As a vegetarian, at 80 years, any problem I have with iron absorption is a result of gastric dystrophy, not dietary intake. But I only rarely need vitamin B12.
Since most men over 40 have an excess of serum iron, causing acute myocardial infarcts, I don't eat any foods which have added iron; as a family, our main source is probably a heavy old iron frying-pan. I consider it a great advantage that non-heme (plant) iron is more poorly absorbed and less stored in the body. I live close to a volcano, and an iron-sand beach, so there is no shortage of iron in the soil. An important point, often forgotten, is that vegetables always have the expected vitamins, before cooking, but if grown on poor soil will be mineral-deficient, often with no visible sign.