A Complete Guide to B Vitamins

by The Puritan's Pride Editorial Team

Eight is enough!  Or is it?  Let’s explore an important octet of beneficial vitamins known as the B-Complex.

The eight vitamins included in the B-Complex are a group of water-soluble compounds obtained through the diet that play important roles in various metabolic processes at the cellular level.  Some you may know by their numerical distinctions (such as B-6 and B-12), and some you may know by other names.  Each B vitamin is chemically distinct, functioning as either a cofactor for metabolic processes or a precursor that’s necessary for the formation of other B vitamins.

If you already associate Vitamin B-12 with energy, then you’re on the right track; vitamins in the B-Complex help maintain energy metabolism by aiding in the breakdown of sugars, fats, carbohydrates, proteins and amino acids to convert food into energy.* They also collaborate with one another to support nervous system health, and they even provide nourishment for the occasional stress of daily living.*  For this reason, B-Complex nutritional supplements are often grouped together under terms like ‘Stress Complex.’

Here’s a breakdown of all B Vitamins, including the four that are no longer considered a part of the B-Complex.

Vitamin B-1

Also known as:  Thiamin or Thiamine

Dietary sources include:  Pork, seeds, cantaloupe, lentils, bread, green peas, and long-grain rice.1

How it works:  Thiamin serves as a cofactor for 4 enzymes that are involved in the catabolism of sugars and amino acids.

Recommended daily intake for adults: 1.1 mg (women), 1.2 mg (men).  Athletes and those engaged in intense exercise may require additional thiamin intake.

Other notes:  Thiamin is on the World Health Organization’s List of Essential Medicines – the most effective and safe medicines needed in a health system.2 Some countries even require its addition to certain foods, such as grains.

Vitamin B-2

Also known as:  Riboflavin

Dietary sources include:  Eggs, green vegetables, milk, and meat.3

How it works:  Riboflavin functions as a precursor of 2 coenzymes necessary for oxidation-reduction reactions in numerous metabolic pathways.  It is also required by the body for cellular respiration.

Recommended daily intake for adults:  1.1 mg (women), 1.3 mg (men).

Other notes:  The name Riboflavin comes from ‘ribose’ – the sugar whose reduced form, ribitol, forms part of its structure.4 Because riboflavin is fluorescent under UV light, it’s often used to detect leaks in industrial systems such as bioreactors.

Vitamin B-3

Also known as:  Niacin or Nicotinic Acid

Dietary sources include:  Niacin is found in protein-rich foods such as tuna, turkey, ground pork and veal, plant foods such as lentils and lima beans,  and even coffee.  It is also commonly present in enriched bread products and fortified cereals.5

How it works:  Niacin is part of a coenzyme needed for carbohydrate and protein metabolism that helps support cellular growth.

Recommended daily intake for adults:  14 mg (women), 16 mg (men).

Other notes:  Between 1906 and 1940 more than 100,000 Americans died from niacin deficiency, known as pellagra.  In the late 1930’s, research scientists identified niacin as a cure for pellagra, and today deficiency is uncommon in the developed world.6

Vitamin B-4

B-4 is a former designation given to the 3 chemical compounds adenine, carnitine, and choline. These three compounds are no longer considered true vitamins.7

Vitamin B-5

Also known as:  Pantothenic Acid

Dietary sources include:  Small quantities are found in nearly every food, with the highest amounts in beef liver, sunflower seeds, and fish.8

How it works:  Pantothenic Acid is converted to coenzyme A in the body, which is important for many reactions involved in energy metabolism.*

Recommended daily intake for adults:  5mg.

Other notes:  The name derives from the Greek pantothen, meaning ‘from everywhere.’

Vitamin B-6

Also known as:  Pyridoxine

Dietary sources include:  Foods that contain large amounts of B-6 include turkey, salmon, bananas, hazelnuts, potatoes and pistachios.9

How it works:  Vitamin B-6 plays a role in protein and carbohydrate metabolism by processing amino acids from food for energy production.  It also supports hearth health, eye health, and is involved in melatonin production.*

Recommended daily intake for adults:  1.3 mg for men and women ages 18-50.  1.5 mg for women 51+, and 1.7mg for men 51+.

Other notes:  Among the most versatile of B vitamins, B-6 is involved in more than 100 enzymatic reactions in the body, most of which involve protein metabolism.*

Vitamin B-7

Also known as:  Biotin

Dietary sources include:  Biotin is found in foods such as whole wheat bread, raspberries, cheese, and pork.10

How it works:  Biotin is a coenzyme involved in the metabolism of proteins, carbohydrates, fats, and amino acids.
Recommended daily intake for adults:  30mcg.

Other notes:  Biotin was formerly known as Vitamin H, derived from haar und haut – German words for ‘hair and skin.’  Biotin supplements are most commonly used to support healthy hair and skin.*

Vitamin B-9

Also known as:  Folic Acid or Folate

Dietary sources include:  Folic Acid occurs naturally in a wide variety of foods, especially in dark green leafy vegetables, fruits, nuts, beans, peas, dairy products, poultry, eggs, seafood, grains, and even some beers.

How it works:  Folic Acid is necessary for the formation and repair of DNA.  As a cofactor, it is particularly important in the rapid cell division necessary for growth.

Recommended daily intake for adults:  400 mcg.

Other notes:  Healthful diets with adequate folate may reduce a woman’s risk of having a child with a brain or spinal cord birth defect.  B-9 is also part of a triad of B vitamins (along with B-6 and B-12) that helps promote heart health.*

Vitamin B-10

Better known as PABA (para-aminobenzoic acid), it’s no longer considered a B vitamin, but rather a ‘B Vitamin Factor’ and an intrinsic component of the folic acid (B-9) molecule.

Vitamin B-11

Another name for salicylic acid – also no longer considered a B vitamin.  White Willow Bark is a common supplemental source of salicylic acid.11

Vitamin B-12

Also known as:  Cyanocobalamin

Dietary sources include:  B-12 can be obtained from animal sources, but it’s not found in vegetables in any significant amount.  Foods such as clams, crab, beef, salmon, chicken, and eggs contain particularly high concentrations of B-12.

How it works:  Vitamin B-12 is a coenzyme involved in the metabolism of every cell in the human body; it is particularly involved in metabolic reactions affecting DNA synthesis and amino acids.*

Recommended daily intake for adults:  2.4 mcg.

Other notes:  B-12 may not be as readily absorbable from the digestive system as we age.  It’s recommended that adults over 50 years of age get most of the recommended intake of B-12 from fortified food or supplements.12

Click Here to Browse B Vitamins at Puritan’s Pride


  1. http://lpi.oregonstate.edu/mic/vitamins/thiamin#food-sources
  2. http://www.who.int/medicines/publications/essentialmedicines/EML2015_8-May-15.pdf
  3. http://lpi.oregonstate.edu/mic/vitamins/riboflavin#food-sources
  4. http://www.ijppsjournal.com/Vol4Issue3/3806.pdf
  5. http://lpi.oregonstate.edu/mic/vitamins/niacin#food-sources
  6. https://med.libretexts.org/LibreTexts/Sacramento_City_College/SCC%3A_Nutri_300_(Coppola)/Chapters/07%3A_Vitamins/7.3%3A_Water_Soluble_Vitamins/Vitamin_B3_(Niacin)
  7. http://onlinelibrary.wiley.com/doi/10.1080/15216540500078939/pdf
  8. http://lpi.oregonstate.edu/mic/vitamins/pantothenic-acid#food-sources
  9. http://lpi.oregonstate.edu/mic/vitamins/vitamin-B6#food-sources
  10. http://lpi.oregonstate.edu/mic/vitamins/biotin#food-sources
  11. https://www.ncbi.nlm.nih.gov/pubmed/20509453
  12. http://lpi.oregonstate.edu/mic/vitamins/vitamin-B12#food-sources