Folate
Vitaminas e mineraisÚltima revisão: 7 de abril de 2026. Abordagem de fontes: contexto padrão de interpretação laboratorial, material médico de referência e orientações clínicas ou de saúde pública quando relevantes.
O que é Folate?
Folate, also known as vitamin B9, is a water-soluble B vitamin essential for DNA synthesis, RNA production, amino acid metabolism, and the formation of red and white blood cells. The body cannot produce folate on its own and must obtain it from dietary sources such as leafy green vegetables, legumes, citrus fruits, and fortified grains, or from supplements in the form of folic acid. Once absorbed in the small intestine, folate is converted to its active form, 5-methyltetrahydrofolate (5-MTHF), which participates in one-carbon metabolism—a critical biochemical pathway involved in methylation reactions throughout the body.
Folate is measured through a blood test that reflects recent dietary intake and absorption. Serum folate is the preferred clinical test in most laboratories. Although red blood cell (RBC) folate has historically been used as a longer-term marker, many laboratories no longer recommend it because of substantial assay variability and limited added clinical value over serum folate combined with vitamin B12, homocysteine, and methylmalonic acid when needed. Folate is particularly critical during periods of rapid cell division, making it indispensable during pregnancy, infancy, and adolescence. Folate deficiency remains one of the most common vitamin deficiencies worldwide, especially in populations without mandatory food fortification.
Por que isso importa
Folate is essential for proper DNA synthesis and cell division. Deficiency leads to megaloblastic anemia, where the bone marrow produces abnormally large, immature red blood cells that cannot function properly. In pregnancy, inadequate folate dramatically increases the risk of neural tube defects such as spina bifida and anencephaly. Folate also plays a key role in homocysteine metabolism—low folate elevates homocysteine levels, which is an independent risk factor for cardiovascular disease, stroke, and dementia. Adequate folate supports mental health, cognitive function, and healthy aging.
Faixas de referência normais
| Grupo | Faixa | Unidade |
|---|---|---|
| Adults (serum) | ≥4.0 | ng/mL |
| Pregnancy (serum) | ≥4.0 | ng/mL |
As faixas de referência podem variar entre laboratórios. Sempre compare seus resultados com as faixas fornecidas pelo seu local de exame.
O que significam níveis altos de Folate
Causas comuns
- Excessive folic acid supplementation
- High dietary intake of fortified foods
- Vitamin B12 deficiency (folate may be elevated while B12 is low)
- Kidney disease (impaired excretion)
- Pernicious anemia (folate is not utilized properly)
Possíveis sintomas
- Usually asymptomatic
- May mask vitamin B12 deficiency symptoms
- Possible digestive discomfort at very high supplement doses
- Insomnia or irritability (rare, with mega-doses)
O que fazer: High folate levels are generally not harmful, but they can mask a concurrent vitamin B12 deficiency, which if untreated can cause irreversible neurological damage. Your doctor should check vitamin B12 levels alongside folate. Reduce supplementation if levels are excessively high, and ensure B12 status is adequate.
O que significam níveis baixos de Folate
Causas comuns
- Inadequate dietary intake of folate-rich foods
- Malabsorption disorders (celiac disease, Crohn's disease)
- Chronic alcohol use (impairs folate absorption and metabolism)
- Medications (methotrexate, phenytoin, sulfasalazine)
- Increased demand during pregnancy and lactation
- MTHFR gene mutations affecting folate metabolism
Possíveis sintomas
- Fatigue and weakness
- Megaloblastic anemia
- Mouth sores and swollen tongue (glossitis)
- Poor concentration and irritability
- Shortness of breath
- Gray hair or hair loss
- Neural tube defects in developing fetuses
O que fazer: Folate deficiency is treated with folic acid supplementation, typically 400–1000 mcg daily, or higher doses for those with malabsorption or MTHFR mutations. Increase dietary intake of folate-rich foods including spinach, asparagus, lentils, and fortified cereals. Women of childbearing age should take at least 400 mcg of folic acid daily to prevent neural tube defects. Your doctor should also check vitamin B12 levels, as the two deficiencies frequently coexist.
Quando o exame de Folate é recomendado?
- When megaloblastic anemia is suspected
- During pregnancy planning and early pregnancy
- When taking medications that interfere with folate metabolism
- If experiencing symptoms of folate deficiency
- When elevated homocysteine levels are found
- In patients with chronic alcohol use or malabsorption disorders
Perguntas frequentes
Biomarcadores relacionados
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Referências e abordagem de revisão
As páginas do glossário de biomarcadores são explicações educativas e devem ser interpretadas junto com as faixas de referência e observações fornecidas pelo seu laboratório e pelo seu médico. Para conhecer nossos padrões editoriais e processo de revisão, veja nossa Política editorial e a nossa revisão de conteúdo.
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Enviar resultados de exames →Aviso médico: Estas informações são apenas educativas e não substituem orientação, diagnóstico ou tratamento médico profissional. As faixas de referência podem variar entre laboratórios. Sempre converse com seu profissional de saúde sobre a interpretação dos seus resultados específicos.