Vitamin B6

Vitamin B₆ (Pyridoxal 5 Phosphate)

Vitamin B₆ (Pyridoxal 5 Phosphate) is a water-soluble vitamin or essential nutrient found naturally in various foods and also added to foods and supplements. Pyridoxal 5 phosphate (PLP) is the active form of vitamin B₆ that has many biological functions and health benefits. Pyridoxine hydrochloride is also the form of vitamin B₆ that is most commonly uses as a dietary supplement due to its chemical stability. Pyridoxal 5 phosphate (PLP) is a coenzyme for many enzymes that help the synthesis of hemoglobin and control the metabolism of amino acids, glucose, and lipids. The phosphate form is inconvertible in our bodies.

The main health benefits of the pyridoxal 5 phosphate form of vitamin B₆  are to developing of the nervous system and the metabolism of protein, carbohydrates, and fats. Therefore, the pyridoxal 5 phosphate form of vitamin B₆ uses mainly for converting food into energy and helps to create neurotransmitters.

Chemically, B₆ vitamers are derivatives of 2-methyl-3-hydroxy-5-hydroxymethyl-pyridine where a C4 position can be substitute by a hydroxymethyl group in pyridoxine, an aminomethyl group in pyridoxamine, and an aldehyde group in pyridoxal.

The alcohol group present in the 5 positions can be esterified to phosphate to form pyridoxine 5 phosphate (PNP), pyridoxamine 5 phosphate (PMP), and pyridoxal 5 phosphate (PLP).

Sources of Vitamin B₆

The main sources of vitamin B₆ for humans are the diet. This vitamin basically occurs in a variety of animal and plant foods.

• Beef liver
• Yellowfin tuna
• Salmon
• Fortified cereals
• Chickpeas
• Bulgur
• Cottage cheese
• Roasted chicken breast
• Poultry
• Potatoes
• Banana

Some vegetables and fruits, dark leafy greens, bananas, papayas, oranges, and cantaloupe contain principally pyridoxine and its phosphate and glucoside forms of B₆. However, pyridoxamine 5 phosphate (PMP) and pyridoxal 5 phosphate (PLP) forms of vitamin B₆ generally occur in meat and fish.

The average B₆ content of human milk is generally low during early childbirth. High-performance liquid chromatography analysis indicates that B₆ in human milk contains pyridoxal, pyridoxal 5 phosphate, pyridoxamine, and pyridoxamine 5 phosphate. The supplementation of mothers with 2.5 or 15 mg of pyridoxine gives similar distribution patterns for the vitamers in milk.

Recommended Daily Intake

Like other B vitamins, our body does not store B₆ and releases any excess in urine. Therefore, people need to get enough vitamin B₆ reached foods or supplements every day.

The daily requirement for B₆ depends on several factors because B₆ controls various biological functions of a person. The recommended daily dietary allowances (RDA) for this vitamin are,

Vitamin B₆ Supplements

Vitamin B₆ supplements are generally available in capsule or tablet form to treat B₆ deficiency. Pyridoxine hydrochloride is available as a licensed drug or supplement for oral administration in most Western countries. This vitamin is converted to pyridoxamine 5 phosphate (PMP) by the enzyme pyridoxal kinase.

The metabolically active form of B₆, pyridoxal 5 phosphate may be obtained during the action of enzymes pyridoxamine phosphate transaminase or pyridoxine 5 phosphate oxidase.

The activity of the enzyme pyridoxine 5 phosphate oxidase depends on flavin mononucleotide (FMN). FMN is a cofactor produced from riboflavin (vitamin B₂).

Most people of all ages in developed countries consume sufficient vitamin B₆ and thus, they do not require supplements. Those who are more likely to have low levels of B₆ and require supplementation may include:

• People who drink excessive alcohol
• People with obesity
• During pregnancy or breastfeeding periods

Functions of Vitamin B₆

Functions of Pyridoxal 5 Phosphate in Metabolism

The main functions of vitamin B₆ or its active form, pyridoxal 5 phosphate are the metabolism of protein, carbohydrates, and fats. In protein metabolism, B₆ generally helps to regulate the balance of amino acids in the body.

Pyridoxal 5 phosphate (PLP) undergoes a condensation reaction with the amino group of amino acids to produce a Schiff base. It forms the basis of most of the enzyme catalyzed reactions in our body.

The coenzyme, pyridoxal 5 phosphate basically involved in glycogenolysis of the body. This form of B₆ enables the breakdown of glycogen into glucose for energy production. Glycogenolysis is primarily found in muscle, liver, and brain.

Pyridoxal 5 phosphate (PLP) form of vitamin B₆ generally required for the normal metabolism of fats and essential fatty acids. Thus, PLP is an essential component of enzymes that facilitate the biosynthesis of sphingolipids. For example, the synthesis of ceramide requires PLP.

Selenomethionine is the primary dietary supplement for selenium. The cofactor, pyridoxal 5 phosphate helps to activate enzymes that allow selenium to uses from the dietary form.

Functions of Vitamin B₆ in Hemoglobin Synthesis

Heme is an iron-binding prosthetic group in metalloproteins. Hemoglobin generally binds and transports oxygen from the lungs to the other tissues of the human body.

The biosynthesis of hemoglobin depends on the activity of the enzyme aminolevulinic acid synthase. Pyridoxal 5 phosphate serves as a coenzyme for the enzyme aminolevulinic acid synthase.

Neurotransmitters

As a coenzyme, vitamin B₆ (Pyridoxal 5 phosphate) basically helps in the biosynthesis of five important neurotransmitters.

These are serotonin, dopamine, epinephrine, norepinephrine, and gamma-aminobutyric acid. These important chemical messengers help to regulate energy in our brains.

Gene Expression

A recent study suggests that pyridoxal 5 phosphate (PLP) has modulated gene expression not only for steroid hormone responsive or PLP dependent enzymes but also for steroid and PLP unrelated proteins such as serum albumin. Therefore, pyridoxal 5 phosphate has been implicated in increasing or decreasing the expression of certain types of genes.

Albumin gene expression by B₆ goes through a novel mechanism. It involves the inactivation of tissue-specific transcription factors, such as HNF-1 or C/EBP.

Vitamin B₆ in Fertility

This vitamin generally raises the levels of the progesterone hormone that makes the body ready for pregnancy. This vitamin also helps in the production of cervical mucus that transports the sperm to reach the egg.

The menstrual cycle for women consists of two phases – the follicular phase and the luteal phase. The luteal phase of the menstrual cycle is generally strengthened by this vitamin.

Various form of this vitamin makes the uterus more receptive and increase the chance of pregnancy. This vitamin also increases or restores libido. Hence, B₆ generally increases the sexuality of men and women.

Uses of Vitamin B₆

Plants synthesize pyridoxine to protect from the ultraviolet B radiation of sunlight. Pyridoxine also participates in the synthesis of chlorophyll.

Animals cannot synthesize any of the various forms of this vitamin. Therefore, they must obtain B₆ via diet, either from plants or other animals.

• The pyridoxal 5 phosphate form of this vitamin uses for protein, carbohydrate, and fat metabolism.
• This vitamin also participates in the production of neurotransmitters, hemoglobin, and the formation of nicotinic acid. Therefore, supplements of vitamin B₆ uses for maintaining a healthy nervous system, skin, muscles, and blood.
• Vitamin B₆ supplementation uses to reduce mild symptoms of morning sickness, nausea, and vomiting during pregnancy.
• Supplementation of this vitamin also protects us from the harmful effects of air pollution by reducing the impact of pollution on the epigenome.
• The forms of vitamin B₆, pure crystalline pyridoxine powder, or pyridoxine hydrochloride supplements are uses in amino acid metabolism and maintain healthy or oily skin.

Benefits of Vitamin B₆

The main health benefits of the active form of vitamin B₆ (pyridoxal 5 phosphate) are to control the nervous system and to maintain the metabolism of the human body. Vitamin B₆ or pyridoxal 5 phosphate (PLP) generally assists more than 100 enzymes in performing various biological functions.

• The main benefit of PLP is for the development of the brain of infants during pregnancy.
• PLP creates neurotransmitters, including serotonin and dopamine.
• This vitamin also helps to create hemoglobin, a part of red blood cells that carries oxygen in the human body.
• PLP is beneficial for regulating and balancing the amino acids in the human body.
• Various forms of this vitamin are also closely involved in hormone synthesis.

Vitamin B₆ and Weight Loss

The pyridoxal 5 phosphate form of vitamin B₆ plays a crucial role in metabolizing protein, fats, and carbohydrates in our bodies. Therefore, in the presence of pyridoxal 5 phosphate, our metabolism speeds up and allows us to burn calories and lose weight more quickly.

Vitamin B₆ Deficiency

Deficiencies of vitamin B₆ are generally uncommon in the United States and other developed countries. The deficiency of B₆ happens if a person has poor intestinal absorption or takes some medicines. The deficiencies of B₆ mostly cause low levels of other B vitamins, such as vitamin B₁₂ and folic acid (folate).

The main signs and symptoms of a B₆ deficiency may include:

• Tingling, numbness, and pain in the hands and feet (peripheral neuropathy)
• Anemia
• Seizures
• Weakened immune system
• Depression
• Confusion
• Seborrheic dermatitis
• Inflammation of the tongue, or glossitis
• Inflammation and cracking of the lips

The vitamin B₆ level generally decreased in women with type 1 diabetes and patients with systemic inflammation, liver disease, rheumatoid arthritis, and those infected with HIV.

There is no single accepted laboratory test to measure the B₆ level. Clinical diagnosis is generally suitable for measuring the deficiency of vitamin B₆. For example, serum pyridoxal phosphate is the most common to measure B₆ deficiency.

Other useful methods to measure vitamin B₆ (Pyridoxal 5 phosphate) levels mostly include UV spectrometry, spectrofluorimetry, mass spectrometry, thin-layer chromatography, high-performance liquid chromatography, electrochemical, and enzymatic methods.