Niacin, colloquially known as B3, was discovered via signs and symptoms of its deficiency; a condition known as pellagra. Pellagra was a prominent condition in the United States prior to the discovery of B3(Gropper, Smith, & Carr, 2018). As a means of appreciating niacin and its relationship to pellagra, the following will explore the same, in addition to sources of niacin and recommended dosages.
Niacin is a generic term to describe two forms of B3: nicotinic acid (has a carboxyl group) and nicotinamide (has an amide group) (Gropper et al., 2018). B3 can be found most abundantly in fish and meats with particularly high levels in organ meats such as liver. Furthermore, B3 is also produced endogenously along the large intestine and within the liver (Gropper et al., 2018). Niacin is central to maintenance of health as it is involved in the synthesis and function of over 200 enzymes within the body. As such, deficiencies in said B vitamin can induce a cascade of unfavorable physiological events, such as pellagra (Gropper et al., 2018).
Signs of pellagra include dermatitis, dementia, diarrhea, and in its most severe manifestation, death (Gropper et al., 2018). Early signs of pellagra are reminiscent of sunburn, which progresses to a hyperpigmented color with a scaly surface (Gropper et al., 2018). Gropper et al. (2018) noted that areas exposed to the sun are often regions that pellagra forms to include the face, neck, elbows, knees, and feet. The following will consider the four signs of Pellagra in greater detail.
Dermatological changes, especially those about the neck, is referred to as Casal’s collar (Gropper et al., 2018). Neurological changes can include headache, fatigue, apathy, peripheral neuritis, confusion, paralysis of extremities, disorientation, and dementia (Gropper et al., 2018). Gastrointestinal manifestations of pellagra include vomiting, nausea, glossitis, cheilosis, inflammation, and diarrhea (Gropper et al., 2018). Left untreated, the final and ultimate progression of pellagra is death. Having considered sings of pellagra, the following will consider causes behind niacin deficiency.
Medications can often be a root cause behind pellagra as they can interfere with niacin absorption. For example, an anti-tuberculosis drug known as isoniazid binds to B6, which inhibits an enzyme (PLP-dependent kynureninase) necessary for niacin synthesis from the amino acid tryptophan (Gropper et al., 2018). Mercaptopurine, a medication used for the treatment of cancer, inhibits an enzyme (NAD phosphorylase) responsible for synthesis of nicotinamide adenine dinucleotide phosphate (NADP) of which nicotinamide is involved (Gropper et al., 2018). Absorption issues at the level of the gut also inhibit niacin and tryptophan uptake such as intestinal cancers, irritable bowel syndrome, and Hartnup disease (genetic disorder affecting absorption of amino acids, to include tryptophan) (Gropper et al., 2018).
Once pellagra is identified, addressing the underlying niacin deficiency is key. As such, Gropper et al. (2018) recommended 300 mg/day of nicotinamide divided over 3 doses per day at 100mg per dose for approximately one month. Once signs and symptoms of pellagra have subsided, recommended dietary allowances (RDA) of said micronutrient is suggested to be 16 mg/day for males and 14 mg/day for females. Whole food sources can include meat, fish, and organs such as liver.
In conclusion, pellagra is a condition manifested from niacin deficiency stemming from inadequate consumption and/or absorption of said micronutrient. Left untreated, pellagra can cause dermatitis, dementia, diarrhea, and in its most severe manifestation, death. Once pellagra is identified, a detailed review of medications, gut health, and nutrition is key as first steps in treating the illness. Such an approach should help inform and guide niacin supplementation, ultimately liberating individuals from B3deficiency.
References
Gropper, S. S., Smith, J. L., & Carr, T. P. (2018). Advanced nutrition and human metabolism(7thed.). Boston, MA: Cengage Learning.
-Michael McIsaac