Vitamin B9 (Folate)

B vitamins are a common deficiency I see. They are very important nutrients needed for energy levels, cognitive and emotional health.

In fact, when looking at any type of mental health issue, it’s a good idea to look at any possible nutrient deficiencies first. Unfortunately, most conventional doctors don’t even consider checking for B9 or B12 deficiencies. Even if lab tests are ordered, the ranges on the lab reports may be based on a sick population rather than on healthy levels. Integrative doctors, on the other hand, will use healthy ranges that are based on ideal levels of these vitamins.

In this article, we’re going to focus on one essential B vitamins: Vitamin B9 (more often called folate). Let’s start with why the B vitamins are called “B” vitamins. This goes back to when vitamins were first being discovered. The first vitamin that was identified was called Vitamin A. So, it made sense that the next vitamin identified after A would be called B. When more B-related vitamins were discovered, they were given numbers after the B.

Vitamin B9 is part of what is called the 8 essential B vitamins. These vitamins are called essential because they are essential to take in through diet. Our bodies cannot make these vitamins from other nutrients in the food we eat. They have to actually be nutrients in those foods.

Let’s start with Vitamin B9, more often referred to as folate.


Folate is a water-soluble essential B vitamin. It’s needed for cell growth, amino acid metabolism, making red and white blood cells, lowering homocysteine (which is important for cardiovascular health) and proper cell division. It’s also needed for an important part of cell repair and liver detoxification called methylation. Folate can be found in foods like leafy greens, liver, and beans, or in supplements like folic acid (the synthetic version of folate). There are also folate supplements available.

The optimal range of folate levels in the blood is 1000-1500 ng/ml.

Folate Deficiency

A folate deficiency can show up as one or more of these symptoms or conditions:

  • Birth defects of the spinal cord and brain (e.g. spina bifida)
  • Anemia
  • Lowered immune function
  • Cardiovascular problems
  • Depression
  • Cognitive decline
  • Liver damage

How can you become deficient in folate? You may not be eating enough folate-rich foods, like green leafy vegetables.

Or, you may not be absorbing the folate you do take in. For example, if you have any gut problems (like Celiac Disease, Crohn’s or Ulcerative Colitis, for example), you may not be able to absorb nutrients well.

Another cause of low absorption is a genetic variation called an MTHFR polymorphism. This affects methylation, mentioned earlier. Depending on which type you have (C677T or A1298C) and whether you received one copy of the gene or two, you could have difficulty converting folate in foods to the active form your body can use. In this case, you’d need to supplement with the active form: 5-methyltetrahydrofolate or 5-MTHF.

Of course, if you’re pregnant, you’ll use up folate more quickly than normal and then become deficient. That’s why prenatal vitamins include folic acid or folate in their formulation.

Additionally, drinking too much alcohol can lower absorption of folate and cause you to lose too much of it in your urine.

Generally, water-soluble vitamins like B vitamins don’t build up in your system that easily. Water soluble vitamins are eliminated from the body in the urine. However, unmetabolized folic acid from supplements may lead to folate excess.

Folate Excess

  • May cover up a B12 deficiency
  • May cause mental decline
  • Taken during pregnancy, may cause insulin resistance and delayed brain development in children
  • May cause cancers to come back out of remission

Both a deficiency and an excess can lead to health problems. For that reason, it’s important to eat a vitamin-rich diet and to take supplements as recommended. If you take more than the recommended dosage, it’s a good idea to monitor levels by testing.

Dr. Laurie Goldman is a medical doctor, psychiatrist, and functional medicine practitioner who’s been in private practice since 1999. She founded Clear Path Wellness to help her patients reach their maximum state of mental and physical health using a personalized, comprehensive approach powered by the principles of functional medicine, which treats the whole person, not just symptoms.   

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B VitaminsFolate (B9) What You Want To Know