Although vitamin B 1 proved to be a single chemical substance thiamin , vitamin B 2 was ultimately found to be a complex of several chemically unrelated heat-stable factors, including niacin, biotin, and pantothenic acid. Recognition that niacin is a vitamin in the early 20th century resulted from efforts to understand and treat a widespread human disease - pellagra.
American epidemiologist and US Public Health Service officer Joseph Goldberger had been instrumental to elucidating the nutritional basis for pellagra. Goldberger conducted a classic series of observational and experimental studies in humans, combined with an extensive series of experiments with an animal model of the condition black tongue in dogs.
Explain the common physical exam findings associated with niacin deficiency. Outline the importance of collaboration and communication amongst the interprofessional team to improve outcomes for patients affected by niacin deficiency. Niacin or vitamin B3 are generic terms for nicotinic acid and nicotinamide niacinamide.
Niacin was initially referred to as the anti-black tongue factor due to niacin's effect on dogs. In the s, pellagra first appeared in Italy and, the name translates to "pella," skin, and "agra," rough or rough skin. Niacin deficiency can occur from a lack of consuming dietary sources containing niacin.
To a lesser extent, niacin is in coffee, tea, and nuts. During meat processing, nicotinamide adenine dinucleotide NAD and nicotinamide adenine dinucleotide phosphate NADP can become hydrolyzed to free nicotinamide. In some foods, such as corn, niacin can be covalently bound to carbohydrates or small peptides, decreasing the bioavailability for absorption in the small intestines. Therefore, some of the earliest signs of pellagra occurred in populations consuming a high corn-based diet.
In addition to dietary sources, the liver can synthesize niacin from tryptophan; thus, a diet containing both niacin and tryptophan is necessary to maintain adequate niacin levels. Excessive and chronic alcohol intake can induce pellagra due to reducing the absorption of niacin. Alcohol use disorder is associated with increased malnutrition and can impair the conversion of tryptophan to niacin.
Further, Hartnup disease results in impaired tryptophan absorption. Isoniazid binds with vitamin B6 and reduces PLP-dependent kynureninase activity, which is a required substance for niacin synthesis. Niacin deficiency results in the condition of pellagra, which, although uncommon in industrialized nations, may be seen in individuals living in poverty or those with extremely low niacin and protein-deficient diets.
Further, individuals with malabsorption, alcohol use disorder, or taking specific medication are at risk of deficiency. In the United States, pellagra is very rare due to the enrichment of processed flour with B vitamins. In the past, native people in North, Central, and South America consumed maize treated with lime or wood ashes, which increased the bioavailability of niacin in maize. Traditional meals consisted of canned fish and stir-fried roselle, or ivy gourd omelets and mung bean noodle soup, or canned fish curry with chili paste and pumpkin.
Within the United States and industrialized nations, with enrichment of foods and an overall decrease in nutritional deficiency-related diseases, pellagra is rarely seen. Further, there were recent reports of pellagra in refugees. Niacin is important for the metabolism of macronutrients carbohydrate, protein, and fat due to being part of the NAD and NADP coenzymes. Additionally, other mechanisms contribute to niacin deficiency.
Altered metabolism of tryptophan presents in carcinoid syndrome, impaired absorption of tryptophan is seen in the autosomal recessive condition Hartnup disease, and prolonged use of certain medications may decrease the production of tryptophan isoniazid or inhibit the conversion of tryptophan to niacin azathioprine, 6-mercaptopurine, or 5-fluorouracil. Dermatitis in pellagra characteristically demonstrates erythematous bullous changes secondary to mild acute inflammation, which leads to degeneration of the stratum corneum, followed by increased cellularity and fibroblasts, capillary dilation, and increased proliferation and thickening of the epidermis.
Inflammatory cells include lymphoid cells and few plasma cells. Hyperpigmentation also occurs. Inflammation also leads to diarrhea. There are also reports of neuronal chromatolysis in motor neurons and edema in glial and ependymal cells. Pellagra is a condition caused by low levels of niacin or its precursor tryptophan. Niacin deficiency results in the condition of pellagra, which includes the triad or "three D's," dermatitis, dementia, diarrhea, and can result in death.
But tests could find no evidence of any of these. Yes, to solve the puzzle, in , an American doctor called Joseph Goldberger photo, right set out to study pellagra.
He believed there was a dietary cause, and performed experiments on the children in orphanages and patients in mental asylums, many of who were suffering from pellagra. He fed half the patients with a varied diet of fresh meat, vegetables, milk and eggs, while the other unlucky half received the normal diet of mostly maize. He had proven the link between pellagra and diet! To find that, he needed to do more experiments, this time on prisoners.
He managed to induce pellagra in inmates that had previously been healthy by simply replacing their standard meals with a purely maize-based one.
The story shifts to Casimir Funk, who was a Polish biochemist with a special interest in diseases caused by dietary deficiencies. The reason was that milling the brown rice removed the husks and kernels, along with an unknown essential ingredient essential for health. Funk managed to isolate this ingredient, which he called vitamine from 'vital amine'. Lack of a 'vitamine' in the diet led to diseases such as beri beri B 1 , scurvy C , or rickets D.
The further complication was that the ingredient Funk had isolated from brown rice husks, and which had been called vitamin B, was actually 4 different molecules, each with a separate biological function.
So they were renamed vitamin B 1 , B 2 , B 3 , etc. The molecule that prevented beri beri turned out to be B 1 thiamine , the one that promoted cell growth was B 2 riboflavin , while the one that prevented pellagra was B 3.
Not quite — it took until for the conclusive experiments proving vitamin B 3 prevented pellagra, first with experiments on dogs where pellagra is manifested as a black tongue , and later in humans. The systematic chemical name for vitamin B 3 is nicotinic acid, but scientists wanted to avoid any links to nicotine , in case the general public might get the incorrect idea that vitamins contain nicotine, or worse, that cigarettes contain vitamins!
The name niacin was chosen from ni cotinic ac id and vitam in. Foods rich in vitamin B 3.
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