Vitamin B6 is a water-soluble vitamin that is found in a variety of forms in the foods we eat as well as in our bodies. These forms include pyridoxal 5'-phosphate (PLP), which appears to be the most active form as a human vitamin. Other forms include pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxamine 5'-phosphate (PMP) and pyridoxine-5'-phosphate (PNP). Nearly half of all WHFoods provide you with measurable amounts of vitamin B6. In addition, you can find nearly 30 excellent or very good sources of this nutrient among our core 100 WHFoods.
There has been substantial debate about blood levels of vitamin B6 and their relationship both to dietary intake and overall health. This debate has centered around the fact that a person can consume the recommended dietary amount of vitamin B6 (our WHFoods recommended level is 1.7 milligrams) and yet have a blood level of vitamin B6 (in the form of plasma PLP) that may not be optimal for metabolism. While we continue to recommend the highest adult Dietary Reference Intake (DRI) level for B6 as established by the National Academy of Sciences, we recognize that this amount might eventually be revised upward based on future research in this area. We would also note that the Tolerable Upper Limit (UL) for vitamin B6 is set at a relatively high level of 100 milligrams for adults, allowing plenty of room for B6 intake substantially above the DRI level.
Hemoglobin is complicated protein present in red blood cells, and one of its primary roles is to help carry oxygen around the body. Heme is a key section of the hemoglobin molecule and the initial production of heme in bodies requires the presence of vitamin B6. (Although heme production can occur in multiple places throughout the body, the primary places involve the liver and bone marrow.) The importance of vitamin B6 in red blood cell production is underscored by relatively rare types of anemia called sideroblastic anemias.
Vitamin B6 is involved at several steps in the metabolism of carbohydrates. In particular, the enzyme that pulls carbohydrates out of storage in the cell (in the form of a molecule called glycogen) requires vitamin B6 for its activity.
While nobody would do an experiment like this in humans, researchers have been able to induce problems in carbohydrate metabolism by feeding rats diets deficient in vitamin B6. Since breakdown of carbohydrates is an ongoing process that occurs in our bodies throughout the day to help us sustain our physical energy level, daily consumption of whole foods rich in B6 also makes good sense for maintaining ongoing energy levels.
Vitamin B6 is one of several B vitamins required for proper production of messaging molecules in our nervous system and brain (called neurotransmitters). Three key neurotransmitters—namely GABA, dopamine, and serotonin—all require vitamin B6 for synthesis.
Just as an example of how important this nutrient can be to proper brain and nervous system, function, there is a condition called pyridoxine-dependent epilepsy where a genetic mutation interferes with normal vitamin B6 function. In people who have this mutation, the brain does not develop properly and epileptic seizures are experienced beginning in infancy. Luckily, this condition is rare.
However, we may be at risk of other more common problems that can be brain and nervous-system related if our B6 intake is poor. Depression is a good example in this area. Researchers in Japan have found that the risk of depressed mood is higher in people with lower levels of vitamin B6 in their diet (in comparision with the general population). Another research group concluded that this link between risk of depression and B6 intake becomes even stronger when dietary folic acid—a nutrient that works very closely with vitamin B6 in brain and nervous system chemistry—is deficient as well. Recent research has also begun to indicate a link between B6 deficiency and risk of development for attention deficit disorder (ADHD). So once again, we are looking at the possible widespread importance of B6 for brain and nervous system support.
Generally speaking, we remove unwanted chemicals from our blood in the liver and kidney, and this process involves two steps. The first of these two steps is to make the chemicals more water soluble to allow for the second step of binding and removal. The number of nutrients required for this first step is long, but vitamin B6 is clearly one of the most important. It is so important that researchers can induce liver dysfunction in animals by feeding them a pyridoxine-depleted diet.
Preliminary research on inflammation-related chronic diseases has shown likely connections between the risk of these diseases and B6 deficiency. Interestingly, in addition to increased risk of these conditions in association with B6 deficiency, the presence of chronic inflammatory conditions also appears to be associated with depletion of vitamin B6.
In animal studies, B6 has been shown to play a role in the development of healthy immune system function. This potential health benefit from B6 appears to be associated with its role in metabolism of the amino acid tryptophan.
As mentioned earlier, B6 plays a well-researched role in the synthesis and metabolism of certain nervous system messaging molecules. While we emphasized the nervous system aspects of this health support role earlier in this section, we would also like to point out that the messaging molecules pathways described earlier involve specific amino acids (building blocks of protein), making B6 a potentially important vitamin for support of general amino acid and protein-related metabolism. Interestingly, many of our WHFoods that rank as excellent or very good sources of protein also rank as excellent or very good sources of B6. This overlap may not be a coincidence, given the role played by B6 in protein and amino acid metabolism. It is also worth mentioning that diets especially high in protein may increase risk of B6 depletion, even though many protein-rich foods are also rich in B6. The reason for this risk involves differing nutrient concentrations in which the concentration of protein in a particular food might be significantly greater than the concentration of B6. While this difference might not be important at ordinary protein intakes, unusually high intakes (for example, intakes well over 100 grams) might make the difference more of an issue.
We see an unusually wide variety of foods listed as good to excellent sources of vitamin B6. As mentioned earlier, nearly half of our WHFoods fall into this category. Plant and animal foods are both well represented. In our top sources by nutrient richness, we see leafy and root vegetables, along with fruit, fish, and fowl. This variety will allow for many choices for a B6-rich diet plan.
With the exception of tuna, all of our excellent sources of vitamin B6 are vegetables. As with so many other nutrients, our discussion of B6-rich foods starts here. We encourage having at least a serving of greens most days, if not every day, along with several other minimally cooked fresh vegetables. And we encourage you not to skimp on the amount, but to consider having 1-1/2 cups in a serving.
In the non-plant category, we have one excellent source of B6 in tuna, and several very good source in beef, chicken, and salmon. And if we continue on into the good category, we pick up shrimp and cod as well.
Some, but not all, fruits are strong sources of vitamin B6. Bananas, pineapples, and avocados are all good to very good sources of this nutrient.
A number of legumes contain between 10-30% of the DRI for vitamin B6 per serving and can be good contributors toward your intake goal. Similarly, a number of the whole grains contain 10-20% of the DRI and can help to build up your daily vitamin B6 nutrition.
|World's Healthiest Foods ranked as quality sources of|
|Bok Choy||1 cup||20.4||0.28||16||14.5||excellent|
|Bell Peppers||1 cup||28.5||0.27||16||10.0||excellent|
|Turnip Greens||1 cup||28.8||0.26||15||9.6||excellent|
|Turkey||4 oz||166.7||0.92||54||5.8||very good|
|Beef||4 oz||175.0||0.74||44||4.5||very good|
|Chicken||4 oz||187.1||0.68||40||3.8||very good|
|Salmon||4 oz||157.6||0.64||38||4.3||very good|
|Sweet Potato||1 cup||180.0||0.57||34||3.4||very good|
|Potatoes||1 cup||160.9||0.54||32||3.6||very good|
|Banana||1 medium||105.0||0.43||25||4.3||very good|
|Winter Squash||1 cup||75.8||0.33||19||4.6||very good|
|Broccoli||1 cup||54.6||0.31||18||6.0||very good|
|Brussels Sprouts||1 cup||56.2||0.28||16||5.3||very good|
|Collard Greens||1 cup||62.7||0.24||14||4.1||very good|
|Beet Greens||1 cup||38.9||0.19||11||5.2||very good|
|Kale||1 cup||36.4||0.18||11||5.2||very good|
|Carrots||1 cup||50.0||0.17||10||3.6||very good|
|Swiss Chard||1 cup||35.0||0.15||9||4.5||very good|
|Asparagus||1 cup||39.6||0.14||8||3.7||very good|
|Mustard Greens||1 cup||36.4||0.14||8||4.1||very good|
|Tomatoes||1 cup||32.4||0.14||8||4.6||very good|
|Leeks||1 cup||32.2||0.12||7||3.9||very good|
|Summer Squash||1 cup||36.0||0.12||7||3.5||very good|
|Chili Peppers||2 tsp||15.2||0.11||6||7.6||very good|
|Sunflower Seeds||0.25 cup||204.4||0.47||28||2.4||good|
|Pinto Beans||1 cup||244.5||0.39||23||1.7||good|
|Green Peas||1 cup||115.7||0.30||18||2.7||good|
|Lima Beans||1 cup||216.2||0.30||18||1.5||good|
|Mushrooms, Shiitake||0.50 cup||40.6||0.12||7||3.1||good|
|Mushrooms, Crimini||1 cup||15.8||0.08||5||5.3||good|
|Green Beans||1 cup||43.8||0.07||4||1.7||good|
|Romaine Lettuce||2 cups||16.0||0.07||4||4.6||good|
|Sea Vegetables||1 TBS||10.8||0.05||3||4.9||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%
The pyridoxine form of vitamin B6 found in foods tend to be fairly stable to storage. It takes approximately one year for about 25% of the B6 in various foods to be lost, and even though this amount is relatively high, there are no foods that we recommend storing for this prolonged period of time. In fact, most of the WHFoods that rank as excellent or very good sources of B6 are foods that we recommend be consumed as fresh as possible.
Prolonged exposure to heat can degrade vitamin B6 in most foods. Perhaps as a result of the difference in structural forms, we see more degradation of this vitamin in animal meats than in vegetables.
Both steaming and boiling result in relatively low amounts of B6 loss. We've see research on Brussels sprouts, for example, showing 10-20% loss of B6 based on these two cooking methods. (As in most research on steaming and boiling, boiling in this study resulted in greater B6 loss than steaming, presumably because of submersion in water allowing more surface-to-water contact with the Brussels sprouts.)
Perhaps counterintuitively, lower pH tends to stabilize the vitamin under heat. So adding a little vinegar or tomato into a sauce, for example, may help keep the vitamin B6 more intact.
Based on National Health and Nutrition Examination Survey (NHANES) data from 2009-2010, average intake of vitamin B6 for men and women 20 years and older —as well as all U.S. citizens ages 2 and older—was above our WHFoods recommended daily intake level for B6 of 1.7 milligrams.
As mentioned earlier in this article, however, there has been significant debate in the clinical research over the relationship between blood levels of vitamin B6 and overall health, and it is possible that consumption of the DRI level for B6 may not support optimal blood levels of the PLP form of this vitamin. Exactly how this specific area of clinical research relates to overall B6 deficiency risk is an area of research that will be important to follow in future studies.
Women who take oral contraceptive pills (OCP) have an increased risk of vitamin B6 deficiency. According to one research group, 40% of OCP users have biochemical evidence for deficiency, a number much greater than would be predicted based on diet alone.
OCP are not unique in their ability to lead to loss of vitamin B6. A number of other medications have been reported to have this effect, including steroids, antibiotics, and drugs used to treat Parkinson's disease.
Even at a consistent dietary intake, people over the age of 65 years show lower blood levels of vitamin B6. There are several proposed explanations for this phenomenon, including decreased absorption, more difficulty activating the vitamin to its most active form, and increased breakdown. Regardless of the cause, older people may need to pay special attention to dietary vitamin B6 intake. In fact, the highest DRI set for B6 by the National Academy of Sciences (other than the DRIs related to pregnancy and lactation) is the DRI for older men of 1.7 milligrams.
The B complex of vitamins works as a team in carbohydrate metabolism, and deficiency of one can affect the whole process in a detrimental way. Because vitamin B6 deficiency is more likely than most of the other B vitamins, it should be a particular focus in making sure that this energy generation process occurs smoothly.
In particular, folic acid and vitamin B12 are intimately related to vitamin B6 in their core biochemical pathways. Each of these is a nutrient with potential for dietary deficiency, each can be prone to damage or absorption problems, and each comes from different food types. We get vitamin B12 from a relatively small number of foods (primarily animal and fermented foods), folic acid predominantly from vegetables and legumes, and vitamin B6 from many food groups. Enjoyment of food diversity is clearly an ideal way.
Every reaction in your body that uses vitamin B6 also uses magnesium as a mineral co-factor. Like vitamin B6, magnesium is a nutrient that many Americans fail to eat enough of on a regular basis. Tuna, spinach, and pumpkin seeds are all examples of foods rich in both vitamin B6 and magnesium. Our Chicken Breast With Honey-Mustard Sauce recipe contains more than the RDA for vitamin B6 and 85% of the requirement for magnesium.
Diets very high in protein are known to increase risk of vitamin B6 depletion. . For this reason, some researchers have suggested increased B6 when protein intake is especially high. For example, we have seen one research study in which researchers recommended nearly double the DRI for B6 with intake of 150 grams of protein per day by young women. Our conclusions from this research are two-fold: first, it does not make sense to consume excessive amounts of protein, unless specifically following a medical food regimen or under other specific health-related circumstances. Second, if you are consuming especially high levels of protein, it makes sense to take a closer look at your B6 intake and make sure that you are focusing on whole foods equally right in protein and B6.
At amounts above the Tolerable Upper Intake Level (UL) of 100 mg per day, vitamin B6 has been reported to cause changes in sensation in the hands and feet. Given that even the 95th percentile of vitamin B6 intake in the U.S. is less than 10 mg per day, reaching 100 mg on a regular basis from foods alone is very unlikely. In fact, every report of vitamin B6 toxicity that we can find involved the use of mega-dose supplementation. We find no reason to be concerned about the health effects of diets rich in vitamin B6, even when this dietary richness involves 200%-500% of the recommended DRI level.
In 1998, the National Academy of Sciences established a set of Dietary Reference Intakes (DRI) that contained Recommended Dietary Allowances (RDA) for vitamin B6 by age and gender. These are summarized in the chart below. Note that the recommendations for infants under one year are Adequate Intake (AI) standards. The RDAs and AIs are as follows:
The Tolerable Upper Intake Limit (UL) for vitamin B6 is set at 100 mg. Given that most foods contain less than a milligram of vitamin B6 per serving, reaching this level of intake without the use of supplements appears impossible. Intakes of vitamin B6 as high as 200-500% of the DRI still fall far below this UL guideline and have no research basis for any concern.
The Daily Value (DV) for vitamin B6 intake is 2 mg per day per 2000 calories. This is the value found on food labels.
As our WHFoods recommended daily intake level for B6, we chose the highest adult DRI level of 1.7 milligrams.