Vitamin B6: Everything You Need to Know

Medically reviewed by Beth Thomas, PharmD

Vitamin B6 (pyridoxine) is a water-soluble compound that is involved in over 100 enzyme reactions in the body.

It is crucial for the following:

• Brain development

• The formation of the energy source glucose

• Immune system function

Vitamin B6 is found in the following foods:

• Fish

• Beans

• Fruits

• Vegetables

Vitamin B6 can also be taken as a dietary supplement.

This article discusses the potential uses of B6, the risks of having too much or too little of it in your body, and how to optimize wellness by incorporating it into your diet.

Supplement Facts

• Active ingredient: Pyridoxine

• Alternate name: Pyridoxine, pyridoxal, pyridoxamine

• Legal status: Over-the-counter supplement (United States).

• Suggested dose: Recommended Dietary Allowance (RDA) of 1.3 to 2 milligrams (mg) daily for adults

• Safety considerations: Not recommended during breastfeeding; may interact with some seizure and Parkinson's medications

Uses of Vitamin B6

Explainer

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

The role of vitamin B6 has been studied extensively for cancer, dementia, and heart health. However, a lot of the evidence is mixed.

It's also been researched for people with depression, anxiety, nausea and vomiting, and more.

Here's a look at the science behind some of vitamin B6's potential uses.

May Increase Cognitive Function

Vitamin B6 has been thought to help maintain mental function and prevent cognitive decline, but there's little compelling evidence that it works.

The theory is that vitamin B6, along with other B-complex vitamins like B12 and folic acid, could help prevent memory loss or dementia by lowering homocysteine in the body. High levels of homocysteine are associated with cognitive impairment. Often these B vitamins have been studied in tandem, so the true effects of vitamin B6 are hard to determine.

Supplementation with B-complex vitamins decreases homocysteine levels in people with Alzheimer's disease or dementia. But interestingly, a corresponding improvement in mental function hasn't been shown. And vitamin B supplementation was shown to have little or no effect on healthy older adults in terms of protecting against cognitive decline.

A review of 21 studies showed that high levels of B6 alone didn't impact the dementia risk of older adults, either.

May Protect Against Cancer

A review of 130 studies suggests that vitamin B6 may protect against cancer.

A higher intake of dietary vitamin B6 (from food sources) was associated with a significantly lower risk of cancer.

High dietary B6 levels were mainly associated with lower risks of cancers of the digestive tract, like esophageal, pancreatic, and colon cancers.

But interestingly, a high total intake of vitamin B6 (from foods plus supplements) had much less of an effect on cancer risk.

This could be because diets high in vitamin B6 are also loaded with other protective nutrients that decrease the odds of cancer.

And only nine of the studies in the review were controlled trials that compared vitamin B6 to a placebo.

The others were observational, meaning no treatment was given.

No significant cancer-lowering effect was seen in the nine controlled trials of vitamin B6.

This means that the role of vitamin B6 in preventing cancer is unclear.

And as a general rule, vitamin and mineral supplements are not recommended for cancer prevention as they may even increase the risk of cancer in some circumstances.

May Improve Heart Health

The role of vitamin B6 in heart health is also controversial.

Higher vitamin B6 intake has been associated with a lower risk of heart disease.

But taking vitamin B supplements has been determined to have little to no effect on survival, or risk of heart disease or stroke.

May Decrease Nausea and Vomiting of Pregnancy

Vitamin B6 is known to have anti-nausea properties. It's often used for nausea and vomiting of pregnancy, but there's limited data to support its benefits.

A study of 77 females found that vitamin B6 was better at decreasing nausea and vomiting during the first trimester than a placebo (sugar pill).

And a review of trials concluded that vitamin B6 was more effective than ginger for nausea and vomiting in pregnancy when it was taken for 60 days or longer.

Additional Uses

In addition to the above uses, vitamin B6 has been studied for the following conditions:

• Anxiety and depression

• Premenstrual syndrome

• Fibromyalgia

• Restless legs syndrome (RLS)

• Tardive dyskinesia

• Behavioral side effects of Keppra (levetiracetam)

So far, the evidence is fairly weak for B6 benefiting any of these conditions.

Explainer

Before taking vitamin B6, involve a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider to help you safely achieve your health goals.

Vitamin B6 Deficiency

Some people may develop a B6 deficiency when:

• Intakes are lower than recommended levels over time.

• They have a specific risk factor for lower-than-normal levels.

• There's a reason they're unable to digest or absorb vitamin B6.

What Causes a Vitamin B6 Deficiency?

Vitamin B6 deficiency is uncommon in the United States.

It's usually found in tandem with low levels of other B-complex vitamins, such as niacin or folate.

Low levels of B6 can be caused by the following:

• Kidney diseases, including end-stage renal disease and chronic renal insufficiency (in which damaged kidneys can't filter out toxins from the blood as well)

• Problems with vitamin absorption, such as celiac disease, Crohn’s disease, or ulcerative colitis

• Genetic diseases like homocystinuria (an inherited condition where the body can't process methionine, an amino acid)

• Long-term use of seizure medications

In cases of deficiency, particularly from a condition or depletion of B6 from a drug, supplementation may be required.

Groups at Risk of Vitamin B6 Deficiency

People with the following conditions are at higher risk for B6 deficiency:

• Kidney dialysis

• Critical illness

• Alcohol dependence

• Pregnancy

• Older age

• Recent surgery

How Do I Know If I Have a Vitamin B6 Deficiency?

Typically a vitamin B6 deficiency will be identified and diagnosed by a healthcare provider through specific labs.

However, some identifying features of a B6 deficiency may include the following:

• Microcytic anemia, characterized by fatigue

• Scaling or cracked lips or mouth (cheilosis)

• Swollen tongue (glossitis)

• Depression

• Confusion

• Seizures

Related: What Is Hyperhomocysteinemia?

What Are Side Effects of Vitamin B6?

Side effects are not common when vitamin B6 is consumed in foods, even in large amounts.

But taking high doses of vitamin B6 supplements over a long period can cause severe side effects like neuropathy (nerve pain) and ataxia (loss of coordination).

Nutrition

The National Institutes of Health (NIH) recommends the following daily amounts of vitamin B6.

As with most vitamins and minerals, these amounts vary depending on age, sex, and pregnancy or lactation (breastfeeding) status.

Most people in the United States get the recommended daily amounts of vitamin B6 through their diets. It's commonly found in foods like the following:

• Meats

• Whole grains

• Potatoes

• Fortified cereal

B6 can be taken as a dietary supplement too.

It's available as a component of multivitamins and B-complex combinations and by itself in capsule, tablet, and liquid forms.

Precautions

Dietary sources (from your food) of vitamin B6 are safe to consume for the typical child or adult.

High levels (more than 50 mg per day) of supplemental B6 are likely safe during pregnancy.

Consult with your healthcare provider for a recommended dose.

It may be best to steer clear of vitamin B6 supplements if breastfeeding, as it may decrease or stop milk production.

Explainer

Ask an RD or RDN, pharmacist, or healthcare provider for more information.

Dosage: How Much Vitamin B6 Should I Take?

Explainer

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

The NIH recommends between 1.3 and 2 mg of dietary vitamin B6 per day for adults and less for children.

Lots of foods are good sources of vitamin B6.

For instance, 1 cup of chickpeas contains 1.1 mg of vitamin B6, 3 ounces of tuna has 0.9 mg, and a banana has 0.4 mg.

Some people may need to take vitamin B6 supplements. While there isn't a specific recommended dose, the following doses have been used in clinical trials:

• 40 mg twice a day for nausea and vomiting during pregnancy

• 3 to 100 mg for cancer prevention

Because of the risk of side effects, ideally, you should aim to supplement with vitamin B6 for only up to six months unless your healthcare provider suggests otherwise.

Explainer

Dietary supplements are not regulated like prescription medications in the United States. Therefore, some may be safer than others. When choosing a supplement, consider factors such as third-party testing, potential drug interactions, and other safety concerns. Talk to a healthcare provider or a registered dietitian nutritionist (RD or RDN) about supplement quality and safety.

What Happens If I Take Too Much Vitamin B6?

Because B6 is water-soluble vitamin, higher than needed amounts of vitamin B6 are typically eliminated in the urine.

Toxicity (or poisoning) is possible if high doses of vitamin B6 are taken for long periods of time. Vitamin B6 toxicity is characterized by:

• Sensory neuropathy (nerve pain)

• Ataxia (loss of coordination)

• Impaired sensations

• Skin lesions

To prevent toxicity, the Food and Nutrition Board has determined upper limits of intake (ULs) for this vitamin and many others. The UL is the maximum amount of the vitamin that should be consumed from all sources, including food and supplements.

The UL for people ages 14 to 18 is 80 mg of vitamin B6 daily. For people 19 and older, it's 100 mg daily.

Interactions

Some prescription medications may lower the levels of vitamin B6 in the body. These include the following:

• Isoniazid, a tuberculosis treatment

• Cancer medications

• Corticosteroids

• Seizure medicines

Vitamin B6 can lower the level of levodopa, a medicine for Parkinson's disease, by up to 67%. But vitamin B6 does not affect levels of levodopa when it's taken in combination with carbidopa (as in prescription Sinemet).

Interestingly, high doses of levodopa and over a period of time may also cause a vitamin B6 deficiency. This is because vitamin B6 breaks down levodopa and may become depleted if there is a lot of levodopa in the body. Consult with your healthcare provider regarding monitoring of your vitamin levels when taking levodopa.

B6 supplementation might also lower levels of the seizure medicines phenytoin and phenobarbital.

How to Store

Store vitamin B6 supplements at room temperature, away from the reach of children and pets.

Discard after one year or according to the product label.

Similar Supplements

Other vitamins that have been studied to protect against heart disease include the following:

• Vitamin A

• Folic acid

• Vitamin C

• Vitamin D

• Vitamin E

Lots of other supplements have been studied as ways to help minimize cancer risk. A few of them are:

• Curcumin

• Green tea

• Omega-3 fatty acids

Whether these supplements can help prevent cancer is still controversial and requires further investigation.

Summary

Vitamin B6 is vital for energy, brain development, and a healthy immune system.

Adult daily requirements of 1.5 to 2 mg are typically obtained through foods like beans, fish, or vegetables.

Vitamin B6 may help with first-trimester morning sickness.

And dietary sources of B6 (from your food) might protect against cancer to an extent. However, remember that vitamin supplements are typically not recommended for cancer prevention.

If you decide to try it, discuss it with your healthcare provider to ensure it's a good fit for you.

Remember that taking too much vitamin B6 can result in severe nerve pain and loss of coordination. Upper limits of intake have been established.

Frequently Asked Questions

What is vitamin B6?

Vitamin B6 is an essential vitamin also known as pyridoxine that is found in foods like beans and meats, and which can also be taken as a dietary supplement.

What does vitamin B6 do?

Vitamin B6 is involved in over 100 enzyme reactions in the body. It plays a role in brain health, immune function, and more.

How much vitamin B6 do I need per day?

Recommended Dietary Allowances for adults range from 1.3 to 2 mg daily.

Read the original article on Verywell Health.