Vitamin comparative studies

Galvis-Sanchez AC, Gil-Izquierdo A and Gil MI. 2003. Comparative study of six pear cultivars in terms of their phenolic and vitamin C contents and antioxidant capacity. J Sci Food Agric 83 995-1003. 

Tesoriere L, Butera D, Pintaudi AM, Allegra M and Livrea MA. 2004. Supplementation with cactus pear (Opuntia ficus-indica) fruit decreases oxidative stress in healthy humans a comparative study with vitamin C. Am J Clin Nutr 80 391-395. 

Citrus juice is rich in ascorbic acid and, therefore, is an important dietary source of this essential vitamin. Our studies were aimed at defining whether vitamin C from citrus sources is comparable with the synthetic vitamin in terms of bioavailability and intestinal absorption. These studies were conducted using human volunteers and guinea pig experimental models (1, 2). 

Deguchi, Y., Morishita, T., and Mutai, M., Comparative studies on synthesis of water-soluble vitamins among human species of Bifidobacteria, Agric. Biol. Chem., 49, 13-19, 1985. 

Leek, J.B., Park, B.K. (1981). A comparative study of the effects of warfarin and brodifacoum on the relationship between vitamin K1 metabolism and clotting factor activity in warfarin-susceptible and warfarin-resistant rats. Biochem. Pharmacol. 30 123-8. 

Krause KH, Bohn T, Schmidt-Gayk H, Prager P, Ritz E. Zur prophylaktischen Gabe von Vitamin D2 und D3 bei Anfallskranken. [Prophylactic treatment of epileptic patients with vitamin D2 and D3. Results of a comparative study of 86 patients.] Nervenarzt 1978 49(3) 174-80. 

Abramovici B, Molard F, Seguin B, Gromenil JC. Comparative study of the tabletability of different grades of vitamin C [in French]. STP... 

Traba M, Navarro A, Marin C, et al. A comparative study of 25-hydroxyvitamin D3 separation in human serum. In Norman AW, Schaefer K, Herrath DV, Grigoleit H-G, eds. Vitamin D, chemical, biochemical and clinical endocrinology of calcium metabolism. New York W de Gryter, 1982 805-7. 

Bilich ii reported excellent results in burns in children when he added novocain and cod-liver oil to nitrofurazone. With this treatment he observed only one ineffective case in 56 patients. The more recent literature confirms previous reports on the clinical usefulness of nitrofurazone. In comparative studies in dermatology a cure rate of 65-2 per cent was reported, whereas Stauber achieved satisfactory results in 90 per cent of his 95 patients with pyogenic dermatoses. In another dermatological investigation a mixture of nitrofurazone, hydrocortisone and Vitamins A and D resulted in a cure rate of 92-3 per cent. For the treatment of burns, Ingham used a nitrofurazone-soluble aerosol which proved to be more effective than four other aerosols with which he compared nitrofurazone. In Russia, nitrofurazone is also used as a constituent in a paste which protects the hands of workmen from penetration by industrial impurities and from irritation caused by industrial oils . ... 

Comparative studies of the physiological properties of vitamin and coenzyme B12 conducted in humans have suggested a more rapid uptake by erythrocytes and greater efficiency of the coenzyme in stimulating the hematopoietic response. Coenzyme B12 has now been established to play a role in a number of enzymic transformations, most of which occur in bacteria, but a few have been described in mammalian cells [94]. 

Thiamine is particularly sensitive to thermal processing the published retention values range from 0 to 95% (Killeit, 1994). Wheat flour extruded with no added water suffered large thiamine losses, and increased barrel temperature decreased the vitamin only at the slowest feed rate used (250 g/min versus 500 and 750 g/min) (Andersson and Hedlund, 1990). In the same study, extrusion conditions did not affect the content of riboflavin (B2) or niacin ascorbic acid (C) decreased with higher temperatures at 10% moisture. Since enriched wheat flour is an important source of B vitamins in the United States, care must be taken to protect these vitamins. Relatively little is known about the stability of synthetic vitamins compared with natural sources, or the effects of added vitamins as opposed to endogenous nutrients. 

The determination of total Be as PN was collaboratively studied by 12 laboratories in a comparative study (Bergaentzle et al. 1995) all the Be vitamers in food were dephosphorylated with acid phosphatase, after which PM was deaminated to PL in the presence of glyoxylic acid and ferrous sulfate. The PL was reduced to PN by sodium borohydride and the total vitamin Be content was determined as one vitamer (PN) by HPLC. Another study reported that the most suitable extraction procedure for determining endogenous total vitamin Be in food (meat, fish, milk) was treatment with 0.1 M hydrochloric acid at 120 °C for 30 min, followed by enzymatic hydrolysis with p-glucosidase alone or in combination with acid phosphatase. Some authors (Ndaw et al. 2000) have recommended the extraction procedure consisting of incubation with papain, a-amylase and phosphatase for 18 h at 37 °C, and compared this protocol with four other extraction protocols involving combinations with acid and enzymatic hydrolysis. 

Kupenov LG (1974) Comparative studies on the variability of vitamin producers... 

Navas-Diaz et al. (1993) quantified low nanogram levels of thiamine, riboflavin, and niacin by fiber-optic fluorodensitometry after silica gel HPTLC with methanol-water (7 3) mobile phase. Perisic-Janjic et al. (1995) used TLC for the analysis of the B-complex vitamins in some commercial pharmaceutical B-complex vitamin products. The stationary phase used was a newly synthesized carbamide formaldehyde polymer (aminoplast) with mobile systems 1-butanol-water-acetone (25 9 5) and 1-butanol-methanol-benzene-water (20 10 10 8). Comparative studies examined the B-complex vitamins on cellulose thin layers. 

Martinez-Sanchez, A., Gil-lzquierdo, A., Gil, M.I., and Ferreres, F. 2008. A comparative study of flavonoid compounds, vitamin C, and antioxidant properties of baby leaf Brassicaceae species. Journal of Agricultural and Food Chemistry, 56(7), 2330-40. doi 10.1021/jl072975+. 

Comparative studies In a prospective randomised trial including 156 participants, the effectiveness of oral and injectable vitamin C in the prevention of contrast-induced nephropathy was evaluated [27 ]. Most of the adverse events were reported as not serious and self-resolving. 

Comparative studies The efficacy of high-dose intramuscular versus oral cholecalciferol therapy (600,000 lU/ day) in elderly patients deficient in vitamin D has been examined [43 ]. At 6weeks, hypercalciuria was reported in one patient in intramuscular group compared with three patients in the oral group and at 12 weeks three patients on intramuscular and one on oral cholecalciferol experienced hypercalciuria. No other adverse events were reported. In another 6-month study to evaluate the effectiveness of one-dose oral versus inframuscular cholecalciferol (300,000 lU) for treatment of hypovitaminosis D, no adverse effects were observed... 

Comparative studies In a 4-month double-blind, randomised trial involving 180 healthy subjects, the ability of vitamin E supplementation to protect erythrocyte membranes from oxidative stress was examined. Vitamin E supplementation was associated with a significant decrease in erythrocyte haemolysis (p<0.05). None of the participants experienced any adverse effects with vitamin E supplementation... 

Whereas these preparations ate extremely useful for obtaining sufficient quantities of the D metabohtes and analogues for study and as possible therapeutic treatments, their cost is high compared to the cost of manufacture of vitamin D. For this reason, the metabohtes ate unlikely to be successful in replacing vitamin D as an ingredient in animal or human nutrition. 

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