Pyridoxine (Vitamin B6)

Pyridoxine in Plasma

Clinical Information

It has 6 chemical forms. Similar to other B vitamins, pyridoxine helps release energy from foods. It is an important cofactor to almost 100 enzymatic reactions, mainly in the protein and amino acid metabolism1, 2.

Signs and Symptoms of Deficiency or Toxicity

Severe deficiency is rare3. But vitamin B6 deficiency may cause a burning sensation in the mouth. A deficient state is also associated with scaling skin, severe gingivitis, irritability, weakness, neuropathy, and seizures4.

Specific vitamin B6 deficiency is rare but can be associated with a deficiency of the other B-vitamins2.

Long-term high supplementation of vitamin B6 in very high doses may result in pain, numbness of the extremities. These symptoms were observed with ingested amounts more than 1,000 mg/day3.

Biomarker and Methods of Analysis


Plasma pyridoxine has has been found to reflect tissue stores and measurements are sensitive to the effects of pregnancy, sex, exercise, age, NSAID, smoking and alcohol consumption5,6.

Supplementation Guide

Several studies show that vitamin B6 supplementation will improve maternal and perinatal outcomes. However, there is insufficient data on the benefits and harm brought about by supplementation in pregnancy7.

For the general population, there are also no established guidelines for supplementation.

Following are the established upper limits for B6 per age group8:

  • For children:
    • 1-2 y.o.: 30 mg
    • 4-8 y.o.: 40 mg
    • 9-13 y.o.: 60 mg
    • 14-18 y.o.: 80 mg
  • For adults, 19 years and older: 100 mg

Some medications interact with vitamin B6. For example, women using oral contraceptives (OC) have been recorded to have lower plasma pyridoxine levels. Anti-tuberculosis medications and anti-parkinsonian drugs also limit the absorption of vitamin B63.

Food Sources

It is found in fish, poultry, nuts, legumes, potatoes, and bananas3.

(1) Huskisson E, Maggini S, Ruf M. The role of vitamins and mineral in energy metabolism and well-being. The Journal of International Medical Research 2007; 35: 277-289
(2) Office of Dietary Supplements-National Institutes of Health. Vitamin B6. Fact Sheet for Health Professionals. Retrieved from
(3) Higdon J, Drake VJ, Delage B. (May 2014). Linus Pauling Micronutrient Information Center. Vitamin B6. Retrieved from
(4) Mayo Clinic Medical Laboratories. (n.d.). Test Catalog. Vitamin B6 (PLP and PA), Plasma. Retrieved from
(5) Bralley, J.A., Lord, R.S. (2012). Laboratory Evaluations for Integrative and Functional Medicine. 2nd ed. Duluth, Ga: Metametrix Institute.
(6) Combs, G. F. Jr., McClung, J.P. (2017). The Vitamins: Fundamental Aspects in Nutrition and Health. 5th ed. Massachussetts: Academic Press.
(7) World Health Organization. (November 2016). WHO recommendation on vitamin B6 supplementation in pregnancy. Retrieved from
(8) Philippine Dietary Reference Intakes. 2015. Department of Science Technology-Food and Nutrition Research Institute.