Vitamins

Scientists studying why animals failed to thrive (deficiency diseases) were the first to discover vitamins. In 1905, one of these early researchers, Cornelius Adrianus Pekelharing, discovered that milk had some unrecognised substance, in very small quantities, that was helpful for normal growth and maintenance of an organisms body.

In 1912, while studying rice, Casimir Funk isolated an organic substance which he described as amine (like an amino acid). Because it was vital to life, he combined the two words to coin the term ‘vitamine’.

The idea to use the now-familiar lettering system can be traced to Cornelia Kennedy who, in her master’s thesis in 1916, was the first “to use ‘A’ and ‘B’ to designate the new dietary essentials.”

Over time, others, including Kennedy’s mentor Elmer McCollum (credited with discovering vitamin A), began incorrectly citing McCollum’s early work as the original source for the classification.

At first, in addition to their alphabet letters, the ‘vitamines’ were also identified as either fat- or water- soluble. In 1920, Jack Cecil Drummond suggested dropping the “e” from vitamine to distinguish vitamins from amines and discarding the adjective soluble.

The five first vitamins discovered, between 1910 and 1920, were named A, B, C, D and E. Vitamin D was originally incorporated with A until it was later discovered that two separate substances were involved.

When a second, similar property to the vitamin originally named B1 (thiamine) was discovered in 1920, both were renamed to B1 (thiamine) and B2 (riboflavin).

The remaining B vitamins were grouped together under the classification of “B complex” due to loose similarities in their properties, their distribution in natural sources and their physiological functions which often rely upon the others being present.

These B complex vitamins are not designated in chronological order, as B12 (cobalamins) was discovered in 1926, B5 (pantothenic acid) and B7 (biotin) in 1931, B6 (pyridoxine) in 1934, B3 (niacin) in 1936 and B9 (folic acid) in 1941. The missing B numbers are substances originally thought to be vitamins, but later reclassified.

Today’s vitamins skip from E to K because, like several of the Bs, substances that were once thought to be vitamins were reclassified. For example, vitamin F is today known as the essential fatty acids (omega-3 and omega-6). Similarly, vitamin G was reclassified as vitamin B2 (riboflavin), and vitamin H is now vitamin B7 (biotin).

Vitamin list

*Some of the B vitamins are no longer called vitamins as they were removed once scientists discovered they were not actually vitamins at all. Two examples are vitamin B4 which is now known as adenine and vitamin B13 now known as orotic acid.

Former vitamins

• Vitamin B4* See>> Adenine
• Vitamin B8 (inositol)
• Vitamin B10 (pteroylmonoglutamic acid)
• Vitamin B11 (pterylheptaglutamic acid)
• Vitamin B13 (oratic acid)
• Vitamin B14 (xanthopterin)
• Vitamin B15 (pangamic acid)
• Vitamin B16, (dimethylglycine, DMG)
• Vitamin B17 (amygdaline)
• Vitamin F See>> Fatty acids
• Vitamin P citrin See>> Flavonoids

Vitamins are organic compounds that are vital for various bodily functions but cannot be synthesised by the human body so are required in the diet. Some substances were initially thought of as being vitamins due to their important roles in the body but then it was discovered that some could be manufactured in the body, so they were reclassified. Others are synthetically made.

Vitamin B8 (inositol) was previously classified as a B vitamin, it’s now understood that the body can produce it from glucose, meaning it is not essential in the diet.

Vitamin B10 (para-aminobenzoic acid) was once considered a B vitamin, but it is now recognised as a non-essential nutrient and is not required in the human diet. It’s a component of folic acid and can be synthesised by gut bacteria.

Vitamin B11 (pteroylmonoglutamic acid) is not a distinct vitamin but rather an older name for the synthetic form of vitamin B9, which is folic acid.

Vitamin B13 (oratic acid) is a molecule synthesised in the body during the process of pyrimidine biosynthesis. It’s created from carbamoyl phosphate and aspartic acid via dihydroorotic acid. This process occurs primarily in the cytoplasm and mitochondria.

Vitamin B14 (xanthopterin) is not an established vitamin, and little is known about it. Older literature mentions a substance isolated from wine that was speculated to be a metabolite of xanthopterin, but little research has been done to analyse it since.

Vitamin B15 (pangamic acid) was initially discovered by Russian scientists who claim it is advantageous to athletes, but little research has been done in the Western world to establish this, so it is no longer considered a vitamin.

Vitamin B16, (dimethylglycine, DMG), is not a true vitamin because it’s produced in the body and its deficiency doesn’t lead to any known ill effects. DMG is synthesised during the metabolism of choline and is also found in certain foods. Specifically, it’s formed when choline donates a methyl group to another molecule, becoming betaine, and then DMG is formed when betaine donates another methyl

Vitamin B17 (amygdaline) is classified as a cyanogenic glycoside, because each amygdalin molecule includes a nitrile group, which can be released as the toxic cyanide anion by the action of a beta-glucosidase. Eating amygdalin will cause it to release cyanide in the human body and may lead to cyanide poisoning. It was touted as a cancer cure but there is no scientific evidence to back this up and it may do more harm than good.

NOTE: The man-made synthetic version of vitamin B3 has anti-vitamin properties meaning it inhibits the absorption of other vitamins and should be avoided. Bran is a food rich in vitamin B3 which is typically lost during the refining process. Anyone who eats high amounts of white bread, white rice, corn syrup or other refined products will not receive adequate amounts of niacin. Even though most of these foods are now fortified, it is still best to eat unrefined food products. See>> Vitamin B3

Vitamins and the intestinal flora

An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesise the compound in sufficient quantities and therefore must be obtained through the diet. Consequently, the name vitamin is conditional upon the whether the organism’s body can manufacture the compound and the particular organism involved.

For example, vitamin C (ascorbic acid) is a vitamin for humans, but not for most other animal organisms. It has been discovered that the human body can synthesise A, B1, B3, B7 and K2 through their gut microbiota and hence they were declassed.

Although the gut microbiota also produces vitamin B12, it is manufactured below the ileum in the intestines so cannot be absorbed. The gut microbiota uses for its own processes and the body must get it from food sources instead therefore it is a vitamin.

Antioxidants

Antioxidants are nutrients, including vitamins and minerals, as well as enzymes, that assist in chemical reactions. Find out what they are and their functions: Antioxidants

Nutrient storage

Human bodily stores for different vitamins vary widely; vitamins A (retinol), vitamin D and vitamin B12 (cyanocobalamin) are stored in significant amounts in the human body, mainly in the liver. However, an adult human’s diet may be deficient in vitamins A and D for many months and B12 in some cases for years, before developing a deficiency condition.

Substances stored by the liver

• Copper
• Glucose (in the form of glycogen)
• Iron
• Vitamins A (1–2 years supply)
• Vitamin D (1–2 months’ supply)
• Vitamin B12 (1–3 years supply)
• Vitamin K

Because water soluble vitamin C and most of the vitamin B complex dissolve in water upon entering the body they cannot be stored for later use. They are eliminated in the urine and sweat meaning a constant daily supply is required.

Vitamins B3 (niacin and niacinamide) is not stored in the human body in significant amounts, so stores may only last a couple of weeks.

These vitamins are all essential for many important cellular processes involving the nervous system, the immune system and the production and maintenance of neurotransmitters, antibodies, hormones, cells, messenger proteins, tissues, bones, skin, teeth and blood vessels.

They are also essential for the utilisation and manufacture of many other organic nutrients and non-organic minerals.

Vitamin D deficiency

Vitamin D deficiency is a condition which those that avoid the sun, use sunscreens, cover up with clothing or stay indoors are particularly prone to. It can lead to a poor immune system and problems with bones, joints and teeth.

Just 10-15 minutes of midday sunshine on the skin can provide all that is required. The suns action on the skin cannot work through windows. Foods rich in vitamin D must be consumed during the winter months. See Vitamin D

Related subjects

• A-Z of nutrients
• About nutrients
• Minerals
• Nutrient deficiencies

External references

University of Michigan. Vitamin B-Complex. http://www.uofmhealth.org/health-library/hn-2922005

Office of Dietary Supplements. Vitamin B12. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

Office of Dietary Supplements. Vitamin B6. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/

Office of Dietary Supplements. Thiamin. https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional

University of Maryland. Vitamin B2 (Riboflavin). http://umm.edu/health/medical/altmed/supplement/vitamin-b2-riboflavin

University of Maryland Medical Center. Vitamin B3 (Niacin). http://www.umm.edu/health/medical/altmed/supplement/vitamin-b3-niacin

Daul, A. & Beuhler, M. (2011). Niacin toxicity resulting from urine drug test evasion. https://www.ncbi.nlm.nih.gov/pubmed/20138459

The Mayo Clinic. Vitamin B6 (pyridoxine). http://www.mayoclinic.org/drugs-supplements/vitamin-b6/safety/hrb-20058788

Sharp, A. & Fedorovich, Y. (2015). Teratogenic effects of pyridoxine on the spinal cord and dorsal root ganglia of embryonic chickens.