Folic acid (vitamin B9) for fertility

On this page

1. What is folic acid?
2. Function and how it works
3. Fertility benefits
4. Recommended daily dose
5. Food sources
6. Cautions and contraindications
7. My Fertility Guide
8. Related pages

1. What is folic acid?

Folic acid (vitamin B9) is a water-soluble B vitamin essential for cell division, DNA synthesis and the prevention of birth defects. It is the single supplement that Western medicine universally recommends to all women trying to conceive and during the first trimester of pregnancy. Despite this, only 26–28% of women take it before pregnancy.

Folic acid is the synthetic form found in supplements and fortified foods, while folate is the natural form found in foods. Some women carry the MTHFR gene variant which reduces their ability to convert folic acid to its active form — for these women, methylfolate (5-MTHF) is preferable.

Reference ranges and recommended intakes vary from country to country — always interpret guidance against the recommendations of your own healthcare authority.

2. Function and how it works

Folic acid plays multiple critical roles in fertility and early pregnancy:

1. Prevents neural tube defects. Folic acid taken before conception and during the first weeks of pregnancy dramatically reduces the risk of spina bifida and other neural tube defects.
2. DNA synthesis and cell division. Folic acid is essential when new genetic material is made during cell division, which occurs at unprecedented speed during early embryonic development.
3. Reduces autism risk. Mothers who do not have enough folic acid in their body at the time of conception have an increased risk of their baby developing autism.
4. Supports language development. Continued folic acid use into pregnancy reduces language development problems in the child.
5. Homocysteine regulation. Folic acid (with B6 and B12) keeps homocysteine in check, which is associated with miscarriage when elevated.
6. Red blood cell production. Folic acid is required for healthy red blood cell formation.

3. Fertility benefits

Folic acid is the most important and best-evidenced supplement for any woman trying to conceive. Adequate intake from at least one month before conception, and continuing through the first trimester, is essential. Men also benefit from folic acid — research has shown that folic acid supplementation in men improves sperm count and quality.

4. Recommended daily dose

I recommend a daily dose of 400 mcg (0.4 mg) of folic acid for women trying to conceive and during the first trimester. Women with a previous pregnancy affected by neural tube defects, those taking certain antiepileptic medications, or those with a known MTHFR variant may be advised to take a higher dose (4 mg or 5 mg) under medical supervision.

Folic acid should be started at least one month before trying to conceive — the neural tube closes within the first four weeks of pregnancy, often before pregnancy is even confirmed.

5. Food sources

Natural folate is found in:

1. Green leafy vegetables (spinach, kale, romaine, rocket)
2. Whole grains
3. Beans, peas and lentils
4. Asparagus, broccoli, Brussels sprouts
5. Citrus fruits
6. Avocados
7. Liver (note: avoid in pregnancy due to vitamin A content)

6. Cautions and contraindications

1. Folic acid can mask vitamin B12 deficiency, so it is best taken alongside vitamin B12, particularly in vegans and vegetarians.
2. Women with the MTHFR gene variant may benefit from methylfolate (5-MTHF) rather than synthetic folic acid.
3. Folic acid is generally very safe; toxicity from oral supplementation is extremely rare.
4. Always consult with a fertility specialist or your doctor before starting any new supplement regime.

7. My Fertility Guide

8. Related pages

• Fertility supplements directory
• Vitamin B12 (cobalamin)
• Vitamin B6 (pyridoxine)
• Iron
• Miscarriage