Quick answer: Folate (vitamin B9) is essential for making DNA, dividing cells, forming red blood cells and processing homocysteine. Low folate can cause fatigue, anemia, mouth sores and mood changes, and it is critical before and during pregnancy. Leafy greens, legumes and liver are rich sources, and some people use methylfolate with guidance.
Key takeaways
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Folate is the B vitamin your body uses to build DNA, make red blood cells and recycle homocysteine.
Low folate can show up as tiredness, mouth sores or mood changes, and diet, alcohol, gut health and MTHFR variants can all play a part.
Leafy greens, legumes and asparagus are good food sources, and folate is usually checked together with vitamin B12.
Folate works closely with B12 and homocysteine, so it often makes the most sense to review these markers together.
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What is Folate?
Folate is a B vitamin needed to build DNA, support cell division and recycle homocysteine through the methylation cycle.
Why Folate matters
Folate matters for DNA synthesis and repair, red blood cell production, methylation and homocysteine processing, and a healthy pregnancy (neural tube development).
Understanding your result
Reference ranges vary by lab, age and sex. Your provider interprets your result against the lab’s range and your overall picture, rather than chasing a single number. Functional labs are optional. They can be helpful in more complex cases.
What low Folate can mean
Low folate can come from low intake of leafy greens and legumes, alcohol use, or absorption problems such as celiac disease. Medications such as methotrexate and some anti-seizure drugs, and increased needs in pregnancy, can also lower it.
What high Folate can mean
High folate usually reflects high intake from supplements or fortified foods. Because it can mask B12 deficiency, B12 should be checked too.
What affects Folate
Folate is affected by diet, alcohol, gut health, genetic variants such as MTHFR, and medications.
Ways to support healthy levels
- Eat leafy greens, legumes, asparagus, avocado and liver
- Check B12 along with folate (see vitamin B12)
- Discuss folic acid or methylfolate with your provider (see who should consider methylfolate)
- Folic acid is recommended before and during pregnancy to prevent neural tube defects
Folate and healthy aging
Folate is central to DNA synthesis and repair and to methylation, the process that switches genes on and off. Low folate can contribute to genomic instability and epigenetic changes, and raises homocysteine, which affects blood vessels and the brain.
What does the research show about folate?
Folate has some of the strongest trial evidence of any nutrient. In the Medical Research Council Vitamin Study, published in 1991, 1,817 women at 33 centers in seven countries who had a previous pregnancy affected by a neural tube defect were randomly assigned to folic acid, a mix of seven other vitamins, both, or neither, starting before conception. Among 1,195 completed pregnancies, 6 neural tube defects occurred in the folic acid groups and 21 in the other groups, a 72% lower risk (relative risk 0.28). The other vitamins showed no significant effect. The limitation is that the women were at high risk, and the study was too small to detect rare side effects.
Folic acid has also been tested for heart and brain health in adults. The CSPPT trial in China, published in 2015, randomly assigned 20,702 adults with high blood pressure and no history of stroke or heart attack to enalapril 10 mg alone or enalapril 10 mg plus folic acid 0.8 mg daily for a median of 4.5 years. First stroke occurred in 2.7% of the folic acid group and 3.4% of the enalapril-only group, a 21% relative reduction (hazard ratio 0.79). Heart attacks and overall deaths did not differ. The limitation is that China does not fortify grain with folic acid, so baseline folate was lower than in the United States, where the benefit may be smaller.
These trials show what folic acid can do when intake is low or the need is high. They do not show that more is always better, and high folic acid intake can mask a B12 deficiency, which is why folate is usually checked together with B12.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have fatigue or anemia, or elevated homocysteine. The same is true if you are planning a pregnancy, or taking medications that affect folate.
See a medical provider promptly for severe fatigue with shortness of breath, numbness or tingling, or confusion.
Folate at a glance
| Topic | What the article explains |
|---|---|
| Main jobs | DNA synthesis and repair, red blood cell production, and methylation |
| What can affect it | Diet, alcohol, gut health, MTHFR variants and medications |
| Food sources | Leafy greens, legumes, asparagus, avocado and liver |
| Often checked with | Vitamin B12 and homocysteine |
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Which of my other results would help put my Folate result in context?
How should I read my folate alongside the rest of my labs and my symptoms?
How often would it make sense to recheck my folate in my situation?
Which daily habits or medications could be influencing my folate before we retest?
Frequently asked questions
What causes low folate?
Low intake, alcohol, absorption issues, some medications and higher needs in pregnancy.
Is methylfolate better than folic acid?
Both raise folate. Folic acid is the form shown in research to lower the risk of neural tube defects; methylfolate may suit some people.
Should I check B12 with folate?
Yes. High intakes of folic acid can hide B12 deficiency.
What foods are high in folate?
Leafy greens, legumes, asparagus, avocado and liver.
What are the symptoms of low folate?
Research has linked low folate to tiredness, weakness, shortness of breath with exertion, a sore or smooth tongue, mouth sores, irritability, and difficulty concentrating. Many of these are related to a type of anemia with large red blood cells, which is also seen with low B12, so both are usually checked together.
What is a normal folate level?
A serum folate level above 4.0 ng/mL is generally considered sufficient, a level from 2.0 to 4.0 ng/mL is often described as borderline, and a level below 2.0 ng/mL is generally considered low or deficient. Lab cutoffs vary, so it is best to compare your result with the range on your own report. Because serum folate reflects recent intake, red blood cell folate and homocysteine are sometimes used for a longer-term picture.
What does folate do for the body?
Folate helps your body make and repair DNA, build healthy red blood cells, and run methylation, the chemical process that recycles homocysteine and supports many other reactions. Needs rise during pregnancy, when folate supports the baby’s early development.
Folate works closely with B12 and homocysteine, so it often makes the most sense to review these markers together.
Book your free 15-minute consult
Prefer to start on your own? Try the free 28-Day Reset for Energy and Focus.
Work with a naturopathic doctor near you
Dr. Kneessi sees patients in person in Odenton and by telehealth anywhere in Maryland. Learn more about visits for Annapolis, Odenton, Crofton, and Severna Park, or read about hormone testing and functional medicine in the area.
You can book a free 15-minute consult, or start with the free 28-Day Reset for Energy and Focus, a short daily email series on sleep, light, movement, and food.
Sources
- Medici V, Halsted CH. Folate, alcohol, and liver disease. Mol Nutr Food Res 2013. PMID: 23136133. https://pmc.ncbi.nlm.nih.gov/articles/PMC3736728/
- Miller JW, et al. Excess folic acid and vitamin B12 deficiency: clinical implications? Food Nutr Bull 2024. PMID: 38987872. https://pmc.ncbi.nlm.nih.gov/articles/PMC11288374/
- De-Regil LM, et al. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev 2015. PMID: 26662928. https://pmc.ncbi.nlm.nih.gov/articles/PMC8783750/
- Homocysteine Lowering Trialists’ Collaboration. Lowering blood homocysteine with folic acid based supplements: meta-analysis of randomised trials. BMJ 1998. PMID: 9569395. https://pmc.ncbi.nlm.nih.gov/articles/PMC28491/
- NIH Office of Dietary Supplements: Folate (Consumer Fact Sheet)
- MedlinePlus: Folic Acid
- MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet 1991. PMID: 1677062. https://pubmed.ncbi.nlm.nih.gov/1677062/
- Huo Y, et al. Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China: the CSPPT randomized clinical trial. JAMA 2015. PMID: 25771069. https://pubmed.ncbi.nlm.nih.gov/25771069/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
