hyperhomocysteinemia or hyperhomocysteinaemia is a medical condition characterized by an abnormally large level of homocysteine in the blood. Hyperhomocysteinemia is a disease which increases risk of other artery or vein diseases. As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of the vitamins pyridoxine (B6), folic acid (B9), or B12 can lead to high homocysteine levels. Supplementation with pyridoxine, folic acid, B12, or trimethylglycine (betaine) reduces the concentration of homocysteine in the bloodstream.
Vitamin B could be easily sourced from liver, fish, meat, eggs and.... Marmite!!!