Vitamin B6 is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts, and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. Vitamin B6 exists in three major forms: pyridoxine, pyridoxal, and pyridoxamine. Pyridoxal phosphate (PLP) is the coenzyme form of B6. A coenzyme enables an enzyme to catalyze a reaction. PLP is an essential coenzyme for many protein metabolism reactions.
Functions
Vitamin B6's functions include:
Helping amino acid and protein metabolism
Enabling red blood cell metabolism
Helping the nervous system function efficiently
Helping the immune system function efficiently
Converting tryptophan (an amino acid) to niacin (a vitamin)
Enabling the breakdown of glycogen to glucose
Aiding in the metabolism, transportation, and distribution of selenium
Assisting in the metabolism of calcium and magnesium
Recommended Intake:
Age Group (in years)
Recommended Dietary Allowance
Females
Males
1-3
0.5 milligrams (mg)
0.5 mg
4-8
0.6 mg
0.6 mg
9-13
1.0 mg
1.0 mg
14-18
1.2 mg
1.3 mg
14-18 Pregnancy
1.9 mg
n/a
14-18 Lactation
2.0 mg
n/a
19-50
1.3 mg
1.3 mg
19-50 Pregnancy
1.9 mg
n/a
19-50 Lactation
2.0 mg
n/a
51 +
1.5 mg
1.7 mg
Vitamin B6 Deficiency
Primary deficiency of vitamin B6 is rare—most foods contain the vitamin. Secondary deficiency may result in certain situations, including malabsorption, alcoholism, some medications, and cigarette smoking. Symptoms of vitamin B6 deficiency include:
The tolerable upper intake level (UL) for vitamin B6 from dietary sources and supplements combined is 100mg per day. Symptoms of vitamin B6 toxicity include:
The following populations may be at risk for vitamin B6 deficiency and may require a supplement:
The Elderly–many older adults have low blood levels of vitamin B6, which may occur from low intake of the vitamin or accelerated hydrolysis and oxidation of the vitamin.
People Who Consume Excessive Amounts of Alcohol–alcohol impairs the conversion and enhances the hydrolysis of the vitamin.
People Who Smoke Cigarettes–cigarette smoking disturbs vitamin B6 metabolism, which contributes to a deficiency. Studies have shown the vitamin level to normalize within two years of quitting smoking.
Vitamin B6, Homocysteine, and Heart Disease
Homocysteine is an amino acid normally found in the blood. However, studies have shown that elevated blood levels of homocysteine can be a risk factor for heart disease and stroke. Because vitamins B6, B12, and folic acid are required for the metabolism of homocysteine, it is thought that a deficiency of any of the three may increase the level of homocysteine in the blood. One would think that taking these vitamins as supplements may offer protection from heart disease. However, clinical intervention trials are needed to clearly determine this.
Areas of Research That Have Not Been Supported by Clinical Data
Headache and Depression–vitamin B6 is needed for the synthesis of neurotransmitters, including serotonin. Low levels of serotonin have been found in individuals suffering from depression and migraine headaches. This led researchers to look at the relationship between vitamin B6, headaches, and depression. So far, vitamin B6 supplements have not proved effective in relieving either.
Premenstrual Syndrome (PMS)–there has been much anecdotal evidence that vitamin B6 can help relieve the symptoms of PMS (depression, irritability, bloating, mastalgia). However, clinical trials have failed to support this idea.
Carpal Tunnel Syndrome–the idea that vitamin B6 can help with carpal tunnel syndrome has been around for about 30 years. Scientific studies have never been able to show this to be true. In fact, there are documented cases of neuropathy caused by excessive amounts of vitamin B6 taken for carpal tunnel syndrome.
Tips for Increasing Your Vitamin B6 Intake
To help increase your intake of vitamin B6:
Sprinkle kidney beans or garbanzo beans on a salad.
Opt for a fortified breakfast cereal—one that is high in fiber—in the morning.
Slice a banana into your oatmeal or cereal.
If you take a vitamin supplement, make sure it contains vitamin B6.
RESOURCES:
American Dietetic Association http://www.eatright.org
Nutrition.gov http://www.nutrition.gov
References:
Facts about dietary supplements. National Institutes of Health website. Available at: http://www.nih.gov/.
Food and Nutrition Information Center, US Department of Agriculture website. Available at: http://www.usda.gov/wps/portal/usdahome.
The Nutrition Desk Reference. Keats Publishing;1995.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
