Vitamin B6
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, so it is a good idea to have them in your daily diet.
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 |
| 19-50 | 1.3 mg | 1.3 mg |
| Pregnancy | 1.9 mg | n/a |
| 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 medicines, and cigarette smoking. Symptoms of vitamin B6 deficiency include:
- Skin inflammation and irritation
- Glossitis (sore or inflamed tongue)
- Confusion
- Depression
- Irritability and nervousness
- Fatigue and sleepiness
- Cheilosis (cracking and scaling of the lips)
- Convulsions
- Anemia
Vitamin B6 Toxicity
The tolerable upper intake level (UL) for vitamin B6 from dietary sources and supplements combined is 100mg per day for adults. Symptoms of vitamin B6 toxicity include:
- Muscle incoordination
- Numbness of the hands and feet
- Nausea
- Skin sores
Major Food Sources
| Food | Serving Size |
Vitamin B6 Content
(mg) |
|---|---|---|
| Breakfast cereal, fortified 25% | ¾ cup |
0.5 (check Nutrition Facts label) |
| Beef liver, pan fried | 3 ounces | 0.9 |
| Potato, boiled | 1 cup | 0.4 |
| Banana | 1 medium | 0.4 |
| Chicken breast, roasted, no skin | 3 ounces | 0.5 |
| Garbanzo beans, canned | ½ cup | 1.1 |
| Turkey, meat only, roasted | 3 oz | 0.4 |
| Ground beef, 85% lean | 3.0 ounces | 0.3 |
| Spagetti sauce | 1 cup | 0.4 |
| Waffles, ready to heat | 1 waffle | 0.3 |
| Mixed nuts, dry roasted | 1 ounce | 0.1 |
| Rice, white, enriched | 1 cup | 0.1 |
| Tuna, fresh | 3 ounces | 0.9 |
| Raisins, seedless | ½ cup | 0.1 |
| Spinach, frozen, boiled | ½ cup | 0.1 |
| Tofu, raw | ½ cup | 0.1 |
Health Implications
Populations at Risk for Vitamin B6 Deficiency
The following populations may be at risk for vitamin B6 deficiency and may require a supplement:
- People Who Consume Excessive Amounts of Alcohol
- People with poor kidney function
- People with autoimmune disorders, such as rheumatoid arthritis, celiac disease, and ulcerative colitis
Vitamin B6, Homocysteine, and Heart Disease
Homocysteine is an amino acid normally found in the blood. 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 trials do not support this idea.
Morning Sickness
There is evidence that high levels of B6 can help alleviate the symptoms of morning sickness during pregnancy.
Areas of Research That Have Not Been Supported by Clinical Data
- 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—There is no evidence to support the idea that B6 can ease 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:
Academy of Nutrition and Dietetics
http://www.eatright.org
American Society for Nutrition
http://www.nutrition.org/
CANADIAN RESOURCES:
Dietitians of Canada
http://www.dietitians.ca/
Health Canada
http://www.hc-sc.gc.ca/
REFERENCES:
Dietary Supplement Fact Sheet: Vitamin B6. National Institutes of Health website. Available at: http://ods.od.nih.gov/factsheets/vitaminb6.asp#h4. Accessed July 21, 2012.
Homocysteine and cardiovascular disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated October 2, 2011. Accessed July 21, 2012.
Pyridoxine. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated May 16, 2011. Accessed July 21, 2012.
Vitamin B6. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15&topicID=114. Updated August 2011. Accessed July 21, 2012.
Last reviewed July 2012 by Brian P. Randall, MD
Last Updated: 7/21/2012