Folic acid — also known as vitamin B9 — is one of the most important nutrients your body needs every single day. It plays a key role in making new cells, producing healthy red blood cells, and helping your body absorb nutrients from food. In this article, you will learn what folic acid does, where to find it in your diet, how much you need, and what happens when you do not get enough.
What Is Folic Acid?
Folic acid is a water-soluble B vitamin. This means your body does not store it for long, so you need a steady supply from food or supplements. It belongs to the same family as vitamins B1, B6, and B12.
The natural form found in food is called folate. The synthetic form — used in supplements and fortified foods — is called folic acid. Both forms do the same job in your body, though your body absorbs the synthetic form more easily.
Folic acid works at the most basic level of your biology. It helps your cells copy their DNA correctly every time they divide. Without it, new cells cannot form properly. This is why folic acid is especially important during periods of rapid growth — like pregnancy, infancy, and adolescence.
What Does Folic Acid Do for Your Body?
The most important job of folic acid is helping your body make new cells. Every day, your body produces billions of new cells to replace old or damaged ones. Folic acid makes this process possible.
Red Blood Cell Production
Your bone marrow uses folic acid to produce healthy red blood cells. Red blood cells carry oxygen from your lungs to every part of your body. Without enough folic acid, your bone marrow cannot make normal red blood cells. Instead, it produces large, misshapen cells that do not work properly. This leads to a condition called megaloblastic anaemia, which we will explain in more detail below.
DNA Synthesis and Cell Division
Folic acid plays a direct role in building and repairing DNA. DNA is the instruction manual inside every cell. When cells divide — which happens constantly throughout your body — they need to copy their DNA accurately. Folic acid helps make this happen. Without it, errors can occur during cell division, which can have serious health consequences.
Nutrient Absorption
Folic acid also helps your body absorb and use other nutrients from the food you eat. Furthermore, it works alongside vitamin B12 to keep your nervous system healthy. These two vitamins are deeply connected, and a shortage of either one can cause similar symptoms.
Folic Acid and Pregnancy
Folic acid is absolutely essential during pregnancy. It is one of the most important nutrients for a developing baby, especially in the very early weeks — often before a woman even knows she is pregnant.
Preventing Neural Tube Defects
The neural tube is the structure in a developing embryo that becomes the baby’s brain and spinal cord. It forms within the first 28 days of pregnancy. If a woman does not have enough folic acid during this time, the neural tube may not close properly. This can lead to serious birth defects, including spina bifida and anencephaly.
Health Canada and healthcare providers across the country strongly recommend that all women who could become pregnant take a daily folic acid supplement. This is because neural tube defects develop so early that waiting until you know you are pregnant may be too late. Health Canada provides guidance on folic acid supplementation for women of childbearing age.
How Much Folic Acid During Pregnancy?
Most health guidelines recommend that women who are pregnant — or planning to become pregnant — take 0.4 to 1.0 mg (400 to 1,000 micrograms) of folic acid daily. Women with a higher risk of neural tube defects may need a higher dose. Your family doctor or midwife can advise you on the right amount for your situation.
In addition to supplements, eating folate-rich foods every day is also important. However, it can be difficult to get enough folate from food alone during pregnancy. This is why supplementation is so widely recommended.
Best Food Sources of Folic Acid
You can find folic acid — or its natural form, folate — in a wide variety of everyday foods. Eating a balanced, varied diet is one of the best ways to keep your levels healthy.
Natural Food Sources
The following foods are among the richest natural sources of folate:
Dark leafy greens — spinach, romaine lettuce, and kale
Asparagus — one of the highest folate-containing vegetables
Green cabbage and Brussels sprouts
Carrots and beets
Legumes — lentils, chickpeas, and black beans
Liver — beef and chicken liver are extremely rich in folate
Dairy products — milk and aged cheeses contain moderate amounts
Eggs
Citrus fruits — oranges and grapefruit
In Canada, many grain products are fortified with folic acid by law. This includes white flour, pasta, cornmeal, and most breakfast cereals. This fortification programme has helped reduce the rate of neural tube defects in Canada significantly since it began in 1998.
Tips for Preserving Folate in Food
Folate is sensitive to heat and light. As a result, cooking vegetables at high temperatures for a long time can destroy much of their folate content. To get the most from your food, try steaming or lightly sautéing vegetables instead of boiling them. Eating some vegetables raw — like spinach in a salad — is also an excellent way to preserve their folate content.
How Much Folic Acid Do You Need Each Day?
Your daily requirement for folic acid depends on your age and life stage. The requirements are measured in micrograms (mcg) of dietary folate equivalents (DFE).
Daily Recommended Amounts
Infants (0–6 months): 65 mcg DFE
Infants (7–12 months): 80 mcg DFE
Children (1–3 years): 150 mcg DFE
Children (4–8 years): 200 mcg DFE
Children (9–13 years): 300 mcg DFE
Teens and adults (14+): 400 mcg DFE
Pregnant women: 600 mcg DFE
Breastfeeding women: 500 mcg DFE
Most healthy Canadians who eat a varied diet can meet these requirements through food alone. However, pregnant women, people with certain health conditions, and older adults may need supplements. The Mayo Clinic offers a detailed overview of folate and recommended daily intakes.
Folic Acid Deficiency: Signs and Causes
A folic acid deficiency occurs when your body does not have enough of this essential vitamin. It is more common than many people realise. However, it is also preventable with a healthy diet and, when needed, supplementation.
Common Causes of Deficiency
Several factors can lead to low folic acid levels:
Poor diet — not eating enough folate-rich fruits, vegetables, and whole grains
Malabsorption disorders — conditions like celiac disease or Crohn’s disease that affect how your gut absorbs nutrients
Heavy alcohol use — alcohol interferes with folate absorption and increases its excretion
Certain medications — some drugs block the body’s ability to use folic acid. These include methotrexate, phenytoin, and some other anticonvulsant medicines
Pregnancy — the body’s demand for folic acid increases dramatically during pregnancy
Kidney dialysis — dialysis removes folate from the blood
Signs and Symptoms of Low Folic Acid
A deficiency in folic acid can cause a range of symptoms. Many of these symptoms develop slowly over time. Common signs include:
Extreme tiredness and low energy
Pale or yellowish skin
Shortness of breath
Heart palpitations
Headaches and difficulty concentrating
Mouth sores or a sore, red tongue
Tingling or numbness in the hands and feet
Muscle weakness
These symptoms overlap with many other conditions. Therefore, it is important not to self-diagnose. A simple blood test from your family doctor can confirm whether your folic acid levels are low.
Megaloblastic Anaemia
The most well-known consequence of severe folic acid deficiency is megaloblastic anaemia. This is a type of anaemia where the bone marrow produces abnormally large red blood cells. These oversized cells do not function properly and cannot carry oxygen efficiently. As a result, the body becomes starved of oxygen, causing fatigue, weakness, and other symptoms listed above.
Megaloblastic anaemia caused by folic acid deficiency is treated with oral folic acid supplements. In some cases — particularly when absorption is the problem — a doctor may prescribe an injectable form called folinic acid (a derivative of folic acid that is easier for the body to use). Healthline provides a thorough explanation of folic acid deficiency and its treatments.
Folic Acid Supplements: What You Need to Know
Folic acid supplements are widely available across Canada without a prescription. You can find them at pharmacies and health food stores in most cities and towns. They come as standalone supplements or as part of a multivitamin or prenatal vitamin.
Who Should Consider a Supplement?
Supplements are especially recommended for:
Women who are pregnant or planning to become pregnant
People with conditions that affect nutrient absorption
People taking medications that interfere with folic acid
Older adults with poor dietary intake
People who drink alcohol heavily
Most standard multivitamins contain 400 mcg of folic acid — enough to meet the needs of most healthy adults. Prenatal vitamins typically contain a higher dose. However, always check the label and speak with your doctor before starting any new supplement.
Can You Take Too Much?
Folic acid is water-soluble, so your body flushes out excess amounts through urine. However, very high doses — above 1,000 mcg per day — are not recommended without medical supervision. Extremely high intake can mask the symptoms of a vitamin B12 deficiency, which could allow nerve damage to go undetected. Your family doctor can help you find the right dose for your needs.
When to See a Doctor
If you think you may have a folic acid deficiency, it is important to speak with a healthcare provider. Do not wait for symptoms to get worse. Early detection and treatment make a big difference.
You should contact your family doctor or visit a walk-in clinic if you experience persistent fatigue, pale skin, shortness of breath, or other symptoms listed above. A simple blood test — available through your provincial health plan at no cost — can check your folate levels quickly and accurately.
Pregnant women or those planning a pregnancy should speak with their family doctor or midwife about folic acid supplementation as soon as possible. Your doctor can also check whether your current diet provides enough folate, or whether a supplement is right for you. Do not rely on guesswork when it comes to your health — your healthcare team is there to help.
Frequently Asked Questions About Folic Acid
What is folic acid used for?
Folic acid is used by the body to make new cells, produce healthy red blood cells, and support DNA synthesis. It is especially important during pregnancy to prevent serious birth defects of the brain and spine. Furthermore, it helps your body absorb nutrients from food more effectively.
How much folic acid should I take during pregnancy?
Most Canadian health guidelines recommend that pregnant women — or women planning to become pregnant — take 0.4 to 1.0 mg (400 to 1,000 mcg) of folic acid daily. Women at higher risk of neural tube defects may need a higher dose prescribed by their doctor. It is best to start taking folic acid at least one to three months before conception.
What are the signs of a folic acid deficiency?
Common signs of a folic acid deficiency include extreme tiredness, pale skin, shortness of breath, mouth sores, and difficulty concentrating. In more severe cases, it can lead to megaloblastic anaemia. If you notice these symptoms, visit your family doctor or a walk-in clinic for a blood test.
What foods are high in folic acid?
Foods rich in folic acid (or its natural form,
