As to whether folic acid supplementation might be "good" or "bad," an alternative explanation is that folic acid may be beneficial in some circumstances and harmful in others. This explanation is potentially attractive if one hypothesizes that the conversion of homocysteine to methionine (for which folate is necessary) is beneficial, but that high doses of folic acid can lead to anti-folate effects by accumulation of "free folic acid." For individuals with an imbalanced metabolic profile but adequate levels of B12, it seems that folic acid supplementation would yield favorable effects by normalizing this profile. However, folic acid supplementation could lead to problematic behaviors through any one or combination of biological scenarios, including accumulation of unmetabolized pteroylglutamic acid (PGA) in serum, B12 deficiency, and/or genotypes known to impede the biochemical conversion of folic acid. Given that negative responses to folic acid supplementation have typically been reported among adolescents and adults, it is further possible that this phenomenon is regulated by maturational processes.