The B complex vitamins form a group of 8 vitamins (thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, and cobalamin) related to cell metabolism. At first, it was believed that it was only one vitamin, but later it was discovered that there are in fact several, with similar functions. They are water-soluble, so they can be lost in the cooking water and, if taken in excess, they are eliminated in the urine (up to a certain limit). It plays an important role in the reactions of energy metabolism, folate synthesis, maturation of hematopoiesis, and integrity of myelin in the central nervous system. The most important natural sources of Vitamin B are yeast, seeds, eggs, liver, meat, and vegetables.
Deficiency of these vitamins usually occurs due to malnutrition. In general, the absorption of the B complex components is rapid, although limited for thiamine and riboflavin. It is important to bear in mind that although this complex can be obtained through food, factors such as cigarettes, alcohol, an unbalanced diet (preservatives, trans fats, colorants, high consumption of flour), low hydration, stress, lack of exercise, and sleep can decrease its absorption, storage, and functions, so it is necessary to replace it through a proper diet.
The Eight Vitamins That Make Up The B Complex
Vitamin B1 – Thiamine
Its absorption occurs in the small intestine (jejunum, ileum) as free thiamine and as thiamine diphosphate (TDP), which is favored by the presence of vitamin C and folic acid but inhibited by the presence of ethanol. It is necessary for the daily diet of most vertebrates and some microorganisms. Its deficiency in the human body causes diseases such as beriberi and Korsakoff syndrome. Chemically, it consists of two interconnected organic cyclic structures: a pyrimidine ring with an amino group and a sulfur thiazole ring linked to the pyrimidine by a methylene bridge. It is found in beer yeast, wheat, cereal germ, pork, liver and kidneys, fish, whole wheat bread, cooked beans, milk, and its derivatives.
B2 – Riboflavin
Vitamin B2 is a yellow water-soluble vitamin, made up of a dimethylated isoalloxazine ring to which ribitol, an alcohol derived from ribose, binds. The three rings make up isoalloxazine and ribitol is the 5-carbon chain at the top. It is a key element in the transformation of food into energy since it favors the absorption of proteins, fats, and carbohydrates. This vitamin is found in its natural state in dry yeast, liver, cheeses, eggs, mushrooms, yogurt, milk, meat, fish, cereals, whole wheat bread, and cooked vegetables. The absence of B2 can cause anemia, liver disorders, conjunctivitis, dryness, dermatitis of the skin and mucous membranes, as well as ulcers in the mouth.
B3 – Niacin
It acts on cell metabolism as part of the coenzyme NAD and NADP. It is absorbed by passive diffusion, it is not stored and the surpluses are eliminated in the urine. Its derivatives, NADH and NAD +, and NADPH and NADP +, are essential in the energy metabolism of the cell and the repair of DNA. Niacin’s functions include the removal of toxic chemicals from the body and its involvement in the production of steroid hormones synthesized by the adrenal gland, such as sex hormones and stress-related hormones. It can be found in vegetables, grains, and mushrooms.
B5 – Pantothenic Acid
It is widely distributed in both the plant and animal kingdoms and is abundant in meat, vegetables, cereal grains, legumes, eggs, and milk. Vitamin B5 is commercially available as the D isomer of pantothenic acid, and also as dexpanthenol and as calcium pantothenate, which are chemicals synthesized in the laboratory from the D isomer of pantothenic acid. Severe deficiency can cause numbness and burning sensation in the hands and feet, headache, extreme tiredness, irritability, restlessness, trouble sleeping, stomach pain, heartburn, diarrhea, nausea, vomiting, and loss of appetite.
B6 – Pyridoxine
It is transformed in the body into its active forms pyridoxal-phosphate, and to a lesser extent, into pyridoxamine phosphate. These forms participate as enzymatic cofactors in numerous biochemical reactions involved in the metabolism of proteins and amino acids, and to a lesser extent, in that of lipids and carbohydrates. It also participates in the synthesis of nucleic acids and hemoglobin. Vitamin B6 deficiency can lead to anemia, itchy rashes, flaky lips, cracks at the corners of the mouth and swollen tongue, depression, confusion, and a weakened immune system.
B7 – Biotin
It is involved in extremely important metabolic processes such as the transformation of carbohydrates, fats, and proteins into energy. Besides, it participates in numerous chemical reactions such as gluconeogenesis. It is composed of a imidazoline ring fused with a tetrahydrothiophene ring. A substitute valeric acid binds to one of the carbon atoms of the tetrahydrothiophene ring. There are three forms of biotin: free biotin, biocytin (e-biotin-L-Lysine), and two sulfoxides L and D of biotin. Biotin deficiency can cause thinning of the hair and loss of body hair; skin rash around the eyes, nose, mouth, and anal area; styes; high concentrations of acid in the blood and urine; seizures; skin infection; brittle nails; and nervous system disorders.
B9 – Folic Acid
It is necessary for the production and maintenance of new cells. This is especially important during periods of rapid cell growth and division such as infancy and pregnancy. Folate is necessary for DNA replication. Folic acid deficiency can cause megaloblastic anemia, glossitis and gastrointestinal problems, elevated plasma homocysteine concentration and is a risk factor for birth defects. Foods where it can be found naturally are: vegetables, liver, legumes, however, folates can be destroyed by cooking at high temperatures or by reheating food.
B12 – Cobalamin
Cobalamin is a stable organic compound containing a cobalt atom, known as pernicious antianemic factor, Castle factor, or animal protein factor. Vitamin B12 plays a fundamental role in the formation of blood cells, nerve envelopes, and various proteins. It participates in the metabolism of carbohydrates and lipids and is essential for the normal growth of the body. In particular, adenosylcobalamin is the coenzyme for the isomerization of 1-methylmalonyl coenzyme A with succinyl-CoA, an important reaction for lipid and glucose metabolism. Other important reactions in which vitamin B12 participates are the biosynthesis of methionine and acetate, in the synthesis of polyglutamate folates, and in the regeneration of folic acid during the formation of erythrocytes. Its deficiency causes anemia and serious neurological disorders.