The effect of a wide range of daily vitamin C intake (350-2250 mg, mean 975 mg) on the serum and urine vitamin C levels was studied in 20 adult hospitalized patients receiving total parenteral nutrition for a period greater than 15 days. Serum vitamin C levels increased with vitamin C administration, but remained within the normal range. Urine vitamin C levels were above normal during total parenteral nutrition in all but one patient. A positive vitamin C "balance" was achieved in all patients. The vitamin C intake positively correlated with the vitamin C urine concentration and vitamin C "balance." Maximal vitamin C retention was 800 mg/day. It is concluded that administration of vitamin C in doses greater than 1000 mg/day is unjustified in those patients receiving total parenteral nutrition who are not hypermetabolic.
This study compares the prophylactic effects of two different diets and routes of feeding on restraint stress-induced gastric erosions in the rat. Thirty male Sprague-Dawley rats were food-deprived and immobilized for 24 hours using a steel wire mesh. A small silicone tube was placed into either the proximal jejunum or the stomach via a laparotomy. There were three groups of ten rats (five jejunum-fed, five stomach-fed), receiving infusions (50 ml/24 h) of: (A) normal saline; (B) free amino acids (Vivonex HN, Norwich Eaton Pharmaceuticals) (60 cal and 0.318 G nitrogen); or (C) a peptide diet, with the nitrogen source as lactalbumin hydrolysate, otherwise identical to B. Gastric acidity was measured every 4 hours. At 24 hours, blood was collected and serum gastrin levels determined. The animals were then sacrificed and the stomachs examined. The results were analyzed using one-way analysis of variance. Fewer gastric erosions and lower serum gastrin levels and gastric acidity were found in animals fed diets B and C, versus animals fed normal saline (p less than 0.05). There was no difference between groups B and C. Our results also show that enteral diets using the jejunal route are better than those using the gastric route in reducing the incidence of stress-induced gastric erosions in rats.
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