Overview
Vitamin B6 is a water-soluble vitamin that is important in carbohydrate, lipid, and amino acid metabolism. It is found in the body in three primary forms: pyridoxine (the common name given mainly to the alcohol form, or pyridoxol); pyridoxal (the aldehyde); and pyridoxamine (theamine).
Vitamin B6 helps the body make several neurotransmitters, chemicals that carry signals from one nerve cell to another. It is needed for normal brain development and function, and helps the body make the hormones serotonin and norepinephrine, which influence mood, and melatonin, which helps regulate the body clock.
Along with vitamins B12 and folic acid (B9), B6 helps control levels of homocysteine in the blood. Homocysteine is an amino acid that is associated with heart disease. Your body needs B6 in order to absorb vitamin B12 and to make red blood cells and cells of the immune system.
It is rare to have a significant deficiency of B6, although studies indicate many people may be mildly deficient, especially children and the elderly. Certain medications can also cause low levels of B6 in the body. Symptoms of mild deficiency include muscle weakness, nervousness, irritability, depression, difficulty concentrating, and short-term memory loss.
Dietary Sources
Good food sources of vitamin B6 include chicken, turkey, tuna, salmon, shrimp, beef liver, milk, cheese, lentils, beans, spinach, carrots, brown rice, bran, sunflower seeds, wheat germ, and whole-grain flour.
Upper Limits
The Council for Responsible Nutrition recommends a safe upper limit of 100 mg / day due to the complete absence of adverse effects in credible, well-designed studies at 100 and 150 mg levels and only marginal evidence of adverse effects at 200 mg (Parry and Bredenson 1985; Brush 1988).
Sources
University of Maryland Medical Center
Council for Responsible Nutrition