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The effect of ascorbic acid administration on the levels of urinary and serum mineral nutrients, Ca, Cu, Fe, K, Mg, Mn, Na and Zn in guinea pigs has been studied. Male guinea pigs received sodium ascorbate solution (equivalent to 1 g ascorbic acid/kg body weight/day) by intraperitoneal injection for 4 weeks. During the ascorbic acid treatment period, serum and urinary ascorbic acid rose markedly. The large quantities of ascorbic acid intake did not influence serum levels of all eight minerals studied when experimental values were compared with controls using the two-tailed Student's t-test. However, when the one-tailed t-test was used, serum copper and zinc levels of the experimental guinea pigs were significantly lower than their respective control values. Excepting sodium, derived from injected sodium ascorbate, no differences in daily urinary excretion of the other seven minerals were observed.

The effect of dietary ascorbic acid on the serum mineral nutrients, Ca, Cu, Fe, K, Mg, Mn, Na and Zn in guinea pigs has been studied. Large amounts of ascorbic acid were administered to experimental animals in their drinking water. The daily ascorbic acid intake from the diet for the control animals was 10 mg/kg body weight. The mean ascorbic acid intakes for the two groups of experimental animals were 366 (37 times control) and 722 (72 times control) mg/kg body weight/day. In the ascorbic acid-treated animals, there was a significant increase in serum ascorbic acid levels in comparison with the controls. No substantial differences were observed in the body weights. The large quantities of dietary ascorbic acid did not influence serum levels of all eight minerals studied when the experimental and control values were compared using the two-tailed Student's t-test. However, serum level of copper in the guinea pigs ingesting a daily dose of 722 mg of ascorbic acid per kg body weight was slightly below control value when one-tailed Student's t-test was used.

Ascorbic acid (246 mg/kg body weight/day) was administered orally to 9-week old female guinea pigs of the Hartley strain over a period of 20 months. The controls received 40 mg/kg body weight/day of ascorbic acid in the diet. Observations were made on body weight, food and water consumption, plasma ascorbic acid, and the total calcium and ionic calcium levels at various times during the growth of these animals. A second experiment was carried out when the guinea pigs were 18 months old. In addition to the oral intake, they received intraperitoneally 623 mg/kg body weight/day of sodium ascorbate for 6 weeks. With this treatment, the ascorbic acid intake for the test animals was 20 times that for the controls. The plasma ascorbic acid and calcium levels of these animals were measured during the treatment. In the ascorbic acid-treated animals, there was a significant elevation in plasma ascorbic acid level in comparison with the controls, but no substantial differences were observed in the body weight, total calcium or ionic calcium levels in the plasma. The results suggest that the administration of large quantities of ascorbic acid does not affect total calcium or ionic calcium levels in the plasma of these animals.

Blood samples form ten healthy subjects, who had been ingesting 3-10 g of ascorbic acid for at least two years, were collected. The ascorbic acid and oxalic acid levels in the plasma of these subjects were measured. The concentrations of oxalic acid in these plasma samples are within the range of plasma oxalate levels of human subjects who were not ingesting ascorbic acid supplements. Large quantities of ascorbic acid (10 g/day) were administered to healthy human subjects. Daily urinary samples of these subjects were collected before and during treatment. Urinary ascorbic acid and oxalic acid levels of these samples were measured. Among the six subjects tested, five experienced no significant change on urinary oxalate excretion. Urinary oxalate level of one subject was significantly elevated upon the large intake of ascorbic acid. But the increased daily excretion of oxylate in this subject is within the changes in urinary oxalate content from consuming normal diets.

Large quantities of ascorbic acid or erythorbic acid were administered to Swiss mice over a period of seven months. Urinary ascorbic acid and erythorbic acid were determined two weeks before termination of the experiment. At the end of the experiment, ascorbic acid and erythorbic acid contents in plasma, liver and brain tissues were measured. In the ascorbic acid-treated mice, there was a marked elevation in plasma and urine ascorbate levels, and there was a 38% increase of ascorbate level in the liver but there was no substantial increase in ascorbate levels in the four brain regions studied, namely the cerebrum, cerebellum, medulla and brain stem, upon large intake of ascorbic acid. In the erythorbic acid-treated mice, erythorbic acid is well absorbed by the gastrointestinal tract, enters the blood stream, and is rapidly excreted in the urine. The results show that erythorbic acid is able to replace 45% of ascorbic acid in the liver and 28-39% of ascorbic acid in the brain tissues. Although erythorbic acid appears in the blood at significantly high level, it does not lower blood ascorbate levels.