Amazoniac
Member
- Identification of 9-cis-retinoic acid, 9,13-di-cis-retinoic acid, and 14-hydroxy-4,14-retro-retinol in human plasma after liver consumption
- Vitamin A supplementation increases ratios of proinflammatory to anti-inflammatory cytokine responses in pregnancy and lactation
@Orion and @stargazer1111, were you pregnant during supplementation? Fetuses don't usually put an arm or a leg out, so be careful in your interpretations.
"[..]a few case reports indicated that vitamin A supplementation of 25,000 IU or more by pregnant women could result in birth defects (4). A recently published epidemiological study even suggests that intake ofvitamin A at levels exceeding 10,000 IU per day may be associated with an increased teratogenic risk (5). A single meal of liver contains, on the average, a 10- to 20-fold higher amount ofvitamin A, and in some countries (e.g. Germany and the Netherlands) regulatory agencies have therefore recommended against consumption of liver during pregnancy. The teratogenic potency of vitamin A, but also its essential functions are in part mediated by its metabolism to active retinoids."
"Buss et al. (6) have shown that liver consumption led to a substantial increase of concentrations of polar retinoids in human plasma, namely 13-cis-4-oxo-retinoic acid (13-cis-4-oxo-RA) and 13-cis-RA, and to a lesser degree to all-trans-4-oxo-RA and all-trans-RA. The relatively low levels of all-trans-RA and its 4-0x0- metabolite led the authors to suggest that the teratogenic risk of liver consumption may be low. In the present study, we describe the identification of novel and active retinoids(Fig. 1) in human plasma after consumption of tied turkey liver; these retinoids have not been detected previously in humans following vitamin A supplementation (7, 8) or liver consumption (6)."
"Fried turkey liver was given as part of a light meal to ten healthy male volunteers (2 g raw weight/kg body weight). The vitamin A content in the liver (retinol plus retinyl esters) was determined by HPLC to be 0.5 ± 0.04 mg total retinol/g raw weight (n=3). Hence, the vitamin A intake was approximately 3,300 IU or 1 mg/kg body weight."
"The major findings of the present study were the identification of two RA isomers, 9-cis-RA and 9,13-di-cis-RA, as well as 14-hydroxy-4,14-retro-retinol (14-HRR), in human plasma following liver consumption. These retinoids must be a result of in vivo metabolism of vitamin A, because levels of these compounds in animal liver are very low - if present at all - (14) and therefore cannot account for the observed plasma levels."
"9-cis-RA and 14-HRR are known to exhibit high activity - in some systems greatly exceeding that of all-trans-RA (18, 19, 26). Additionally, 9-cis-RA induced dysmorphogenic effects in a wide variety of systems (16- 19). Furthermore, the plasma levels of 13-cis-RA, 13-cis-4-0x0-RA, and all-tram-RA were significantly elevated over endogenous levels and could therefore also contribute to vitamin A induced teratogenicity. Our quantitative exposure data on highly active retinoids following consumption of a liver meal provide an additional rationale for caution against high vitamin A intake during pregnancy."
"Buss et al. (6) have shown that liver consumption led to a substantial increase of concentrations of polar retinoids in human plasma, namely 13-cis-4-oxo-retinoic acid (13-cis-4-oxo-RA) and 13-cis-RA, and to a lesser degree to all-trans-4-oxo-RA and all-trans-RA. The relatively low levels of all-trans-RA and its 4-0x0- metabolite led the authors to suggest that the teratogenic risk of liver consumption may be low. In the present study, we describe the identification of novel and active retinoids
"Fried turkey liver was given as part of a light meal to ten healthy male volunteers (2 g raw weight/kg body weight). The vitamin A content in the liver (retinol plus retinyl esters) was determined by HPLC to be 0.5 ± 0.04 mg total retinol/g raw weight (n=3). Hence, the vitamin A intake was approximately 3,300 IU or 1 mg/kg body weight."
I didn't know that 'polar bear' used to be called 'turkey' in 1996. It's a hospitalizing amount (~230,000 IU).
"The major findings of the present study were the identification of two RA isomers, 9-cis-RA and 9,13-di-cis-RA, as well as 14-hydroxy-4,14-retro-retinol (14-HRR), in human plasma following liver consumption. These retinoids must be a result of in vivo metabolism of vitamin A, because levels of these compounds in animal liver are very low - if present at all - (14) and therefore cannot account for the observed plasma levels."
"9-cis-RA and 14-HRR are known to exhibit high activity - in some systems greatly exceeding that of all-trans-RA (18, 19, 26). Additionally, 9-cis-RA induced dysmorphogenic effects in a wide variety of systems (16- 19). Furthermore, the plasma levels of 13-cis-RA, 13-cis-4-0x0-RA, and all-tram-RA were significantly elevated over endogenous levels and could therefore also contribute to vitamin A induced teratogenicity. Our quantitative exposure data on highly active retinoids following consumption of a liver meal provide an additional rationale for caution against high vitamin A intake during pregnancy."
- Vitamin A supplementation increases ratios of proinflammatory to anti-inflammatory cytokine responses in pregnancy and lactation
@Orion and @stargazer1111, were you pregnant during supplementation? Fetuses don't usually put an arm or a leg out, so be careful in your interpretations.
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