Folic acid - Vitamin B9
What are the roles of vitamin B9?
Vitamin B9 is involved in many fundamental biological processes:
- DNA and RNA synthesis and repair: essential for cell replication, particularly in rapidly renewing tissues such as bone marrow, the digestive tract and the developing foetus.
- Red blood cell formation: participates in the maturation of erythrocytes in the bone marrow, in cooperation with vitamin B12
- Neural tube development: essential in the first weeks of pregnancy for the correct closure of the neural tube, precursor of the brain and spinal cord.
- Amino acid metabolism: involved in the conversion of homocysteine to methionine, helping to maintain normal blood homocysteine levels
- Support for neurological function: involved in the synthesis of neurotransmitters such as serotonin, dopamine and noradrenaline
- Cardiovascular health: adequate folate levels help reduce hyperhomocysteinemia, an independent cardiovascular risk factor
What are the dietary sources of folate?
| Category | Folate-rich foods | Approximate content |
|---|---|---|
| Green leaf vegetables | Spinach, arugula, romaine lettuce, kale, Swiss chard | 100 to 200 µg per 100 g cooked |
| Pulses | Lentils, chickpeas, kidney beans, black beans, edamame | 150 to 360 µg per 100 g cooked |
| Offal | Beef or chicken liver (exceptionally concentrated source) | Up to 600 µg per 100 g |
| Eggs | Mainly in egg yolk | About 47 µg per egg |
| Enriched cereals | Folic acid-enriched flours, breads and breakfast cereals (mandatory enrichment in Canada since 1998) | Varies by product |
| Citrus fruits and juices | Orange, grapefruit, fresh orange juice | 30 to 50 µg per 100 mL |
| Other vegetables | Asparagus, broccoli, avocados, beets, Brussels sprouts | 50 to 150 µg per 100 g |
What are the recommended daily requirements?
| Population | Recommended intake (µg EFA/day) | Remarks |
|---|---|---|
| Adults (men and women) | 400 µg | Reference intake for the general population |
| Women of childbearing age | 400 to 800 µg | Supplementation recommended as soon as pregnancy is planned |
| Pregnant women | 600 µg (and up to 5 mg depending on risk) | Increased need at conception and throughout the first trimester |
| Nursing mothers | 500 µg | Increased needs to support milk production |
| Children (1 to 13 years) | 150 to 300 µg | Increasing needs with age |
| Teenagers (ages 14 to 18) | 400 µg | Same needs as adults |
EFA: dietary folate equivalents. 1 µg dietary folate = 0.5 µg folic acid supplement taken on an empty stomach, or 0.6 µg taken with a meal.
Vitamin B9 and pregnancy: why is it so important?
Folic acid supplementation before and during pregnancy is one of the best-documented preventive interventions in perinatal medicine. The neural tube (precursor to the brain and spinal cord) closes between days 21 and 28 after conception, often before pregnancy is even confirmed. Folate deficiency at this critical stage significantly increases the risk of neural tube defects, the most serious of which are spina bifida (incomplete closure of the spinal column) and anencephaly (absence of brain development).
Health Canada and the Society of Obstetricians and Gynaecologists of Canada (SOGC) recommend that all women of childbearing age take a folic acid supplement of 0.4 mg (400 µg) per day, ideally at least three months before conception and until the end of the first trimester. Women with risk factors (history of pregnancy affected by neural tube defects, diabetes, epilepsy on anticonvulsants, obesity) may require higher doses of up to 5 mg per day, depending on medical assessment.
What are the signs and causes of vitamin B9 deficiency?
| Common causes | Signs and symptoms of deficiency |
|---|---|
| A diet low in green vegetables and legumes | Megaloblastic anemia: fatigue, pallor, shortness of breath, palpitations |
| Pregnancy and breastfeeding (increased needs not covered) | Neural tube defects in the fetus |
| Chronic alcoholism (reduced absorption and altered metabolism) | Glossitis (red, painful tongue), recurrent mouth ulcers |
| Intestinal malabsorption: celiac disease, Crohn's disease, small bowel resection | Neuropsychiatric disorders: irritability, depression, memory problems |
| Drugs that interfere with folate metabolism: methotrexate, trimethoprim, phenytoin, sulfasalazine | Hyperhomocysteinemia with increased cardiovascular risk |
| MTHFR gene mutation reduces dietary folate conversion | Intrauterine growth retardation, prematurity, placental abruption |
How is vitamin B9 deficiency diagnosed?
- Serum folate assay: reflects recent folate intake, can be rapidly lowered by dietary restriction
- Erythrocyte folate assay (intraerythrocyte): more accurate reflection of long-term tissue reserves, less influenced by recent intakes
- Blood count: look for megaloblastic anemia with macrocytosis (high VGM) and neutrophil hypersegmentation
- Vitamin B12 dosage: always associated, as a B12 deficiency can mask or mimic a B9 deficiency and vice versa.
- Homocysteine assay: elevated in B9 and/or B12 deficiency, functional marker for deficiency of these vitamins
When and how to supplement?
Folic acid supplementation is recommended in several well-defined clinical situations:
- Intended pregnancy and first trimester: 0.4 mg to 5 mg per day depending on individual risk level assessed by the physician
- Blood-documented deficiency: therapeutic dose generally 1 to 5 mg daily for several weeks until corrected
- Taking antifolate drugs (methotrexate, sulfasalazine): systematic supplementation to limit adverse effects associated with folate antagonism
- Chronic malabsorptive diseases: continuous supplementation adapted to biological monitoring
- Alcoholism in treatment: correction of deficiency as part of comprehensive nutritional management
- Homozygous MTHFR C677T mutation: some experts recommend the methylfolate form (5-MTHF), which can be directly assimilated without enzymatic conversion.
Consult at Clinique Omicron
If you're planning a pregnancy, have signs of vitamin B9 deficiency, or would like a complete nutritional check-up, Clinique Omicron's doctors at our Quebec locations can prescribe the appropriate tests, interpret your results and guide you through a supplementation program tailored to your clinical situation.
The content of this page is provided for informational purposes only and is not intended to replace the advice of a qualified healthcare professional. Consult a physician for any symptoms, questions or decisions you may have regarding your health.
Omicron Clinic
Need to consult a doctor?
Treatment within 24-48 hours. In-clinic or telemedicine, anywhere in Quebec.
Insurance receipts. 7j/7. No family doctor required.