The key facts

  • Doses of overlapping components from different supplements add up, even if each package is taken according to the instructions
  • Prolonged excess of B6 can damage the peripheral nerves: numbness, tingling, burning in the hands and feet
  • Excess zinc interferes with copper absorption, which can cause anemia and impaired nervous system function

Dose accumulation when combining supplements

Before adding another supplement to your usual vitamins, you need to check whether their ingredients overlap — otherwise you can end up with an excess of a substance even while following the instructions on each package. This warning was issued in a conversation with Gazeta.Ru by physician, clinical pharmacologist and Candidate of Medical Sciences Ekaterina Rumyantseva.

The vitamin B6 example

The doctor gave an example with vitamin B6: a person takes a B-complex vitamin and then buys magnesium. If magnesium also contains B6, the body receives the vitamin from two products in a single day, and counting its amount separately from each package is no longer enough. «A person is simultaneously taking a B-complex vitamin and a supplement with magnesium and vitamin B6. If both supplements contain vitamin B6, their daily doses add up,» Rumyantseva commented. According to her, the consequences can be more serious than they seem: prolonged excess of B6 can damage the peripheral nerves. Possible symptoms include numbness, tingling and burning in the hands and feet.

The zinc problem

A similar problem arises with zinc, but with different consequences. If a person is already taking a vitamin-mineral complex with zinc and decides to separately take a complex «for immune support,» which often contains this trace element, its amount increases due to the second supplement. With prolonged excess, zinc interferes with copper absorptionthe publication's interlocutor said, and a copper deficiency can cause anemia and impaired nervous system function. Thus, by taking additional products, a person risks developing a deficiency of a substance the body needs.

How to avoid excess

Ingredients should be checked before starting a new supplement: you need to compare all supplements, find overlapping components and add up their daily doses. Studying only the product names will not help, since magnesium may be found in a complex with vitamin B6, and a vitamin-mineral supplement «for immune support» — with zinc. It is the full ingredient list that makes it possible to notice such an overlapRumyantseva concluded. Earlier, as the publication notes, Russians were explained why weight-loss supplements do not work.

Why this matters

The recommendation is relevant to everyone who combines several supplements: the risk arises even when each package is formally taken correctly according to the instructions. The practical takeaway from the pharmacologist's words is to check the full ingredient lists of the products you already take before buying a new supplement and to add up the doses of overlapping components, since excess B6 and zinc lead to nerve damage and copper deficiency, respectively.