Article

Carrot Leaves Maintain Liver Vitamin A Concentrations in Male Mongolian Gerbils Regardless of the Ratio of α- to β-Carotene When β-Carotene Equivalents Are Equalized

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Abstract

Background Carrots are an important horticultural crop that contain provitamin A carotenoids (PACs). Orange carrots have high concentrations of α-carotene, which upon central cleavage yields 1 retinal and 1 α-retinal molecule. The leaves of carrot plants are a source of PACs when consumed. Objective Male Mongolian gerbils aged 27–30 d were used to assess the bioefficacy of carrot leaves to maintain vitamin A (VA) status and investigate whether the ratio of α- to β-carotene (α:β-carotene) affected bioefficacy. Methods After 3 wk depletion, baseline gerbils were killed (n = 6) and the remaining gerbils (n = 60) were divided into 6 groups to receive 4 VA-deficient, carrot leaf–fortified feeds (1:1.4, 1:2.5, 1:5.0, and 1:80 α:β-carotene ratio) equalized to 4.8 nmol/g β-carotene equivalents (βCEs), or VA-deficient feed with (VA+) or without (VA−) retinyl acetate supplements. Carrot-leaf powder from 4 carrot plants with differing α:β-carotene ratios was used. After 4 wk, gerbils were killed and tissues were collected and analyzed for retinoids by HPLC. Results VA+ had higher total liver VA (means ± SD 0.91 ± 0.29 μmol) than all other groups (range: 0.40–0.62) (P ≤ 0.03), and the carrot leaf treatments did not differ from baseline (0.55 ± 0.09 μmol). VA− (0.40 ± 0.23 μmol VA/liver) did not differ from the leaf-fed groups, but 30% became VA deficient (defined as <0.1 μmol VA/g liver). α-Retinol accumulated in livers and lungs and was correlated to total α-carotene consumption (R2 = 0.83 and 0.88, respectively; P < 0.0001). Bioefficacy factors ranged from 4.2 to 6.2 μg βCE to 1 μg retinol. Conclusions Carrot leaves maintain VA status and prevent deficiency in gerbils regardless of the α:β-carotene ratio. The bioconversion of PACs from carrot leaves to retinol is similar to what has been reported for other green leafy vegetables, making the consumption of carrot leaves a viable method to improve dietary PAC intake.

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α-Retinol has utility in determining chylomicron trafficking of vitamin A to tissues given that it will not be recirculated in blood on retinol binding protein (RBP). In this study, α-retinol was used as a chylomicron tag to investigate short-term uptake from high-dose supplements given to piglets as a model for neonates. The distribution of orally administered α-retinol doses in liver and extrahepatic tissues was assessed at varying times after dosage. Male piglets (n = 24 per group) from vitamin A-depleted sows were orally given 26.2 or 52.4 μmol of α-retinyl acetate, the molar equivalent of 25,000 and 50,000 IU of vitamin A, respectively. Tissues were collected and analyzed by HPLC. Lung (6.46 ± 2.94 nmol/g), spleen (22.1 ± 11.3 nmol/g), and adrenal gland (17.0 ± 11.2 nmol/g) α-retinol concentrations peaked at 7 h after dose, and, by 7 d, α-retinol was essentially cleared from these tissues (≤0.25 ± 0.12 nmol/g). This demonstrates that the lung, spleen, and adrenal gland receive substantial vitamin A from chylomicra to maintain concentrations. Conversely, storage of α-retinol in the liver reached a plateau at 24 h (1.72 ± 0.58 μmol/liver) and was retained through 7 d (2.10 ± 0.38 μmol/liver) (P > 0.05). This indicates that α-retinol was not substantially utilized locally in the liver nor transported out from the liver via RBP. In serum, the majority of α-retinol was in the ester form, which confirms that α-retinol does not bind to RBP but does circulate. α-Retinyl esters were detectable at 7 d in the serum but were not different from baseline. Collectively, these data suggest that crucial immune organs need constant dietary intake to maintain vitamin A concentrations because α-retinol was quickly taken up by tissues and decreased to baseline in all tissues except long-term storage in the liver.
Article
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.
Article
Stepwise multiple regression of five sensory parameters and 21 objective variables demonstrated that sugars and individual or summed total volatile terpene compounds are important in determining raw carrot flavor. The relative importance of each objective variable varies by the location in which carrots are grown and the genetic background of the carrot. Harsh, turpentine-like flavors are associated with the presence of the volatiles, particularly γ-terpenine and total volatiles, and a reduction in sugars. The reverse is true for sweetness and overall preference which are enhanced by sugars and diminished by volatiles. Overall carrot flavor is heightened by a reduction in total volatiles. Sucrose levels correlate positively and reducing sugars negatively with volatile terpene levels. For the growing sites represented, genetic variation was significant for reducing sugars, terpinolene, sucrose, α-phellandrene, limonene, and total volatiles, while environmental variation was significant for dry weight, refractive index, carotenoids, sucrose, total sugars, and terpinolene.
Article
The physiological potencies of five geometric isomers (all-trans, neo (2-mono-cis), 6-mono-cis, 2,6-di-cis, and 2,4-di-cis) of vitamin A aldehyde and of α-vitamin A aldehyde have been determined. All-trans and neo-(2-mono-cis)-vitamin A aldehydes have the same biopotency of 3,070,000 u./g., about 91% the molar bioactivity of all-trans-vitatnim A acetate. The 6-mono-cis- and 2,6-di-cis-vitamin A aldehydes have the relatively low biopotencies of 637,000 and 581,000 u./g., respectively, about 18% the molar bioactivity of all-trans-vitamin A acetate. The 2,4-di-cis-vitamin A aldehyde has a biopotency of 1,610,000 u./g., about 48% the molar bioactivity of all-trans-vitamin A acetate. The α-ionone analog of vitamin A aldehyde has less than 2% the potency of vitamin A acetate and during metabolism it is converted to the corresponding α-vitamin A alcohol which is stored in the liver.
Article
About 13% of the carotene in leaves of pigmented carrots was in the -form. -Carotene was absent from the leaves of all types of ‘white’ -rooted carrots except second generation albinos, although the content of β-carotene was normal. -Carotene was present in cotyledons of those carrots which had, or would later have, any carotene ( or β) in their roots even at a stage too early for the roots yet to be coloured.
Article
The usefulness of the solvent mixture dichloromethane/methanol for lipid extraction and the determination of lipid classes and fatty acids in samples of different natures was conducted. Two different extraction methods were compared, one containing chloroform/methanol, another containing dichloromethane/methanol. Total lipid extraction showed some minor differences but no variation in the lipid classes. Regarding the fatty acid profile, in Echium virescens seeds, 17 major fatty acids could be identified and quantified, and all were equally extracted when either solvent system was employed. In Echium acanthocarpum hairy roots, 17 major fatty acids were quantified, showing some statistical differences for one cell line in favor of chloroform. The data obtained from the liquid nutrient medium were also comparable. The cod roe sample showed 31 major fatty acids, showing no statistical differences between the two solvent systems. Contrarily, the CH 2Cl 2 method was able to extract 31 main fatty acids found in European seabass dorsal muscle more efficiently than the CHCl 3 method. The results indicate that, for lipid extraction and fatty acid assessment, dichloromethane/methanol can readily replace the commonly employed chloroform/methanol, thus avoiding the major health, security, and regulatory problems associated with the use of chloroform.
Article
α-Retinol (αR) is a structural isomer of retinol [vitamin A (VA)] that does not bind to serum retinol-binding protein (RBP). In this study, α-retinyl acetate (αRA) was synthesized and given orally (35 μmol) to VA-deficient lactating sows (n = 11) to assess its potential to trace RBP-independent retinol transport and tissue uptake. The αRA dose primarily appeared in sow serum as 4 α-retinyl esters (αRE) with peak serum total αR concentrations (the sum of the alcohol and ester forms) detected at 2 h (70 ± 23 nmol/L, mean ± SEM) postdose. From 0 to 40 h postdose, the percentage of serum total αR in the alcohol form did not increase. Rapid αR uptake into sow milk was observed with peak concentrations (371 ± 83 nmol/L) at 7.5 h postdose, consistent with the uptake of αRE from chylomicra. A high percentage of the αRA dose (62 ± 15%, mean ± SD) was present in the livers of sows (n = 6) killed 22-28 d postdose. Approximately 15-26% of the sow αRA dose was transferred to the livers of the nursing piglets (n = 17) after 3 d. In piglets and sows, a similar percentage of hepatic total αR was detected in the ester form as that of hepatic total retinol. Taken together, these data suggest that an oral dose of αRA effectively traces the uptake, esterification, chylomicron transport, and hepatic storage of retinol and may be useful for deciphering the role of RBP-independent delivery of retinol to other tissues.
Article
There is little evidence to support the general assumption that dietary carotenoids can improve vitamin A status. We investigated in Bogor District, West Java, Indonesia, the effect of an additional daily portion of dark-green leafy vegetables on vitamin A and iron status in women with low haemoglobin concentrations (Every day for 12 weeks one group (n=57) received stirfried vegetables, a second (n=62) received a wafer enriched with β-carotene, iron, vitamin C, and folic acid, and a third (n=56) received a non-enriched wafer to control for additional energy intake. The vegetable supplement and the enriched wafer contained 3·5 mg β-carotene, 5·2 mg and 4·8 mg iron, and 7·8 g and 4·4 g fat, respectively. Assignment to vegetable or wafer groups was by village. Wafers were distributed double-masked. In the enriched-wafer group there were increases in serum retinol (mean increase 0·32 [95% Cl 0·23-0·40] μmol/L), breastmilk retinol (0·59 [0·35-0·84] μmol/L), and serum β-carotene (0·73 [0·59-0·88] μmol/L). These changes differed significantly from those in the other two groups, in which the only significant changes were small increases in breastmilk retinol in the control-wafer group (0·16 [0·02-0·30] μmol/L) and in serum β-carotene in the vegetable group (0·03 [0-0·06] μmol/L). Changes in iron status were similar in all three groups.An additional daily portion of dark-green leafy vegetables did not improve vitamin A status, whereas a similar amount of β-carotene from a simpler matrix produced a strong improvement. These results suggest that the approach to combating vitamin A deficiency by increases in the consumption of provitamin A carotenoids from vegetables should be re-examined.
Article
Beta-carotene is a predominant source of vitamin A in developing countries. Genetically selected "high carotene" carrots could have an impact on the vitamin A and antioxidant status of people if widely adopted. A 3 x 3 crossover study in humans (n = 10) evaluated the difference in uptake and clearance of alpha- and beta-carotene from carrots genetically selected and traditionally bred to have high, typical, or no carotene. Subjects were fed white (0 mg alpha- and beta-carotene/d), orange (1.8 mg alpha-carotene and 2.6 mg beta-carotene/d), or dark-orange (4 mg alpha-carotene and 7 mg beta-carotene/d) carrots in muffins for 11 d, with a 10-d washout phase between treatments. Serum carotenoid and retinol concentrations were measured by HPLC. C-reactive protein (CRP), an indicator of underlying inflammation or infection which may lower serum retinol, was measured at the beginning of each period. A significant treatment effect occurred for serum alpha- and beta-carotene concentrations (P < 0.001), and a trend towards a negative effect of subjects' BMI on concentrations (P= 0.08). A significant treatment by sequence interaction was observed (P = 0.038), which was attributable to a difference in serum alpha- and beta-carotene concentrations between carrot treatments in the first period. Serum retinol remained stable for the first 20 d of the intervention and then decreased (P = 0.02). CRP was not elevated in any subject. High carotene carrots provide more provitamin A carotenoids than the typical store-bought variety, without a change in flavor. The availability of high carotene carrots could readily increase consumption of beta-carotene and potentially impact the vitamin A status of those individuals who are deficient or at risk of depletion.
Article
Concentrations of individual carotenoids and tocopherols were determined in abdominal adipose tissue from 19 adults undergoing corrective surgery. Samples were extracted and saponified before separation and quantitation of carotenoids and tocopherols by reverse-phase high-performance liquid chromatography. Total carotenoid concentration varied 40-fold between individuals, from 0.34 to 13.51 micrograms/g adipose tissue. Beta-carotene and lycopene were the predominant carotenoids, averaging 20.2 and 18.5% of total carotenoids, respectively. In 10 of 19 subjects, the lycopene concentration exceeded that of beta-carotene. Total tocopherol concentrations varied 11-fold, with alpha-tocopherol representing 80.6 +/- 8.1% of the total. Absolute concentrations of both carotenoids and tocopherols were more variable than their relative concentrations. Both beta-carotene and lycopene concentrations were highly correlated with total carotenoid content but there was no correlation between beta-carotene and lycopene or between beta-carotene and alpha-tocopherol concentrations.
Article
IN the course of an earlier investigation into the utilization of carotene by the rat as a source of vitamin A, it was noted that there was a consistent difference between the absorption spectra of the liver non-saponifiable fractions from those rats fed vitamin A and those fed a mixture of 90 per cent beta- and 10 per cent alpha-carotene1. This difference was in the magnitude of the absorbance at 311 mµ as compared with that at 326 mµ. The alpha-ionone analogue of vitamin A was afterwards synthesized2 and the absorption maxima were found to be at 311 mµ (E1%1cm, 1,650), and 325 mµ. (E1%1cm, 1,500). This alpha-vitamin A was found to be biologically inactive but was found to be stored in the liver in the same way as vitamin A (ref. 3).
Article
There is little evidence to support the general assumption that dietary carotenoids can improve vitamin A status. We investigated in Bogor District, West Java, Indonesia, the effect of an additional daily portion of dark-green leafy vegetables on vitamin A and iron status in women with low haemoglobin concentrations (< 130 g/L) who were breastfeeding a child of 3-17 months. Every day for 12 weeks one group (n = 57) received stir-fried vegetables, a second (n = 62) received a wafer enriched with beta-carotene, iron, vitamin C, and folic acid, and a third (n = 56) received a non-enriched wafer to control for additional energy intake. The vegetable supplement and the enriched wafer contained 3.5 mg beta-carotene, 5.2 mg and 4.8 mg iron, and 7.8 g and 4.4 g fat, respectively. Assignment to vegetable or wafer groups was by village. Wafers were distributed double-masked. In the enriched-wafer group there were increases in serum retinol (mean increase 0.32 [95% CI 0.23-0.40] mumol/L), breastmilk retinol (0.59 [0.35-0.84] mumol/L), and serum beta-carotene (0.73 [0.59-0.88] mumol/L). These changes differed significantly from those in the other two groups, in which the only significant changes were small increases in breastmilk retinol in the control-wafer group (0.16 [0.02-0.30] mumol/L) and in serum beta-carotene in the vegetable group (0.03 [0-0.06] mumol/L). Changes in iron status were similar in all three groups. An additional daily portion of dark-green leafy vegetables did not improve vitamin A status, whereas a similar amount of beta-carotene from a simpler matrix produced a strong improvement. These results suggest that the approach to combating vitamin A deficiency by increases in the consumption of provitamin A carotenoids from vegetables should be re-examined.
Article
Vitamin A (retinol) is a necessary nutrient for vision, reproduction, growth, and immune function. Pro-vitamin A carotenoids are an important source, especially in developing countries. While preformed vitamin A is readily available from foods, carotenoids are much more difficult to assimilate. A number of factors have been identified that either enhance or hinder the bioavailability of carotenoids. These have been presented in the literature and given the mnemonic SLAMENGHI by some researchers. The following factors are summarized: Species of carotenoid, molecular Linkage, Amount in the meal, Matrix Properties, Effectors, Nutrient status, Genetics, Host specificity, and Interactions between factors. Identifying which of these are key issues for the general public, and promoting the increased consumption of fruits and vegetables with moderate and high levels of pro-vitamin A carotenoids, are important to vitamin A status and overall good health.
Article
Five different colored carrots were analyzed for their carotenoid profile and underwent sensory evaluation to determine consumer acceptance (n = 96). Four major carotenoids were identified and quantified by use of HPLC methods. High beta-carotene orange carrots were found to contain the greatest concentration of total carotenoids. Except for the white, all the carrots are a significant source of bioavailable carotenoids. Sensory evaluation showed the high beta-carotene orange and white carrots to be favored over the yellow, red, and purple carrots in both blind and nonblind treatments (P < 0.01). However, all the carrots were well accepted by the consumer panel. With this information, carrot growers should be encouraged to cultivate specialty carrots to provide sources of both vitamin A precursors and phytochemicals.
Article
Recent evidence suggests that the vitamin A equivalency of beta-carotene from plant sources is lower than previously estimated. We assessed the effect of 60 d of daily supplementation with 750 microg retinol equivalents (RE) of either cooked, puréed sweet potatoes; cooked, puréed Indian spinach (Basella alba); or synthetic sources of vitamin A or beta-carotene on total-body vitamin A stores in Bangladeshi men. Total-body vitamin A stores in Bangladeshi men (n = 14/group) were estimated by using the deuterated-retinol-dilution technique before and after 60 d of supplementation with either 0 microg RE/d (white vegetables) or 750 microg RE/d as sweet potatoes, Indian spinach, retinyl palmitate, or beta-carotene (RE = 1 microg retinol or 6 microg beta-carotene) in addition to a low-vitamin A diet providing approximately 200 microg RE/d. Mean changes in vitamin A stores in the vegetable and beta-carotene groups were compared with the mean change in the retinyl palmitate group to estimate the relative equivalency of these vitamin A sources. Overall geometric mean (+/-SD) initial vitamin A stores were 0.108 +/- 0.067 mmol. Relative to the low-vitamin A control group, the estimated mean changes in vitamin A stores were 0.029 mmol for sweet potato (P = 0.21), 0.041 mmol for Indian spinach (P = 0.033), 0.065 mmol for retinyl palmitate (P < 0.001), and 0.062 mmol for beta-carotene (P < 0.002). Vitamin A equivalency factors (beta-carotene:retinol, wt:wt) were estimated as approximately 13:1 for sweet potato, approximately 10:1 for Indian spinach, and approximately 6:1 for synthetic beta-carotene. Daily consumption of cooked, puréed green leafy vegetables or sweet potatoes has a positive effect on vitamin A stores in populations at risk of vitamin A deficiency.
Article
The vitamin A value of spinach and carrots needs to be measured directly. The objective was to determine the vitamin A value of intrinsically labeled dietary spinach and carrots in humans. Spinach and carrots were intrinsically labeled by growing these plants in 25 atom% 2H2O nutrient solution. Growth in this medium yielded a range of trans beta-carotene (tbeta-carotene) isotopomers with a peak enrichment at molecular mass plus 10 mass units. Seven men with a mean (+/-SD) age of 59.0 +/- 6.3 y and a body mass index (in kg/m2) of 25.7 +/- 1.5 consumed puréed spinach (300 g, 20.8 micromol tbeta-carotene equivalents) or carrots (100 g, 19.2 micromol tbeta-carotene equivalents) with a standardized liquid diet (no extra fiber) in random order 4 mo apart. Seven women with a mean (+/-SD) age of 55.5 +/- 6.3 y and a body mass index of 26.4 +/- 4.2 consumed puréed spinach only (300 g, 20.0 micromol tbeta-carotene equivalents). A reference dose of [13C8]retinyl acetate (8.9 micromol) in oil was given to each subject 1 wk after each vegetable dose. Blood samples were collected over 35 d. Areas under the curve for total labeled serum beta-carotene responses were 42.4 +/- 8.5 nmol.d per micromol spinach beta-carotene and 119.8 +/- 23.0 nmol.d per micromol carrot beta-carotene (P < 0.01). Compared with the [13C8]retinyl acetate reference dose, spinach tbeta-carotene conversion to retinol was 20.9 +/- 9.0 to 1 (range: 10.0-46.5 to 1) and carrot tbeta-carotene conversion to retinol was 14.8 +/- 6.5 to 1 (range: 7.7-24.5 to 1) by weight. Spinach and carrots can provide a significant amount of vitamin A even though the amount is not as great as previously proposed. Food matrices greatly affect the bioavailability of plant carotenoids, their efficiency of conversion to vitamin A, or both.
Article
The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of alpha-carotene isolated from carrots compared with beta-carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n = 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were killed to determine liver VA. Gerbils were divided into 3 treatment groups (n = 9/group) and given 35, 35, or 17.5 nmol retinyl acetate, alpha-carotene or beta-carotene, respectively, in 2 divided doses 5 h apart each day. The remaining 5 gerbils received oil vehicle. Gerbils were killed after 3 wk of supplementation. Serum samples and livers were collected and analyzed for VA. Liver extracts were subsequently saponified to quantify alpha-retinol. Serum retinol concentrations did not differ among the groups. Liver retinyl palmitate concentrations were significantly higher in the retinyl acetate treatment group (0.198 +/- 0.051 micromol/g; P < 0.05) than in all other groups. The alpha- and beta-carotene treatments resulted in similar retinyl palmitate concentrations, i.e., 0.110 +/- 0.026 and 0.109 +/- 0.051 micromol/g, respectively, which did not differ from the concentrations in gerbils killed at baseline (0.123 +/- 0.024 micromol/g). The oil group had significantly less retinyl palmitate (0.061 +/- 0.029 micromol/g; P < 0.05) than all other groups. alpha-Retinol was detected in livers of the alpha-carotene group (0.062 +/- 0.013 micromol/g). Thus, twice the amount of purified alpha-carotene maintained VA status as well as beta-carotene in VA-depleted gerbils. Conversion factors were approximately 5.5 microg alpha-carotene or approximately 2.8 mug beta-carotene to 1 microg retinol.
Article
Biofortification of maize with beta-carotene has the potential to improve vitamin A status in vitamin A deficient populations where maize is a staple crop. Accurate assessment of provitamin A carotenoids in maize must be performed to direct breeding efforts. The objective was to evaluate carotenoid extraction methods and determine essential steps for use in countries growing biofortified maize. The most reproducible method based on coefficient of variation and extraction efficiency was a modification of Kurilich and Juvik (1999). Heat and saponification are required to release carotenoids from biofortified maize and remove oils interfering with chromatographic analysis. For maize samples with high oil content, additional base may be added to ensure complete saponification without compromising results. Degradation of internal standard before carotenoids were released from the maize matrix required the addition of internal standard after heating to prevent overestimation of carotenoids. This modified method works well for lutein, zeaxanthin, beta-cryptoxanthin, alpha-carotene, and beta-carotene.
Article
Periodic supplementation to infants and young children is encouraged in developing countries by the WHO. We investigated vitamin A (VA) in extrahepatic tissues of piglets after supplementation with retinyl acetate to determine long-term storage. 3, 4-Didehydroretinyl acetate (DRA) as a tracer was used to evaluate uptake from chylomicra in 4 h. Sows were fed a VA-depleted diet throughout pregnancy and lactation. Male castrated piglets (n = 28, 11.6 +/- 0.5 d) from these sows were weaned onto a VA-free diet for 1 wk, assigned to 4 groups, and dosed orally with 0, 26.2, 52.4, or 105 micromol VA. After 10 d, 5.3 micromol DRA was administered to determine short-term uptake of 3, 4-didehydroretinol (DR). Four hours later, piglets were killed; adrenal glands, kidney, lung, and spleen were collected and analyzed for retinol and DR. Retinol concentrations of kidney and adrenal gland were higher than control, but treated groups did not differ. Retinol concentration was highest in kidney (1.70-2.52 nmol/g), followed by adrenal gland (0.30-0.48 nmol/g), lung (0.15-0.21 nmol/g), and spleen (0.11-0.15 nmol/g). Total retinol in kidney and spleen was different among the groups (P < 0.05). Unesterified retinol was the major VA form; the percent retinol of total VA was lowest in adrenal glands. DR did not differ among the groups. In 4 h, the minimum estimated chylomicron contribution to tissue DR was 63-280% higher than the maximum DR exposure from retinol-binding protein. Constant dietary intake may be important in maintaining VA concentrations in extrahepatic tissues.
Carrot leaf protein: preliminary trials with whole leaf using rabbits
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Xanthophylls as provitamin A carotenoids
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Efficiency of using peanut hay and carrot-tops hay for feeding growing rabbits
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Preventing micronutrient deficiencies: food abundance and diversity are fundamental
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Nutritional value and suitability of carrot whole top as green fodder
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