Vergleichende Untersuchungen zum Vitamin-B6-Status gravider und nichtgravider Ratten bei unterschiedlicher Vitamin-B6-Versorgung

Abstract

In a two-factorial experiment the influence of graded vitamin B6 supplements on the vitamin B6 status of pregnant and nonpregnant rats was examined. Additionally the question concerning a vitamin B6 super-retention in pregnancy should be investigated. The experiment was carried out with 69 female SPF-Sprague-Dawley rats. Nine rats served as controls and were killed at the beginning of the experiment. On the first experimental day half of the remaining animals were mated at an average body weight of 210 g. The rats were then divided into five dietary groups, each containing 6 gravid and 6 nongravid animals. Throughout the experiment the rats received a semisynthetic casein-starch diet, containing 1, 6, 12, 24, and 48 mg vit. B6/kg respectively. The trial ended at day 19 of pregnancy. Liver, right and left gastrocnemius muscle and the remaining carcass (without the intestinum and the reproductive product of the pregnant animals) were microbiologically analysed for their vitamin B6 contents. The vitamin B6 status of the liver, which contained an average of 8.4 micrograms vit. B6/g fresh matter (FM) was not influenced by pregnancy. In muscle and carcass, however, pregnancy caused significantly reduced vitamin B6 levels of 4.8 and 2.6 micrograms vit. B6/g FM. Compared to the concentrations of the nongravid animals the values of the gravid rats were decreased by 6 and 7% respectively. The vitamin B6 supply of 1 mg/kg diet caused significantly lowered vitamin B6 concentrations in muscle and carcass of all animals. Intake levels of more than 6 ppm vitamin B6, however, did not further improve the vitamin B6 status of these organs. The carcass was only poorly affected by the vitamin B6 supplementations. Significant differences in vitamin B6 concentrations were only found between the 1 and 48 ppm vitamin B6 treatment. The whole vitamin B6 pool of the maternal organism, except the reproductive product, decreased in pregnancy from an average of 651 to 596 micrograms vitamin B6. Because of these results a super-retention could not be proved for vitamin B6. Moreover, a recommendation for the optimal vitamin B6 requirement in pregnancy was derived from the present results. Accordingly a supply of 6 mg vit. B6/kg diet, equivalent to a daily intake of 80 micrograms vitamin B6, is thought to be adequate to ensure an optimal vitamin B6 status in pregnant rats.

Effect of feeding various dietary vitamin B6concentrations during gestation and lactation on vitamin B6level in liver and carcass of rat dams

“…We rather assumed that especially in carcass neither an excessive accumulation of vitamin B 6 nor a rapid loss of considerable amounts of vitamin B 6 in the case of deficiency occur. This is in agreement with the findings of study of Reithmayer et al (1985a) in which carcass was only poorly affected by various vitamin B 6 supplementations, both in pregnant and growing rats. In pregnant rats, saturation of vitamin B 6 in liver occurred at a dietary vitamin B 6 supplementation of 6 mg/kg (Reithmayer et al, 1986).…”

“…A dose-response-relationship between the dietary vitamin B 6 intake and the vitamin B 6 status has been determined in several studies with growing, pregnant and lactating rats (Benedikt et al, 1996c, Reithmayer et al, 1985aand b, Roth-Maier and Kirchgeßner, 1981and 1989. However, there are less results to date about the effect of various dietary vitamin B 6 supplies during gestation on the vitamin B 6 level of lactating rats.…”

“…Results originating from liver clearly show that an adequate vitamin B 6 intake during lactation can not compensate for a vitamin B 6 -deficient diet in gestation and vice versa an adequate vitamin B 6 supply during gestation is not able to compensate for a suboptimal vitamin B 6 supply during lactation, even not in the case of feeding excessive vitamin B 6 of 180 mg/kg. Since it has been shown that there is not any anabolism of vitamin B 6 during gestation (Reithmayer et al, 1985a) it is unlikely that the high levels of exceeding dietary vitamin B 6 during gestation was transfered to the offspring. We rather assumed that especially in carcass neither an excessive accumulation of vitamin B 6 nor a rapid loss of considerable amounts of vitamin B 6 in the case of deficiency occur.…”

“…ROTH-MAIER et al requirement during gestation maintains relatively high vitamin B 6 concentration in maternal tissue of lactating rats. Previous results have definitely shown that about 6 mg/kg vitamin B 6 in the diet meets the vitamin B 6 requirement in gestation and lactation (Reithmayer et al, 1985a, Benedikt et al, 1996b. In a study of Benedikt et al (1996a) it has been found that an elevation of vitamin B 6 supply during gestation led to an increase in vitamin B 6 concentration in blood of 40%, whereas concentration in milk increased by about 53% measured at day 14, respectively day 13 of lactation.…”

The effect of dietary riboflavin supplementation during pregnancy and lactation on riboflavin concentrations of milk, liver and carcass of lactating rats

“…For thiamin, it has been demonstrated that a high supply during pregnancy increases thiamin storage in the body, and therefore the thiamin supply during pregnancy markedly influences both the thiamin status during lactation and the thiamin concentrations in the milk (R oth ‐M aier et al 1990; K irchgessner et al 1997). In contrast, for vitamin B 6 it has been shown that a high supply during pregnancy does not produce additional storage (R eithmayer et al 1985), and therefore vitamin B 6 supply during pregnancy only had a slight influence on the vitamin B 6 status during lactation (R oth ‐M aier et al 1996; B enedikt et al 1996). In order to investigate the physiological behaviour of riboflavin in this respect, rats were fed diets with various supplementary levels of riboflavin during pregnancy and lactation and the concentrations of riboflavin were determined in the liver and carcass after pregnancy and lactation and in the milk of lactating rats.…”