Overview

Vitamin B6 (pyridoxine) is a water-soluble nutrient that cannot be made in the human body. You need to get B6 from the foods you eat or through nutritional supplements. This is a part of the B Vitamins group and is important for everyday functioning.

The functional (active) form of vitamin B6 is the Pyridoxal 5’ phosphate (PLP). PLP is a coenzyme (smaller molecules that help enzymes create a reaction in the body). The range of B6 in the blood is usually measured in terms of PLP levels.

Starting from the breaking down of carbohydrates, fats, and proteins to supporting brain health, PLP helps more than a hundred enzymes in the body to do their job right.

It is not surprising that B6 is considered a very important B vitamin. Here are some of the top benefits of maintaining right B6 levels in the blood.

• Prevents the risk of brain disorders including Alzheimer’s disease
• Helps improve mood and reduces symptoms of depression
• Helps in hemoglobin production
• Promotes heart health and prevents clogging of arteries
• Certain studies relate sufficient vitamin B6 levels with reduced risks of developing cancer
• Can make symptoms of Premenstrual Syndrome (PMS) better

The Story Behind Vitamin B6

It was only in the early 1900s that physicians and pathologists started working on the idea of inadequate nutrition leading to diseases. The idea that lack of nutrition can cause a variety of health conditions including death was intriguing to the great minds.

Scientists from the Merck Group of Pharma in the early 20th century played a great role in developing B Group vitamins on an industrial scale and this paved the way for the easy availability of B complex supplements to match growing needs in the community.

In 1934, Paul Gyorgy, an American biochemist and nutritionist was experimenting on rats, feeding them artificially created diets rich in already discovered B vitamins (B1 and B2).

He discovered that the rats developed skin allergies with the diet and when he fed them baker’s yeast, the condition disappeared. 

He then extracted a particular compound from the yeast that helped cure skin allergies and named it vitamin B6. Later, Gyorgy and his fellow scientists also ended up extracting B6 from wheat germ and fish.

Paul Gyorgy is also known for the discovery of vitamin B2 and biotin and was later awarded the National Medal of Science for his efforts.

Molecular aspects

When you obtain vitamin B6 through natural sources, fortified foods, or supplements, it enters the stomach and then moves to the small intestine. Jejunum and ileum are two parts of the small intestine and B6 is absorbed here.

The process of absorption is known as passive diffusion (the molecules flow easily with no effort from a region of high concentration to a region of low concentration). The absorbed molecules are acted upon by a protein enzyme known as alkaline phosphatase. The vitamin is then converted to PLP in the jejunum’s inner layer.

PLP is passed on to the tissues and it helps the various enzymes in the body work effectively.

The remains of B6 after it gets converted to PLP are sent out through the urine. One of the major products sent out is 4-pyridoxic acid. In fact, up to 60% of ingested B6 is sent out as 4-pyridoxic acid.

People whose bodies do not absorb the right amounts of vitamin B6 have negligible 4-pyridoxic acid in the urine, and this is a clear indication of B6 deficiency.

Did You Know?

Did you know that vitamin B6 is considered a complementary and alternative therapy for children diagnosed with autism?

From the time vitamin B6 was identified, there has been a group of scientists attempting to treat neurological disorders with these. The studies started in the 1950s for people with schizophrenia. They were treated with extra high doses of vitamin B6 and improvements were noted. 

The Autism Research Institute (ARI) noted that about 49% of children who were treated with a combination of vitamin B6 and magnesium supplements showed improvements.

The relationship between vitamin B6 and autism is still being analyzed globally. We will hopefully find solid results very soon. 

Recommended values

The Dietary recommended Intake (DRI) of vitamin B6 was set by the Food and Nutrition Board. The values depend on age and gender.

What Happens When You Take Excess Of Vitamin B6

While mildly excess doses of vitamin B6 don’t cause any adverse effects, when you consume very high oral doses of B6 supplements for an extended period of time, it can result in certain sensory, skin, and gastric impairments.

Severely high doses of B6 can result in:

• Ataxia (inability to control body movements)
• Painful lesions in the skin
• Photosensitivity
• Gastric problems like heartburn and nausea

Here is a table that shows the daily tolerable upper limits for vitamin B6 in the body. Consuming more B6 than the levels mentioned here will cause the above side effects.

What Happens When You Have Vitamin B6 Deficiency

Usually, a person will not be deficient in just vitamin B6. He/she will have lower concentrations of other B complex vitamins too. Mild vitamin B6 deficiency does not show a lot of symptoms. 

Severe deficiency or a prolonged period of deficiency will result in the following conditions.

• Skin conditions like lesions and dermatitis
• Conjunctivitis
• Neurological symptoms like confusion and depression
• Lowered immunity levels
• Mouth ulcers and glossitis (swollen tongue)
• Microcytic anemia (lack of enough hemoglobin in Red Blood Cells)

In infants and younger children, lack of vitamin B6 is known to cause irritability and seizures. 

Non-genetic factors affecting Vitamin B6 levels

• Inadequate nutrient consumption - If you are not eating a variety of foods or have limited access to fresh plant and animal-based ingredients, you may be showing general vitamin B deficiency which will also include a lack of B6. 

• Alcoholism - Consumption of excessive alcohol prevents complete absorption of vitamin B6 from foods. People who drink excessively are at high risk of developing vitamin B6 deficiency. Cutting back on alcohol, enjoying a variety of food options, and choosing fortified meals all help ensure normal B6 levels.

• Renal diseases - People with kidney-related issues show lowered levels of vitamin B6 in the body. Patients who have undergone kidney transplantation or are on dialysis both show symptoms similar to those with B6 deficiency. Renal patients with B6 deficiency-like symptoms should talk to their doctors about supplements to manage the condition.

• Autoimmune Disorders - Autoimmune disorders are characterized by inflammation in the body and inflammation results in lowered PLP levels in the blood. This directly leads to vitamin B6 deficiency. Some of the autoimmune disorders that can cause B6 deficiency are Rheumatoid Arthritis, Crohn’s disease, Irritable Bowel Syndrome (IBS), and Celiac’s disease.
• Interaction with medications - Few medicines including Cycloserine (antibiotic), Theophylline (to treat respiratory diseases), and anti- epileptic medication (drugs to prevent epileptic seizures) can cause loss of vitamin B6 in the blood. If you are on these medications, then do consider taking supplements to match your increased needs.

Genetic association

There are two genes that cause people to require more vitamin B6 than the usual recommended ranges. 

ALPL

The ALPL gene plays a role in breaking down vitamin B6 from complex to simpler forms. It produces enzymes that help in clearance of B6.

A particular variant (type) of the gene can cause 12-18% lowered vitamin B6 rates in the body. Individuals with this type are likely to require more vitamin B6 levels.

Compensate by eating vitamin B6 rich foods, consume oral B group supplements and choose fortified foods. Around 89% Africans, 52% Caucasians, and 44% Asians carry this type of gene.

MTR

The MTR gene is responsible for converting folate into sources usable by the body.

A particular type of the gene is said to result in reduced MTR activity and causes a 30% increase in the risk of developing colorectal cancer. These individuals are likely to require more vitamin B6 levels (about twice more than the DRI values) to bring down the risk.

Oral supplements help match increased B6 needs. Fortified foods also make a difference.

Around 31% of Africans, 17% Caucasians, and 13% Asians carry this type of gene.

Recommendations for healthy Vitamin B6 levels

• It is recommended that you get a major amount of your B6 needs from the foods you eat. You can include fresh fruits, vegetables, grains, protein-rich meat, legumes and nuts and seeds to get vitamin B6 naturally.
• Get your genetic testing done to see if you are likely to require more vitamin B6. If so, compensate with B6 supplements and fortified foods.
• People with renal diseases and those with autoimmune disorders both have to talk to their doctors to understand if their B6 needs are higher. 
• Talk to your doctor to know if your current medications interfere with vitamin B6 absorption in the body. If so, match the needs by choosing fortified foods.
• Opting for a broad B complex supplement will ensure all your B vitamin levels including B6 are in the right ranges. 

Summary

1. Vitamin B6 is a water-soluble nutrient available in food sources like poultry, red meat, legumes, grains, and fruits and vegetables. 
2. Prolonged or extreme vitamin B6 deficiency can show out symptoms like dermatitis, lowered immunity levels, mouth ulcers, and neurological conditions like depression and confusion.
3. While moderately excess amounts of vitamin B6 are relatively safe, extremely high doses can cause uncontrolled body movements, photosensitivity, and gastric issues.
4. Some of the common causes of vitamin B6 deficiency are bad diet habits, excessive smoking, the presence of renal and autoimmune diseases, and the use of certain types of medications. 
5. Some people are genetically designed to have lower absorption rates of vitamin B6 in the body. They will have to compensate with fortified foods and supplements.

References

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1265394/?page=1

https://pubmed.ncbi.nlm.nih.gov/23183295/

https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/vitamin-b-complex.html

https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/

https://www.massgeneral.org/children/autism/lurie-center/vitamin-b6

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6357176/

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/alpl