What do the B vitamins each do?

B complex is not one substance. It is a group of water-soluble vitamins that tend to occur in the same foods.

What does each one do?

Under the annex to Thai Ministry of Public Health Notification No. 447 (B.E. 2566):

B1, thiamine contributes to normal energy-yielding metabolism from carbohydrate, to the normal function of muscle and the nervous system, and to the normal function of the heart.

B2, riboflavin contributes to normal energy-yielding metabolism from carbohydrate, protein and fat, and to the maintenance of normal red blood cells, skin, mucous membranes and vision.

B3, niacin contributes to normal energy-yielding metabolism, to the normal function of the nervous system, and to the maintenance of normal skin and the mucous membrane of the GI tract.

B5, pantothenic acid contributes to normal energy-yielding metabolism.

B6 contributes to normal red blood cell formation and to the normal function of the nervous and immune systems.

B9, folate contributes to normal red blood formation and normal amino acid synthesis.

B12 contributes to the normal function of the brain and nervous system, and to the synthesis of an essential substance for red blood cell formation.

Biotin contributes to the maintenance of normal hair, skin and mucous membranes.

Why are they sold together?

Because they occur together in the same foods, and several of them work in the same metabolic pathways, so they are commonly formulated as one product.

What does "normal energy-yielding metabolism" mean?

It means these vitamins are involved in the processes by which the body turns food into usable energy.

Where do they come from in food?

Wholegrains, meat, liver, eggs, milk, dried beans, nuts and leafy greens.

B12 occurs only in animal foods and fortified products, so anyone eating a strict vegetarian diet needs to plan for it.

Do they need to be taken daily?

Most B vitamins are water-soluble and the body stores little of them. B12 is the exception and is held in the liver for longer. Regular intake matters more than large occasional amounts.

Dietary supplements are not intended to prevent, treat or cure any disease.