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.

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and processing Factors that affect function

Drug-nutrient interaction Nutrient interaction Health conditions Supplements Food Sources Public Recommendations References

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

What foods provide vitamin B6?

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

Very good food sources of vitamin B6 include garlic, tuna, cauliflower, mustard greens, banana, celery, cabbage, crimini mushrooms, asparagus, broccoli, kale, collard greens, Brussels sprouts, cod and chard.

 

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of vitamin B6 (pyridoxine). Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of vitamin B6 (pyridoxine) contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

World's Healthiest 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	1 cup	41.4	0.44	22.0	9.6	excellent
Bell peppers, red, raw, slices	1 cup	24.8	0.23	11.5	8.3	excellent
Turnip greens, 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	1 cup	28.5	0.21	10.5	6.6	very good
Cayenne pepper, dried	2 tsp	11.2	0.08	4.0	6.4	good
Mustard greens, 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
Crimini mushrooms, 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, steamed	1 cup	43.7	0.22	11.0	4.5	very good
Turmeric, powder	2 tsp	16.0	0.08	4.0	4.5	good
Kale, boiled	1 cup	36.4	0.18	9.0	4.5	very good
Collard greens, boiled	1 cup	49.4	0.24	12.0	4.4	very good
Brussel sprouts, boiled	1 cup	60.8	0.28	14.0	4.1	very good
Watermelon, diced	1 cup	48.6	0.22	11.0	4.1	very good
Cod, baked/broiled	4 oz-wt	119.1	0.52	26.0	3.9	very good
Swiss 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, ripe	1 cup	37.8	0.14	7.0	3.3	good
Snapper, baked/broiled	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
Summer squash, cooked, slices	1 cup	36.0	0.12	6.0	3.0	good
Eggplant, cooked, cubes	1 cup	27.7	0.09	4.5	2.9	good
Cantaloupe, cubes	1 cup	56.0	0.18	9.0	2.9	good
Romaine lettuce	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 molasses	2 tsp	32.1	0.10	5.0	2.8	good
Calf's liver, braised	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, 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
Salmon, chinook, baked/broiled	4 oz-wt	261.9	0.52	26.0	1.8	good
Yam (Dioscorea species), cubed, cooked	1 cup	157.8	0.31	15.5	1.8	good
Flaxseeds	2 tbs	95.3	0.18	9.0	1.7	good
Winter squash, baked, cubes	1 cup	80.0	0.15	7.5	1.7	good
Strawberries	1 cup	43.2	0.08	4.0	1.7	good
Avocado, slices	1 cup	235.1	0.41	20.5	1.6	good
Pineapple	1 cup	76.0	0.13	6.5	1.5	good
Grapes	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

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