vitamin-a2 and Body-Weight

Dietary α-carotene is present in oranges and purple-orange carrots. Upon the central cleavage of α-carotene in the intestine, α-retinal and retinal are formed and reduced to α-retinol (αR) and retinol. Previous reports have suggested that αR has 2% biopotency of all-trans-retinyl acetate due in part to its inability to bind to the retinol-binding protein. In the present work, we carried out three studies. Study 1 re-determined αR's biopotency compared with retinol and 3,4-didehydroretinol in a growth assay. Weanling rats (n 40) were fed a vitamin A-deficient diet for 8 weeks, divided into four treatment groups (n 10/group) and orally dosed with 50 nmol/d retinyl acetate (14.3 μg retinol), α-retinyl acetate (143 μg αR), 3,4-didehydroretinyl acetate (14.2 μg DR) or cottonseed oil (negative control). Supplementation was continued until the control rats exhibited deficiency signs 5 weeks after the start of supplementation. Body weights and AUC values for growth response revealed that αR and DR had 40-50 and 120-130% bioactivity, respectively, compared with retinol. In study 2, the influence of αR on liver ROH storage was investigated. The rats (n 40) received 70 nmol retinyl acetate and 0, 17.5, 35 or 70 nmol α-retinyl acetate daily for 3 weeks. Although liver retinol concentrations differed among the groups, αR did not appreciably interfere with retinol storage. In study 3, the accumulation and disappearance of αR over time and potential liver pathology were determined. The rats (n 15) were fed 3.5 μmol/d α-retinyl acetate for 21 d and the groups were killed at 1-, 2- and 3-week intervals. No liver toxicity was observed. In conclusion, αR and didehydroretinol are more biopotent than previously reported at sustained equimolar dosing of 50 nmol/d, which is an amount of retinol known to keep rats in vitamin A balance.

Topics: Animals; Area Under Curve; Body Weight; Diet; Dietary Supplements; Dose-Response Relationship, Drug; Drug-Related Side Effects and Adverse Reactions; Growth; Liver; Male; Rats; Rats, Sprague-Dawley; Vitamin A; Vitamin A Deficiency; Weaning

Relationships between increased adiposity and fat-soluble vitamin storage and metabolism are poorly understood. To examine these associations, 6% or 21% dietary fat was fed to rats for 11 weeks and tissue vitamin A storage determined. Two levels of supplemental vitamin A were administered. At the end of the tenth week, 3,4-didehydroretinol (DR) was administered orally, and its kinetics were followed for 1 week in serum and tissues. Model-based compartmental analysis was applied to these data. Kidney total retinol (R) concentrations were elevated in rats fed 6% compared with 21% dietary fat (n = 24/group). The fractional transfer coefficient (FTC) describing the movement of tracer from plasma to extravascular stores was two times higher in the 6% compared with the 21% fat group. Consistent with the elevated renal R in 6% fat fed rats, there was a 2-fold increase in the FTC representing tracer distribution from plasma to kidney in the 6% compared with 21% fat group. Taken together with a fat main effect on renal vitamin A, our data support the evidence that faster turnover of kidney R may help set the mechanism governing vitamin A tissue distribution during deficiency. Rats fed 21% versus 6% dietary fat conserved hepatic R more efficiently.

Topics: Adipose Tissue; Adiposity; Animals; Body Weight; Dietary Fats; Diterpenes; Liver; Male; Models, Biological; Obesity; Rats; Rats, Sprague-Dawley; Retinoids; Retinyl Esters; Vitamin A; Vitamin A Deficiency

Concentrations of vitamins A1 (retinol), A2 (3,4-didehydroretinol) and E (alpha-tocopherol) in the liver and blubber of ringed seals from Lake Saimaa (Phoca hispida saimensis), Lake Ladoga (P. h. ladogensis), the Baltic Sea (P. h. botnica) and Spitsbergen (P. h. hispida) were determined by high-performance liquid chromatography. The freshwater seals had much lower levels of vitamin A1 but higher levels of vitamin A2 than the marine seals. The concentrations of vitamin E in the livers of the subspecies studied were high compared with earlier reports of seals, but the ranges were large. The livers of the marine seals contained more vitamin E than the livers of the freshwater seals, but the levels in the blubber were uniform in all populations, except in old specimens from the Baltic. The differences between the freshwater and marine seals are suggested to be due mainly to diet. The ratios of A1 to A2 in the liver and blubber and in the fish diet were similar for the marine seals and for the freshwater seals (but differed in the marine and freshwater populations), which suggests no great differences in the absorption, transport and metabolism of the two analogues. Blubber was an important storage site for the vitamins studied, and age-dependent increases were detected, especially for vitamin E. In the 2-month to 2-year-old ringed seals of Lake Saimaa, however, the vitamin E concentration in the blubber was not affected by age.

Topics: Adipose Tissue; Animals; Body Weight; Chromatography, High Pressure Liquid; Diet; Female; Fresh Water; Liver; Male; Seals, Earless; Seawater; Vitamin A; Vitamin E

The modified-relative-dose-response (MRDR) test, which has been used extensively throughout the world for assessing vitamin A status, has been simplified. The major methodologic change resulting from the current studies in Indonesia is the use of graded standard doses of 3,4-didehydroretinyl acetate (DRA) based on the age range of the population of interest. Instead of a dose of 0.35 mumol/kg body wt, standard doses of 5.3 mumol for children younger than 6 y, 7.0 mumol for children between 6 and 12 y of age, and 8.8 mumol for adults and children > 12 y of age are suggested for field use. The acceptable time between administering the oral dose and obtaining a blood sample was validated as being 4-7 h in a group of children (n = 84) by taking two blood samples per child between 3 and 7 h after dosing with DRA. Furthermore, DRA in vitamin E-containing corn oil, with or without the addition of 4.6 mmol all-rac-alpha-tocopheryl acetate/L, was found to be stable for > or = 18 mo at 2 degrees C and at -20 degrees C, but not at 22 degrees C or at 37 degrees C. When DRA was stored in amber glass vials, stability was affected more by temperature than by exposure to room light. In keeping with earlier studies in adults, the ratio of 3,4-didehydro-retinol to retino tends to be independent of body weight. Indeed, slower growing children (ie, those with lower weight-for-age) may have a somewhat better vitamin A status than their heavier counterparts.

Topics: Adult; Body Weight; Child; Child, Preschool; Dose-Response Relationship, Drug; Humans; Indonesia; Vitamin A; Vitamin A Deficiency

The vitamin A statuses of two groups of Indonesian women were compared by using the modified-relative-dose-response (MRDR) test: 1) lactating, nonpregnant women of lower socioeconomic status (n = 64) and 2) better-educated, premenopausal, nonpregnant, nonlactating women (n = 14). At times from 3 to 6 h after dosing, the mean ratio of dehydroretinol to retinol (DR/R) in the serum was approximately threefold higher in the lactating women than in the control group, eg, 0.109 +/- 0.073 and 0.034 +/- 0.015, respectively, at 5 h. At a provisional DR/R cutoff of 0.06, the vitamin A statuses of 70% of the lactating women and of 7% of the control women were judged to be inadequate. Only 7% of the variability in abnormal MRDR ratios could be attributed to body weight. Both abnormal and normal responses were highly reproducible when performed 0.5-3.25 mo after the first test.. The vitamin A statuses of two groups of Indonesian women recruited from the suburban areas surrounding Bogor in West Java, Indonesia, were compared by using the modified-relative-dose-response (MRDR) test: 1) 64 lactating nonpregnant women of lower socioeconomic status aged 17-37 years with 1-10 children; and 2) better-educated, pre-menopausal, nonpregnant, nonlactating women, 29-41 years old, with 0-4 children (n = 14) recruited from the staff at the Nutrition Research and Development Center in Bogor. The two groups differed significantly in weight (P 0.001) and age (P 0.001). At times from 3 to 6 hours after dosing, the mean ratio of dehydroretinol to retinol (DR/R) in the serum was approximately threefold higher in the lactating women than in the control group, e.g., 0.109 + or - 0.073 and 0.034 + or - 0.015, respectively, at 5 hours. The slopes of the response means between the groups showed a highly significant difference (P 0.001). The mean DR/Rs obtained by combining 5-hours and 5-hours-predicted values for lactating and control groups were 0.109 + or - 0.073 and 0.034 + or - 0.015, respectively. These two values also showed a highly significant difference (p 0.001). At a provisional DR/R cutoff of 0.06, the vitamin A statuses of 70% of the lactating women and of 7% of the control women were judged to be inadequate. The MRDR values of the control group also show a significant negative correlation with body weight (P 0.01). The slopes [(change in DR/R)/kg body wt] were -0.0055/kg (-0.0036/kg for n - 1) and -0.0015/kg for the lactating and control groups, respectively. Only 7% of the variability in abnormal MRDR ratios could be attributed to body weight. Both abnormal and normal responses were highly reproducible when performed 0.5 -3.25 months after the first test. Thus, safe, low-dose oral supplements of vitamin A ( 8000 IU) should be made available to lactating and pregnant mothers in at-risk populations. Nontoxic provitamin A carotenoids might be preferable as supplements.

Topics: Administration, Oral; Adolescent; Adult; Body Weight; Dose-Response Relationship, Drug; Female; Humans; Indonesia; Lactation; Nutrition Assessment; Reproducibility of Results; Socioeconomic Factors; Suburban Population; Vitamin A; Vitamin A Deficiency

The vitamin A statuses of preschool-aged children without clinical eye signs of vitamin A deficiency in two villages near Bogor, West Java, Indonesia, were studied by the modified-relative-dose-response (MRDR) test and the conjunctival impression cytology (CIC) method. In the second village the relative-dose-response (RDR) test was also applied. Of the children examined, 71% in the first village (group 1, n = 75) and 36% in the second village (group 2, n = 83) fell below the third percentile of the WHO reference standard of weight-for-age. The following provisional cutoff values for inadequate vitamin A status in Indonesia were used: MRDR (> or = 0.06), RDR (> or = 20%), CIC (an abnormal impression in one eye). The percent abnormal values were as follows: group 1--MRDR 48%, CIC 51%; group 2--MRDR 12%, RDR 11%, CIC 5%. Thus, the indicators gave concordant results for the two populations but did not necessarily identify the same individuals at risk. The consistency of the RDR test was much improved by increasing the oral dose of 3.5 mumol and by retesting only after a 3-wk interval.

Topics: Administration, Oral; Body Weight; Child; Child, Preschool; Chromatography, High Pressure Liquid; Conjunctiva; Cytological Techniques; Dose-Response Relationship, Drug; Humans; Indonesia; Infant; Nutrition Assessment; Nutritional Status; Reference Standards; Rural Population; Vitamin A; Vitamin A Deficiency

Vitamin A-deficient diet affected the body weight or growth of Heteropneustes fossilis, a freshwater siluroid rich in 3-4,dehydroretinol. The fish lost body weight after 20-30 days of administration of vitamin A-deficient diet. Cessation of growth occurred owing to vitamin A-deprivation, whereas control fish after supplementation of vitamin A continued their growth. Initial growth of the fish after administration of vitamin A-deficient diet is regulated by its initial vitamin A-reserve, whereas successive deficiency lead to the cessation of growth or weight loss. Supplementation of retinyl acetate to vitamin A-deficient fish compensate the loss of body weight.

Topics: Animals; Body Weight; Diet; Diterpenes; Fishes; Intestines; Liver; Retinyl Esters; Vitamin A