vitamin B6 pyroxidine

Vitamin B6 (pyroxidine) is one of the B vitamins that is primarily involved in metabolism.  It is an essential vitamin, which means that it is not synthesized by the body and must be obtained through diet or supplementation.  Additionally, vitamin B6 is a water-soluble vitamin, which means that it is not readily stored in the body and should be consumed on a regular basis to ensure optimal health. 

The name vitamin B6 actually includes six different compounds that perform the same or similar function.  These compounds include pyridoxine, pyridoxal, pyridoxamine, and their respective ester compounds. 

Where is vitamin B6 (pyroxidine) found?

There are many food sources of vitamin B6.  It is found in plant-based sources in potatoes, starchy vegetables, non-citrus fruits, and fortified breakfast cereals.  Some animal-derived sources include fish and liver.

Vitamin B6 can also be found in supplements, generally as pyridoxine hydrochloride.  Vitamin B6 is available in multivitamin supplements, B-complex supplements, or supplements containing only vitamin B6.

Why is it important?

Vitamin B6 has many essential functions in the body.  For example, it helps in the development of neurotransmitters, which are the chemical compounds that help neurons communicate with each other.  It also helps maintain the level of the amino acid homocysteine in the blood.

Two specific forms of vitamin B6 are pyridoxal 5-phosphate (PLP) and pyridoxamine 5-phosphate (PMP).  Both of these forms help metabolize amino acids and proteins in the body.  PLP in particular helps metabolize carbohydrates and fats from the diet.

What is the RDA?

The Recommended Dietary Allowance (RDA) for vitamin B6 is 1.3mg for men between 14 and 50 years of age and 1.7mg for men over 50.  The RDA is 1.3mg for women between 14 and 50 years of age, 1.5mg for women over 50, and 1.9mg and 2.0mg for pregnant women and lactating women, respectively. 

The RDA for vitamin B6 is 1.0mg for children between nine and thirteen years of age, 0.6mg for children between four and eight years of age, 0.5mg for infants between one and three years, 0.3mg for infants between seven and twelve months, and 0.1mg for infants under seven months of age.  Vitamin B6 is passed on through breast milk when the mother has a healthy diet, and it is also added to infant formulas.

These values are given by the National Institutes of Health, and the RDA represents the daily intake sufficient to meet the dietary needs of 97-98% of healthy individuals.  A cup of canned chickpeas contains 65 percent of the RDA, and three ounces of fresh yellowfin tuna contains 53 percent of the RDA for vitamin B6.

How much is too much?

The tolerable upper intake level (UL) for vitamin B6 is 100mg for men and women above 19 years and 80mg for all teenagers between 14 and 18 years.  The UL for vitamin B6 is 60mg for children between nine and thirteen years, 40mg for children between four and eight years, and 30mg for children between one and three years.  The UL is not established for infants under twelve months.  The UL represents the maximum daily intake that is unlikely to cause negative health effects. 

There aren’t any reported side effects for consuming excess amounts of vitamin B6 through food sources.  There have been reported side effects from consuming too much vitamin B6 through supplements, however.  Continuous oral administration of pyridoxine doses between one and six grams for over a year can cause sensory neuropathy and ataxia, however these effects generally stop after discontinuation of supplementation. 

In addition, excess intake of vitamin B6 through supplements can result in light sensitivity, nausea, heartburn, and painful skin lesions.

What are the benefits of vitamin B6?

One interesting benefit of vitamin B6 is that it might help reduce the symptoms of morning sickness in pregnant women.  One study found that pregnant women who took 25mg tablets of vitamin B6 in the form of pyridoxine hydrochloride every eight hours for three days had significantly reduced symptoms compared to those who took a placebo.

Vitamin B6 could also potentially help reduce the symptoms of premenstrual syndrome (PMS).  An analysis of nine studies including 940 PMS patients found that vitamin B6 supplementation up to 100mg daily was associated with reduced PMS symptoms.  This effect was particularly observed for mood-related symptoms, and this could perhaps be attributed to the fact that vitamin B6 (pyroxidine) helps produce neurotransmitters.

Some scientists believe that vitamin B6 could potentially help reduce the risk of age-related cognitive decline.  One study of 70 males between 54 and 81 years of age found that higher blood levels of vitamin B6 were associated with better performance on two different memory tests.  However, as a whole, the evidence surrounding vitamin B6 and cognitive decline is inconclusive.

Vitamin B6 deficiency

Some groups have a higher risk of vitamin B6 deficiency than others, although vitamin B6 deficiency is quite rare in developed countries.  One example is those with autoimmune disorders, such as rheumatoid arthritis, Crohn’s disease, ulcerative colitis, celiac disease, and inflammatory bowel disease.  They tend to have lower blood PLP concentrations, however the cause of this is unknown. 

People with reduced kidney function, such as those with renal disease and chronic renal insufficiency, might have an increased risk of vitamin B6 deficiency as they often have reduced PLP levels.  The mechanism for this is also unknown.

People with alcoholism often have lower concentrations of PLP because alcohol metabolism produces a product called acetaldehyde.  This product can make PLP more susceptible to degradation.

Insufficient vitamin B6 levels are associated with decreased immune function, depression, confusion, swollen tongue, and dry, scaly skin on the lips and mouth. Vitamin B6 deficiency is also associated with irritability and seizures in infants.

Supplementation

Vitamin B6 (pyroxidine) deficiency can fortunately be corrected with vitamin B6 supplementation.  Pyridoxine tablets between 50 and 100mg daily can treat the deficiency in adults, although larger doses might be needed for certain cases.  Vitamin B6 deficiency can also be prevented through supplementation or a healthy, balanced diet that meets the RDA for vitamin B6.

If you think you have a vitamin B6 deficiency or are at an increased risk, consider getting your blood levels tested.  As always, consult your doctor before you begin taking any vitamin or mineral supplement, to make sure your medications or health conditions don’t make it a serious risk.

References:

Johnson, L., MD, PhD. (2019, August). Vitamin B6 Deficiency and Dependency – Nutritional Disorders. Retrieved August 21, 2020, from https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency-dependency-and-toxicity/vitamin-b6-deficiency-and-dependency

Office of Dietary Supplements – Vitamin B6. (24, February 20). Retrieved August 20, 2020, from https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/

Riggs, K. M., Spiro, A., Tucker, K., & Rush, D. (1996). Relations of vitamin B-12, vitamin B-6, folate, and homocysteine to cognitive performance in the Normative Aging Study. American Journal of Clin Nutr, 63(3), 306-314. doi:10.1093/ajcn/63.3.306

Sahakian, V., Rouse, D., Sipes, S., Rose, N., & Niebyl, J. (1991). Vitamin B6 is effective therapy for nausea and vomiting of pregnancy: A randomized, double-blind placebo-controlled study. Obstetrics Gynecol, 78(1), 33-36.

Stover, P. J., & Field, M. S. (2015). Vitamin B-6. Advances in Nutrition, 6(1), 132-133. doi:10.3945/an.113.005207

Wyatt, K. M., Dimmock, P. W., Jones, P. W., & Shaughn O’Brien, P. M. (1999). Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: Systematic review. BMJ, 318(7195), 1375-1381. doi:10.1136/bmj.318.7195.1375

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