Generality
Pellagra is a disease caused by the deficiency or failure to absorb niacin, also known as vitamin B3, nicotinic acid or vitamin PP (from the English Pellagra Preventing).
Still on the subject of acronyms, pellagra is differently known as the disease of the three Ds, in reference to the symptomatological trio that characterizes it: diarrhea, dermatitis and dementia. Without treatment, the prognosis is poor, so much so that English speakers speak of a 4 D disease (dementia, dermatitis, diarrhea And death, "death")
Causes
In addition to niacin deficiency, pellagra can also be caused or aggravated by a deficiency of the amino acid tryptophan.
In fact, the human body is able to transform tryptophan into nicotinic acid (60 mg of tryptophan is equivalent to 1 mg of niacin).
The mainly maidic diet of the beginning of the last century, which saw corn polenta as the staple food of the peasant people, was one of the main causes of pellagra, long endemic in Italy since the early decades of the eighteenth century. The proteins of corn are in fact low in tryptophan and the niacin contained in its seeds is poorly absorbable, as it is covalently linked to small peptides (niacinogens) and to carbohydrates (niacitin).
The Maya, despite having a "diet based mainly on corn, did not suffer from pellagra, since maidic niacin becomes available through treatment in a basic environment (the niacin contained in tortillas, unlike that present in polenta, is therefore absorbable by the body" ).
In addition to poor dietary intake, pellagra can be caused by ineffective intestinal absorption; it can therefore develop following defective absorption due to lesions of the digestive system, for example due to alcoholism, gastroresection or intense smoking. Rare causes of pellagra are represented by the deviation of the metabolism of tryptophan towards serotonin, due to the action of a malignant carcinoid, and by iatrogenic pharmacological factors (isoniazid, acetylpridine, thiosemicarbazone, metopterin, 5-fluorouracil, azathioprine, etc.). People with eating disorders such as anorexia nervosa are also at risk of subclinical pellagra.
Where is Vitamin PP found?
Good natural resources of vitamin PP are represented by whole grains, meat, fish, eggs, brewer's yeast, peanuts and liver. The recommended intake level is 6.6 mg / 1000 kcal, with a minimum of 19 mg / day for men and 14 mg / day for women.
Diagnosis
The diagnosis of pellagra, as well as on the recognition of symptoms and skin manifestations, is confirmed by low urinary levels of the specific metabolites of niacin.
Symptoms
For further information: Pellagra symptoms
Scaly skin (dermatitis), diarrhea, mental confusion, insomnia, nervousness, mental slowdown, apathy, depression, dementia, delirium, inflammation of the mucous membranes, dry and chapped lips with evident cracks in the corners of the mouth, anal fissures, fissures in the nostrils, stomatitis, gingivitis, severe and showy glossitis and achlorhydria - histamine-resistant hypochlorhydria.
To this symptomatological set are added the lack of appetite (anorexia, mainly aimed at meat foods), asthenia, anemia, hypotension, hypoproteinemia and vomiting.
The skin lesions of pellagra are the result of an "abnormal sensitization of the skin to sunlight; they tend to appear symmetrically on areas exposed to the sun - such as arms, legs, face, neck and upper chest - abruptly stopping where the skin is covered by clothing. Initially similar to burns, they then tend to become reddish, tending to brown, rough and scaly, similar to roasted meat, which they also smell.
In the major forms, in the absence of treatment, the prognosis is poor; the course is chronic, with spontaneous regressions in autumn and winter, and exacerbations in the first spring suns; these become more and more serious, to the point of causing the so-called pellagrous dementia, as well as a profound cachectic state.
Pellagra treatment and therapy
In humans, pellagra is rarely caused by simple niacin deficiency, as evidenced by the poor response to treatment with nicotinamide (a derivative of nicotinic acid); better results are obtained by combined administration of multivitamins (B vitamins, such as B1, B2, B3, B6 E B12) and high-protein diet. The specific therapeutic intervention for pellagra is completed by corrections of the causes of malabsorption, protection from sunlight and the topical application of antibacterial, soothing, antifungal and photoprotective dressings.
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