In this article the most important functions of vitamin B6 are discussed, the best food sources of this vitamin are provided, and the intake recommendations and toxicity symptoms are given.
B6 is a water-soluble vitamin. Its chemical name is pyridoxine, but you may also come across the slightly modified names pyridoxal or pyridoxamine.
All forms of vitamin B6 are absorbed by intestinal cells and converted to pyridoxal. Through the blood, pyridoxal molecules enter the liver, where they are converted into pyridoxal phosphate, a biologically active form. It is in this chemical form that vitamin B6 does its job in the human body.
Vitamin B6 is absorbed from food by an average of about 75%. Vitamin B6 in the form of supplements is absorbed better, about 95%.
Functions of vitamin B6 and deficiency symptoms
Here follow the most well-studied functions of vitamin B6:
- Vitamin B6 is needed for metabolism, especially for protein utilization through amino acid synthesis. Amino acids are the building blocks of proteins.
- Vitamin B6 regulates the action of steroid hormones and is necessary for blood formation and normal functioning of the immune and nervous systems.
- Together with vitamins B11 (Folic acid) and B12, B6 maintains optimal levels of amino acid homocysteine in our body.
- Without adequate intake of B6, the metabolism of the amino acid tryptophan is disrupted. Tryptophan precedes the production of the neurotransmitter serotonin. That is, without tryptophan, the production of serotonin is impossible. Therefore, even a relatively small B6 deficiency can lead to symptoms of depression.
Long-term B6 deficiency can lead to anaemia, nervous disorders, and lowered immunity. Other symptoms of vitamin B6 deficiency include dermatitis with cheilosis (scaling on the lips and cracks at the corners of the mouth), glossitis (swollen tongue) and depression. A significant deficiency in children can lead to seizures.
Having said all that, I must note that in developed countries, B6 deficiency is relatively rare.
How much vitamin B6 do we need and what are the major sources of this vitamin
Vitamin B6 intake recommendations vary slightly from country to country. On average, the recommended daily allowance is 1.5 – 1.8 mg.
A lot of vitamin B6 is found in bananas, meat, fish, potatoes, pumpkins, watermelon, sunflower seeds and avocados. One medium sized banana and one medium sized avocado provide both approximately 25 % RDA of vitamin B6.
In smaller quantities, vitamin B6 is found in eggs, nuts, cereals, legumes, vegetables and dairy products.
Alcohol consumption leads to the breakdown of vitamin B6 in the body.
Vitamin B6 is partially destroyed by heating.
Too much vitamin B6?
Can you actually take too much vitamin B6? The tolerable maximum intake level of vitamin B6 is 25 mg per day for adults. For children, this limit is significantly lower (5-15 mg depending on age).
Unfortunately, not all countries regulate the maximum amount of vitamins in dietary supplements. Therefore, there are synthetic drugs on sale that contain more B6 than is considered safe for health (> 25 mg).
In general, the use of vitamin supplements for most people is not necessary, as it does not provide any additional health benefits. If you still take dietary supplements, then for safety reasons it is recommended not to take more than 100% of the recommended daily allowance. That is, in the case of vitamin B6, not more than 1.5 mg per day.
Of course, there are situations in which a specialist can prescribe a mega dosing. For example, pregnant women with toxicosis are sometimes prescribed 25-50 mg of vitamin B6 per day. As a rule, such interventions do not last long and do not harm health. But I definitely do not recommend taking mega doses on your own initiative, without discussing it with your health care provider.
Prolonged daily use of too high doses of the synthetic vitamin B6 can cause disorders of the nerve endings in the arms and legs. It is known that long-term daily use of dietary supplements containing more than 25 mg of vitamin B6 can lead to so-called peripheral neuropathy. This disease is accompanied by weakness, numbness or pain in the palms and soles.