The purpose of the present study was to determine the dietary predictors of visceral adipose tissue (VAT) area in overweight young adults. A total of 109 young adults (fifty males and fifty-nine females) ate ad libitum in a university cafeteria for 14 d. All food and beverages consumed in the cafeteria were measured using observer-recorded weighed plate waste. Food consumption outside the cafeteria (i.e. snacks) was assessed by multiple-pass 24 h recall procedures. VAT was determined using computed tomography. Stepwise regression demonstrated that the best predictor of visceral adiposity in women was total dietary fat (P ≤ 0·05). In men, the model for predicting visceral adiposity included Ca and total dietary fat. We concluded that total dietary fat is the best predictor of VAT area in both men and women. While this relationship was independent in women, in men there was a synergistic relationship between dietary fat consumption and Ca consumption in predicting VAT.

Suboptimal vitamin D status among the South Asian UK population is widely reported; however, its impact on bone health is unclear. The aim of the present study was to conduct a comparative investigation of vitamin D status in postmenopausal South Asian (SA) and Caucasian (C) women and its relationship to parathyroid hormone (PTH) concentration, biochemical markers of bone turnover and bone quality. A cross-sectional study of community-dwelling women aged 50–66 years was carried out. A total of sixty-six SA women of Pakistani origin and forty-two C women living in the same community were recruited. Fasting blood was taken for the measurement of vitamin D, PTH and biochemical markers of bone turnover, including type-1 collagen β C-telopeptide (βCTX), procollagen type-1 amino-terminal propeptide (P1NP), and bone-specific alkaline phosphatase (BAP) activity. Bone quality was assessed using broadband ultrasound attenuation (BUA). Total serum 25-hydroxyvitamin D (25(OH)D) was significantly lower in the SA women than the C women (medians: SA 10·5 v. C 47·1 nmol/l; P < 0·001) This was associated with a significantly elevated serum PTH concentration in the SA group (medians: SA 7·3 v. C 4·5 pmol/l; P < 0·01). BAP activity was also significantly higher in the SA group, indicating elevated osteoblast activity and bone turnover (medians: SA 23·0 v. C 20·0 U/l; P < 0·05). No significant differences were observed between the two groups for P1NP, βCTX or BUA. Although the SA women had significantly higher serum PTH and lower 25(OH)D concentrations than C women, this was not associated with significantly higher markers of bone resorption, or reduced bone quality in the SA women.

Feeding pregnant rats a protein-restricted (PR) diet induces altered expression of candidate genes in the liver of the adult offspring, which can be prevented by supplementation of the PR diet with folic acid (PRF). We investigated the effect of maternal nutrition during pregnancy on the liver transcriptome in their adult male offspring. Pregnant rats were fed control, PR or PRF diets. Male offspring were killed on day 84. The liver transcriptome was analysed by microarray (six livers per maternal dietary group) followed by post hoc analysis of relative mRNA levels and gene ontology. These results were confirmed for selected genes by real-time RT-PCR. There were 311 genes that differed significantly ( ≥ 1·5-fold change; P < 0·05) between PR offspring (222 increased) and control offspring, while 191 genes differed significantly between PRF offspring (forty-five increased) compared with offspring of control dams. There were sixteen genes that were significantly altered in both PR and PRF offspring compared with controls. Ion transport, developmental process, and response to reactive oxygen species (RROS) and steroid hormone response (SHR) ontologies were altered in PR offspring. Folic acid supplementation prevented changes within RROS and SHR response pathways, but not in ion transport or developmental process. There was no effect of maternal PR on mRNA expression of imprinted genes. Insulin 1 and Pleckstrin homology-like domain family A member 2 were increased significantly in PRF compared with PR offspring. The present findings show that the pattern of induced changes in the adult liver transcriptome were dependent on maternal protein and folic acid intakes during pregnancy.

Numerous studies have reported an association between cognitive impairment in old age and nutritional factors, including dietary fat. Retinoic acid (RA) plays a central role in the maintenance of cognitive processes via its nuclear receptors (NR), retinoic acid receptor (RAR) and retinoid X receptor (RXR), and the control of target genes, e.g. the synaptic plasticity markers GAP-43/neuromodulin and RC3/neurogranin. Given the relationship between RA and the fatty acid signalling pathways mediated by their respective NR (RAR/RXR and PPAR), we investigated the effect of a high-fat diet (HFD) on (1) PUFA status in the plasma and brain, and (2) the expression of RA and fatty acid NR (RARβ, RXRβγ and PPARδ), and synaptic plasticity genes (GAP-43 and RC3), in young male Wistar rats. In the striatum of rats given a HFD for 8 weeks, real-time PCR (RT-PCR) revealed a decrease in mRNA levels of RARβ ( − 14 %) and PPARδ ( − 13 %) along with an increase in RXRβγ (+52 %). Concomitantly, RT-PCR and Western blot analysis revealed (1) a clear reduction in striatal mRNA and protein levels of RC3 ( − 24 and − 26 %, respectively) and GAP-43 ( − 10 and − 42 %, respectively), which was confirmed by in situ hybridisation, and (2) decreased hippocampal RC3 and GAP-43 protein levels (approximately 25 %). Additionally, HFD rats exhibited a significant decrease in plasma ( − 59 %) and brain ( − 6 %) n-3 PUFA content, mainly due to the loss of DHA. These results suggest that dietary fat induces neurobiological alterations by modulating the brain RA signalling pathway and n-3 PUFA content, which have been previously correlated with cognitive impairment.

The slow digestible disaccharide isomaltulose (iso; Palatinose™) is available as novel functional carbohydrate ingredient for manufacturing of low glycaemic foods and beverages. Although basically characterised, various information on physiological effects of iso are still lacking. Thus, the objective of the present study was to expand scientific knowledge of physiological characteristics of iso by a set of three human intervention trials. Using an ileostomy model, iso was found to be essentially absorbed, irrespective of the nature of food (beverage and solid food). Apparent digestibility of 50 g iso from two different meals was 95·5 and 98·8 %; apparent absorption was 93·6 and 96·1 %, respectively. In healthy volunteers, a single dose intake of iso resulted in lower postprandial blood glucose and insulin responses than did sucrose (suc), while showing prolonged blood glucose delivery over 3 h test. In a 4-week trial with hyperlipidaemic individuals, regular consumption of 50 g/d iso within a Western-type diet was well tolerated and did not affect blood lipids. Fasting blood glucose and insulin resistance were lower after the 4-week iso intervention compared with baseline. This would be consistent with possible beneficial metabolic effects as a consequence of the lower and prolonged glycaemic response and lower insulinaemic burden. However, there was no significant difference at 4 weeks after iso compared with suc. In conclusion, the study shows that iso is completely available from the small intestine, irrespective of food matrix, leading to a prolonged delivery of blood glucose. Regular iso consumption is well tolerated also in subjects with increased risk for vascular diseases.

Anthocyanins are natural pigments abundant in various fruits and berries that are involved in the prevention of various chronic diseases. Their low concentrations in plasma and urine are explained in part by their complex chemistry and the formation of still uncharacterised metabolites. The aim of the present study was to follow the distribution of anthocyanins in the body using 14C-labelled cyanidin 3-O-glucoside (Cy3G) fed by gavage to mice. After the administration of 22·2 kBq 14C-Cy3G (0·93 mg), radioactivity was detected in most organs tested over the following 24 h with a peak observed in inner tissues at 3 h. The major fraction of the radioactivity (44·5 %) was found in the faeces collected 24 h after ingestion. At 3 h after oral administration of 141 kBq 14C-Cy3G (4·76 mg), most of the radioactivity (87·9 % of intake) was recovered in the gastrointestinal (GI) tract, especially in the small intestine (50·7 %) and the caecum (23 %). At this time, 3·3 % of the radioactivity was detected in urine. There was minimal accumulation (0·76 %) of radioactivity in tissues outside the GI tract. Distribution of radioactivity varied among organs, with liver, gallbladder and kidneys showing the highest radioactivity. Taken as a whole, these results show that Cy3G is poorly absorbed in the mouse.

The present study focused on the hypothesis that dietary supplementation with medium-chain TAG (MCT) will improve cognitive function in aged dogs by providing the brain with energy in the form of ketones. Aged Beagle dogs were subjected to a baseline battery of cognitive tests, which were used to establish cognitively equivalent control or treatment groups. The dogs in the treatment group were maintained on a diet supplemented with 5·5 % MCT. After an initial wash-in period, all the dogs were tested with a battery of cognitive test protocols, which assessed sequentially landmark discrimination learning ability, egocentric visuospatial function and attention. The groups were maintained on the diets for 8 months. The MCT-supplemented group showed significantly better performance in most of the test protocols than the control group. The group differences also varied as a function of task difficulty, with the more difficult task showing greater supplementation effects than the easier tasks. The group given the MCT supplement showed significantly elevated levels of β-hydroxybutyrate, a ketone body. These results indicate, first, that long-term supplementation with MCT can have cognition-improving effects, and second, that MCT supplementation increases circulating levels of ketones. The results support the hypothesis that brain function of aged dogs can be improved by MCT supplementation, which provides the brain with an alternative energy source.

Four goats (20 (SD 2·5) kg) fitted with ruminal, duodenal and ileal cannulae were used in a 4 × 4 Latin square design to estimate the effects of a dietary starch source on the duodenal and ileal flows of endogenous N (EN) and endogenous amino acids (EAA) in growing goats. Goats were fed total mixed rations containing four starch sources (mainly from maize (MR), wheat (WR), paddy (PR) and sorghum (SR) treatments). There were no significant (P>0·05) effects of the dietary starch source on the intestinal flows of EN and EAA. The duodenal flows of EN were 2·40, 2·39, 2·18 and 1·56 g/d for the MR, WR, PR and SR treatments, respectively, as determined by the difference method, and the duodenal flows of EAA were 10·76, 11·29, 10·95 and 10·96 g/d by estimation with the amino acid profile method. The flows of EN and EAA at the ileum were 1·17, 1·12, 1·01, 0·70 and 4·87, 4·95, 4·94, 4·99 g/d, respectively, as estimated by the water-soluble method. The average intestinal reabsorption of EN and EAA was 57·5 %, and the endogenous Leu by the MR treatment was significantly (P < 0·05) lower than that of the other three treatments. The present results indicate that losses of endogenous protein in the intestine were not affected by the dietary starch source.

Environmental perturbations during early mammalian development can affect aspects of offspring growth and cardiovascular health. We have demonstrated previously that maternal gestational dietary protein restriction in mice significantly elevated adult offspring systolic blood pressure. Therefore, the present study investigates the key mechanisms of blood pressure regulation in these mice. Following mating, female MF-1 mice were assigned to either a normal-protein diet (NPD; 18 % casein) or an isocaloric low-protein diet throughout gestation (LPD; 9 % casein), or fed the LPD exclusively during the pre-implantation period (3·5 d) before returning to the NPD for the remainder of gestation (Emb-LPD). All offspring received standard chow. At 22 weeks, isolated mesenteric arteries from LPD and Emb-LPD males displayed significantly attenuated vasodilatation to isoprenaline (P = 0·04 and P = 0·025, respectively), when compared with NPD arteries. At 28 weeks, stereological analysis of glomerular number in female left kidneys revealed no significant difference between the groups. Real-time RT-PCR analysis of type 1a angiotensin II receptor, Na+/K+ ATPase transporter subunits and glucocorticoid receptor expression in male and female left kidneys revealed no significant differences between the groups. LPD females displayed elevated serum angiotensin-converting enzyme (ACE) activity (P = 0·044), whilst Emb-LPD males had elevated lung ACE activity (P = 0·001), when compared with NPD offspring. These data demonstrate that elevated offspring systolic blood pressure following maternal gestational protein undernutrition is associated with impaired arterial vasodilatation in male offspring, elevated serum and lung ACE activity in female and male offspring, respectively, but kidney glomerular number in females and kidney gene expression in male and female offspring appear unaffected.

Obesity predisposes to an increased incidence of diabetes and CVD. Also, obesity is a pro-inflammatory state. Regulatory T cells (Tregs) are essential negative regulators of inflammation and are down-regulated in pro-inflammatory states. Animal models of obesity are associated with decreased Tregs. The dietary modulation of Tregs could be used as a therapeutic strategy to control inflammation. Epigallocatechin gallate (EGCG) is a potent anti-inflammatory agent and an active ingredient of green tea and is suggested to have a role as a preventive agent in obesity, diabetes and CVD. The role of EGCG in the modulation of Tregs has, however, not been studied. Thus, the aim of the present study was to determine the effect of EGCG on the number and function of Tregs in obese and lean human subjects in vitro, and to delineate its specific regulation mechanisms. Tregs were isolated from normal-weight and obese subjects. Tregs were cultured in the absence or presence of EGCG (20 μm) for 24 h. Foxp3-expressing Tregs were enumerated using flow cytometry. Histone deacetylase (HDAC) activity and nuclear NF-κBp65 level were measured by ELISA and Western blots. Obese subjects had lower Tregs and IL-10 production than lean subjects. EGCG treatment significantly enhanced the number of Foxp3-expressing Tregs and IL-10 production in vitro (P < 0·05) in both groups. Also, EGCG decreased NF-κB activity and increased HDAC activity and HDAC-2 expression in Tregs (P < 0·05) in both groups. Thus, in part, EGCG enhances the functionality of Tregs, i.e. IL-10 production and number by suppressing the NF-κB signalling pathway via inducing epigenetic changes.

Many studies have been done on the hypocholesterolaemic effect of probiotic yoghurt. The results, however, are not conclusive. The aim of the present study was to test the effect of probiotic and conventional yoghurt on the lipid profile in women. In a randomised trial, ninety female volunteers aged 19–49 years were assigned to three groups. Subjects consumed daily 300 g probiotic yoghurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 or 300 g conventional yoghurt or no yoghurt for 6 weeks. Fasting blood samples, 3 d dietary records and anthropometric measurements were collected at baseline (T1), end of week 3 (T2) and end of week 6 (T3). Lipid profile parameters were determined by enzymic methods. Results showed no significant difference in lipid profile within any group throughout the study. Comparing mean differences (T1 − T3) among the three groups showed: no difference in TAG and LDL-cholesterol, a decrease in cholesterol in both conventional (P < 0·05) and probiotic yoghurt groups (P < 0·005) compared with the control group, a decrease in total:HDL-cholesterol ratio for conventional (P < 0·05) and probiotic yoghurt groups (P < 0·001) compared with the control group, and an increase in HDL-cholesterol in the probiotic yoghurt group (P < 0·05) compared with the control group. Positive changes in lipid profile were observed in both yoghurt groups. Any added effect, therefore, is due to the consumption of fermented milk products.

We examined whether there are sex differences in the effect of vitamin supplements on birth outcomes, mortality and morbidity by 2 years of age among children born to HIV-infected women in Tanzania. A randomised placebo-controlled trial was conducted among 959 mother–infant pairs. HIV-infected pregnant women were randomly assigned to receive a daily oral dose of one of four regimens: multivitamins (vitamins B-complex, C and E), vitamin A plus β-carotene, multivitamins including vitamin A plus β-carotene or placebo. Supplements were administered during pregnancy and continued after delivery. The beneficial effect of multivitamins on decreasing the risk of low birth weight was stronger among girls (relative risks (RR) = 0·39, 95 % CI 0·22, 0·67) than among boys (RR = 0·81, 95 % CI 0·44, 1·49; P for interaction = 0·08). Maternal multivitamin supplements resulted in 32 % reduction in mortality among girls (RR = 0·68, 95 % CI 0·47, 0·97), whereas no effect was found among boys (RR = 1·20, 95 % CI 0·80, 1·78; P for interaction = 0·04). Multivitamins had beneficial effects on the overall risks of diarrhoea that did not differ by sex. Vitamin A plus β-carotene alone increased the risk of HIV transmission, but had no effects on mortality, and we found no sex differences in these effects. Sex differential effects of multivitamins on mortality may be due to sex-related differences in the immunological or genetic factors. More research is warranted to examine the effect of vitamins by sex and better understand biological mechanisms mediating such effects.

The perinatal nutritional environment impacts upon the health and well-being of mother and child also in the long term. The aim of the present study was to determine the safety and efficacy of perinatal probiotic-supplemented dietary counselling by evaluating pregnancy outcome and fetal and infant growth during the 24 months' follow-up. Altogether, 256 women were randomised at their first trimester of pregnancy into a control and a dietary intervention group. The intervention group received intensive dietary counselling provided by a nutritionist and were further randomised, double-blind to receive probiotics (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12; diet/probiotics) or placebo (diet/placebo). Firstly, probiotic intervention reduced the frequency of gestational diabetes mellitus (GDM); 13 % (diet/probiotics) v. 36 % (diet/placebo) and 34 % (control); P = 0·003. Secondly, the safety of this approach was attested by normal duration of pregnancies with no adverse events in mothers or children. No significant differences in prenatal or postnatal growth rates among the study groups were detected. Thirdly, distinctive effects of the two interventions were detected; probiotic intervention reduced the risk of GDM and dietary intervention diminished the risk of larger birth size in affected cases; P = 0·035 for birth weight and P = 0·028 for birth length. The results of the present study show that probiotic-supplemented perinatal dietary counselling could be a safe and cost-effective tool in addressing the metabolic epidemic. In view of the fact that birth size is a risk marker for later obesity, the present results are of significance for public health in demonstrating that this risk is modifiable.

Lycopene in fruits and vegetables occurs mostly (80–97 %) in the all-E configuration, whereas a considerable proportion of lycopene in the human body is present as Z-isomers. The Z-isomers offer potentially better health benefits and show improved antioxidant activity in vitro when compared with the all-E-isomer. The absorption of dietary lycopene is a complex process involving transfer of the carotenoid from the food matrix into micelles, uptake by enterocytes, packaging into chylomicrons and finally secretion into plasma. Isomerisation could take place at any of these individual steps. By exploiting in vitro and in vivo models, we traced lycopene isomerisation during absorption using various methods to mimic gastric and duodenal conditions, incorporation into mixed micelles, absorption and metabolism by various Caco-2 cell clones, and performed a postprandial study in human subjects to identify the profile of lycopene isomers in plasma chylomicrons. We demonstrate that all-E-lycopene remains unchanged during its passage in the gastrointestinal tract, including its incorporation into mixed micelles. The key site of lycopene isomerisation is inside the intestinal cells resulting in 29 % of lycopene as Z-isomers. Lycopene isomerisation in the various Caco-2 cell clones is consistent with that observed in human chylomicrons formed in a postprandial state. There is no selection in the release of lycopene isomers from enterocytes. Although there is a huge inter-individual variability of total lycopene absorption reported both in in vitro intestinal cell lines as well as in human chylomicrons, the lycopene isomer profile is quite similar.

The aim of the present study was to assess reproducibility and relative validity of a self-administered FFQ used in the PREDIMED Study, a clinical trial for primary prevention of CVD by Mediterranean diet in a population at high cardiovascular risk. The FFQ was administered twice (FFQ1 and FFQ2) to explore reproducibility at 1 year. Four 3 d dietary records (DR) were used as reference to explore validity; participants therefore recorded their food intake over 12 d in the course of 1 year. The degree of misclassification in the FFQ was also evaluated by a contingency table of quintiles comparing the information from the FFQ2 and the DR. A total of 158 men and women (aged 55–80 years) were asked not to modify their dietary habits during the study period. Reproducibility for food groups, energy and nutrient intake, explored by the Pearson correlation coefficient (r) ranged 0·50–0·82, and the intraclass correlation coefficient (ICC) ranged from 0·63 to 0·90. The FFQ2 tended to report higher energy and nutrient intake than the DR. The validity indices of the FFQ in relation to the DR for food groups and energy and nutrient intake ranged (r) from 0·24 to 0·72, while the range of the ICC was between 0·40 and 0·84. With regard to food groups, 68–83 % of individuals were in the same or adjacent quintile in both methods, a figure which decreased to 55–75 % for energy and nutrient intake. We concluded that FFQ measurements had good reproducibility and a relative validity similar to those of FFQ used in other prospective studies.

Relatively small lifestyle modifications related to weight reduction, physical activity and diet have been shown to decrease the risk of type 2 diabetes. Connected with diet, low consumption of meat has been suggested as a protective factor of diabetes. The aim of the present study was to examine the association between the consumption of total meat or the specific types of meats and the risk of type 2 diabetes. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention cohort included middle-aged male smokers. Up to 12 years of follow-up, 1098 incident cases of diabetes were diagnosed from 24 845 participants through the nationwide register. Food consumption was assessed by a validated FFQ. In the age- and intervention group-adjusted model, high total meat consumption was a risk factor of type 2 diabetes (relative risk (RR) 1·50, 95 % CI 1·23, 1·82, highest v. lowest quintile). The result was similar after adjustment for environmental factors and foods related to diabetes and meat consumption. The RR of type 2 diabetes was 1·37 for processed meat (95 % CI 1·11, 1·71) in the multivariate model. The results were explained more by intakes of Na than by intakes of SFA, protein, cholesterol, haeme Fe, Mg and nitrate, and were not modified by obesity. No association was found between red meat, poultry and the risk of type 2 diabetes. In conclusion, reduction of the consumption of processed meat may help prevent the global epidemic of type 2 diabetes. It seems like Na of processed meat may explain the association.

Belgium until recently lacked a systematic survey of dietary habits of its inhabitants. The present study evaluated dietary composition in Belgium with respect to energy and macronutrient intakes. Information on food intake was collected using a repeated non-consecutive 24 h recall (2–8 weeks apart) with the validated software package EPIC-SOFT, in combination with a FFQ (self-administered) covering sixty food items. The database of consumed food items was linked to food composition data. Usual macronutrient intake was estimated by the Nusser method. A representative sample of the Belgian population was randomly selected from the national register following a multi-stage procedure. Information on dietary intake was obtained from 3245 subjects aged 15 years and older. Mean energy percentage (E %) of total fat (37·9 E %) and SFA (16·0 E %) was higher than the dietary reference intakes (DRI). Mean E % of total carbohydrates (45·8 E %) was lower than the DRI, while mean E % of mono/disaccharides was 20·3. Total fat and SFA intakes were higher and total carbohydrate and sugar intakes were lower in the older age categories than in the younger age categories. The percentage of energy from SFA intake was lower and that from carbohydrates was higher than that found in an earlier Belgian study. Further efforts are necessary to improve dietary macronutrient intake, taking into account differences in age categories. In addition, it will be important to monitor its changes regularly using trend analyses.

The objective was to examine the effect of BMI on the incidence of various infectious diseases in institutionalised, geriatric subjects. In a retrospective cohort study we analysed medical records of 619 patients aged 75 years and older (mean age 87·6 (sd 6·4) years) who were treated in a geriatric hospital in Vienna, Austria. The total incidence rate of infection in this population was 0·80 per person-year. The most frequent infections were urinary tract infections (0·30 per person-year), followed by infections of the lower respiratory tract (0·19 per person-year), diarrhoea (0·12 per person-year) and other infections (0·20 per person-year). Incidence risk ratios were obtained by a multiplicative Poisson regression model. There was a J-shaped curve in the incidence of infections recorded by BMI with a nadir at 27–28 kg/m2. Compared with the reference group with a BMI of 24–27·9 kg/m2, subjects with a lower BMI had a higher incidence rate of infections. The incidence risk ratios, adjusted for sex, age and chronic diseases, were 1·62 (95 % CI 1·21, 2·17) for those with a BMI of < 20 kg/m2 and 1·84 (95 % CI 1·40, 2·42) for those with a BMI of 20–23·9 kg/m2. However, also patients with a BMI of 28 kg/m2 and above had a higher incidence rate of infections, with an incidence risk ratio of 1·54 (95 % CI 1·07, 2·22). These results show that both underweight and obesity are associated with a higher risk of infections in institutionalised geriatric patients.

The objective was to quantify the vitamin A equivalency of β-carotene in two diets using a dual-isotope dilution technique and the apparent β-carotene absorption as measured by the oral–faecal balance technique. Seventeen healthy adults with an ileostomy completed the 4-week diet-controlled, cross-over intervention study. Each subject followed both diets for 2 weeks: a diet containing vegetables low in β-carotene content with supplemental β-carotene in salad dressing oil (‘oil diet’; mean β-carotene intake 3·1 mg/d) and a diet containing vegetables and fruits high in β-carotene content (‘mixed diet’; mean β-carotene intake 7·6 mg/d). Daily each subject consumed a mean of 190 μg [13C10]β-carotene and 195 μg [13C10]retinyl palmitate in oil capsules. The vitamin A equivalency of β-carotene was calculated as the dose-corrected ratio of [13C5]retinol to [13C10]retinol in serum. Apparent absorption of β-carotene was determined with oral–faecal balance. Isotopic data quantified a vitamin A equivalency of [13C10]β-carotene in oil of 3·6:1 (95 % CI 2·8, 4·6) regardless of dietary matrices differences. The apparent absorption of (labelled and dietary) β-carotene from the ‘oil diet’ (30 %) was 1·9-fold higher than from the ‘mixed diet’ (16 %). This extrinsic labelling technique can measure precisely the vitamin A equivalency of β-carotene in oil capsules, but it does not represent the effect of different dietary matrices.