If you eat too much folic acid (a B vitamin found in supplements and fortified foods), it can hide the early blood signs that you're low on vitamin B12, so doctors might not catch the problem until your nerves are already damaged.

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Adverse Effects of Excessive Folic Acid Consumption and Its Implications for Individuals With the Methylenetetrahydrofolate Reductase C677T Genotype

Narrative Review

2025 Feb

Too much folic acid can hide the warning signs of low vitamin B12, so doctors might not notice the problem until serious brain damage has already happened — and this study says that’s a real risk.

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Source Study

Adverse Effects of Excessive Folic Acid Consumption and Its Implications for Individuals With the Methylenetetrahydrofolate Reductase C677T Genotype

Score: 1

DOI: 10.7759/cureus.79374

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If a pregnant woman takes too much folic acid—more than 1000 micrograms a day—and her blood has very high levels of folate and B12, her baby might be more likely to develop autism, as if these nutrients together are sending mixed signals to the developing brain.

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