Vitamin B6

Vitamin B6 (pyridoxine)

Overview:

Vitamin B6, also called pyridoxine, is one of 8 B vitamins. All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body metabolize fats and protein. B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.

All B vitamins are water-soluble, meaning that the body does not store them.

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 nor-epinephrine, which influence mood, and melatonin, which helps regulate the body clock.

Along with vitamins B12 and B9 (folic acid), B6 helps control levels of homocysteine in the blood. Homocysteine is an amino acid that may be 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 serious deficiency include muscle weakness, nervousness, irritability, depression, difficulty concentrating, and short-term memory loss. Vitamin B6, which is abundant in dark leafy greens, peas, broccoli and potatoes, helps your body use the nutrients from the other foods you eat. It also plays a role in your body's production of hemoglobin, which is responsible for carrying oxygen from your lungs to every cell in your body. Some factors, such as your protein intake and the strength of your immune system, can influence the amount of vitamin B6 you need.

Recommended Intake:

Daily recommendations for dietary vitamin B6 are listed below.

                             Pediatric                                                                                         Adult

·         Infants 0 - 6 months: 0.1 mg (adequate intake) ·         Infants 7 months - 1 year: 0.3 mg (adequate intake) ·         Children 1 - 3 years: 0.5 mg (RDA) ·         Children 4 - 8 years: 0.6 mg (RDA) ·         Children 9 - 13 years: 1 mg (RDA) ·         Boys 14 - 18 years: 1.3 mg (RDA) ·         Girls 14 - 18 years: 1.2 mg (RDA)

·         19 - 50 years: 1.3 mg (RDA) ·         Men 51 years and older: 1.7 mg (RDA) ·         Women 51 years and older: 1.5 mg (RDA) ·         Pregnant women: 1.9 mg (RDA) ·         Breastfeeding women: 2.0 mg (RDA)

Larger doses have been used in some studies, but you should not take doses above 100 mg per day without a health care provider's supervision. Large doses of B6 may cause nerve damage.

Protein Intake Considerations:

If you have a high protein intake, you may need more B6 than the IOM recommends, according to Oregon State University researchers who published a paper in the "Journal of Nutrition" in 1996. The enzyme pyridoxal 5'-phosphate, or PLP, a form of vitamin B6 in your body, works with other enzymes to metabolize amino acids from the protein you eat. If you take in large amounts of dietary protein, you have a greater need for PLP sources to help your body use the protein and you should consult your doctor about your vitamin B6 needs.

Toxicity - Precautions:

Some supplements offer mega doses of vitamin B6, but the IOM warns against taking more than 100 milligrams per day. High concentrations of pyridoxine can lead to a neurological condition called sensory neuropathy, which can cause numbness of the extremities, pain or difficulty walking, according to the Linus Pauling Institute. it is safer to get your B6 from food rather than from a synthetic supplement.

Dietary Sources:

Good food sources of vitamin B6 include chicken, turkey, tuna, salmon, shrimp, beef liver, beans, milk, cheese, lentils, beans, leafy greens, spinach, carrots, brown rice, bran, sunflower seeds, wheat germ, whole-grain flour, bananas, papaya, strawberries and cantaloupe,

Possible Interactions:

If you are being treated with any of the following medications, you should not use vitamin B6 supplements without first talking to your health care provider.

Drugs that reduce levels of B6 in the body -- If you take any of these medications, be sure to get enough B6 in your diet:

·         Cycloserine (Seromycin), used to treat tuberculosis

·         Hydralazine (Apresoline), used to treat high blood pressure

·         Isoniazid, used to treat tuberculosis

·         Penicillamine, used to treat rheumatoid arthritis

·         Theophylline (TheoDur), used to treat asthma

Antibiotics, Tetracycline -- All B complex vitamins, including vitamin B6, interfere with the absorption and effectiveness of antibiotic tetracycline. You should take tetracycline at different times from vitamin B6 and other B vitamins.

Antidepressant Medications -- Taking vitamin B6 supplements may improve the effectiveness of some tricyclic antidepressants such as nortriptyline (Pamelor), especially in elderly people. Other tricyclic antidepressants include amitriptyline (Elavil), desipramine (Norpramin), and imipramine (Tofranil).

On the other hand, antidepressants called monoamine oxidase inhibitors (MAOIs) may reduce blood levels of vitamin B6. Examples of MAOIs include phenelzine (Nardil) and tranylcypromine (Parnate).

Amiodarone (Cordarone) -- This drug, used to treat an irregular heartbeat, makes your skin more sensitive to sunlight. Taking vitamin B6 along with this drug may increase your risk of sunburn, blistering, or a rash.

Chemotherapy drugs -- Vitamin B6 may reduce certain side effects of 5-fluorouracil and doxorubicin, medications used to treat cancer. Talk to your doctor before taking any supplement if you are undergoing chemotherapy.

Erythropoietin (EPO) -- Erythropoietin therapy, used to treat severe anemia, may decrease vitamin B6 levels in red blood cells.

Levodopa (L-dopa) -- Vitamin B6 reduces the effectiveness of levodopa, a medication used to treat Parkinson's disease. However, it does not seem to have the same effect on the combination of levodopa and carbidopa. Your doctor may be able to determine a dose of B6 that can safely help reduce side effects of levodopa. Taking vitamin B6 along with levodopa should be done only under your doctor’s supervision.

Phenytoin (Dilantin) -- Vitamin B6 makes phenytoin, a medication used to treat seizures, less effective.