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Discovered in the late 1920s, 3,4-didehydroretinol (DROL, vitamin A2) plays a significant biological role in freshwater fish. The functions of this vitamin have been investigated but to a far lesser extent than those of retinol (ROL, vitamin A1). A recent study indicating all-trans DROL has 119-127% vitamin A biological activity compared to that of all-trans ROL suggests the significance of DROL for addressing vitamin A deficiency (VAD) in comparison to ROL may be currently overlooked. Freshwater fish such as small indigenous fish species (SIS), with high DROL content can be a promising dietary source for reducing VAD in areas where SIS are readily available and consumed. In this paper, the discovery and biological relevance of DROL are reviewed and furthermore, the vast potential of production and consumption of DROL-rich SIS in food-based strategies to combat VAD in Bangladesh and other developing countries with high prevalence of VAD is highlighted.

Boiled biofortified cassava containing β-carotene can increase retinyl palmitate in triacylglycerol-rich plasma. Thus, it might alleviate vitamin A deficiency. Cassava requires extensive preparation to decrease its level of cyanogenic glucosides, which can be fatal. Garification is a popular method of preparing cassava that removes cyanogen glucosides. Our objective was to compare the effectiveness of biofortified gari to gari prepared with red palm oil. The study was a randomized crossover trial in 8 American women. Three gari preparations separated by 2-week washout periods were consumed. Treatments (containing 200-225.9 g gari) were as follows: biofortified gari (containing 1 mg β-carotene), red palm oil-fortified gari (1 mg β-carotene), and unfortified gari with a 0.3-mg retinyl palmitate reference dose. Blood was collected 6 times from -0.5 to 9.5 hours after ingestion. Triacylglycerol-rich plasma was separated by ultracentrifugation and analyzed by high-performance liquid chromatography (HPLC) with diode array detection. Area under the curve for β-carotene, α-carotene, and retinyl palmitate increased after the fortified meals were fed (P < .05), although the retinyl palmitate increase induced by the red palm oil treatment was greater than that induced by the biofortified treatment (P < .05). Vitamin A conversion was 2.4 ± 0.3 and 4.2 ± 1.5 μg pro-vitamin A carotenoid/1 μg retinol (means ± SEM) for red palm oil and biofortified gari, respectively. These results show that both treatments increased β-carotene, α-carotene, and retinyl palmitate in triacylglycerol-rich plasma concentrations in healthy well-nourished adult women, supporting our hypothesis that both interventions could support efforts to alleviate vitamin A deficiency.

Beta-cryptoxanthin is a common carotenoid that is found in fruit, and in human blood and tissues. Foods that are rich in beta-cryptoxanthin include tangerines, persimmons and oranges. Beta-cryptoxanthin has several functions that are important for human health, including roles in antioxidant defense and cell-to-cell communication. Most importantly, beta-cryptoxanthin is a precursor of vitamin A, which is an essential nutrient needed for eyesight, growth, development and immune response. We evaluate the evidence for beta-cryptoxanthin as a vitamin A-forming carotenoid in this paper. Observational, in vitro, animal model and human studies suggest that beta-cryptoxanthin has greater bioavailability from its common food sources than do alpha- and beta-carotene from theirs. Although beta-cryptoxanthin appears to be a poorer substrate for beta-carotene 15,15' oxygenase than is beta-carotene, animal model and human studies suggest that the comparatively high bioavailability of beta-cryptoxanthin from foods makes beta-cryptoxanthin-rich foods equivalent to beta-carotene-rich foods as sources of vitamin A. These results mean that beta-cryptoxanthin-rich foods are probably better sources of vitamin A, and more important for human health in general, than previously assumed.

Discovered in the late 1920s, 3,4-didehydroretinol (DROL, vitamin A

Mixing of a particle-laden material during peristaltic flow in the stomach has not been quantified in vivo. Gastric mixing plays a key role in the digestion process; it determines the availability of acid and enzymes to individual food particles and controls the length of time particles will spend in the antral region, where they are subjected to mechanical breakdown from antral contraction waves. Solid particle mixing has been quantified using a dual-indigestible marker technique (TiO2 and Cr2O3) in soft (cooked brown and white rice) and rigid (raw and roasted almonds) particle meals fed to growing pigs. All meals consisted of two portions. Each portion was separately marked by one of the two indigestible markers, and the portions were sequentially fed to the pigs. At time periods ranging from 20 to 720 min after completion of the meal, ten intragastric chyme samples were taken from each pig to determine the marker concentration and pH value. Gastric pH was not homogeneous throughout the stomach and varied over time, with differences observed between soft and rigid meals (p

Vitamin A (VA) is an essential micronutrient in fish, vital for reproduction, vision and immunity. Freshwater fish species store and use VA in the form of retinol (ROL), as well as uncommon forms such as 3,4-didehydroretinol (DROL) and 3-hydroxyretinol (3ROL). We developed and validated an HPLC method capable of measuring ROL, DROL and 3ROL in the feed and tissues of North American freshwater fish, for which little information on retinoid concentrations is available. DROL and ROL were higher than expected in both fish feed and fish liver (at 9.5–29.6 mg kg−1 DROL and 26.9–79.2 mg kg−1 ROL for feed; and 19.8–548.8 μg g−1 DROL and 10.4–128.8 μg g−1 ROL for liver). Interestingly, DROL concentrations were lower than ROL in fish feed, but often substantially higher in fish liver. Concentrations of ROL and DROL were similar to each other in muscle. 3ROL was detected in fish liver only. To our knowledge, this is the first publication to measure DROL concentrations in North American farm-raised fish and commercial fish feed. Monitoring of not only ROL, but DROL and 3ROL as well, may be advisable to better assess the VA content of fish feed and tissue.

There is a general lack of knowledge regarding the absorption and tissue storage of the provitamin A carotenoid β-cryptoxanthin. The present study investigated the whole-body tissue distribution of β-cryptoxanthin in an appropriate small animal model, the Mongolian gerbil (Meriones unguiculatus), for human provitamin A carotenoid metabolism. After 5 d of carotenoid depletion, five gerbils were euthanised for baseline measurements. The remaining gerbils were placed in three weight-matched treatment groups (n 8). All the groups received 20 μg/d of β-cryptoxanthin from tangerine concentrate, while the second and third groups received an additional 20 and 40 μg/d of pure β-cryptoxanthin (CX40 and CX60), respectively, for 21 d. During the last 2 d of the study, urine and faecal samples of two gerbils from each treatment group were collected. β-Cryptoxanthin was detected in the whole blood, and in twelve of the fourteen tissues analysed. Most tissues resembled the liver, in which the concentrations of β-cryptoxanthin were significantly higher in the CX60 (17·8 (sem 0·7) μg/organ; P= 0·004) and CX40 (16·2 (sem 0·9) μg/organ; P= 0·006) groups than in the CX20 group (13·3 (sem 0·4) μg/organ). However, in intestinal tissues, the concentrations of β-cryptoxanthin increased only in the CX60 group. Despite elevated vitamin A concentrations in tissues at baseline due to pre-study diets containing high levels of vitamin A, β-cryptoxanthin maintained those vitamin A stores. These results indicate that β-cryptoxanthin is stored in many tissues, potentially suggesting that its functions are widespread.

Background: The potential of b-cryptoxanthin (CX)–rich foods to form vitamin A (VA) in humans in not well understood. Objective: We measured the effects of consuming CX and b-carotene (BC)–rich foods on plasma and breast milk VA and carotenoids in lactating women with low VA status. Design: Participants were randomly assigned to 4 groups (n = 34, 34, 34, and 33, respectively) receiving orange-fleshed sweet potatoes (OFSPs) (12 mg BC/d), tangerines (5.3 mg CX/d), whitefleshed sweet potatoes (WFSPs) with a VA supplement (0.5 mg/d), or WFSPs 2 times/d, 6 d/wk for 3 wk. All except the VA group received placebo capsules identical in appearance to VA supplements. Changes in plasma and breast milk VA, BC, and CX were measured. Results: Plasma retinol increased in the VA group. Plasma BC in the OFSP group and CX in the tangerine group increased 250% and 830%, respectively; apparent relative absorption in the CX group, considering the amounts consumed, was 4 times that in the BC group. Mean (6SEM) changes in milk VA in the OFSP (0.028 6 0.074 mmol/L) and tangerine (0.067 6 0.091 mmol/L) groups did not differ from those in the control (20.077 6 0.068 mmol/L) or VA (0.277 6 0.094 mmol/L) group. Milk CX increased in the tangerine group. Conclusions: VA capsules increased plasma and milk VA concentrations. The greater change in CX concentrations in the tangerine group than in BC concentrations in the OFSP group suggests that CX in tangerines was better absorbed, but both foods failed to increase milk VA concentrations. This trial was registered at clinicaltrials.gov as NCT01420406. Am J Clin Nutr doi: 10.3945/ajcn. 113.058180.

Almonds are an important dietary source of lipids, protein, and α-tocopherol. It has been demonstrated that the physical form of almond kernels influences their digestion and absorption, but the role of thermal processes on the digestion of almonds has received little attention. The objectives of this study were to examine the gastric emptying and nutrient composition of gastric chyme from pigs (used as a model for the adult human) fed a single meal of either raw or roasted almonds over a 12-h postprandial period (72 pigs total, 6 pigs at each diet-time combination). Concentrations of glucose, triacylglycerols, and α-tocopherol in peripheral plasma during the 12-h postprandial period were determined. For dry matter and lipid, the gastric emptying profile was not different between raw and roasted almonds. Roasting almonds also did not influence gastric pH, or plasma glucose or triacylglycerols levels. In contrast, the gastric emptying of protein was more rapid for raw almonds compared to roasted almonds (P < 0.01) and intragastric protein content exhibited segregation (P < 0.001) throughout the stomach, with raw almonds having a higher level of segregation compared to roasted almonds. Postprandial plasma α-tocopherol levels were, on average 33% greater (P < 0.001) after consumption of raw almonds, most likely as a result of the higher concentration of α-tocopherol in raw almonds compared to roasted almonds. Roasting of almonds did not influence the overall gastric emptying process, but did lead to differences in the distribution of protein in the stomach and to the gastric emptying of protein.

Citrus contains nutrients and phytochemicals that may be beneficial for health. We collected citrus production and consumption data and estimated the amount of these compounds that are consumed. We then compared the amounts of citrus and citrus-derived compounds used in studies that suggest a health benefit to the amounts typically found in citrus. Data is scarce, but suggests that citrus consumption might improve indices of antioxidant status, and possibly cardiovascular health and insulin sensitivity.

Biofortification of cassava with the provitamin A carotenoid β-carotene is a potential mechanism for alleviating vitamin A deficiency. Cassava is a staple food in the African diet, but data regarding the human bioavailability of β-carotene from this food are scarce. The objective of the present study was to evaluate provitamin A-enhanced cassava as a source of β-carotene and vitamin A for healthy adult women. The study was a randomised, cross-over trial of ten American women. The subjects consumed three different porridges separated by 2 week washout periods. Treatment meals (containing 100 g cassava) included: biofortified cassava (2 mg β-carotene) porridge with added oil (15 ml peanut or rapeseed oil, 20 g total fat); biofortified cassava porridge without added oil (6 g total fat); unfortified white cassava porridge with a 0·3 mg retinyl palmitate reference dose and added oil (20 g total fat). Blood was collected six times from − 0·5 to 9·5 h post-feeding. TAG-rich lipoprotein (TRL) plasma was separated by ultracentrifugation and analysed using HPLC with coulometric array electrochemical detection. The AUC for retinyl palmitate increased after the biofortified cassava meals were fed (Psd3·1) and 4·5 (sd3·1) μg β-carotene:1 μg retinol, with and without added oil, respectively. These results show that biofortified cassava increases β-carotene and retinyl palmitate TRL plasma concentrations in healthy well-nourished adult women, suggesting that it is a viable intervention food for preventing vitamin A deficiency.

The objective of this study was to determine the release and bioaccessibility of β-carotene from fortified almond butter using in vitro digestion models. Two types of fortifiers were investigated: β-carotene oil (oil) and whey protein isolate (WPI)-alginate-chitosan capsules containing β-carotene oil (capsule). Shaking water bath and Human Gastric Simulator (HGS) digestion models assessed the impact of gastric peristalsis on the release of β-carotene. Bioaccessibility of β-carotene was measured as percent recovered from the micelle fraction. There was greater release of β-carotene from oil fortified almond butter in the HGS model (87.1%) due to peristalsis than the shaking water bath model (51.0%). More β-carotene was released from capsule fortified almond butter during intestinal digestion. However, more β-carotene was recovered from the micelle fraction of oil fortified almond butter. These results suggest that a WPI-alginate-chitosan capsule coating may inhibit the bioaccessibility of β-carotene from fortified almond butter.

Vitamin A deficiency (VAD) is an important cause of blindness and premature death. Red palm oil (RPO) is the richest food source of VA-forming carotenoids. RPO carotenoid concentration and bioavailability were evaluated and this data used to estimate the amount of RPO needed to meet VA requirements. Amounts ranged from 6.7 to 29.2 g/d (1.5 to 6.5 tsp/d), which are easily consumed. The amount of RPO needed to supply recommended dietary intakes of VA for all 208100000 individuals most in danger for VAD worldwide for 1 y is 0.80 million metric tons, a fraction of annual world palm oil production. Despite its abundance, RPO has seldom been used for VAD prevention on a national level. Pareto charts were constructed to highlight the variables that influence the ability of RPO to prevent VAD on the national level. The most important variable by far was refining method. Most refining methods are designed to remove color and flavor from RPO, resulting in a bland product that lacks carotenoids. Thus, the important barriers to the use of RPO as a food-based intervention to prevent VAD appear to be that: (1) RPO requires refining, limiting its profitability and availability for small farmers. (2) The goal of most refining methods is to create a low-cost bland, odorless, and colorless fat which requires removal of carotenoids. (3) Cost, since RPO use competes with high-dose VA supplements, which are heavily subsidized. It appears that RPO could prevent VAD in many food-deficit countries if carotenoids were conserved during oil refining, and costs were low enough to make it an attractive alternative to nutritional supplements.

Vitamin A deficiency continues to be a major public health concern in the developing world effecting over 200 million people. Interventions including carotenoid-rich fruits and vegetables, containing α- and β-carotene, and β-cryptoxanthin, are being tested for their potential to alleviate vitamin A deficiency in several countries. Thus, there is a need for a faster isocratic reverse-phase high pressure liquid chromatography (HPLC) method than the methods currently available. Efficient extraction procedures for biological samples are also valuable to save time, materials, and cost. We developed an HPLC method and compared several extraction methods for carotenoids, retinoids, and vitamin E in plasma and human breast milk. The method uses an Agilent 1100 system equipped with a Waters Spherisorb ODS2 column (3 × 125 mm 3 μm) and similar guard column (ThermoScientific ODS2 3 × 20 mm 3 μm). Mobile phase of 7:2:1 acetonitrile:dichloromethane:methanol was run at 0.5 mL min−1, and run times were complete in approximately 8 min. This rapid method uses little solvent and provides excellent results in the analysis of these fat-soluble nutrients. Analyte measurements were repeatable using standards and plasma and were accurate compared to NIST certified and reference serum values. The validated HPLC method was applied to the analysis of plasma samples from a vitamin A intervention study.

Several studies suggest that β-cryptoxanthin has a greater plasma response from its common food sources than other carotenoids such as β-carotene and lycopene. The hypothesis of this study is that changes in plasma β-cryptoxanthin concentrations will be greater than changes in plasma β-carotene or lycopene concentrations even if these carotenoids are fed in a similar food matrix, such as citrus fruit. We tested this hypothesis by measuring changes in plasma concentrations of β-cryptoxanthin, lycopene, and β-carotene after feeding measured amounts of canned tangerines and pink grapefruit to healthy nonsmoking adult humans. Volunteers served as their own controls and received both citrus fruit treatments randomly. In the first study, 8 subjects ate single meals of 234-304g of tangerines or 60-540g of pink grapefruit. The second study compared changes in plasma carotenoid concentration caused by feeding 234g of tangerines or 540g of pink grapefruit to 11 subjects. Blood was collected 5 times within 24hours after each citrus meal. Carotenoid concentrations were analyzed by reversed-phase high-performance liquid chromatography. Plasma β-cryptoxanthin concentrations increased within 5hours and then stabilized, remaining high throughout the 24hours measured. Plasma concentrations of lycopene and β-carotene did not change. These results show that β-cryptoxanthin concentrations increased after a citrus fruit meal, but lycopene and β-carotene concentrations did not change after a similar citrus fruit meal. These results support our hypothesis that changes in plasma β-cryptoxanthin are greater than changes in plasma lycopene or β-carotene, even when these carotenoids are fed in a similar food matrix.

California is a major producer of tangerines and oranges, which contain carotenoids that form vitamin A. Deficiencies of this vitamin are common in southern Asia and Africa, causing blindness and more than one-half million deaths each year. We evaluated the potential of tangerines and oranges to prevent vitamin A deficiency worldwide by measuring their carotenoid concentrations, estimating the amounts needed to meet the recommended safe nutrient intake for vitamin A and determining their availability in countries with vitamin A deficiency. We conclude that tangerines - particularly Satsuma mandarins, which have high concentrations of the carotenoid beta-cryptoxanthin - but not oranges, could be useful in preventing vitamin A deficiency, though not as the sole source.

Vitamin A (VA) deficiency causes over 600000 deaths per year, mostly of young children or pregnant women. Populations prone to VA deficiency obtain about 82% of their VA from plant sources that are rich in pro-VA carotenoids such as beta-carotene. Orange-fleshed sweet potatoes (OFSP) are an especially good source. We evaluated OFSP carotenoid concentrations, bioaccessibility, and cooking and storage, then used this to estimate the amount of OFSP needed to supply 100% of VA for people at risk for deficiency. The grams/day of OFSP needed to meet VA requirements varies with age and sex, and with the amount of beta-carotene in the OFSP. Amounts ranged from 6 to 33 g/d (0.02 to 0.13 cups/d) for a 3-y-old child with marginal VA status; to 68 to 381 g/d, (0.27 to 1.49 cups/d) for a lactating woman with good status. These are amounts that can be eaten on a daily basis. The amount of OFSP needed to supply the VA requirement to all of the 208.1 million people most in danger of VA deficiency for 1 y is 2.1 to 11.7 million metric tons, or 2% to 11% of current world sweet potato production. The most important factor influencing the effectiveness of sweet potato for preventing VA deficiency, by far, is the variety of sweet potato used. Fat in the diet is also important. We conclude that OFSP could prevent VA deficiency in many food-deficit countries—if OFSP were substituted for white, cream, yellow, or purple sweet potatoes.

Objective Studies show low correlations between dietary intake and serum concentrations of lycopene, which make it difficult to assess the effectiveness of dietary interventions with this phytonutrient. We hypothesized that 1) combining food-frequency questionnaires (FFQs) and 3-d diet records (3D-DRs) by the triads method would improve the validity of this relation and 2) correcting dietary information for differences in lycopene absorption from food matrices would further improve validity. Methods We measured dietary intakes of lycopene from 49 adults by 3D-DR and FFQ. Serum lycopene was measured by high-performance liquid chromatography with diode array detection. Cholesterol and triacylglycerol concentrations were measured spectrophotometrically. Lycopene-containing foods were given absorption factors based on literature and laboratory values. Associations between dietary and serum lycopene were modeled using multiple regression. The triads method was used for validation of relations among FFQ, 3D-DR, and serum lycopene. Results Raw data showed low correlations between dietary and serum lycopene ( r = +0.15 for 3D-DR, +0.35 for FFQ). Mathematical modeling showed that the 3D-DR and FFQ methods must be used to collect accurate dietary information for lycopene. Validity coefficients calculated by the triads method were +0.34 for 3D-DR and +0.78 for FFQ. Correcting for absorption increased the validity coefficient to +0.72 for 3D-DR and from +0.45 to +0.66 for serum lycopene. Conclusion The relation between dietary intake and serum concentrations of lycopene and other carotenoids can be improved by collecting 3D-DR and FFQ data and by adjusting dietary information for nutrient absorption.

Our objective was to quantify the absorption and conversion to retinoids of a 1.01-nmol, 3.7-kBq oral dose of (14)C-beta-carotene in 8 healthy adults. The approach was to quantify, using AMS, the elimination of (14)C in feces for up to 16 d after dosing and in urine for up to 30 d after dosing. The levels of total (14)C in undiluted serial plasma samples were measured for up to 166 d after dosing. Also, the levels of (14)C in the retinyl ester (RE), retinol (ROH), and beta-carotene fractions that were isolated from undiluted plasma using HPLC were measured. The apparent digestibility of the (14)C was 53 +/- 13% (mean +/- SD), based on the mass balance data, and was generally consistent with the area under the curve for zero to infinite period of (14)C that was eliminated in the feces collections made up to 7.5 d after dosing. Metabolic fecal elimination, calculated as the slope per day (% (14)C-dose/collection from d 7.5 to the final day), was only 0.05 +/- 0.02%. The portion of the (14)C dose eliminated via urine was variable (6.5 +/- 5.2%). Participants [except participant 6 (P6)] had a distinct plasma peak of (14)C at 0.25 d post-dose, preceded by a shoulder at approximately 0.1 d, and followed by a broad (14)C peak that became indistinguishable from baseline at approximately 40 d. Plasma (14)C-RE accounted for most of the absorbed (14)C early after dosing and P1 had the longest delay in the first appearance of (14)C-RE in plasma. The data suggest that plasma RE should be considered in estimating the ROH activity equivalent of ingested beta-carotene.

β-Cryptoxanthin, a carotenoid found in fruits and vegetables such as tangerines, red peppers, and pumpkin, has several functions important for human health. Most evidence from observational, in vitro, animal model, and human studies suggests that β-cryptoxanthin has relatively high bioavailability from its common food sources, to the extent that some β-cryptoxanthin-rich foods might be equivalent to β-carotene-rich foods as sources of retinol. β-Cryptoxanthin is an antioxidant in vitro and appears to be associated with decreased risk of some cancers and degenerative diseases. In addition, many in vitro, animal model, and human studies suggest that β-cryptoxanthin-rich foods may have an anabolic effect on bone and, thus, may help delay osteoporosis.

Isotope tracer studies, particularly radiocarbon measurements, play a key role in biological, nutritional, and environmental research. Accelerator mass spectrometry (AMS) is now the most sensitive detection method for14C, but AMS is not widely used in kinetic studies of humans. Part of the reason is the expense, but costs would decrease if AMS were used more widely. One component in the cost is sample preparation for AMS. Biological and environmental samples are commonly reduced to graphite before they are analyzed by AMS. Improvements and mechanization of this multistep procedure is slowed by a lack of organized educational materials for AMS sample preparation that would allow new investigators to work with the technique without a substantial outlay of time and effort. We present a detailed sample preparation protocol for graphitizing biological samples for AMS and include examples of nutrition studies that have used this procedure.

We recently observed that ethanol feeding impairs 10-formyltetrahydrofolate (10-FTHF) dehydrogenase (EC 1.5.1.6.) and 10-FTHF hydrolase activity in rats. In the present study, we explored the effects of folate deficiency or sufficiency combined with alcoholic intake on 10-FTHF and possible mechanisms by which chronic ethanol ingestion produces folate deficiency.Sprague-Dawley rats were fed either folate-sufficient (FS) or folate-deficient (FD) diets; with or without ethanol (E) for four weeks. Hepatic 10-FTHF dehydrogenase and hydrolase activity, plasma folate and homocysteine were measured at baseline and after feeding experimental diets.Liver weight increased slightly with either folate deficiency or ethanol consumption. In rats fed the folate-sufficient diet with ethanol (FSE), plasma folate was decreased slightly (p0.05) and plasma homocysteine elevated compared to rats fed the FS diet without ethanol. Ethanol did not affect plasma folate and plasma homocysteine in FD rats. Red-blood cell (RBC) folate was increased similarly in rats by ethanol feeding (FSE and FDEFS and FD). Feeding folate deficient or ethanol (FSE, FD and FDE) diets depressed hepatic activities of 10-FTHF dehydrogenase, which catalyzes the oxidative deformylation of 10-FTHF to tetrahydrofolate (THF) and carbon dioxide. Rats consuming the FDE diet had the lowest enzyme activities of the experimental groups, implying that folate deficiency and ethanol consumption each affect enzyme activity.We confirm that ethanol decreases hepatic 10-FTHF dehydrogenase activity and show that this decrease occurs irrespective of folate status. This shows that modulation of 10-FTHF is one possible mechanism by which ethanol intake decreases folate status and affects one-carbon metabolism.

The final step of triacylglycerol biosynthesis is catalyzed by acyl CoA:diacylglycerol acyltransferase (DGAT) enzymes. The two known DGATs, DGAT1 and DGAT2, are encoded by unrelated genes. Although both DGAT1 and DGAT2 knockout mice have reduced tissue triacylglycerol contents, they have disparate phenotypes, prompting us to investigate whether the two enzymes have unrecognized functional differences. We now report that DGAT1 exhibits additional acyltransferase activities in vitro, including those of acyl CoA:monoacylglycerol acyltransferase (MGAT), wax monoester and wax diester synthases, and acyl CoA:retinol acyltransferase (ARAT), which catalyze the synthesis of diacylglycerols, wax esters, and retinyl esters, respectively. These activities were demonstrated in in vitro assays with membranes from insect cells or homogenates from COS7 cells overexpressing DGAT1. Wax synthase and ARAT activities were also demonstrated in intact COS7 cells expressing DGAT1. Additionally, cells and tissues from DGAT1-deficient mice exhibited reduced ARAT activity, and the mice had increased levels of unesterified retinol in their livers on a high-retinol diet. Our findings indicate that DGAT1 can utilize a variety of acyl acceptors as substrates in vitro and suggest that these activities may be relevant to the in vivo functions of DGAT1.

This human study was conducted to evaluate the effect of chronic alcohol consumption on plasma concentrations of lipid and the antioxidative system in 44 Korean alcoholics and 45 age-, sex-, and nationality-matched nonalcoholic subjects. Plasma triacylglycerols and atherogenic index were higher in alcoholics than in control subjects. Plasma total cholesterol was not different among groups, but plasma high-density lipoprotein cholesterol was lower in alcoholics. There were positive correlations between ethanol consumption and plasma lipid peroxide and atherogenic index in all subjects; there were negative correlations between ethanol consumption and plasma high-density lipoprotein cholesterol in all subjects. There were no significant differences between alcoholics and control subjects in plasma concentrations of α-tocopherol, although plasma α-tocopherol/lipid tended to be lower in alcoholics. Plasma retinol was lower in alcoholics. These results suggest that chronic ethanol consumption can contribute to increased risk for vascular diseases in Korean alcoholics.

Vascular complications such as atherosclerosis hinder the treatment of diabetes. We hypothesized that moderate supplementation with β-carotene might help prevent diabetic vascular complications through its impact on lipid metabolism. Forty Sprague-Dawley rats were fed AIN-76 control diet, or the same diet supplemented with β-carotene (7.2 mg/kg diet) for 3 weeks, then diabetes was induced in half of the rats by streptozotocin. Diabetic and normal rats were fed the experimental diets for 2 more weeks. β-Carotene did not reduce blood glucose in diabetic rats. Plasma triglycerides were increased by diabetes, but reduced by β-carotene. Plasma total cholesterol was increased by diabetes. High-density lipoprotein cholesterol did not differ between groups. However, the atherogenic index of diabetic rats was higher than that of control rats, and β-carotene feeding decreased it. Fecal excretion of cholesterol and coprostanone was decreased by diabetes, and β-carotene tended to increase this excretion. Fecal excretion of bile acid showed similar tendencies, as did neutral steroids. These results suggest that dietary supplementation with β-carotene may reduce plasma triglycerides and other indices of diabetic risk, and thus may decrease the incidence of diabetic vascular complications through the normalization of lipid metabolism in patients with diabetes.

Use of isotopes as tracers has had an important role in elucidating key features of vitamin A and retinoid metabolism in animal models and humans. Their use has shown that beta-carotene absorption is variable, and that the appearance of beta-carotene and its metabolites in the blood by time since dosing follows characteristic patterns. Retinol formed from beta-carotene shows a different pattern, as does lutein. In this article, we summarize and discuss insights and some surprises into the absorption and metabolism of vitamin A, beta-carotene, and lutein that were gained with the use of isotope tracers in humans, rats, and cells as models.

We used reversed-phase HPLC with diode array detection to simultaneously measure the major isoforms of vitamins A, E, and the carotenoids in serum from 55 healthy people with spinal cord injuries. Typically, the method measured retinol (vitamin A), alpha-tocopherol (vitamin E) and beta-carotene, alpha-carotene, lutein, lycopene, and cryptoxanthin (carotenoids). gamma-Tocopherol (vitamin E), 25-hydroxycalciferol (vitamin D), and the carotenoid zeaxanthin could also be measured when they were present in high concentrations. Healthy people with spinal cord injuries were more likely than similar people without injuries to have low concentrations of alpha-tocopherol, and to a lesser extent retinol and beta-carotene.

The vitamin A activity of beta-carotene is variable and surprisingly low in women. The reasons for this are not well understood. The vitamin A activity of beta-carotene in men is still uncertain. Contributions of dietary factors compared with individual traits are largely unknown.Our objective was to measure the intrinsic variability in the vitamin A activity of beta-carotene among healthy, well-fed men living in a controlled environment.We used a double-tracer test-retest design. We dosed 11 healthy men orally with 30 micromol hexadeuterated (D6) retinyl acetate (all-trans-19,19,19,20,20,20-[2H6]retinyl acetate) and then with 37 micromol D6 beta-carotene (19,19,19,19',19',19'-[2H6]beta-carotene) 1 wk later. Doses were taken with breakfasts containing 16 g fat. We measured D6 retinol, D6 beta-carotene, and trideuterated (D3) retinol (derived from D6 beta-carotene) concentrations in plasma. Areas under the plasma concentration x time since dosing curves (AUCs) were determined for D6 retinol, D6 beta-carotene, and D3 retinol.All men had detectable D6 retinol concentrations in plasma. The mean (+/-SE) absorption of D6 beta-carotene in all subjects was 2.235 +/- 0.925%, and the mean conversion ratio was 0.0296 +/- 0.0108 mol retinol to 1 mol beta-carotene. Only 6 of 11 men had sufficient plasma concentrations of D6 beta-carotene and D3 retinol that we could measure. The mean absorption of D6 beta-carotene in these 6 subjects was 4.097 +/- 1.208%, and the mean conversion ratio was 0.0540 +/- 0.0128 mol retinol to 1 mol beta-carotene.The vitamin A activity of beta-carotene, even when measured under controlled conditions, can be surprisingly low and variable.

International research efforts, including those funded by HarvestPlus, a Challenge Program of the Consultative Group on International Agricultural Research (CGIAR), are focusing on conventional plant breeding to biofortify staple crops such as maize, rice, cassava, beans, wheat, sweet potatoes, and pearl millet to increase the concentrations of micronutrients that are commonly deficient in specific population groups of developing countries. The bioavailability of micronutrients in unfortified staple crops in developing regions is typically low, which raises questions about the efficacy of these crops to improve population micronutrient status. This review of recent studies of biofortified crops aims to assess the micronutrient bioavailability of biofortified staple crops in order to derive lessons that may help direct plant breeding and to infer the potential efficacy of food-based nutrition interventions. Although reducing the amounts of antinutrients and the conduction of food processing generally increases the bioavailability of micronutrients, antinutrients still possess important benefits, and food processing results in micronutrient loss. In general, biofortified foods with relatively higher micronutrient density have higher total absorption rates than nonbiofortified varieties. Thus, evidence supports the focus on efforts to breed plants with increased micronutrient concentrations in order to decrease the influence of inhibitors and to offset losses from processing.

Biofortification of cassava with β-carotene is currently being tested in African populations where cassava is a staple food and vitamin A deficiency is a public health problem. Measuring the impact of traditional African processing and cooking on β-carotene concentration and bioaccessibility of cassava-based foods can help direct plant breeding efforts and estimate the potential impact of biofortified cassava on vitamin A status. Biofortified cassava was processed and cooked to prepare the following traditional dishes: gari, eba, fermented and non-fermented fufu, and boiled cassava. Eba, non-fermented fufu, and gari retained the most β-carotene (43.6, 42.2, and 41.0%, respectively) while boiled cassava and fermented fufu retained the least (24.9, and 21.7%, respectively). Gari and boiled cassava bioaccessibility was 17- and 12-fold higher than raw cassava, respectively (P < 0.001), while increases in bioaccessible β-carotene concentrations in eba, and fufu products were not significant. Unfortunately, aft...

The purpose of the study was to evaluate the effect of a low carotenoid diet (83 micrograms Beta-carotene) on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations of nine pre-menopausal women.Subjects lived on the metabolic research unit of the Western Human Nutrition Research Center (WHNRC), where diet, exercise and other activities were controlled. Five subjects (Group C, control group) consumed a low carotenoid diet and received an additional 0.5 mg/day of Beta-carotene while four subjects (Group P, placebo group) received only the low carotenoid diet during days 1 to 60 (period 1). All subjects received 0.5 mg/day of Beta-carotene during days 60 to 100 (period 2), plus three capsules/day mixed carotenoid supplement (Neo-Life Company) during study days 100 to 120. Changes in MDA-TBA concentrations were analyzed during the study periods and between the groups.At the start of the study (day 1), no significant difference in the MDA-TBA concentration was observed between the control (Group C) and the placebo (Group P) subjects. During period 1 (days 2 to 60), when Group P subjects consumed the low carotenoid diet without supplementation, the MDA-TBA values for Group P rose markedly and were significantly (p0.05) higher than the MDA-TBA values for Group C subjects who were receiving carotenoid supplementation. During period 2 (days 60 to 100) when both groups received carotenoid supplementation, the MDA-TBA values of Group P subjects were significantly (p0.05) reduced to the point where they were similar to the MDA-TBA values for Group C subjects.These findings provide evidence to support the beneficial effects of carotenoids in preventing lipid peroxidation in the cells. Further studies are needed to identify the exact mechanism by which carotenoids prevent lipid peroxidation and the amount needed for normal activity.

Beta-carotene research has progressed rapidly in the past few years. New techniques have allowed accurate measurements of beta-carotene concentrations in plasma, tissues, and diet. New animal models, stable isotope techniques, and human depletion and repletion experiments are leading an explosion in the information about beta-carotene utilization in humans. These advances are leading to a better understanding of the possibilities and limitations of the influence of beta-carotene on human health. This review summarizes important new developments in beta-carotene research, and provides an interpretation of how these results reflect the impact of beta-carotene and human health.

We developed supercritical fluid procedures for extracting vitamin A and beta-carotene from vitamin supplements and calf liver tissue. The SF extracts could be injected onto an HPLC column without further pretreatment. Samples were analysed by RP-HPLC using diode array detection or by spectrophotometry. Recoveries were very good. SF extracts from a vitamin preparation of uniform composition had an R.S.D. of 4%. Extracts from calf liver supplements were predictably more heterogeneous. The SF extraction method is less labor intensive then traditional liquid-liquid procedures for extracting vitamin A and carotenoids from tissues.

Almonds are an important dietary source of lipids, protein, and α-tocopherol. It has been demonstrated that the physical form of almond kernels influences their digestion and absorption, but the role of thermal processes on the digestion of almonds has received little attention. The objectives of this study were to examine the gastric emptying and nutrient composition of gastric chyme from pigs (used as a model for the adult human) fed a single meal of either raw or roasted almonds over a 12-h postprandial period (72 pigs total, 6 pigs at each diet-time combination). Concentrations of glucose, triacylglycerols, and α-tocopherol in peripheral plasma during the 12-h postprandial period were determined. For dry matter and lipid, the gastric emptying profile was not different between raw and roasted almonds. Roasting almonds also did not influence gastric pH, or plasma glucose or triacylglycerols levels. In contrast, the gastric emptying of protein was more rapid for raw almonds compared to roasted almonds (P0.01) and intragastric protein content exhibited segregation (P0.001) throughout the stomach, with raw almonds having a higher level of segregation compared to roasted almonds. Postprandial plasma α-tocopherol levels were, on average 33% greater (P0.001) after consumption of raw almonds, most likely as a result of the higher concentration of α-tocopherol in raw almonds compared to roasted almonds. Roasting of almonds did not influence the overall gastric emptying process, but did lead to differences in the distribution of protein in the stomach and to the gastric emptying of protein.

Vitamin A (VA) deficiency causes disability and mortality. Cassava can be crossbred to improve its β-carotene (BC) content; typical white cassava contains negligible amounts of BC. However, cassava contains cyanide and its continued consumption may lead to chronic disability. Our objective was to estimate the risk–benefit of consuming BC-enhanced cassava to increase VA intake. A total of ten American women were fed white and BC-enhanced cassava. BC and cyanide data from the feeding study were combined with African cassava consumption data to model the potential daily BC, VA and cyanide intakes of African women. If BC-enhanced cassava replaced white cassava in the diets, it could theoretically meet recommended VA intakes for the following percentages of individuals from six African countries that consume cassava as a staple crop: Angola (95 %), Central African Republic (95 %), Congo (about 100 %), Ghana (99 %), Mozambique (99 %) and Nigeria (92 %). Cyanide intake after minimal preparation of cassava could be thirteen to thirty-two times the reference dose (RfD), a toxicological exposure reference, but could be completely removed by extensive soaking. This study demonstrates that consumption of BC-enhanced cassava, processed to maintain BC and remove cyanide, theoretically increases VA intakes for African populations and other areas of the world where cassava is a staple crop.

Because starvation or exhaustive exercise can significantly modify indices of platelet aggregation and blood coagulation, we investigated whether exercise training and energy restriction for weight-loss diets could also affect these indices. Ten healthy overweight women participated in an exercise program that gave an energy deficit of 15% for 98 days. Five women also ate 50% less food, giving them an overall energy deficit of 65%. Their diet contained > 100% of the recommended dietary allowance of all nutrients except energy. There were significant differences with time on the study (possibly caused by exercise training) for red blood cell, white blood cell, and platelet counts as well as activated partial thromboplastin times (APTT) and platelet aggregation induced by collagen. Prothrombin time (PT) showed significant differences between groups, presumably caused by differences in energy intake. However, the changes caused by moderate exercise training and energy restriction diets are mild and probably have little physiological significance.

Vitamin A and thyroid hormone status are interrelated. Much of vitamin A is derived from dietary carotenoids, so we investigated whether carotenoid depletion might influence thyroid hormone status. Nine healthy adult women were fed a low carotenoid diet (58 μg/day) for 68 days then repleted with the same diet supplemented with 15,000 μg of carotenoid/day for 28 days. The women lived on a metabolic unit, where their dietary intakes, exercise, and activities were controlled. Serum thyroid stimulating hormone (TSH) increased significantly after 39 days of carotenoid depletion (P < 0.02), followed by significant increases in serum thyroxine (total T4), then free thyroxine (FT4), and free triiodothyronine (FT3; all p < 0.02). TSH and total T4 concentrations stabilized during carotenoid repletion but remained significantly elevated over baseline. Serum triiodothyronine (total T3), transthyretin, and total protein concentrations were not influenced by carotenoid depletion. Thus, carotenoid depletion may induce increases in some serum thyroid hormone concentrations in healthy young adult women.

The effect of consuming a low carotene diet (approximately 60 micrograms carotene/day) on oxidative susceptibility and superoxide dismutase (SOD) activity in women living in a metabolic research unit was evaluated. The diet had sufficient vitamins A, E, and C. The women ate the diet supplemented with 1500 micrograms/day beta-carotene for 4 days (baseline), then the unsupplemented diet for 68 days (depletion), followed by the diet supplemented with15,000 micrograms/day carotene for 28 days (repletion). Production of hexanal, pentanal, and pentane by copper-oxidized plasma low density lipoproteins from carotene-depleted women was greater than their production of these compounds when repleted with carotene. Erythrocyte SOD activity was depressed in carotene-depleted women; it recovered with repletion. Thiobarbituric acid reactive substances in plasma of carotene-depleted women were elevated and diminished with repletion. Dietary carotene seems to be needed, not only as a precursor of vitamin A, but also to inhibit oxidative damage and decrease oxidation susceptibility.

Millions of people worldwide have severe chronic physical disabilities (e.g., polio, spinal cord injury). We hypothesized that these people are at risk for poor antioxidant nutrient intakes and status, because of their typically low energy expenditures and low socioeconomic status. We surveyed antioxidant nutrient intakes and concentrations in subjects with physical disabilities and age matched non-disabled controls. Only one subject with physical disabilities ate five or more servings of vegetables per day. The group had low intakes of vegetables (minus potatoes) and citrus fruits, and trends for low intakes of all antioxidant nutrients. Serum a-tocopherol and total carotenoid concentrations were lower in subjects with physical disabilities, while retinol and individual carotenoids showed non-significant lower trends. Since adequate antioxidant nutrients are associated with decreased chronic disease risk, nutrition professionals might improve the health of patients with physical disabilities by periodically monitoring their intakes and status of antioxidant nutrients.