Marmite is rich in B vitamins including thiamin (B1), riboflavin (B2), niacin (B3), folic acid (B9) and vitamin B12. The sodium content of the spread is high and has caused concern, although it is the amount per serving rather than the percentage in bulk Marmite that is relevant. The main ingredient of Marmite is yeast extract, which contains a high concentration of glutamic acid. Marmite is not gluten free, as it is made with wheat, and although it is thoroughly washed, it may contain small quantities of gluten.