Vitamin B9 (Folic Acid) – Benefits, Sources, Deficiency Symptoms and Side Effects

vitamin b9

Arguably, no conventional nutrient has undergone as much of a research renaissance in recent years as  Vitamin B9 (folate). Many people are familiar with the name of this B complex vitamin, and it has long been recognized as a key nutrient in human health. Low intakes of folate can have devastating effects, ranging from birth defects to blood diseases and possibly even cancers.

Much more recent in our understanding of this critical B vitamin is its many different forms in food, and its influence far beyond birth defects, blood diseases, and cancers.



  • Supports a Healthy Pregnancy

Folate is known to be one of the most critical vitamins for a healthy and vibrant pregnancy, which is why it’s added synthetically to nearly all prenatal vitamins. For pregnant women, a folate deficiency is especially risky because it can potentially lead to neural tube defects, including spina bifida, anencephaly, malformations of the limbs and heart complications.

Spina bifida is a defect of the fetus’s spine in which part of the spinal cord and its meninges are exposed through a gap in the underdeveloped backbone. Anencephaly is the absence of a major portion of the fetus’s brain, skull and scalp that occurs during embryonic development early into pregnancies. Folic acid supplementation has been shown to lengthen mean gestational age of the fetus and lower the risk of preterm births (although it comes with other risks).

Folate functions as a coenzyme (or cosubstrate) in single-carbon transfers in the synthesis of nucleic acids (DNA and RNA) and metabolism of amino acids. Because folate is needed for DNA copying and building new cells, you can see why low levels result in various types of developmental issues, even some that remain an issue once the baby is born and continuing to grow.

In order to prevent neural tube defects, the FDA supplements many processed grains with folic acid, knowing that grain products make up a large percentage of the average American’s diet. According to the FDA, the recommended daily value in order to prevent folate deficiency is set at 400 micrograms and 600 micrograms for pregnant women, however, we know that obtaining this level from synthetic folic acid is not as beneficial as getting natural folate from folate-rich foods. Some superfoods for a healthy pregnancy that provide folate include leafy greens, sprouted beans, avocados and citrus.

  • Helps the Body Utilize Iron, Vitamin B12 and Amino Acids

A folate deficiency can contribute to anemia, which is a condition that develops when red blood cells are improperly formed. An important folate-dependent reaction in the body is the conversion of the methylation of deoxyuridylate to thymidylate in the formation of DNA, which is required for proper cell division. When this process is impaired, this initiates megaloblastic anemia, one of the hallmarks of folate deficiency.

Folate also helps vitamn B12 to be absorbed, so some experts are therefore concerned that high folic acid intakes might “mask” vitamin B12 deficiency until its neurological consequences become irreversible. Vitamin B12 benefits the body in many ways, including helping with nutrient absorption, energy expenditure and brain function — therefore, undiagnosed deficiency can be very risky.

  • Might Help Prevent Cancer

Low blood folate levels are associated with an increased risk of cervical, breast, colon, brain and lung cancer. Epidemiologic evidence generally indicates that a high intake of folate-rich foods offers protection against the development of some common cancers, but the relationship between folic acid and cancer is complicated, as you’ve learned.

In the NIH-AARP Diet and Health Study, a cohort study of more than 525,000 people aged 50 to 71 years in the U.S., individuals with total folate intakes of 900 micrograms/day or higher had a 30 percent lower risk of developing colorectal cancer than those with intakes less than 200 micrograms/day.

On the other hand, observations in animal and human studies demonstrate that an overly abundant intake of folate among those who harbor existing foci of neoplasia might do the opposite and raise risk of certain cancers. The pharmaceutical form of the vitamin is distinct from natural forms of the vitamin and, therefore, the most protection comes from eating real foods!

  • Supports Heart Health

Just like other B vitamins, folate plays an important role in reducing high levels of homocysteine in the blood. Homocysteine is a compound that has been linked to an increased risk of heart attacks and strokes when it lingers in the blood.

Homocysteine is an amino acid (the building blocks of proteins). It’s not possible to get homocysteine from the diet — instead, it must be made internally from methionine, another amino acid that is found in meat, fish and dairy products. Vitamins B6, B12 and folate are needed to make this reaction occur.

One of the most important folate-dependent reactions in the body is the conversion of homocysteine to methionine that occurs during the synthesis of important methyl donors. This helps normalize homocysteine levels and plays a positive role in the process of metabolizing minerals and antioxidant activities.

Generally, studies show that people who consume higher levels of folate have a lower risk of cardiovascular disease than those who have a lower intake. Although folic acid (and vitamin B12) supplements can lower homocysteine levels, research indicates that these supplements do not actually decrease the risk of cardiovascular disease, although they might provide protection from stroke.

Since we know that a diet high in plant foods like vegetables and fruits can help lower heart disease risk, this seems like the safest way to obtain folate and also benefit cardiovascular health.

  • Protects Cognitive Function and Might Help Prevent Dementia and Alzheimer’s

Most observational studies show a relationship between elevated homocysteine levels and a greater risk for Alzheimer’s disease and dementia. Some observational studies have also found correlations between low folate concentrations and poor cognitive function.

However, even though increasing folic acid through supplementing can help reduce homocysteine concentrations, this hasn’t been shown to improve cognitive function and prevent disease. A better natural Alzheimer’s treatment is to focus on obtaining plenty of nutrients, including natural folate from a variety of unprocessed whole foods.

  • Can Help Prevent Depression

While folate alone might not prevent depression, it appears that a balanced diet with plenty of veggies and plant foods might act like a natural remedy for depression. In clinical and observational studies, folate status has been linked to depression and poor response to antidepressants. In study involving 2,948 people aged 1 to 39 years in the U.S., folate concentrations were significantly lower in individuals with major depression than in those who had never been depressed.

Results from a study of 52 men and women with major depressive disorder showed that only one of 14 subjects with low folate levels responded to antidepressant treatment compared with 17 of 38 subjects with normal folate levels.


Deficiency Symptoms

·         Poor immune function; frequently getting sick

·         Chronic low energy (including chronic fatigue syndrome)

·         Poor digestion; issues like constipation, bloating and IBS

·         Developmental problems during pregnancy and infancy, including stunted growth

·         Anemia

·         Canker sores in the mouth and a tender, swollen tongue

·         Changes in mood, including irritability

·         Pale skin

·         Premature hair graying



Folate is found in small amounts in many foods. Good sources include:

  • broccoli
  • brussels sprouts
  • liver
  • spinach
  • asparagus
  • peas
  • chickpeas
  • fortified breakfast cereals


World’s Healthiest Foods ranked as quality sources of vitamin B9

Food Serving
Cals Amount
Lentils 1 cup 229.7 358.38 90 7.0
Asparagus 1 cup 39.6 268.20 67 30.5
Spinach 1 cup 41.4 262.80 66 28.6
Turnip Greens 1 cup 28.8 169.92 42 26.5
Broccoli 1 cup 54.6 168.48 42 13.9
Beets 1 cup 74.8 136.00 34 8.2
Romaine Lettuce 2 cups 16.0 127.84 32 36.0
Bok Choy 1 cup 20.4 69.70 17 15.4
Cauliflower 1 cup 28.5 54.56 14 8.6
Parsley 0.50 cup 10.9 46.21 12 19.0
Pinto Beans 1 cup 244.5 294.12 74 5.4
Garbanzo Beans 1 cup 269.0 282.08 71 4.7
Black Beans 1 cup 227.0 256.28 64 5.1
Navy Beans 1 cup 254.8 254.80 64 4.5
Kidney Beans 1 cup 224.8 230.10 58 4.6
Papaya 1 medium 118.7 102.12 26 3.9
Brussels Sprouts 1 cup 56.2 93.60 23 7.5
Green Peas 1 cup 115.7 86.78 22 3.4
Bell Peppers 1 cup 28.5 42.32 11 6.7
Green Beans 1 cup 43.8 41.25 10 4.2
Celery 1 cup 16.2 36.36 9 10.1
Cabbage 1 cup 43.5 36.00 9 3.7
Summer Squash 1 cup 36.0 36.00 9 4.5
Strawberries 1 cup 46.1 34.56 9 3.4
Tomatoes 1 cup 32.4 27.00 7 3.8
Leeks 1 cup 32.2 24.96 6 3.5
Fennel 1 cup 27.0 23.49 6 3.9
Lima Beans 1 cup 216.2 156.04 39 3.2
Dried Peas 1 cup 231.3 127.40 32 2.5
Avocado 1 cup 240.0 121.50 30 2.3
Peanuts 0.25 cup 206.9 87.60 22 1.9
Sunflower Seeds 0.25 cup 204.4 79.45 20 1.7
Quinoa 0.75 cup 222.0 77.70 19 1.6
Winter Squash 1 cup 75.8 41.00 10 2.4
Oranges 1 medium 61.6 39.30 10 2.9
Cantaloupe 1 cup 54.4 33.60 8 2.8
Onions 1 cup 92.4 31.50 8 1.5
Collard Greens 1 cup 62.7 30.40 8 2.2
Pineapple 1 cup 82.5 29.70 7 1.6
Raspberries 1 cup 64.0 25.83 6 1.8
Carrots 1 cup 50.0 23.18 6 2.1
Beet Greens 1 cup 38.9 20.16 5 2.3
Mushrooms, Crimini 1 cup 15.8 18.00 5 5.1
Kiwifruit 1 2 inches 42.1 17.25 4 1.8
Kale 1 cup 36.4 16.90 4 2.1
Swiss Chard 1 cup 35.0 15.75 4 2.0
Mushrooms, Shiitake 0.50 cup 40.6 15.22 4 1.7
Basil 0.50 cup 4.9 14.42 4 13.3
Eggplant 1 cup 34.6 13.86 3 1.8
Mustard Greens 1 cup 36.4 12.60 3 1.6
Lemons and Limes 0.25 cup 13.4 12.20 3 4.1


How much vitamin B9 do I need?

Adults need 0.2mg of folic acid a day.

Folic acid cannot be stored in the body, so you need it in your diet every day.

Most people should be able to get the amount they need by eating a varied and balanced diet.

However, if you are pregnant, thinking of trying to have a baby or likely to become pregnant, it is recommended that you take a 0.4mg (400 micrograms) folic acid supplement daily from the time you stop using contraception until the 12th week of pregnancy. This is to help prevent birth defects of the central nervous system, such as spina bifida, in your baby.

If you have a family history of conditions like spina bifida (known as neural tube defects), you may need to take a higher dose of 5mg of folic acid each day until the 12th week of pregnancy. This is available on prescription from your GP. Women with diabetes and those taking anti-epileptic medicines should speak to their GP for advice, as they may also need to take a higher dose of folic acid.

Side Effects

Taking doses of folic acid higher than 1mg can disguise vitamin B12 deficiency.

An early symptom of vitamin B12 deficiency is anaemia. However, taking large amounts of folic acid treats the anaemia without treating the B12 deficiency. If a vitamin B12 deficiency is not noticed, it can eventually damage the nervous system.

This is particularly a concern for older people, because it becomes more difficult to absorb vitamin B12 as you get older.

Folate from whole food sources doesn’t pose much of a risk, but folic acid supplements can interact with several medications and aggravate health conditions as mentioned earlier. Aside from posing a risk of cancer and autoimmune problems, anyone taking Methotrexate, a medication used to treat cancer and autoimmune diseases, is at risk for compilations when taking folic acid since this medication impacts folate absorbability.

Taking antiepileptic medications used to treat epilepsy or psychiatric diseases along with folic acid supplements might cause a reduction in serum levels of these medications. The same goes for medications like Sulfasalazine used primarily to treat ulcerative colitis.


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