Frank folate deficiency is rare in the US, where grain products have been fortified with folic acid since 1998, but some people have marginal status, including people with alcohol use disorder or malabsorption and people taking certain medicines. Inadequate folate around conception and in early pregnancy raises the risk of neural tube defects (spina bifida, anencephaly).
Common symptoms
Fatigue, weakness, shortness of breath (from megaloblastic anemia)
Forgetfulness or mood changes (especially older adults)
Most folate deficiency is asymptomatic until anemia develops
At-risk groups
Women planning pregnancy or in early pregnancy (important for lowering neural tube defect risk)
Women of reproductive age generally (defects occur before pregnancy is recognized)
People with alcohol use disorder
People with GI conditions affecting absorption (celiac, tropical sprue, Crohn's)
People taking methotrexate, sulfasalazine, or some anticonvulsants (phenytoin, carbamazepine)
People with the MTHFR 677C>T gene variant, who convert folate to its active form less efficiently
Older adults, especially institutionalized
People on hemodialysis
When to see a doctorHealth authorities advise all women who could become pregnant to take 400 mcg of folic acid daily, because adequate folate before and in early pregnancy may reduce the risk of neural tube defects. Otherwise, persistent fatigue with sore tongue or mouth ulcers warrants a serum or RBC folate test plus B12 (deficiencies share symptoms but have different consequences).