vitamin B6

What can foods high in vitamin B6 do for you?

  • Support a wide range of activities in your nervous system
  • Promote proper breakdown of sugars and starches
  • Help prevent homocysteine build-up in your blood

What events can indicate a need for more high-vitamin B6 foods ?

  • Fatigue or malaise
  • Anemia
  • Skin disorders including eczema and seborrheic dermatitis
  • Convulsions or seizures

Excellent sources of vitamin B6 include bell peppers, turnip greens, and spinach.

 

Description

What is vitamin B6?

First researched in the mid-1930's, vitamin B6 is one of the best-studied of all B vitamins and has one of the greatest varieties of chemical forms. The forms of this vitamin all begin with the letters "pyr," and include pyridoxine, pyridoxal, pyridoxamine, pyridoxine phosphate, pyridoxal phosphate, and pyridoxamine phosphate.

The vitamin was not originally given this name, however, but was referred to as "antidermatitis factor." This term pointed to the skin (dermis) because skin inflammation (dermatitis) seemed to increase when foods with B6 were eliminated from the diet. Topical B6 creams are used to this day in treatment of skin inflammation, particularly in relationship to symptoms of seborrheic dermatitis.

How it Functions

What is the function of vitamin B6?

Much of the body's chemistry depends upon enzymes. Enzymes are proteins that help chemical reactions take place. Because vitamin B6 is involved with more than 100 enzymatic reactions, its function in the body is diverse and far-reaching.

Synthesis of essential molecules

It is difficult to find a chemical category of molecules in the body that do not depend in some way on vitamin B6 for their production. Many of the building blocks of protein, called amino acids, require adequate supplies of B6 for synthesis. Nucleic acids used in the creation of DNA in our genes also require this vitamin.

Because amino acids and nucleic acids are such critical parts of new cell formation, vitamin B6 can be regarded as an essential part of the formation of virtually all new cells in the body. Heme (the protein center of our red blood cells) and phospholipids (our cell membrane components that allow messaging between cells) also depend on vitamin B6 for their creation.

Processing of carbohydrate

The processing of carbohydrate (sugar and starch) in our body depends on availability of vitamin B6. This vitamin is particularly important in facilitating the breakdown of glycogen (a special form of starch) stored in our muscle cells and to a lesser extent in our liver. Because carbohydrate processing plays such a key role in certain types of athletic events, researchers have looked closely at the role vitamin B6 plays in carbohydrate processing during physical performance.

Support of nervous system activity

The role of vitamin B6 in our nervous system is very broad, and involves many aspects of neurological activity. One aspect focuses on the creation of an important group of messaging molecules called amines. The nervous system relies on formation of these molecules for transmission of messages from one nerve to the next. (The molecules can be classified as "neurotransmitters" for this reason.) Amines are one type of neurotransmitter in the nervous system. They are often made from parts of protein called amino acids, and the key nutrient for making this process happen is vitamin B6. Some of the amine-derived neurotransmitters that require vitamin B6 for their production include serotonin, melatonin, epinephrine, norepinephrine, and GABA.

Support of sulfur and methyl metabolism

The movement of sulfur-containing molecules around the body is especially important for hormonal balance and elimination of toxic substances through the liver. Because vitamin B6 is able to remove sulfur groups from other molecules, it helps the body maintain flexibility in handling sufur-containing compounds.

Vitamin B6 plays a similar role with respect to methyl-containing molecules. The term "methyl group" refers to a chemical structure that has only one carbon atom and three hydrogen atoms. Many important chemical events in the body are made possible by the transfer of methyl groups from one place to another. For example, genes in the body can be switched on and turned off in this way, and cells can use the process to send messages back and forth.

The attachment of methyl groups to toxic substances is one way of making them less toxic and encouraging their elimination from the body. It is also a way of ensuring that substances like homocysteine, which can build up excessively in the blood and lead to risk of cardiovascular disease, are kept within a healthy range.

Deficiency Symptoms

What are deficiency symptoms for vitamin B6?

Because of its key role in the formation of new cells, vitamin B6 is especially important for healthy function of body tissue that regenerates itself quickly. The skin is exactly this type of tissue, and it is one of the first to show problems when B6 is deficient. Many skin disorders have been associated with B6 deficiency, and they include eczema and seborrheic dermatitis.

The key role of vitamin B6 in the nervous system also results in many nerve-related symptoms when B6 is deficient. These symptoms can include convulsions and seizures in the case of severe deficiency. The critical role of vitamin B6 in the formation of red blood cells means that B6 deficiency can also result in symptoms of anemia, malaise, and fatigue. When anemia is exclusively related to B6 deficiency, it is usually classified as hypochromic, microcytic (pernicious) anemia.

Toxicity Symptoms

What are toxicity symptoms for vitamin B6?

Imbalances in nervous system activity have been shown to result from high levels of supplemental vitamin B6 intake. These imbalances do not seem to occur until supplementation exceeds 2 grams per day. The National Academy of Sciences has set a Tolerable Upper Intake Level (UL) for vitamin B6 of 100 milligrams for adults 19 years and older, largely based on the issue of imbalanced nervous system activity described above.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect vitamin B6?

Although historically described as one of the most stable of the B vitamins, large amounts of vitamin B6 are lost during most forms of cooking and processing. Loss of B6 from canning of vegetables is approximately 60-80%; from canning of fruits, about 38%; from freezing of fruits, about 15%; from conversion of grains to grain products, between 50-95%; and from conversion of fresh meat to meat by-products, 50-75%.

When food is heated in the context of simple home cooking, the acidity of the food often determines how much B6 is lost or retained. In general, the more acidic the food, the poorer the B6 retention. Also, in the context of the home kitchen, the freezing of foods high in B6 can result in the loss of approximately 1/3 to 1/2 of the total B6 content. Because foods high in B6 are typically not eaten raw, a good solution to these processing problems is to consume plentiful amounts of foods high in B6.

Factors that Affect Function

What factors might contribute to a deficiency of vitamin B6?

In addition to dietary insufficiency, smoking and the use of many prescription medications can contribute to vitamin B6 deficiency. Medications that deplete the body's supply of B6 are listed in the medications section of this nutrient profile.

Drug-Nutrient Interactions

What medications affect vitamin B6?

A long list of prescription medications has been linked to depletion of the body's B6. These medications include birth control pills and oral estrogens; diuretics, including furosemide; barbiturates, including phenobarbitol and phenytoin; anti-epileptic drugs, including carbamazepine; asthma-related drugs, including theophylline; aminoglycosides, including gentamicin used for bacterial infection; tuberculosis drugs, including isoniazid and rifampin; and anti-fibrotic drugs, including beta-aminopropionitrile.

Nutrient Interactions

How do other nutrients interact with vitamin B6?

As a member of the B vitamin family, B6 has key interactions with many of its family members. B6 is essential for making vitamin B3 (niacin) from the amino acid tryptophan. In Down's syndrome, for example, some of the problems related to vitamin B3 deficiency appear to be lessened by intake of vitamin B6. Vitamins B2 and B3 are both needed to convert vitamin B6 into its various chemical forms, and imbalances in vitamin B1 metabolism create imbalances in vitamin B6 metabolism. B6 deficiency can also reduce the body's absorption of vitamin B12.

Health Conditions

What health conditions require special emphasis on vitamin B6?

Vitamin B6 may play a role in the prevention and/or treatment of the following health conditions::

  • Cardiovascular system conditions, including atherosclerosis, hyperhomocysteinemia, and hypertension
  • Nervous system conditions, including carpal tunnel syndrome, depression, diabetic neuropathy, autism and epilepsy
  • Skin conditions, including acne, eczema, and seborrheic dermatitis
  • Also linked to B6 status are alcoholism, adrenal function, asthma, HIV/AIDS, kidney stones, PMS, and vaginitis.

Form in Dietary Supplements

What forms of vitamin B6 are found in dietary supplements?

Vitamin B6 is most commonly sold in the form of pyridoxine hydrochloride (pyridoxine HCl). However, alternative forms of the vitamin, for example, pyridoxal-5-phophate, are also widely available and often preferred by healthcare practitioners since they constitute the biologically active forms of the vitamin.

Individuals who are not experiencing health benefits from supplementation with pyridoxine hydrochloride, or who have a history of liver problems that might prevent activation of pyridoxine, should consider supplementation with pyridoxal-5-phosphate.

Food Sources

Introduction to Nutrient Rating System Chart

The following chart shows the foods which are either excellent, very good or good sources of this nutrient. Next to each food name you will find the following information: the serving size of the food; the number of calories in one serving; DV% (percent daily value) of the nutrient contained in one serving (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. For more detailed information on our Nutrient Rating System, please click here.

 

Foods Ranked as quality sources of:
vitamin B6 (pyridoxine)
Food Serving
Size
Cals Amount
(mg)
DV
(%)
Nutrient
Density
World's
Healthiest
Foods Rating
Spinach (boiled, with salt) 1 cup 41.4 0.44 22.0 9.6 excellent
Red Bell Peppers (sliced, raw) 1 cup 24.8 0.23 11.5 8.3 excellent
Greens, Turnip, Cooked 1 cup 28.8 0.26 13.0 8.1 excellent
Garlic 1 oz-wt 42.2 0.35 17.5 7.5 very good
Tuna, Yellowfin, Baked/Broiled 4 oz-wt 157.6 1.18 59.0 6.7 very good
Cauliflower (boiled, drained) 1 cup 28.5 0.21 10.5 6.6 very good
Pepper, Cayenne, Dried 2 tsp 11.2 0.08 4.0 6.4 good
Greens, Mustard, Boiled 1 cup 21.0 0.14 7.0 6.0 very good
Banana 1 each 108.6 0.68 34.0 5.6 very good
Celery, Raw 1 cup 19.2 0.10 5.0 4.7 very good
Cabbage (shredded, boiled) 1 cup 33.0 0.17 8.5 4.6 very good
Mushrooms, Crimini, Raw 5 oz-wt 31.2 0.16 8.0 4.6 very good
Asparagus, Boiled 1 cup 43.2 0.22 11.0 4.6 very good
Broccoli (pieces, steamed) 1 cup 43.7 0.22 11.0 4.5 very good
Turmeric, Ground 2 tsp 16.0 0.08 4.0 4.5 good
Kale, Fresh, Boiled 1 cup 36.4 0.18 9.0 4.5 very good
Collard Greens, Boiled, Drained 1 cup 49.4 0.24 12.0 4.4 very good
Brussels Sprouts, Boiled 1 cup 60.8 0.28 14.0 4.1 very good
Watermelon 1 cup 48.6 0.22 11.0 4.1 very good
Cod, Pacific, Fillet, Baked, Broiled 4 oz-wt 119.1 0.52 26.0 3.9 very good
Chard, Boiled 1 cup 35.0 0.15 7.5 3.9 very good
Leeks, Boiled 0.50 cup 16.1 0.06 3.0 3.3 good
Tomato, Red, Raw, Ripe 1 cup 37.8 0.14 7.0 3.3 good
Snapper, Baked 4 oz-wt 145.2 0.52 26.0 3.2 good
Carrots, Raw 1 cup 52.5 0.18 9.0 3.1 good
Squash, Summer, All Varieties 1 cup 36.0 0.12 6.0 3.0 good
Eggplant, Boiled 1 cup 27.7 0.09 4.5 2.9 good
Cantaloupe 1 cup 56.0 0.18 9.0 2.9 good
Lettuce, Romaine 2 cup 15.7 0.05 2.5 2.9 good
Potato, Baked, with Skin 1 cup 133.0 0.42 21.0 2.8 good
Onions, Raw 1 cup 60.8 0.19 9.5 2.8 good
Blackstrap Cane Molasses 2 tsp 32.1 0.10 5.0 2.8 good
Liver, Calf 4 oz-wt 187.1 0.56 28.0 2.7 good
Chicken Breast, Roasted 4 oz-wt 223.4 0.64 32.0 2.6 good
Halibut, Baked/Broiled 4 oz-wt 158.8 0.45 22.5 2.6 good
Sweet Potato (small, baked with skin) 1 each 95.4 0.25 12.5 2.4 good
Green Peas-Boiled 1 cup 134.4 0.35 17.5 2.3 good
Ginger Root 1 oz-wt 19.6 0.05 2.5 2.3 good
Turkey Breast, Roasted 4 oz-wt 214.3 0.54 27.0 2.3 good
Venison 4 oz-wt 179.2 0.43 21.5 2.2 good
Beef Tenderloin, Lean Broiled 4 oz-wt 240.4 0.49 24.5 1.8 good
Chinook Salmon Fillet-Baked/Broiled 4 oz-wt 261.9 0.52 26.0 1.8 good
Yam, Dioscorea species, Cubes, Cooked 1 cup 157.8 0.31 15.5 1.8 good
Flax Seeds 2 tbs 95.3 0.18 9.0 1.7 good
Squash, Winter, All Varieties 1 cup 80.0 0.15 7.5 1.7 good
Strawberries, Fresh 1 cup 43.2 0.08 4.0 1.7 good
Avocado, All Varieties 1 cup 235.1 0.41 20.5 1.6 good
Pineapple 1 cup 76.0 0.13 6.5 1.5 good
Grapes, Concord 1 cup 61.6 0.10 5.0 1.5 good
World's Healthiest
Foods Rating
Rule
excellent DV>=75% OR Density>=7.6 AND DV>=10%
very good DV>=50% OR Density>=3.4 AND DV>=5%
good DV>=25% OR Density>=1.5 AND DV>=2.5%

Public Health Recommendations

What are the current public health recommendations for intake of vitamin B6?

In 2000, the National Academy of Sciences established Recommended Dietary Allowances for vitamin B6 for all individuals 1 year and older, and Adequate Intake (AI) levels for infants under 1 year of age. These recommendations are as follows:

  • 0-6 months: 100 micrograms
  • 6-12 months: 300 micrograms
  • 1-3 years: 500 micrograms
  • 4-8 years: 600 micrograms
  • Males 9-13 years: 1.0 milligram
  • Males 14-50 years: 1.3 milligrams
  • Males 51 years and older: 1.7 milligrams
  • Females 9-13 years: 1.0 milligram
  • Females 14-50: 1.2 milligrams
  • Females 51 years and older: 1.5 milligrams
  • Pregnant females of any age: 1.9 milligrams
  • Lactating females of any age: 2.0 milligrams

References

  • Bodwell CE, Erdman JW (Eds). Nutrient interactions. Marcel Dekker, Inc., New York, 1998;165,301-304.
  • Bryan J, Calvaresi E, Hughes D et al. Short-term folate, vitamin B-12 or vitamin B-6 supplementation slightly affects memory performance but not mood in women of various ages. J Nutr 2002 Jun;132(6):1345-56.
  • Coleman M, Sobel S, Bhagavan HN, et al. A double-blind study of vitamin B6 in Down's syndrome infants. Part 1 - clinical and biochemical results. J Ment Def Res 1985;29:233.
  • Effersoe H. The effect of topical application of pyridoxine ointment on the rate of sebaceous secretion in patients with seborrheic dermatitis. Acta Dermatol 1954;3:272-277.
  • Fennema OR (Ed.). Food chemistry. Second edition. Marcel Dekker, New York, 1985.
  • Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995.
  • Gvozdova LG, Paramanova EG, Goriachenkova EV, et al. The content of Pyridoxal coenzymes in the blood plasma of patients with coronary atherosclerosis on a background of therapeutic diet and after supplemental intake of vitamin B6. Vop Pitan 1966;25:40-44.
  • Gyorgy P. Developments leading to the metabolic role of vitamin B6. Am J Clin Nutr 1971;24:1250-1256.
  • Korpela TK, Christen P (Eds). Biochemistry of vitamin B6. Proceedings of the 7th International Congress on Chemical and Biological Aspects of Vitamin B6 Catalysis. Birkhauser Congress Reports, Life Sciences, Vol. 2, Birkhauser Verlag, Basel, 1987.
  • Leklem JE. Vitamin B6. In: Machlin LJ (Ed). Handbook of vitamins. Second edition. Dekker, New York, 1991;341-392.
  • Merrill AH, Burnham FS. Vitamin B-6. Chapter 18 in: Brown ML (Ed). Present knowledge in nutrition. Sixth Edition. International Life Sciences Institute Nutrition Foundation, Washington, DC, 1990;157-159.
  • National Academy of Sciences. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B-6, Vitamin B-12, Pantothenic Acid, Biotin, and Choline. Institute of Medicine, Food and Nutrition Board, National Academy of Sciences. Washington, DC, National Academy Press, 1998;390-422.
  • Ooylan LM, Hart S, Porter KB, Driskell JA et al. Vitamin B-6 content of breast milk and neonatal behavioral functioning. J Am Diet Assoc 2002 Oct; 102(10):1433-8.
  • Sauberlich HE. Vitamins - how much is for keeps. Nutr Tod 1980;22:20.
  • Schaumberg H, Kaplan J, Windebank A, et al. Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome. N Engl J Med 1983;309:445-448.
  • Williams MH. Vitamin and mineral supplements to athletes: do they help. Clin Sports Med 1984;3:623-637.
  • Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: the new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706.

This page was updated on: 2005-05-30 15:47:48
© 2002 The George Mateljan Foundation