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Vitamin B3

life science Maturity 11-13 Next article →

Vitamin B3 is a vital family of nutrients required for human life. It consists of three distinct forms, known as vitamers: nicotinic acid, nicotinamide, and nicotinamide riboside. These vitamers are essential because the human body cannot produce them on its own. Instead, the body must obtain them through diet or use the amino acid tryptophan to create them. Once consumed, all three forms are converted into a critical molecule called nicotinamide adenine dinucleotide, or NAD. NAD is a coenzyme that serves as a fundamental building block for many biological processes.

FDA Supplement Facts Label 2016 III
FDA Supplement Facts Label 2016 III

To understand how vitamin B3 works, we must look at the role of NAD. NAD and its phosphorylated version, NADP, act as essential helpers in various chemical reactions. They are used in transfer reactions that assist with DNA repair and calcium mobilization. Furthermore, NAD plays a central role in human metabolism. It acts as a coenzyme in two major energy-producing pathways: glycolysis and the Krebs cycle. These processes allow our cells to convert food into the energy needed to function. Without these specific chemical steps, our cellular machinery would fail.

There are important differences between the specific vitamers of B3. While nicotinic acid and nicotinamide share the same vitamin activity, they behave differently in the body. Nicotinic acid has pharmacological and lipid-modifying effects, meaning it can influence cholesterol levels. However, it can also cause a side effect known as flushing, where the skin becomes red and warm. Nicotinamide does not cause this flushing or affect cholesterol in the same way. Because of this, health organizations like the World Health Organization often recommend nicotinamide to treat deficiencies. This allows patients to receive remedial amounts without the discomfort of skin flushing.

History shows how our understanding of these nutrients has evolved. Scientists identified nicotinamide riboside as a form of B3 as recently as 2004. In 1942, the United States government officially adopted the terms "niacin" and "niacinamide." These names were chosen to prevent the public from confusing the vitamins with nicotine, which is toxic. These terms were later included in the United States Adopted Name dictionary in 1961. Today, the term "niacin" is used internationally by groups like the WHO and FDA. It now broadly includes all dietary precursors that can prevent a B3 deficiency.

A severe lack of vitamin B3 leads to a serious disease called pellagra. Pellagra is characterized by several distinct symptoms, including diarrhea and sun-sensitive dermatitis. This skin condition can cause hyperpigmentation and a thickening of the skin. Patients may also experience inflammation of the mouth and tongue, as well as headaches and tiredness. In more advanced stages, pellagra can cause delirium, dementia, and even death if left untreated.

Pellagra2
Pellagra2

This deficiency is most common in areas where maize, or corn, is a staple food. Because maize is low in digestible niacin, many cultures use a cooking technique called nixtamalization. This process involves treating the maize with alkali ingredients to increase the bioavailability of the vitamin.

Other medical conditions can also impact B3 levels. Hartnup disease is a hereditary disorder where the body fails to absorb the amino acid tryptophan. Because tryptophan is a precursor for niacin, this leads to a deficiency similar to pellagra. Additionally, carcinoid syndrome can cause a deficiency because the body diverts tryptophan to form serotonin instead. To monitor niacin status, scientists do not look at plasma concentrations. Instead, they measure the excretion of a specific metabolite called N1-methyl-nicotinamide in a 24-hour urine collection. For adults, a value below 5.8 μmol/day is considered a deficient status.

Interestingly, the components of vitamin B3 are not unique to Earth. Scientists have detected nicotinic acid and nicotinamide in carbonaceous chondrite meteorites. They have also found these molecules in samples returned from the asteroids 162173 Ryugu and 101955 Bennu. This connection links the fundamental chemistry of human metabolism to the wider composition of our solar system. It shows that the very substances that keep our cells running are also scattered throughout space.

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File:FDA Supplement Facts Label 2016 III.png
FDA Supplement Facts Label 2016 III.png
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File:Inositol nicotinate.png
Inositol nicotinate.png
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