B vitamins

B vitamins refer to  a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells.

B vitamins share similar names (B1, B2, B3, etc.).

B vitamins are chemically distinct individual compounds that often coexist in the same foods.

The 8 B vitamins are referred to as a vitamin B complex. 

Individual B vitamins are referred to by the specific number or name of each vitamin, such as B1 for thiamine, B2 for riboflavin, and B3 for niacin, etc.

Some B vitamins are more commonly recognized by name than by number, for example pantothenic acid, biotin, and folate.

Each B vitamin is either a cofactor/coenzyme for key metabolic processes or is a precursor needed to make one and is thus an essential nutrient.

Vitamin B1 is Thiamine, a coenzyme in the catabolism of sugars and amino acids.

Vitamin B2 is Riboflavin, a precursor of coenzymes called FAD and FMN, which are needed for flavoprotein enzyme reactions, including activation of other vitamins.

Vitamin B3 Niacin (nicotinic acid), is a precursor of coenzymes called NAD and NADP, which are needed in many metabolic processes.

Vitamin B5 Pantothenic acid A precursor of coenzyme A and therefore needed to metabolize many molecules.

Vitamin B6 – Pyridoxine is a coenzyme in many enzymatic reactions in metabolism.

Vitamin B7 Biotin A coenzyme for carboxylase enzymes, needed for synthesis of fatty acids and in gluconeogenesis.

Vitamin B9 Folate A precursor needed to make, repair, and methylate DNA; a cofactor in various reactions; especially important in aiding rapid cell division and growth, such as in infancy and pregnancy.

Vitamin B12 Cobalamins Commonly cyanocobalamin or methylcobalamin in vitamin supplements. 

It is a coenzyme involved in the metabolism of every cell of the human body, especially affecting DNA synthesis and regulation, but also fatty acid metabolism and amino acid metabolism.

B-vitamin numbering scheme, has been altered by the subsequent  discovery of some compounds to be either not essential for life or manufactured by the body, thus not meeting the two essential qualifiers:  for a numbers 4, 8, 10, 11, and others.

B vitamins are found in highest abundance in certain edible insects such as termites.

B vitamins are abundant in meat, eggs, and dairy products.

Processed carbohydrates such as sugar and white flour tend to have lower B vitamin than their unprocessed counterparts. 

It is required that the B vitamins thiamine, riboflavin, niacin, and folic acid be added back to white flour after processing: enriched flour.

B vitamins are particularly concentrated in meat such as turkey, tuna and liver.

Sources for B vitamins also include spinach, legumes, whole grains, asparagus, potatoes, bananas, chili peppers, breakfast cereals.

The B12 vitamin is not abundantly available from plant products.

B12 deficiency a legitimate concern for those maintaining a vegan diet. 

Increasing vitamin B intake can be achieved by using dietary supplements. 

B vitamins are commonly added to energy drinks.

Being soluble in water, excess B vitamins are generally readily excreted,.

Athletes and elderly may need to supplement their intake of B12 and other B vitamins due to problems in absorption and increased needs for energy production.

In cases of severe deficiency, B vitamins, especially B12, may also be delivered by injection.

Diabetics may supplement thiamine based on high prevalence of low plasma thiamine concentration and increased thiamine clearance associated with diabetes.

Folate deficiency in early embryo development has been linked to neural tube defects, and pregnant women are encouraged to increase daily dietary folate intake or take a supplement.

Vitamin B1 Thiamine has a central role in the release of energy from carbohydrates. 

Thiamine is involved in RNA and DNA production, as well as nerve function. 

Thiamine active form is a coenzyme thiamine pyrophosphate (TPP), which takes part in the conversion of pyruvate to acetyl coenzyme A in metabolism.

Riboflavin, vitamin B2 is involved in release of energy in the electron transport chain, the citric acid cycle, as well as the catabolism of fatty acids.

Vitamin B3 Niacin is composed of two structures: nicotinic acid and nicotinamide. 

The two co-enzyme forms of niacin are nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).

NAD) and nicotinamide adenine dinucleotide phosphate (NADP) 

play an important role in energy transfer reactions in the metabolism of glucose, fat and alcohol.

NAD carries hydrogens and their electrons during metabolic reactions, including the pathway from the citric acid cycle to the electron transport chain. 

NADP is a coenzyme in lipid and nucleic acid synthesis.

Vitamin B5 Pantothenic acid is involved in the oxidation of fatty acids and carbohydrates. 

Coenzyme A, which can be synthesised from pantothenic acid, is involved in the synthesis of amino acids, fatty acids, ketone bodies, cholesterol, phospholipids, steroid hormones, neurotransmitters, such as acetylcholine, and antibodies.

Vitamin B6 Pyridoxine, pyridoxal, pyridoxamine

The active form pyridoxal 5′-phosphate (PLP) serves as a cofactor in many enzyme reactions mainly in amino acid metabolism including biosynthesis of neurotransmitters.

Vitamin B7-Biotin plays a key role in the metabolism of lipids, proteins and carbohydrates. 

Biotin is a critical co-enzyme of four carboxylases: 

acetyl CoA carboxylase, which is involved in the synthesis of fatty acids from acetate.

pyruvate CoA carboxylase, involved in gluconeogenesis.

β-methylcrotonyl CoA carboxylase, involved in the metabolism of leucine.

Propionyl CoA carboxylase, which is involved in the metabolism of energy, amino acids and cholesterol.

Vitamin B9-Folate

Folate acts as a co-enzyme in the form of tetrahydrofolate (THF), which is involved in the transfer of single-carbon units in the metabolism of nucleic acids and amino acids. 

THF is involved in purine and pyrimidine nucleotide synthesis, is required for normal cell division, especially during periods of rapid growth like pregnancy and infancy.  

Folate also aids in the production of red blood cells.

Vitamin B12-Cobalamin- is involved in the cellular metabolism of carbohydrates, proteins and lipids, and is essential in the production of blood cells in bone marrow, and for nerve sheaths and proteins.

Some vitamin deficiency diseases may result from the lack of sufficient B vitamins. 

Deficiencies of other B vitamins can result in symptoms that are not part of a named deficiency disease.

Vitamin B1 Thiamine deficiency causes beriberi. 

Symptoms of this nervous system include weight loss, emotional disturbances, Wernicke encephalopathy, impaired sensory perception, weakness and pain in the limbs, periods of irregular heartbeat, and edema. 

In advanced cases, heart failure and death may occur 

Chronic thiamine deficiency can cause the alcoholic related Korsakoff syndrome, an irreversible dementia characterized by amnesia and compensatory confabulation.

Vitamin B2-Riboflavin deficiency can cause ariboflavinosis, which may result in cheilosis, sensitivity to sunlight, angular cheilitis, glossitis, seborrheic dermatitis or pseudo-syphilis, pharyngitis, hyperemia, and edema of the pharyngeal and oral mucosa.

Vitamin B3-Niacin deficiency, along with a deficiency of tryptophan, causes pellagra. 

Symptoms include aggression, dermatitis, insomnia, weakness, mental confusion, and diarrhea. 

In advanced cases, pellagra may lead to dementia and death;

Vitamin B5 Pantothenic acid deficiency can result in acne and paresthesia, although it is rare

Vitamin B6 Pyridoxine deficiency causes seborrhoeic dermatitis-like eruptions, pink eye and neurological symptoms.

Vitamin B7 Biotin deficiency does not typically cause symptoms in adults, other than cosmetic issues such as decreased hair and nail growth,

but may lead to impaired growth and neurological disorders in infants. 

Folate Folic acid deficiency results in a macrocytic anemia, and elevated levels of homocysteine. 

Deficiency in pregnant women can lead to birth defects, particularly neural tube defects such as spina bifida and anencephaly.

Vitamin B12 Cobalamins Vitamin B12 deficiency results in a macrocytic anemia, elevated methylmalonic acid and homocysteine, peripheral neuropathy, sense loss, change in mobility, memory loss and other cognitive deficits. 

Vitamin B12 deficiency is most likely to occur among elderly people.

Its absorption through the gut declines with age.

The  autoimmune disease pernicious anemia is another common cause. 

Vitamin B12 deficiency also cause symptoms of mania and psychosis, irreversible damage to the brain and nerve system, including paralysis.

Because water-soluble B vitamins are eliminated in the urine, taking large doses of certain B vitamins usually only produces transient side effects, only exception is pyridoxine.

General side effects of excessive dosage may include restlessness, nausea and insomnia. 

These side effects are almost always caused by dietary supplements and not food.

Vitamin Upper Intake Level (UL) Harmful effects:

Vitamin B1 None

Vitamin B2 None

Vitamin B3 US Intake of 3000 mg/day of nicotinamide and 1500 mg/day of nicotinic acid are associated with nausea, vomiting, and signs and symptoms of liver toxicity. 

Other effects: glucose intolerance, and ocular effects.

The nicotinic acid form may cause vasodilatory effects, also known as flushing, including redness of the skin, often accompanied by an itching, tingling, or mild burning sensation, pruritus, headaches, and increased intracranial blood flow, and occasionally accompanied by pain.

Vitamin B5 None No toxicity known.

Vitamin B6 in excess associated with neurological impairment.

Vitamin B7 None No toxicity known.

Folate excess masks B12 deficiency, which can lead to permanent neurological damage.

Vitamin B12 None established


Leave a Reply

Your email address will not be published. Required fields are marked *