Vitamin B6

Also indexed as: PLP, Pyridoxal-5’-Phosphate, Pyridoxine

What is it?

Vitamin B6 is the master vitamin for processing amino acids—the building blocks of all proteins and some hormones. Vitamin B6 helps to make and take apart many amino acids and is also needed to make the hormones, serotonin, melatonin, and dopamine.

Vitamin B6 aids in the formation of several neurotransmitters and is therefore an essential nutrient in the regulation of mental processes and possibly mood.

In combination with folic acid and vitamin B12, vitamin B6 lowers homocysteine levels—an amino acid linked to heart disease and stroke, and possibly other diseases as well, such as osteoporosis, and Alzheimer’s disease.

A rare, but severe, form of childhood epilepsy results from an inborn error in the metabolism of vitamin B6. Children with this form of epilepsy have an abnormal dependence on vitamin B6 and are usually mentally retarded. Seizure activity is reversible with intravenous injections of vitamin B6, which must be administered by a doctor.1

In some,2 3 but not all,4 studies, vitamin B6 supplements improved glucose tolerance in women with diabetes caused by pregnancy.

Where is it found?

Potatoes, bananas, raisin bran cereal, lentils, liver, turkey, and tuna are all good sources of vitamin B6.

Vitamin B6 has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
3Stars

Anaemia (if deficient and for genetic vitamin B6-responsive anaemia)

Autism

Depression (in women taking oral contraceptives)

High homocysteine (in combination with folic acid and vitamin B12)

Morning sickness

Premenstrual syndrome
2Stars

Age-related cognitive decline

Asthma

Canker sores

Carpal tunnel syndrome

Childhood intelligence (for deficiency)

Depression (associated with premenstrual syndrome)

Diabetes (gestational only)

Low back pain (in combination with vitamin B1 and vitamin B12)

MSG sensitivity

Pregnancy and postpartum support (if homocysteine levels are elevated)

Schizophrenia

Vertigo
1Star

Acne

Alcohol withdrawal support

Alzheimer’s disease (in combination with iron and coenzyme Q10)

Amenorrhea

Atherosclerosis

Attention deficit disorder

Coeliac disease

Eating disorders (for bulimia)

Epilepsy

Fibrocystic breast disease

Heart attack

HIV support

Hypoglycaemia

Kidney stones

Osgood-Schlatter disease (in combination with manganese and zinc)

Osteoporosis (to lower homocysteine)

Parkinson’s disease (with Sinemet® or Eldepryl®)

Photosensitivity

Pre- and post-surgery health

Preeclampsia

Seborrheic dermatitis

Sickle cell anaemia

Stroke

Tardive dyskinesia
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Who is likely to be deficient?

Vitamin B6 deficiencies are thought to be very rare. Vitamin B6 deficiency can cause impaired immunity, skin lesions, and mental confusion. A marginal deficiency sometimes occurs in alcoholics, patients with kidney failure, and women using oral contraceptives. Some doctors believe that most diets do not provide optimal amounts of this vitamin. People with kidney failure have an increased risk of vitamin B6 deficiency.5 Vitamin B6 has also been reported to be deficient in some people with chronic fatigue syndrome.6

How much is usually taken?

The most common supplemental intake is 10–25 mg per day. However, high amounts (100–200 mg per day or even more) may be recommended for certain conditions.

Are there any side effects or interactions?

Vitamin B6 is usually safe, at intakes up to 200 mg per day in adults.7 However, neurological side effects can sometimes occur at that level.8 Levels higher than 200 mg are more likely to cause such problems. Vitamin B6 toxicity can damage sensory nerves, leading to numbness in the hands and feet as well as difficulty walking. The National Academy of Sciences performed an analysis of vitamin B6 studies. They determined the safe upper limit for long-term use is 100 mg per day. However, under supervision of a healthcare professional, up to 200 mg per day of vitamin B6 can be safely taken by most men and nonpregnant women for limited periods of time. Pregnant and breast-feeding women should not take more than 100 mg of vitamin B6 per day without a doctor’s supervision.

Since vitamin B6 increases the bioavailability of magnesium, these nutrients are sometimes taken together.

Are there any drug interactions?
Certain medicines may interact with vitamin B6. Refer to drug interactions for a list of those medicines.

References

1. Nabbout R, Soufflet C, Plouin P, Dulac O. Pyridoxine dependent epilepsy: a suggestive electroclinical pattern. Arch Dis Child Fetal Neonatal Ed 1999;81:F125–9.

2. Spellacy WN, Buhi WC, Birk SA. Vitamin B6 treatment of gestational diabetes mellitus. Am J Obstet Gynecol 1977;127:599–602.

3. Coelingh HJT, Schreurs WHP. Improvement of oral glucose tolerance in gestational diabetes by pyridoxine. BMJ 1975;3:13–5.

4. Rao RH, Vigg BL, Rao KSJ. Failure of pyridoxine to improve glucose tolerance in diabetics. J Clin Endocrinol Metab 1980;50:198–200.

5. Makoff R. Vitamin replacement therapy in renal failure patients. Miner Electrolyte Metab 1999;25:349–51 [review].

6. Heap LC, Peters TJ, Wessely S. Vitamin B status in patients with chronic fatigue syndrome. J R Soc Med 1999;92:183–5.

7. Gaby AR. Literature review & commentary. Townsend Letter for Doctors June 1990;338–9.

8. Parry G, Bredesen DE. Sensory neuropath with low-dose pyridoxine. Neurology 1985;35:1466–8.