Vitamin B9 is an essential nutrient for your brain.

Lack of vitamin B9 can induce high homocysteine levels, which in turn leads to cognitive decline and mood disorders.

As a nootropic, Vitamin B9 plays a role in myelination of your nerves and is essential for the synthesis of mood-regulating neurotransmitters such as dopamine and serotonin.

Vitamin B9 is essential for:

  • Mood – Keeping your vitamin B9 levels high is one sure way to reduce the risk of depression or anxiety. Vitamin B9 is even believed to boost the efficacy of antidepressants.
  • Memory and Cognition – Folate, a type of vitamin B9, plays a key role in gene expressions, RNA and DNA synthesis, and myelination of your nerves. When there’s enough myelin sheath encasing your nerves, neurons can send fast and smooth signals to each other – leading to faster thinking and sharper memory.
  • Regulates Homocysteine – Vitamin B9 helps keep homocysteine levels at bay. Why is this important? If for no other reason, then because high homocysteine levels link to poor cerebral blood flow, among many other health problems.

What is Vitamin B9

Vitamin B9 is a water-soluble nutrient belonging to the B complex family.

There are two main types of vitamin B9 that people ingest: folate and folic acid.

While folate is found naturally occurring in foods and high-quality supplements. Folic acid is a synthetic variation of vitamin B9. Some people might have a hard time absorbing folic acid.

Like other essential vitamins, your body can’t make vitamin B9 on its own.

It’s important to get enough of it daily through diet – or supplementation.

During early childhood, your brain needs vitamin B9 to fully develop.

Later in adulthood, vitamin B9 helps maintain healthy cognition and mood, thanks to its role in balancing homocysteine levels.

In fact, chronically low intake of vitamin B9 can lead to high homocysteine levels.

High homocysteine is linked to cognitive impairment and premature brain aging, among other health issues. (1)

How it Works

Vitamin B9 plays a part in countless processes within your body.

Here are the two that stand out, in terms of brain function:

  1. Vitamin B9, aka Folate, helps with depression – Folate is involved in the creation of nucleoproteins, phospholipids, and neurotransmitters. Low levels of folate link to depression and dementia. Some research suggests that folate is so important it can boost the effects of antidepressants. As you’ll find out later.
  2. Vitamin B9 improves brain neuroplasticity – Like we mentioned, your brain needs folate to create dopamine, serotonin, and epinephrine. These are key neurotransmitters for your mood. Without enough folate, levels of your neurotransmitters plummet which can lead to depression and literal brain shrinkage.
man doing yoga on the beach representing vitamin B9 effects on the mind

Which Brain Pathways Does Vitamin B9 Target?


Folate is the most bioavailable form of vitamin B9.

It readily converts to L-Methylfolate in your body. L-Methylfolate is the active form of vitamin B9 which your body uses to synthesize neurotransmitters such as serotonin and dopamine. (2)

Low folate levels link to mood disorders. And folate supplementation is suggested to be of huge importance in this regard – supporting serotonin production in the brain. (3)

What’s more, vitamin B9 helps your body to create SAMe. (4)

Also known as S-Adenosyl-methionine, SAMe is an amino acid critical for bright mood and healthy cognition.

Brain Protection

As I briefly mentioned, your body needs vitamin B9 to get rid of excess homocysteine.

Now, why is this so important?

The answer lies in the effects of homocysteine on your vascular system; homocysteine damages and irritates your blood vessels and promotes blood clotting. (5)

Not good for your heart, nor the brain.

Vitamin B9 and homocysteine work in a seesaw-like manner.

When one is high, the other plummets down. (6)

  • When you have enough vitamin B9, your body converts homocysteine to methionine. This in turn links to better mental performance. (7)

Ultimately, by regulating homocysteine levels, vitamin B9 improves your cerebrovascular system; preventing the damage and irritation of your blood vessels in the brain and protecting from cognitive decline.

how folate affects nerves brain map

Clinical Evidence of Vitamin B9’s Benefits

Vitamin B9 Improves Cognition

  1. This study assessed the link between vitamin B9 levels and cognitive function in 260 older men and women.

After thorough research, the study found that there was a strong link between having low folate levels and suffering from memory and cognitive impairments. (8)

  1. Another study looked at the effects of supplementing 50mg of vitamin B9 to 38 folate-deficient patients.

After 12 days, the subjects showed significant improvements in their performance, mood, memory, and overall cognitive function. (9)

Vitamin B9 (Folate) Helps With Depression

A lot of people who suffer from depression find antidepressants ineffective.

Curious to find out why these medications weren’t working, experts set out to do some research.

  1. And so we come to the first study, where Dr. Jerome Sarris did a meta-analysis on studies which used nutritional supplements alongside antidepressants.

The research review found that omega-3 supplements boosted the effectiveness of antidepressant medications.

They also found that vitamin B9 improved the success of antidepressants in treating depression.

However, this study review found that inositol or folic acid had no benefits on depressed patients.

Therefore, it is important which type of vitamin B9 is used for combining with antidepressants. Methyl folate being the most effective form. And folic acid being ineffective.

The research concluded that vitamin D, omega-3s, SAMe, and methyl folate all boost antidepressant’s positive effects. (10)

  1. In another study from Italy, researchers compared the effects of antidepressant drug Trazadone with vitamin B9 in the form of methyl folate on depression.

People in this study received either 100mg of Trazadone or 50mg of vitamin B9 daily.

After one month, the depression score test revealed better results in those who took vitamin B9 than those treated with Trazadone. (11)

Vitamin B9 Dose

The optimal dose for vitamin B9 in the form of Folate is 500mcg per day.

However, you shouldn’t take vitamin B9 alone, unless your doctor specifically prescribes this therapy.

Supplementing with isolated B vitamin can cause deficiencies of other B vitamins.

Thus, it’s always advised to take vitamin B12, B2, B3, and B6 alongside B9. Or simply a B complex formula.

Side Effects

The folate form of vitamin B9 is extremely safe and non-toxic.

Any excess amount of the vitamin gets filtered by your kidneys and excreted through urine.

That said, folic acid, the synthetic form of vitamin B9, isn’t safe in high doses.

High amounts of folic acid can compromise your cognition and the immune system.

Other side effects of using too much folic acid include:

  • Inability to sleep
  • Loss of appetite
  • Nausea
  • Skin reactions
  • Digestive issues
  • Seizures

Medications that interfere with the absorption of folic acid include: chemotherapy drugs, antacids, anti-seizure medications, antibiotics, Daraprim, ibuprofen, and Methotrexate, Azulfidine, and Dilantin.

Your Questions Answered – FAQ

Does folate help with anxiety? Vitamin B9 in the form of folate can definitely help with anxiety if you are deficient in this nutrient. Folate is critical for the creation of neurotransmitters such as dopamine and serotonin. Both of these play a key role in mood regulation. What’s more, studies show that folate deficiency can lead to anxiety and depression.

Can folate be toxic? Research suggests that for healthy people, oral intake of folate isn’t toxic even in very high doses. (12)

Can folic acid cause headaches? According to research, folic acid helps reduce migraines linked to high homocysteine blood levels. However, since folic acid is a synthetic form of vitamin B9, high amounts of it can cause side effects – including headaches.

brazil nuts folate source


Vitamin B9 is an essential water-soluble nutrient belonging to the family of B vitamins.

Your brain loves when you supply it with enough vitamin B9 daily.

Optimal levels of this nutrient help with:

  • Mood – vitamin B9 is essential for the synthesis of neurotransmitters, including dopamine, serotonin, and norepinephrine. All of which regulate mood.
  • Neuron communication – vitamin B9 is involved in the formation of myelin sheath which encases your nerves and plays a role in neuron signaling.
  • Memory and brain protection – When your vitamin B9 levels are low, your homocysteine shoots up. High homocysteine links to a whole host of health issues, including cognitive decline and cerebrovascular dysfunction.

The two main forms of vitamin B9 are folic acid and folate.

While folate is naturally occurring in foods, folic acid is all but natural. It’s a synthetic form of vitamin B which some people can’t absorb.

What’s more, folic acid can cause side effects in high enough doses, while folate doesn’t.

So when it comes to choosing the right vitamin B9 supplement, fancy packaging alone won’t cut it.

Instead, look at the dosage, and most importantly – the quality of the ingredients you’re getting.

You might also like: How do Nootropics Work? Evidence-Based Benefits of Nootropics For Your Brain


  1. Folic acid and psychopathology. (source)
  2. Vitamin B Supplementation: What's the Right Choice for Your Patients? (source)
  3. Folate and depression—a neglected problem. (source)
  4. Folate, vitamin B₁₂, and S-adenosylmethionine. (source)
  5. Homocysteine, oxidative stress, and vascular disease. (source)
  6. Folate - Oregon State University. (source)
  7. Vitamin B Supplementation: What's the Right Choice for Your Patients? (source)
  8. Association between nutritional status and cognitive functioning in a healthy elderly population. (source)
  9. Blood folate deficiencies and cognitive functions in aging. Authors: Rapin JR, Le Poncin M, Grebyl J.
  10. Adjunctive Nutraceuticals for Depression: A Systematic Review and Meta-Analyses. (source)
  11. Oral 5'-methyltetrahydrofolic acid in senile organic mental disorders with depression: results of a double-blind multicenter study. (source)
  12. Folic acid safety and toxicity: a brief review. (source)

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