Deficiency riboflavin

The most obvious change in riboflavin-deficient rats occurs in the skin. According to Follis the fur becomes ragged, and the hairs become uneven in length and encrusted with a red-brown substance. The hair then begins to fall out, areas of alopecia develop and the skin then becomes scaly. 

Wintrobe, W. Buschke, R. H. Follis, and S. Humphreys, Bull. Johns 

In addition to these changes a number of workers have found that cataracts develop in riboflavin-deficient animals. Day and co-workers,Win-trobe and co-workers,and Bourne and Pyke were able to confirm Day s work, but some other workers were not so successful. In the development of such cataracts the earliest signs of change were found to be epithelial proliferation and degeneration of fibers. Then the fibers broke down completely and the lens became an opaque amorphous mass. Pirie found that histological changes in the eyes in riboflavin deficiency were similar to those produced by tryptophan deficiency. 

Most of the organs and tissues show some changes in riboflavin deficiency, but according to Wolbach and Bessey these changes are due simply to inanition and are not specific for deficiency of the vitamin. 

Some authors have recorded changes in the nervous system in riboflavin-deficient animals. Lippincott and Morris have recorded degeneration of the dorsal columns in the spinal cord, and degeneration of the peripheral nerves has also been described (Street et al and Wintrobe et 

Apparently, the suboptlmal growth in all rats in cadmium, lead and tin studies was due to riboflavin deficiency (66). Unfortunately, the death of the principal investigator of cadmium, lead and tin essentiality (Klaus Schwarz) prevented further studies which would have answered the question whether deficiencies of those elements would depress growth in rats which were not riboflavin-deficient. This question may remain unanswered for some time because, to my knowledge, studies concerned with the essentiality of cadmium, lead, and tin are not currently pursued in another laboratory. 

The reports which suggest the essentiality of cadmium, lead and tin can also be criticized in the following manner  

The basal diets were not adequately described, thus preventing the confirmation of the growth findings in another 

ACS Symposium Series American Chemical Society Washington, DC, 1980. 

Because of the previously discussed questions and criticisms, I conclude that cadmium, lead and tin should not be Included in the list of essential trace metals at the present time. 

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An en2ymatic method for assessing riboflavin deficiency in humans has been developed (74). It is based on the fact that NADPH-dependent glutathione reductase of red cells reflects riboflavin fluctuations. 

Riboflavin was first isolated from whey in 1879 by Blyth, and the structure was determined by Kuhn and coworkers in 1933. For the structure determination, this group isolated 30 mg of pure riboflavin from the whites of about 10,000 eggs. The discovery of the actions of riboflavin in biological systems arose from the work of Otto Warburg in Germany and Hugo Theorell in Sweden, both of whom identified yellow substances bound to a yeast enzyme involved in the oxidation of pyridine nucleotides. Theorell showed that riboflavin 5 -phosphate was the source of the yellow color in this old yellow enzyme. By 1938, Warburg had identified FAD, the second common form of riboflavin, as the coenzyme in D-amino acid oxidase, another yellow protein. Riboflavin deficiencies are not at all common. Humans require only about 2 mg per day, and the vitamin is prevalent in many foods. This vitamin... 

Although riboflavin is fundamentally involved in metabolism, and deficiencies are found in most countries, it is not fatal as there is very efficient conservation of tissue riboflavin. Riboflavin deficiency is characterized by cheilosis, lingual desquamation and a seborrheic dermatitis. Riboflavin nutritional status is assessed by measurement of the activation of erythrocyte glutathione reductase by FAD added in vitro. 

The answers are 404-e, 405-c. (Hardman, pp 1555-1557, 1559-1561.) Angular stomatitis, dermatitis, and corneal vascularization are considered classic signs of human riboflavin deficiency, although multiple B vitamins may be involved. 

Riboflavin needs have been found to vary with different strains of white Leghorn chickens,56, 57 and there appears to be a sex difference in that females require less and thus show greater resistance to riboflavin deficiency. 

Najjar and co-workers58 found on diets furnishing only 60 to 90 ig. of riboflavin per day that the urinary excretion (human) was about twice the intake, and the fecal excretion was about 5 to 6 times the intake. This indicates that for certain individuals on certain diets synthesis of riboflavin by intestinal organisms is sufficient to take care of the entire riboflavin needs. The authors conclude that riboflavin may not be a dietary essential in all cases. If this finding is valid, it certainly points to the probability that human needs vary widely because riboflavin deficiencies in human beings have been observed a great many times on many different types of diets. 

Riboflavin deficiency may result in the production of skin lesions,... 

Nutritional Folate deficiency Iron deficiency Vitamin Bi (thiamine) deficiency Vitamin B2 (riboflavin) deficiency Vitamin Bg (pyridoxine) deficiency Vitamin B12 (cyanocobalamin) deficiency... 

Riboflavin (vitamin B2) is found in liver, milk, meat, green vegetables, cereals and mushrooms. It is active in the form of two coenzymes, flavin mononucleotide and flavin adenine dinucleotide. As a coenzyme for proton transfer in the respiratory chain it is indispensable for energy-release from carbohydrates, lipids and proteins. Riboflavin deficiency only occurs in combination with deficiencies of other members of the vitamin B family. The symptoms of such deficiency consist of angular stomatitis, lesions of the cornea, dermatoses and normochromic normocytic anaemia. 

Riboflavin deficiency is not associated with a major human disease, although it frequently accompanies other vitamin deficiencies. Deficiency symptoms include dermatitis, cheilosis (fissuring at the corners of the mouth), and glossitis (the tongue appearing smooth and purplish). 

VITAMIN B2 (Riboflavin). Some earlier designations for this substance included vitamin G, lactoflavin, hepatoflavin, ovoflavin, veidoflavin. The chemical name is 6,7-dimcthyl-9-d-l ribityl isolloxazine. Riboflavin is a complex pigment with a green fluorescence. Riboflavin deficiency frequently accompanies pellagra and the typical lesions of both nicotinic acid and riboflavin deficiency are found in that disease. See also Niacin. 

Riboflavin deficiency is not associated with a specific disease per se (19,80,81). However, a lack of riboflavin in the diet produces changes in the eye, including photophobia, corneal opacity and ulceration, presenile cataracts, circumcomeal infections, and reduced tearing, as well as skin lesions, especially around the mouth, nose, and ears. 

Vitamin deficiencies, in general, bring about a reduction in monooxygenase activity, although exceptions can be noted. Riboflavin deficiency causes an increase in P450 and... 

A note on the rapid conversion of fevo-kynurenine to anthranilic acid, and the conjugation of the latter with glucuronic acid by riboflavin-deficient rat-liver and rat-kidney slices, has recently appeared.148... 

Esophageal cancer can also be influenced by other nutrients. Riboflavin (B ) deficiency results in severe changes in the epithelium of the oral tissues and esophagus in rats and primates. The effects of riboflavin deficiency in human populations are well known (29,30) but animal models for investigation of consequences of the deficiency have been used very little. 

Dr. Henry Foy (personal communication) has drawn attention to the severe effects of riboflavin deficiency in the baboon, with particular attention to the dysplasia of the epithelium of the oral cavity and esophagus. Dr. Foy has pursued these studies for many years at the Wellcome Research Laboratories in Nairobi. We have observed similar lesions in the Rhesus monkey, and have further pursued the effects of riboflavin deficiency in the rat. We have superimposed an esophageal carcinogen (MBN) on the deprived, damaged oral cavity and esophageal epithelium. Table IX lists results of a five month study, emphasizing the profound enhancement the deficiency can have on the esophagus (31). 

Skin wound healing was investigated in a riboflavin-deficient rat model epithelialization was prolonged, wound contraction slowed and total collagen content reduced by 25%.114... 

Apparently the content of the active metabolite pyridoxamine S -phosphalc is lower in human than in mouse or hamster skin.120 When inflammatory response was assessed in a pyridoxine or riboflavin deficient rat model, data suggested enhanced inflammation in pyridoxine but not riboflavin... 

Roe, D.A., Riboflavin deficiency mucocutaneous signs of acute and chronic deficiency, Semin. Dermatol., 10, 293, 1991. 

Lakshmi, R., Lakshmi, A.V., and Bamji, M.S., Skin wound healing in riboflavin deficiency, Biochem. Med. Metab. Biol., 42, 185, 1989. 

Riboflavin Deficiency How would a riboflavin deficiency affect the functioning of the citric acid cycle Explain your answer. 

Riboflavin deficiency and the dietary means to prevent such deficiency have been known since the late 1930 s when early accounts of the clinical signs of riboflavin deficiency were published ( ). 

In conclusion, we have found that the presently set Recommended Dietary Allowances for riboflavin for women are inadequate even when they are not exercising, and that their riboflavin requirements are Increased by exercise. Weight reduction per se does not have an effect on riboflavin requirements. However, women who are exercising and on a weight reduction diet may get an inadequate amount of the vitamin because of their restricted food intake. We have no evidence, at least in the U.S., that athletes are at risk for clinical riboflavin deficiency. We do not think that it is necessary for those engaged in exercise to take megadoses of this B vitamin or of other B vitamins. 

Dietary deficiency is relatively widespread, yet is apparently never fatal there is not even a clearly characteristic riboflavin deficiency disease. In addition to intestinal bacterial synthesis of the vitamin, there is very efficient conservation and reutilization of riboflavin in tissues. Flavin coenzymes are tightly enzyme bound, in some cases covalently, and control of tissue flavins is largely at the level of synthesis and catabolism of flavin-dependent enzymes. 

Riboflavin phosphate and FAD may be either covalently or noncovalenfly bound at the catalytic sites of enzymes. Even in those enzymes in which the binding is not covalent, the flavin is tightly bound in many cases, the flavin has a role in maintaining or determining the conformation of the enzyme protein. In some cases, the flavin is incorporated into the nascent polypeptide chain, while it is stUl attached to the ribosome. However, in others a flavin-free apoenzyme is synthesized and accumulates in riboflavin deficiency (Section 7.5.2). 

Intestinal bacteria synthesize riboflavin, and fecal losses of the vitamin may be five- to six-fold higher than intake. It is possible that bacterial synthesis makes a significant contribution to riboflavin intake, because there is carrier-mediated uptake of riboflavin into colonocytes in culture. The activity of the carrier is increased in riboflavin deficiency and decreased when the cells are cultured in the presence of high concentrations of riboflavin. The same carrier mechanism seems to be involved in tissue uptake of riboflavin (Said et al., 2000). 

Tissue concentrations of flavin coenzymes in hypothyroid animals may be as low as in those fed a riboflavin-deficient diet, in hypothyroid patients, erythrocyte glutathione reductase (EGR) activity may be as low, and its activation by FAD added in vitro (Section 7.5.2) as high, as in riboflavin-deficient subjects. Tissue concentrations of flavin coenzymes and EGR are normalized by the administration of thyroid hormones, with no increase in riboflavin intake (Cimino et al., 1987). 

Acyl CoA dehydrogenases in fatty acid /S-oxidation. These enzymes are especially sensitive to riboflavin depletion, and riboflavin deficiency is characterized by impaired fatty acid oxidation and organic aciduria (Section 7.4.1). These are also the enzymes affected in riboflavin-responsive organic acidurias. 

Riboflavin deficiency is relatively common, yet there is no clear deficiency disease and the condition never seems to be fatal. This presumably reflects the high degree of conservation of riboflavin in tissues (Section 7.2.3). There is only a relatively small difference between the concentration of flavins at which tissues are saturated and the lowest levels in prolonged depletion of experimental animals. In deficiency, most of the flavin coenzymes released by the catabolism of enzymes are reutilized. 

The main effect of riboflavin deficiency is on lipid metabolism. In experimental animals on a riboflavin-free diet, feeding a high-fat diet leads to more marked impairment of growth, and a higher requirement for riboflavin to restore growth. There are also changes in the patterns of long-chain polyunsaturated fatty acids in membrane phospholipids. 

In animals, the production of CO2 from [ Cjpalmitate or octanoate is not consistendy affected by riboflavin deficiency, possibly as a result of increased activity of carnitine palmitoyl transferase, which is more a response to food deprivation than to riboflavin deficiency. However, the production of C02 from [ C] adipic acid is significandy reduced, and responds rapidly (with some overshoot) to repletion with the vitamin. It has been suggested that the abiUty to metabolize a test dose of [ Cjadipic acid may provide a sensitive means of investigating ribodavin nutritional status in human beings (Bates, 1989, 1990). 

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