This vitamin is a coenzyme important in the digestion of protein.
The richest sources of vitamin B6 are meats (especially organ meats), fortified soy-based meat substitutes, poultry, fish (especially tuna), legumes, nuts, peanut butter, whole grains, fortified cereals, and various fruits and vegetables¾particularly potatoes and bananas.
A shortage of vitamin B6 may lead to nervous-system problems that bring on confusion and depression. Other symptoms include skin disorders, anemia, cracks at the corners of the mouth, inflammation of the mucous membranes of the mouth, dizziness, nausea, and kidney stones.
Although an excess of vitamin B6 is generally excreted in the urine, it's not true that large doses from supplements are harmless, as once believed. (The vitamin used to be prescribed as a palliative for water retention and other symptoms of premenstrual syndrome.) People who take more than 200 milligrams per day (about 100 times the Food and Nutrition Board's Recommended Dietary Allowance) will, after a few months or years (sooner if the doses are higher), develop problems with sensory nerves.
Vitamin B6 and Heart Disease
Vitamin B6 appears to help vitamin B12 and folate (another B vitamin) curb levels of homocysteine in the blood, thereby protecting against heart disease. (See Folate.) Of the three vitamins, B6's contribution seems to be the weakest. All three are under intense study and should make headlines over the next few years. (Check Diet Power's News/Update page for the latest.)
Your Daily Allowance
Diet Power sets your Personal Daily Allowance (PDA) of vitamin B6 at the Recommended Dietary Allowance (RDA).
The RDA is sometimes cited in milligrams (mg): 1.3 for males 14* to 50 years old, 1.7 for men 51 and older, 1.2 for females 14* to 18 years old, 1.3 for women 19 to 50 years old, 1.5 for women 51 and older, 1.9 for pregnant women, and 2.0 for nursing mothers.
When it's cited in micrograms (µg), the corresponding numbers are 1000 times larger: 1300 for males 14* to 50 years old, 1700 for men 51 and older, 1200 for females 14* to 18 years old, 1300 for women 19 to 50 years old, 1500 for women 51 and older, 1900 for pregnant women, and 2000 for nursing mothers.
The Tolerable Upper Intake Level (UL) for vitamin B6 is 80 milligrams (or 80,000 micrograms) per day for people aged 14* to 18 and 100 milligrams (or 100,000 micrograms) per day for people 19 and older, regardless of sex or reproductive state.
* Please remember that Diet Power is not designed for people younger than 15.
Revising Your Allowance
If your doctor recommends a different PDA, you can change it with the Personal Daily Allowance Editor.
Color Coding of This Nutrient
The vitamin-B6 bar in your personal Nutrient History is:
· blue for "good" if you've logged 100 to 150 percent of your PDA
· red for "bad" if you've logged less than 100 percent of your PDA
· yellow for "caution" if you've logged more than 150 percent of your PDA
· missing if you've logged no vitamin B6.
In the nutrient profile of a food or recipe, the vitamin-B6 bar is:
· green for "good" if getting your entire PDA of calories from this item would give you more than 150 percent of your PDA of vitamin B6
· magenta for "bad" if getting all your calories from the item would give you less than 50 percent of your PDA of vitamin B6
· blue for "neutral" otherwise
· missing if the amount of vitamin B6 is either zero or (when the term Vitamin B6 is grayed out) unknown.
How Complete Are Diet Power's Vitamin-B6 Readings?
For the 8500 generic items in the Food Dictionary: fairly complete. Only 11 percent list their vitamin-B6 content as "unknown."
For the 2500 chain-restaurant items: totally incomplete. All list vitamin B6 as "unknown."
For all 11,000 items combined: not terribly complete. About 29 percent list vitamin B6 as "unknown."
These figures mean that if you frequently log chain-restaurant foods (or user-added foods with missing vitamin-B6 readings), your Nutrient History may underreport your intake of vitamin B6 by a few points.
To see whether a particular food has a vitamin-B6 reading, open the Food Dictionary and check the food's nutrient profile. If you find a question mark beside "Vitamin B6," it means the amount is unknown. (To see all foods with unknown vitamin-B6 readings, click the dictionary's PowerFoods tab and sort the foods by vitamin-B6 power; then scroll toward the bottom of the list until you see foods with question marks in the "Power Rating" column.)
Vitamin B6 on Food Labels
Food labels are not required to report vitamin B6 content, but some do. They may cite the amount in milligrams, percent of Daily Value, or both.
The Daily Value for vitamin B6 is 2.0 milligrams, or 2000 micrograms. This amount is not necessarily right for you, however¾it's a rough estimate meant to cover most of the U.S. population.
For more label regulations, see Labels, Food.