Iron

HFE C282Y homozygotes absorb more iron than they can use, and the excess accumulates in the liver, heart and pancreas over decades. Hereditary haemochromatosis is treated by removing iron.

So an iron supplement is the wrong direction for this group, and iron is in a great many multivitamins bought by people who never checked. This is the rare case where a common genotype and an over-the-counter product point opposite ways.

It is also not a reason to avoid iron on your own reading of a raw file. Iron deficiency is common and is diagnosed from blood tests, not from a genotype; anyone with a C282Y result should take it to a doctor rather than act on it.