Sources and Physiologic functions Sources Eggs, poultry, fish, liver and eggs are all good sources of this vitamin. Meat and milk have lower amounts. 96% of pyridoxine found in animal sources can be obtained from animals. Intestinal bacteria can make vitamin B6 in healthy people. This vitamin is also found in legumes and potatoes, as well as bananas, carrots, potatoes, yeast and watermelon.
Populations at Risk: Because this vitamin is so widely distributed, it is very rare to have a deficiency. This is except for chronic alcoholics or women who use oral contraceptives. Preeclamptic mothers, infants born to preeclamptic mothers and mothers who are deficient in B6 may be at high risk. Supplementation with B6 should be provided for patients taking Cycloserine, Cycloserine or Hydantoin as well as hydralazine and isoniazid. This vitamin is more needed in high-protein diets.
Mild deficiencies of vitamin B6 can be rare but severe deficiencies are not uncommon. Second National Health and Nutrition Examination Survey II (NHANES II), data on 11,658 adults aged 19 to 74 years, showed that 71% and 90% of males and 90% respectively ate less than the 1980 recommended daily allowance (RDA). Vitamin B6 is the most commonly deficient water-soluble vitamin among elderly. Elderly people may be at risk from taking single drugs or drug combinations. Elderly men and women can help to minimize the potential for drug-nutrient and drug-food interactions. It is possible to avoid drug-induced nutritional deficiencies by advising elderly drug-taking seniors on the proper levels of nutrition intake. A study comparing the nutritional intakes of American children aged between 2 and 10 years found that vitamin B6 was below the RDA for more than half of the population.
Use of birth control pills and occupational exposure to carbon dioxide can cause vitamin B6 deficiency or increase vitamin B6 requirements. Both compounds cause adverse psychological/neurological disorders such as extreme irritability, manic depressive tendencies, headaches, and other variables, but related disorders presumably by disrupting normal vitamin B6 metabolism and vitamin B6 administration has been found to alleviate their adverse psychological symptoms. This interrelation needs to be further investigated experimentally. The combination of CS2 and OCs may cause an increased disruption in tryptophan metabolism, which could in turn lead to exaggerated psychological sequelae.
Signs & Symptoms of Deficiency In infants, convulsive seizure and hyperactivity are common presenting symptoms. Diarrhea is another common symptom. Patients with tuberculosis who are on isoniazid and have a pyridoxine deficit may experience anemia and peripheral neuritis. Vitamin B6 therapy is effective in treating homocystinurics with dislocations of the eyes, osteoporosis (brittle bone), mental retardation, and spontaneous blood clots which can cause heart attacks and even death.
BiochemistryVitaminB6 is a term that refers to pyridoxine (pyridoxal), pyridoxal and pyridoxamine. They all serve as precursors for the biologically active coenzyme pyridoxal. Pyridoxalphosphate is a coenzyme responsible for reactions in protein metabolism and conversion of tryptophan into niacin, fat metabolic, carbohydrate metabolism and nerve and brain energy. Vitamin B6 is a powerful antioxidant that can reduce the severity of homocystinuria. This rare condition usually arises from a defect or mutation in an enzyme responsible for degrading homocysteine.
Safety: Neurologic disturbances can be caused by a deficiency or excessive intake of pyridoxine. Sensory neuropathy is most commonly caused by intakes exceeding 600 mg per day. However, some evidence suggests that lower doses may cause symptoms. The determinant of toxicity is how long the exposure continues. One study suggests that some toxicity may be linked to a daily intake of 117mg/day for an average of 2.9 years. The control group, however, had an average intake 116 mg/day over a period of 1.6 years. Some women in both groups were taking 50 mg/day. This raises questions about the reliability of the telephone survey used to diagnose neuropathy.
Vitamin B6 can be toxic in doses up to 1000 times the recommended daily allowance. A daily intake of 2-5 g of pyridoxine per day can cause difficulty walking and tingling sensations in your legs and feet. The toxic dose can cause unsteadiness in walking, difficulty handling small objects, and numbness in the hands. Recovery begins within 2 months of stopping vitamin B6 supplementation. After stopping taking vitamin B6 supplements, complete recovery can take between 2 and 3 years. One study found that pyridoxine abuse can cause pure central-peripheral distal Axonopathy. The daily intake of pyridoxine was between 0.2 and 5 g/d. However, symptoms developed in an inverse relationship to the duration of the consumption. All patients who received adequate follow-up showed improvement after discontinuing pyridoxine.
Is pyridoxine safe to be used long-term in large populations, including children? Retrospective analysis of multiple studies shows that adults can take pyridoxine at doses as low as 100mg/day. There isn’t enough information to suggest any dosage for children. The major neurologic problem is peripheral neuropathy. There are many causes. Pyridoxine can cause neuropathy in people with pre-existing neuropathy. Predisposing factors include alcohol, drugs, food, toxic exposures at work or home, as well as family history. This may cause peripheral neuropathy in patients who are not taking the same doses of pyridoxine. It is not clear how long the exposure to pyridoxine causes neuropathy. Neurologic injury can occur in a matter of days with extreme doses, but chronic low doses are relatively safe.
Treatment with vitamin B6 or vitamin B12 led to the development of acne vulgaris and/or eruption of an acneiform anthema in 14 patients. The most frequently affected were females. It is common to see skin symptoms even in the absence of acne vulgaris. Acneiform exanthema is characterized by small, loosely distributed papules or pustules that appear on the skin after treatment with vitamin B6 and B12. They are found on the forehead, chin, upper arms and chest. It is unknown what the cause of this change may be. The acneiform rash usually disappears after treatment with vitamin B6 and vitamin B12 has been stopped.
Recommendations RDA In mg.
Infants born up to 6 months – 0.3mg
Infants 6 months to 1 year – 0.6mg
Children from 1 to 3 years old – 1.0mg
Children aged 4 to 6 years – 1.1mg
Children 7-10 years old – 1.4mg
Adolescent males 11-14 years old – 1.7mg
Adolescent girls 11-14 years old – 1.4 mg
Adolescent males between 15 and 18 years old – 2.0mg
Adolescent females between 15 and 18 years old – 1.5mg
Adult males aged 19 to 50 years – 2.0mg
Adult females aged 19 to 50 years – 1.6mg
Adult males 51 yr plus – 2.0mg
Adult females 51 yr plus – 1.6mg
Pregnant Women – 2.2mg
Lactating Mothers (first 6 months) – 2 mg
Lactating Mothers (6th Month) – 2.1mg
Food Source Serving Dimension/Amount #of mg/serving
Chicken (dark meat) 3.5 oz 0.37 mg
Chicken (light meat) 3.5 oz 0.63 mg
Atlantic Salmon (wild, raw) 3.0 oz 0.70 mg
Tuna (canned with water) 3.0 Oz 0.30 M
Liver (beef braised), 3.5 oz 0.91m
Live (veal braised 3.5oz 0.91 mg
Boil 1 cup of navy beans (0.30 mg)
Peanuts (dry roasted) 1 oz 0.07 mg
Potato (boiled) 1 medium 0.40 mg
Banana 1 medium 0.66m
Prunes (dried) 10 0.22 mg
Watermelon 1 cup 0.23 mg
Avocado 1 medium 0.48 mg
The Literature: Prevention of Heart Disease
Hyperhomocysteinemia, a risk factor for atherosclerosis, is associated with deficiencies of vitamin B6, folate, and cobalamin. Patients who received vitamin B6 to treat carpal tunnel syndrome or other degenerative conditions had 27% less risk of developing myocardial damage or acute cardiac chest pain. Dr. Ellis discovered that the average age of death from myocardial injury in elderly patients who died at home was 8 years earlier for those who had taken vitaminB6 than those who hadn’t. Vitamin B6 may have a preventive effect on the progression of coronary disease. This could be due to the increased production of pyridoxalphosphate, a coenzyme required for the catabolism and metabolism of homocysteine.
The serum total homocysteine level (tHcy), is linked to pregnancy complications, neural tube defects and cognitive impairment in elderly people. A total of 80 epidemiological and clinical studies have shown that elevated levels of tHcy are a common cardiovascular risk factor. Oral treatment with 300mg/d pyridoxine does not reduce the fasting level of tHcy in healthy subjects or patients with vascular disease. However, patients who take pyridoxine (between 10 and 250 mg/d), have an abnormal postmethionine load. When combined with folic acids, almost all achieve a normal postmethionine level.
A randomized trial showed that Pyridoxine reduced ADP- and epinephrine-induced aggregates by 48% (p 0.011). It also prolongs bleeding and coagulation times. The total plasma cholesterol and total plasma lipid levels were significantly lower with Pyridoxine, while the HDL-cholesterol levels were higher. It is believed that oral vitamin B6 reduces platelet aggregation in healthy subjects.
A study showed that pyridoxine treatment of hypertensive patients significantly decreased systolic (p > 0.01), diastolic (p > 0.005) and plasma NE (p > 0.005) within four weeks. These patients received a dose of 5 mg/kg/day of pyridoxine. This suggests that pyridoxine might be helpful in hypertension treatment.
Since the formation of neurotransmitters, Pyridoxine has been recognized as an essential cofactor. It has been used as a therapeutic adjunct for a wide range of neurotransmitter disorders. These conditions include seizures, Parkinson’s disease and depression. Premenstrual syndrome, carpal tunnel syndrome, and other clinical uses of pyridoxine are two examples. Due to the potential neurotoxicity of vitamin pyridoxine, it is important that vitamin intake be part of your medical history.
Vitamin B6 is recommended for diabetic neuropathy. Vitamin B6 deficiency was believed to be the cause of neuropathy in diabetics. Numerous studies have shown that vitamin B6 supplementation may not be beneficial for these patients. One study involved 18 patients suffering from symptomatic diabetes neuropathy. They were either treated with placebo or with pyridoxine. There was no difference in fasting plasma glucose, motor neuro conduction velocity or ophthalmic examination between the two groups at the end and beginning of the study. These results indicate that vitamin B6 deficiencies are not a contributing factor to diabetic peripheral neuropathy.
A relative pyridoxine deficit was found in 14 women suffering from gestational diabetes. The oral glucose tolerance was significantly improved after 14 days of treatment with vitamin B6 or pyridoxine 100 mg/day. The hypothesis was that gestational diabetes could be caused by increased xanthurenic acid synthesis in pregnancy. Vitamin B6 treatment makes the production of xanthurenic acid normal. It restores tryptophan metabolism, and improves oral glucose tolerance in patients suffering from gestational diabetes.
There is limited evidence that pyridoxine might be effective in treating kidney stones. For 180 days, twelve recurrent stone-formers with hyperoxaluria were given pyridoxine HCl (10 mg/day), daily for a total of 12 days. The 90th day of pyridoxine therapy resulted in a significant decrease in urinary oxalate (p less that 0.05). Thus, pyridoxine-HCl (10 mg/day), is therapeutic for hyperoxaluric stones formers.
Review of four cross-sequential, double-blind therapeutic trials with 60 autistic kids examined the effects on behavioral improvement of vitamin B6 and magnesium. Children who took both magnesium and B6 showed modest behavioral improvement, but not when they were taking either of them individually.
Vitamin B6 is an important cofactor in the development of the central nervous system. It may have an impact on brain development and cognitive function. Recent animal studies have shown that vitamin B6 deficiencies during pregnancy and lactation can alter the function of certain receptors, which are important for learning and memory. Although the exact mechanism behind this deficiency is not known, it has been demonstrated that brain development can suffer from neurochemical and morphological changes such as tremors and irritability. Numerous studies suggest that lactating mothers and pregnant women might have lower vitamin B6 intakes than the recommended daily allowance. This could affect their children’s vitamin B6 status. Unsupplemented lactating moms may have a milk vitamin A6 level of less than 100mg/L. This can put infants at high risk for seizures. This level of vitaminB6 in milk may not cause clinical signs of frank vitaminB6 deficiency. However, it could affect the child’s normal development. An Egyptian study found evidence of such an effect in an infant study that showed abnormal behavior in babies whose mothers had lower levels than 85 mg/L vitamin B6.
Many conditions in neurology could be treated with pyridoxine. It is clear that patients suffering from depression, chronic pain, headaches, or serotonin deficiency are all affected by pyridoxine. This opens up a variety of therapeutic options. Comparing amitriptyline to treat headaches seems to yield about the same efficacy. However, side effects are likely to be more severe with the amitriptyline. Medical authorities believe that many behavioral disorders are caused by excessive exposure to chemicals that are pyridoxine antagonists. Supplementation in the early stages of the disease may help reduce aggression and hyperactivity.
Interaction with Medications
To prevent peripheral neuropathy, some patients require vitamin B6 (pyridoxine), supplementation during isoniazid therapy (INH). In vivo, pyridoxine can be converted into coenzymes, which are essential for the metabolism of protein and carbohydrates. INH seems to inhibit the activity of pyridoxine during these metabolic functions. It is highly recommended to use pyridoxine supplementation routinely to prevent peripheral neuropathy in high-risk populations.
Carpal Tunnel Syndrome
Vitamin B6 can be used to treat carpal tunnel syndrome, and other related disorders in patients who are deficient in vitamin B6. Study results showed that a higher concentration of plasma pyridoxal 5’-phosphate (PLP), particularly in unsupplemented men, was associated with less pain/discomfort and tingling, as well as nocturnal awakening. Higher plasma vitamin C levels or a relative shortage of plasma vitamin PLP (higher ASC/PLP) were associated with higher sensory latencies and more frequent symptoms. This suggests that vitamin C supplementation with vitamin B6 deficiency might be harmful to the median nerve, and could promote the development CTS hand/wrist symptoms. There are strong relationships between plasma vitamin levels (specific symptoms) and both components CTS (median nerve slowing and/or vitamin C supplementation). Particularly important in terms of symptoms is the interaction between plasma PLP, ASC. Vitamin B6 is often recommended for carpal tunnel syndrome.
Review of 12 controlled trials of vitamin B6 for the treatment of premenstrual syndrome revealed weak evidence of its positive effects. The trials had a limited number of participants, which is a major problem. A more recent, well-designed study involved 120 women who were randomly assigned to either an active drug or placebo. In symptom reduction, Pyridoxine 300 mg/d did not show any greater benefit than placebo.
Vitamin B6 and Exercise
Vitamin B6 could play an important role during exercise response. Vitamin B6 is vital for the production of energy while exercising. Poor vitamin B6 status can cause poor exercise performance. Vitamin B6 supplementation can increase plasma growth hormone levels during and immediately after exercise. Although the physiologic implications of these changes have not been investigated, they are believed to increase muscle mass as well as reduce body fat. Low dietary vitamin D6 intakes may be an issue for female athletes or those who are involved in low-body weight sports (e.g., gymnasts, dancers, and wrestlers).
There is limited evidence that vitamin B6 might be helpful in asthma. Double-blind, five-month follow-up of 76 children with asthma was conducted. The results showed significant improvement in their asthma after receiving 200 mg of pyridoxine daily and reducing their doses. These data indicate that children suffering from severe bronchial asthma experienced a blockage in their tryptophan metabolism. Long-term treatment with high doses of pyridoxine was beneficial. A double-blind, placebo-controlled study compared pyridoxine 300 mg daily to placebo for asthma treatment. Patients who required steroids to treat their asthma had a 9-week follow-up. Treatment with oral pyridoxine did not improve outcomes.
There is limited evidence that vitamin B6 may be beneficial for the treatment of depression. In a well-designed experiment, the augmentation effect of vitamin B1 and B2 in depression patients aged over 60 was evaluated. In a well-designed study, the vitamin-treated group demonstrated a greater improvement in cognitive function and ratings of depression than those who were given placebo. Consider B complex vitamin augmentation for the treatment of geriatric depressive disorder.
Summary: Pyridoxine plays an essential role in protein, fat, and carbohydrate metabolism, folic Acid synthesis, and glandular and endocrine functions. Pyridoxine is essential for the production of serotonin and dopamine and aids with the formation of many neurotransmitters. It is an essential nutrient in the regulation and maintenance of mood and mental processes.
Many claims have been made regarding the positive effects of vitamin B6 in a variety of conditions, including atherosclerosis and attention deficit disorder, autism.
There is strong evidence that vitamin B6 may have a preventative effect on the development of coronary artery disease. Vitamin B6 supplementation was not shown to reduce fasting plasma homocysteine levels, but it has been shown to lower the postmethionine load, which may explain its cardioprotective effects.
It has been shown to be as effective as amitriptyline for chronic headaches in well-designed studies. Vitamin B6 therapy might be beneficial for many clinical conditions such as depression and chronic pain, which can be caused by serotonin deficiencies. Vitamin B6 is an essential cofactor in neurotransmitter production and may be used as a therapeutic adjunct to treat seizures, Parkinson’s disease and behavioral abnormalities in children and adults. Vitamin B6 has also been shown to be effective in treating carpal tunnel syndrome in people with vitamin B6 deficiencies. Vitamin B6 supplementation can improve exercise performance.
Supplementation should be given to those who are most at risk, such as athletes, chronic alcoholics and women on oral contraceptives. For normal cognitive function and the development of the central nervous system, pregnant and lactating mothers should consume sufficient vitamin B6.