Is B12 useful for fertility?

The provided knowledge contexts contain no direct information about vitamin B12 and fertility. B12 is essential for DNA synthesis, cell division, and red blood cell formation – processes relevant to reproduction. A deficiency could theoretically impair fertility, but the evidence from the given sources is absent. The contexts cover DNA tests for skin glycation, food intolerance, NQO1, FOXO3, and PCSK9 – none relate to B12 or fertility. Therefore, an evidence-based statement is not possible from this material. The evidence rating is 'unclear'. For reliable guidance, consult clinical studies or guidelines.