Niacin deficiency

Introduction Generally, there is no shortage of niacin in the diet. Only the area where the corn is the main food is easy to be lacking. The main reason is that the niacin in the corn is combined and is not absorbed and utilized, and the tryptophan in the corn is small, which cannot satisfy the human body's synthetic niacin. need. Niacin deficiency can be induced by certain gastrointestinal disorders and long-term fever, such as increased absorption or consumption of niacin. Taking a large amount of isoniazid can interfere with the action of pyridoxine, affecting the conversion of tryptophan to niacin, and can also cause niacin deficiency. Lack of niacin in humans will cause pellagra. Typical symptoms are symmetrical dermatitis, diarrhea, and dementia (three-D symptoms). The occurrence of the disease is mostly secondary, so the diagnosis is mainly based on typical symptoms and incentives. Laboratory tests can reveal varying degrees of anemia, low acidity, protein or cast in the urine, and hematoporphyrin. X-ray examination of the gastrointestinal tract can reveal changes in intestinal function and mucosal morphology. Yantai coastal scenery adjusts grain varieties to diversify and increase the content of niacin in the diet as the main measure to prevent and treat this disease. Niacin is widely found in animal and plant tissues, but it is mostly in small amounts. The most abundant niacin in plant foods are yeast, peanuts and beans. Animal foods have higher levels of niacin, such as liver, kidney, lean meat, etc., and the content of tryptophan is also high. Treatment of corn with alkali, free niacin can be released and used by the body, therefore, the promotion of corn flour plus alkali is very important to prevent this disease. In 1988, China recommended a dietary niacin supply of 5 mg per 4,180 joules of heat. It is generally prescribed that the amount of niacin supplied in the diet is 10 times that of vitamin B1.

Cause

Causes of niacin deficiency

The niacin required by the human body can be converted by tryptophan, and about 60 mg of tryptophan is converted into 1 mg of niacin, so 1 mg of niacin or 60 mg of arginine is called 1 nicotinic acid equivalent. Normal adult lactation requires an increase of 5 niacin equivalents. Lean meat, poultry, peanuts and other niacin rich in content; yeast also contains more niacin; milk and eggs niacin content is low, but tryptophan content is high; keratin and tryptophan content of the grain low.

Primary niacin deficiency occurs mostly in corn-based areas and can be endemic. Some niacin in corn is bound, unless it is treated with alkali first, usually not absorbed by the digestive tract, and it contains more leucine, which has the function of nicotinamide mononucleoside formation, resulting in niacin deficiency. . Niacin deficiency is considered to be a disease caused by vitamin and amino acid deficiency and imbalance. A variety of chronic and sub-acute diseases (such as cirrhosis, chronic diarrhea, tuberculosis, cancer, chronic alcoholism, etc.) due to long-term loss of appetite, increased demand, gastrointestinal malabsorption and other factors can lead to secondary niacin deficiency disease. Long-term use of isoniazid in tuberculosis patients may cause niacin deficiency. Similarly, anticancer drugs can also cause niacin deficiency. Carcinoids convert 60% of the tryptophan metabolism (normally only 1%) to serotonin, which can lead to niacin deficiency. The cause of congenital tryptophan deficiency is the absorption and dysfunction of tryptophan in the small intestine and renal tubules. It can also cause fatigue, loss of appetite, emotional instability, apathy, weight loss, etc., and lack specificity. Typical manifestations are dermatitis, mental and neurological syndrome, and digestive system syndrome, either alone or in combination. In addition, often accompanied by other vitamins and nutrient deficiency symptoms.

an examination

Related inspection

Protein electrophoresis

Examination and diagnosis of niacin deficiency

In the early stage, it only showed fatigue, loss of appetite, emotional instability, apathy, weight loss, etc., lacking specificity. Typical manifestations are dermatitis, mental and neurological syndrome, and digestive system syndrome, either alone or in combination. In addition, often accompanied by other vitamins and nutrient deficiency symptoms.

First, dermatitis: often bilateral, symmetrical and appear in exposed parts, such as face, neck, back of the hand, forearm extension side, foot back, front side of the calf, etc., related to light third, can also appear in the armpit, under the breast Friction parts such as the groin, perineum, elbow and knee. In the early stage of the onset, similar to sunburn, there may be blistering, rubbing, and hair loss infections. Chronic thick skin, cracks, scaling, hyperkeratosis, and pigmentation.

Second, mental and neurological syndrome: including: 1 organic psychosis, manifested as memory loss, disorientation, mental disorder; 2 encephalopathy syndrome, manifested as drowsiness, unconsciousness, limb gear-like rigidity, continuous sucking and grip reflection. In addition, there are often a dull sensation of the extremities and multiple peripheral neuritis, which is associated with a deficiency of B vitamins such as thiamine. Sometimes accompanied by subacute spinal cord lateral cord combined degeneration symptoms, may be related to vitamin B12 deficiency.

Third, digestive system syndrome: scarlet tongue inflammation, tongue peeling, stomatitis is a characteristic of acute niacin deficiency, starting from the edge of the tongue, with the development of the disease can be oral ulceration, increased salivation, tongue edema, can appear ulcer. Esophagitis can cause difficulty in swallowing; enteritis and digestive gland atrophy cause diarrhea, stool is watery or mushy. Also accompanied by a lack of stomach acid. The possibility of keratitis, anal inflammation, vaginitis, and scrotal inflammation is related to riboflavin and vitamin B6 deficiency.

Differential diagnosis

Niacin deficiency is confusing

Fat-soluble vitamin deficiency: Fat-soluble vitamins include vitamins A, D, E, and K. They are insoluble in water and soluble in lipids and fatty solvents. Fat-soluble vitamins coexist in the food with lipids and are absorbed along with the lipids. The absorbed fat-soluble vitamin is transported in the blood by specifically binding to lipoproteins and certain specific binding proteins. The fat-soluble vitamins A, D, E, and K have certain biological functions, and once they are lacking, the corresponding symptoms will appear.

Lack of nutritional metabolism: evidence of disease-deficient disease, such as dystrophic vitamin B1 and folate deficiency, and lack of nutritional metabolism leading to symptoms and signs of dysfunction, which can be used as a mental disorder associated with nutritional metabolic diseases. Diagnostic conditions.

Nutritional metabolic diseases associated with mental disorders mostly refer to neuropsychiatric disorders caused by vitamins or other nutrients lacking metabolic disorders and insufficient energy supply, such as niacin, vitamin B1 and folic acid deficiency. It meets the diagnostic criteria for mental disorders caused by physical illness and has evidence of nutritional metabolic diseases. The mental symptoms vary with the severity of the primary disease.

In the early stage, it only showed fatigue, loss of appetite, emotional instability, apathy, weight loss, etc., lacking specificity. Typical manifestations are dermatitis, mental and neurological syndrome, and digestive system syndrome, either alone or in combination. In addition, often accompanied by other vitamins and nutrient deficiency symptoms.

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