Whether most people would benefit from manganese supplementation remains unclear. While there is no recommended dietary allowance, the National Research Council’s “estimated safe and adequate daily dietary intake” is 2–5 mg.¹ The Institute of Medicine recommends that intake of manganese from food, water and dietary supplements should not exceed the tolerable daily upper limit of 11 mg per day. In contrast, the 5–15 mg often found in high-potency multivitamin-mineral supplements is generally considered to be a reasonable level by many doctors, though many manufacturers are likely to reformulate their products to contain no more than 11 mg per daily amount.