3, 4-Didehydroretinol kinetics differ during lactation in sows on a retinol depletion regimen and the serum:milk 3, 4-didehydroretinol:retinol ratios are correlated.

3, 4-Didehydroretinol (DR) metabolism was previously followed in vitamin A (VA)-replete lactating sows. This study followed DR appearance and clearance after dosage in serum and milk during 2 lactation cycles in sows (n = 8) fed VA-free feed for 3 gestation-lactation cycles. During lactations 2 and 3, 35 µmol 3, 4-didehydroretinyl acetate was given orally after overnight food deprivation. Blood and milk were collected at 0, 1.5, 3, 5, 7, 9, 16, 24, 36, 48, 60, and 72 h; livers were obtained at kill. Samples were analyzed for DR, retinol (R), and 3, 4-didehydroretinyl esters. During lactations 2 and 3, the 5-h serum DR:R ratios were 0.028 ± 0.017 and 0.069 ± 0.042, respectively, and serum R concentrations were 0.75 ± 0.23 and 0.86 ± 0.37 µmol/L, respectively. The DR:R ratio and serum R were 0.018 ± 0.013 and 0.94 ± 0.12 µmol/L, respectively, in VA-replete sows from the same herd. After lactation 3, liver VA was 0.23 ± 0.05 µmol/g, indicating low-normal VA status. Serum DR area-under-the curve from 0 to 48 h increased as liver stores decreased. Thirteen to 23% of DR dose was secreted into milk, consistent with VA-replete sows. Milk DR concentrations were greater during lactation 3 than 2. Peak concentration occurred earlier and the half-life was shorter for milk DR in the more VA-depleted sows. The milk and serum DR:R were correlated from 3 to 9 h (r = 0.70; P < 0.0001) and increased as VA stores decreased regardless of serum R concentration. Milk DR:R may replace serum measurements during lactation.

Eating frequency is associated with energy intake but not obesity in midlife women.

Midlife women tend to gain weight with age, thus increasing risk of chronic disease. The purpose of this study was to examine associations between overweight/obesity and behavioral factors, including eating frequency, in a cross-sectional national sample of midlife women (n = 1,099) (mean age = 49.7 years, and BMI = 27.7 kg/m²). Eating behaviors and food and nutrient intakes were based on a mailed 1-day food record. BMI was calculated from self-reported height and weight, and level of physical activity was assessed by self-reported questionnaire. After exclusion of low-energy reporters (32% of sample), eating frequency was not associated with overweight/obesity (P > 0.05) and was not different between BMI groups (normal, 5.21 ± 1.79; overweight, 5.16 ± 1.74; obese, 5.12 ± 1.68, P = 0.769). Adjusted logistic regression showed that eating frequency, snacking frequency, breakfast consumption, eating after 10 PM and consuming meals with children or other adults were not significantly associated with overweight/obesity. Total energy intake increased as eating frequency increased in all BMI groups, however, obese women had greater energy intake compared to normal weight women who consumed the same number of meals and snacks. Intake of fruit and vegetables, whole grains, dietary fiber, dairy, and added sugars also increased as eating frequency increased. While eating frequency was not associated with overweight/obesity, it was associated with energy intake. Thus, addressing total energy intake rather than eating frequency may be more appropriate to prevent weight gain among midlife women.

Small quantities of carotenoid-rich tropical green leafy vegetables indigenous to Africa maintain vitamin A status in Mongolian gerbils ( Meriones unguiculatus).

Leafy vegetables are important sources of provitamin A carotenoids. Information on their ability to provide vitamin A is often misleading because of the methodology used to assess bioefficacy. Mongolian gerbils were used to evaluate the bioefficacy of provitamin A carotenoids in tropical leafy vegetables (i.e. Solanum nigrum, Moringa oleifera, Vernonia calvoana and Hibiscus cannabinus) that are indigenous to Africa. Gerbils (n 67) were vitamin A-depleted for 5 weeks. After a baseline kill (n 7), the gerbils were weight-matched and assigned to six treatment groups (n 10; four vegetable groups; negative and positive controls). For 4 weeks, the treatments included 35 nmol vitamin A (theoretical concentrations based on 100 % bioefficacy) in the form of vegetables or retinyl acetate. In addition to their diets, the control and vegetable groups received daily doses of oil, while the vitamin A group received retinyl acetate in oil matched to prior day intake. Serum and livers were analysed for vitamin A using HPLC. Serum retinol concentrations did not differ among groups, but total liver vitamin A of the vitamin A and vegetable groups were higher than that of the negative control group (P < 0.0001). Liver beta-carotene 15,15'-monooxygenase-1 expression levels were determined for two vegetable groups and were similar to the positive and negative controls. Conversion factors for the different leafy vegetables were between 1.9 and 2.3 microg beta-carotene equivalents to 1 microg retinol. Small quantities of these vegetables maintained vitamin A status in gerbils through efficient bioconversion of beta-carotene to retinol.

Sweet potato beta-carotene bioefficacy is enhanced by dietary fat and not reduced by soluble fiber intake in Mongolian gerbils.

Orange-fleshed sweet potato (OFSP) is an important source of beta-carotene (betaC). Provitamin A bioefficacy from plant foods is influenced by dietary fat and fiber. We fed 3% OFSP powder diets with varying amounts of fat and soluble fiber to vitamin A (VA)-depleted Mongolian gerbils (n = 85) for 3 wk (8 groups, n = 10/group; control, n = 9) following a baseline kill (n = 6). OFSP diets differing in fat (3, 6, and 12%) contained 0.24% soluble fiber. Two additional 3% OFSP diets contained 6% fat and 3 or 9% white-fleshed sweet potato (WFSP) powder with soluble fiber contents of 0.42 and 0.80%, respectively. Control, VA-, and betaC-supplemented groups were included. Simulated digestion experiments compared the bioaccessibility of betaC from boiled vs. oil stir-fried OFSP. All OFSP diets maintained VA status and 12% fat and WFSP-added diets improved VA status above baseline (P < 0.05). Bioefficacy, as bioconversion factors, in gerbils fed 12% fat (3.5 +/- 1.4 microg betaC:1 microg VA) was improved over the 3% fat and betaC groups (6.5 +/- 3.7 and 6.7 +/- 3.7 microg betaC:1 microg VA, respectively) (P < 0.05) but did not differ from WFSP-added groups or the 6% fat group with no WFSP. Stir-frying doubled the efficiency of betaC incorporation into micelles during small intestinal digestion in support of the stimulatory effect of dietary fat on bioefficacy in vivo. Soluble fiber intake derived from WFSP did not influence bioefficacy. Replacing WFSP with OFSP will affect VA status if adopted by target groups.

Biofortified carrot intake enhances liver antioxidant capacity and vitamin a status in mongolian gerbils.

Biofortification efforts have increased concentrations of bioactive compounds in carrots. We measured the antioxidant potential and vitamin A bioefficacy of 4 biofortified carrot varieties [purple/orange, purple/orange/red, orange/red, and orange] in Mongolian gerbils (n = 73). Following a 4-wk vitamin A depletion period and baseline kill (n = 7), freeze-dried carrot powders were mixed into purified feeds and fed to 6 groups (n = 11/group) for 4 wk. White carrot-fed control and vitamin A-supplemented groups were used to calculate carrot provitamin A bioefficacy. Antioxidant capacities of carrot powders, sera, and livers were determined using the 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assay and carotenoid and retinol concentrations were determined by HPLC. Antioxidant capacity of liver extracts from the 4 colored carrot-fed groups [10.1 +/- 1.2 mumol Trolox equivalent antioxidant capacity (TEAC)/g] was significantly higher than the white carrot-fed control group (9.3 +/- 0.9 mumol TEAC/g) and vitamin A-supplemented group (8.8 +/- 1.4 mumol TEAC/g) (P < 0.05). Liver retinol stores in the colored carrot-fed groups (0.62 +/- 0.13 to 0.67 +/- 0.08 mumol retinol/liver) did not differ and were higher than the white carrot-fed control group (0.32 +/- 0.08 mumol retinol/g) (P < 0.0001). Serum antioxidant capacity and retinol did not differ among treatment groups. Liver antioxidant capacity and vitamin A stores were higher in gerbils fed colored carrots than in those fed white carrots. Antioxidant activity is one of several proposed mechanisms by which plant foods, like biofortified carrots, may provide additional health benefits beyond maintenance of vitamin A status.

Retinol to retinol-binding protein (RBP) is low in obese adults due to elevated apo-RBP.

Elevated serum retinol-binding protein (RBP) concentration has been associated with obesity and insulin resistance, but accompanying retinol values have not been reported. Assessment of retinol is required to discriminate between apo-RBP, which may act as an adipokine, and holo-RBP, which transports vitamin A. The relations between serum RBP, retinol, retinyl esters, BMI, and measures of insulin resistance were determined in obese adults. Fasting blood (> or =8 h) was collected from obese men and women (n = 76) and blood chemistries were obtained. Retinol and retinyl esters were quantified by HPLC and RBP by ELISA. RBP and retinol were determined in age and sex-matched, nonobese individuals (n = 41) for comparison. Serum apo-RBP was two-fold higher in obese (0.90 +/- 0.62 microM) than nonobese subjects (0.44 +/- 0.56 microM) (P < 0.001). The retinol to RBP ratio (retinol:RBP) was significantly lower in obese (0.73 +/- 0.13) than nonobese subjects (0.90 +/- 0.22) (P < 0.001) and RBP was strongly associated with retinol in both groups (r = 0.71 and 0.90, respectively, P < 0.0001). In obese subjects, RBP was associated with insulin (r = 0.26, P < 0.05), homeostatic model assessment of insulin resistance (r = 0.29, P < 0.05), and quantitative insulin sensitivity check index (r = -0.27, P < 0.05). RBP was associated with BMI only when obese and nonobese subjects were combined (r = 0.25, P < 0.01). Elevated serum RBP, derived in part from apo-RBP, was more strongly associated with retinol than with BMI or measures of insulin resistance in obese adults. Investigations into the role of RBP in obesity and insulin resistance should include retinol to facilitate the measurement of apo-RBP and retinol:RBP. When evaluating the therapeutic potential of lowering serum RBP, consideration of the consequences of vitamin A metabolism is paramount.

Ingestion of excessive preformed vitamin A by mothers amplifies storage of retinyl esters in early fetal livers of captive Old World monkeys.

Excessive preformed vitamin A (VA) intake is contraindicated during pregnancy because of teratogenic concerns. Recent studies have provided biochemical and histologic evidence of chronic hypervitaminosis A in captive Old World monkeys consuming laboratory diets containing high concentrations of retinyl acetate. To investigate the effects of maternal chronic overconsumption of preformed VA on VA storage in early fetal liver, we analyzed monkey fetal livers ranging from 35 to 93 d gestational age (comparable with mid-first to late second trimester in humans) for VA (n = 19) and retinoic acid (n = 9). Retinyl esters were identified in all fetal livers, and retinol, on a percentage basis, was more abundant in younger fetuses. Liver VA concentration increased with gestational age, ranging from 0.0011 to 0.26 micromol/g in the youngest (35 d) and oldest fetuses (93 d), respectively. Liver VA concentrations (mean +/- 1 standard deviation) were 0.023 +/- 0.008 micromol/g in early gestation and 0.19 +/- 0.06 micromol/g in midgestation fetuses. All-trans retinoic acid concentrations were higher in early gestation (99.2 +/- 57.0 pmol/g, n = 6) than in midgestation (18.2 +/- 6.1 pmol/g, n = 3) but were variable. Liver VA concentrations from midgestation fetuses were higher than those in fetal human and monkey livers from later stages of development, when growth and VA accumulation rates are assumed to be highest. Therefore, excessive intake of preformed VA by the mothers results in amplified early fetal liver retinyl ester storage.

One-time graded doses of vitamin A to weanling piglets enhance hepatic retinol but do not always prevent vitamin A deficiency.

BACKGROUND: Vitamin A supplements are administered to infants in developing countries at immunization contacts; doses of 50000 IU vitamin A are recommended. Doses of 100000 IU are given to children aged 0.5-1 y. The efficacy of these doses has not been adequately determined. OBJECTIVE: We aimed to quantify liver vitamin A after the administration of vitamin A doses to piglets. Piglets are a good model for infants because of their similar size, gastrointestinal anatomy, and vitamin A requirements. DESIGN: Castrated male piglets born to sows fed a vitamin A-depleted diet throughout 1 (parity A) or 3 (parity B) pregnancy and lactation cycles were randomly assigned to receive 1 of 4 oral vitamin A doses (ie, 0, 25000, 50000, or 100000 IU) at weaning (days 9-14). A vitamin A-depleted diet was fed until the piglets were killed on day 10. Serum retinol was measured on days 1, 2, 4, 7, and 10. The modified relative dose response was measured before supplementation and at the time of killing, and liver vitamin A concentration was measured. RESULTS: In both parities, 25000 IU did not result in a mean liver retinol reserve > 0.07 micromol/g liver (the deficiency cutoff). The 50000-IU dose increased mean reserves above 0.07 micromol/g only in parity A. Liver vitamin A reserves with the 100000-IU treatment were only 5% above those with the 50000-IU treatment. The modified relative dose-response test reflected differences in liver vitamin A stores in parity B, and the 0-IU group differed significantly from the 100000-IU group (P = 0.011). CONCLUSION: This piglet model suggests that, for supplementation to infants <6 mo old, a 50000-IU dose is likely to be more efficacious in mitigating deficiency than is a 25000-IU dose.

Beta-carotene from red carrot maintains vitamin A status, but lycopene bioavailability is lower relative to tomato paste in Mongolian gerbils.

Red carrots contain lycopene in addition to alpha- and beta-carotene. The utility of red carrot as a functional food depends in part on the bioavailability of its constituent carotenoids. Lycopene bioavailability was compared in Mongolian gerbils (Meriones unguiculatus) fed freeze-dried red carrot and tomato paste (Study 1, n = 47) and whole food extracts dissolved in cottonseed oil (Study 2, n = 39). Diets and supplements were equalized for lycopene and intakes did not differ. Both studies utilized negative (oil) and positive [purified lycopene (Lyc)] controls. In Study 1, vitamin A liver stores (0.68 +/- 0.13 micromol/liver) of the red carrot group did not differ from baseline (0.63 +/- 0.13 micromol/liver) and were greater than those of the tomato paste (0.43 +/- 0.12 micromol/liver), Lyc (0.51 +/- 0.14 micromol/liver), and control (0.38 +/- 0.17 micromol/liver) groups (P < 0.003). A similar pattern was observed in Study 2. In both studies, hepatic lycopene was higher in the tomato paste (82.7 +/- 26.7 and 80.7 +/- 20.2 nmol/liver) groups compared with red carrot groups (59.3 +/- 21.9 and 39.5 +/- 14.1 nmol/liver, P < 0.0001). Hepatic lycopene from tomato paste was higher than Lyc in Study 1, but tomato paste extract and Lyc did not differ in Study 2, when both were dissolved in oil. Red carrot maintains vitamin A status, but constituent beta-carotene may interfere with lycopene bioavailability. These results confirm prior studies in humans on the relative bioavailability of lycopene from red carrots and tomato paste and expand them by suggesting the mechanism and determining vitamin A value.

Caregiver knowledge, attitudes and practices regarding vitamin A intake by Dominican children.

Vitamin A deficiency (VAD) is a major concern in the Dominican Republic. Successful educational interventions are based on needs assessment data specific to the population for which behavioural change is desired. The purpose of this study was to establish a foundation for nutrition education efforts for caregivers of young children to prevent VAD in the Dominican Republic. A cross-sectional survey was administered to caregivers (N = 151) from rural/peri-urban villages in five provinces to assess vitamin A knowledge and attitudes, frequency of consumption of foods rich in vitamin A by an index child (age range 3-9 years), and food-related practices contributing to vitamin A intake. Caregiver knowledge regarding vitamin A was low in all villages regardless of differences in socio-economic status and level of education. A majority of the caregivers (67%) reported having a garden, but produce from the garden was thought mainly to provide a financial benefit vs. a nutritional benefit for the family. Several vegetables rich in vitamin A used as seasoning, mango, and unripe banana and plantain were commonly consumed by children as reported by caregivers. Educational interventions should focus on basic vitamin A knowledge regarding sources as well as symptoms of deficiency. Education should also emphasize increasing the variety of foods rich in provitamin A carotenoids grown in home gardens.

Vitamin A toxicity in wild-caught African green vervet monkeys (Chlorocebus aethiops) after 2 years in captivity.

Primate lab diets typically contain high vitamin A concentrations when compared with human recommended intakes. In this study, we analyzed the vitamin A contents of liver and serum from 13 adult female African green vervet monkeys (Chlorocebus aethiops). These monkeys were wild-caught and held in captivity for 2 y, during which time they consumed a standard primate diet. Liver vitamin A concentration (mean +/- 1 standard deviation) was 14.6 +/- 2.3 micromol retinol/g liver; subtoxicity in humans is defined as at least 1 micromol/g liver. The serum retinol concentration (0.93 +/- 0.21 microM) was not elevated. Hypertrophy and hyperplasia of hepatic stellate cells were present which, in conjunction with elevated hepatic vitamin A concentrations, are evidence of toxicity. Although the ramifications of chronically toxic vitamin A status in experimental monkeys have not been defined, this state may influence nonhuman primate research outcomes and confound data interpretation. The validity of bone mineral research using nonhuman primates is of greatest concern, in light of the association between vitamin A toxicity and compromised bone health.

Bioavailability of beta-carotene (betaC) from purple carrots is the same as typical orange carrots while high-betaC carrots increase betaC stores in Mongolian gerbils (Meriones unguiculatus).

Vitamin A (VA) deficiency is a worldwide public health problem. Biofortifying existing sources of beta-carotene (betaC) and increasing dietary betaC could help combat the issue. Two studies were performed to investigate the relative betaC bioavailability of a betaC supplement to purple, high-betaC orange, and typical orange carrots using Mongolian gerbils (Meriones unguiculatus). In study 1, which used a traditional bioavailability design, gerbils (n 32) received a diet containing orange, purple, or white carrot powder, or white carrot powder +a betaC supplement. In study 2, which included betaC-biofortified carrots, gerbils (n 39) received orange, high-betaC orange, purple, or white carrot powder in their diet. Both studies lasted 21 d and the gerbils were killed to determine the effect of carrot type or supplement on serum and liver betaC, alpha-carotene, and VA concentrations. Liver stores of betaC or VA in the gerbils did not differ between orange and purple carrot diets when equal amounts of betaC from each of the diets were consumed (P>0.05). Both the orange and purple carrot diet resulted in higher liver VA compared with the supplement (P<0.05). High-betaC carrots resulted in more than 2-fold higher betaC and 1.1 times greater VA liver stores compared with typical orange carrots (P<0.05). These results suggest that high-betaC carrots may be an alternative source of VA to typical carrots in areas of VA deficiency. Second, phenolics including anthocyanins and phenolic acids in purple carrot do not interfere with the bioavailability of betaC from purple carrots.

Extra-hepatic vitamin A concentrations in captive Rhesus (Macaca mulatta) and Marmoset (Callithrix jacchus) monkeys fed excess vitamin A.

Recent work examining vitamin A (VA) status of rhesus monkeys (Macaca mulatta) used as models for human biomedical research has revealed subtoxic hepatic VA concentrations. Livers of marmoset monkeys (Callithrix jacchus), another experimental animal, were also high in VA as was serum retinyl ester concentration. Both species consumed common research diets that provided up to four times the amount of VA (retinyl acetate) as currently recommended by the National Research Council. To further define the effects of chronically high dietary VA as found in many human subpopulations, we analyzed lung and kidney tissues from subtoxic rhesus and marmoset monkeys (n = 10 each) for retinol and retinyl esters. Marmoset kidneys contained 0.88 +/- 0.66 micromol VA/g and was nearly the same as hepatic VA at 1.40 +/- 0.44 micromol/g (p = 0.143). In contrast, rhesus kidney VA concentrations were 0.0100 +/- 0.0032 micromol/g, even though liver reserves were 18.8 +/- 6.4 micromol VA/g (p < 0.0001). Lung tissue VA concentrations, 0.0022 +/- 0.0012 and 0.0061 +/- 0.0025 micromol/g for marmosets and rhesus, respectively, were lower as compared with kidney (p < 0.011). Kidney and lung VA in monkeys with adequate, but not excessive, VA stores have not been determined; hence, interpretation of these findings is limited to tissue retinol and retinyl ester profiles and extrapolation from other species rather than direct comparison to "normal" values.