Tanker milk variability according to farm feeding practices: vitamins A and E, carotenoids, color, and terpenoids.

The aim of this work was to study the variability in the composition of bulk milk mixtures of fat-soluble compounds (vitamins A and E, carotenoids, and terpenoids) and assess the links with milk production conditions. Milk from 10 collection trips in the French department of the Haute-Loire (10 to 36 herds per trip) was sampled in the tanker twice during the winter period and 3 times during the grazing season. The collection trips differed in their altitude (440 to 1,150 m) and the forage system (grass or based on corn silage). Vitamins A and E, carotenoids, and terpenoids of the 50 tanker loads of milk were analyzed. Data of milk production conditions in the 204 farms made it possible to constitute indicators for the collection trip and to define 50 mean herds. The relationships between mean herd characteristics (breed, stage of lactation, and feed) and milk characteristics were investigated. The constituents of tanker loads of milk were comparable to those observed in milk produced by groups of animals receiving contrasting diets (rich in concentrate or corn silage vs. pasture). The characteristics of the milk differed according to the period; those produced at grazing were more yellow (1.02 +/- 0.4; mean of difference) and richer in beta-carotene, lutein, vitamin E (2.0 +/- 1.2, 0.23 +/- 0.12, and 6.1 +/- 5.0 mug/g of fat, respectively), and sesquiterpenes (2.7 +/- 2.5) than winter. The variations observed for beta-carotene, lutein, and vitamin E were linked to the proportion of grazed grass or grass silage in the forage (r = 0.66, 0.69, and 0.51, respectively), unlike the vitamin A content. During grazing, 20 of the 32 terpenoids identified were associated with the proportion of permanent grassland available for grazing or cut. These results show that feeding is an effective way to modify the quality of dairy products, even in the case of bulk tank milk mixtures. Dairy plants could market different milks, which would contain specific compositions.

Variations in carotenoids, fat-soluble micronutrients, and color in cows' plasma and milk following changes in forage and feeding level.

The main aim of this work was to assess factors affecting the secretion of carotenoids in cows' milk. Our objectives were 1) to determine the kinetics of the decrease in carotenoids in plasma, milk, and adipose tissues following a switch from a high- to a low- carotenoid diet; and 2) to specify whether, during lipomobilization, the restitution of these compounds stored in the adipose tissues is sufficient to modify their secretion in milk. During the preexperimental period, 32 cows in midlactation were fed a grass silage-based diet, and were then assigned to 4 groups; 2 groups were maintained on the grass silage diet and 2 were switched to a late hay diet. For each forage diet, one group was fed according to net energy for lactation and nitrogen requirements, and the other was submitted to an energetic underfeeding, with similar forage and carotenoid intake between groups. Variations in concentration of carotenoids and color index (CI) of plasma and milk were monitored over 8 wk. Other components of nutritional interest; i.e., vitamin E (VE), vitamin A, and fatty acids, were also measured. The switch from grass silage to hay diet induced a rapid decrease in concentration of betal-carotene (BC) and VE and in the CI of plasma and milk during the first 2 wk. Pools of BC in adipose tissues also decreased by 40%. Concentrations of BC at the end of the experiment for silage and hay groups were 5.10 and 1.71 microg/mL in plasma and 0.17 and 0.07 microg/mL in milk, respectively. The energetic underfeeding did not affect BC concentration in plasma and induced a small increase in milk BC concentration, related to a decreased milk yield. In the silage group, the energetic underfeeding after 3 to 4 wk induced a decrease in CI and VE of plasma, but not of milk. The fatty acid profile in milk was modified by the change from grass silage to hay diet (C10 to C14 and linoleic acid increased; stearic and linolenic acid percentages decreased) and by underfeeding (oleic, vaccenic, and rumenic acid percentages increased). This study shows that BC and VE levels persist in midlactation cows' plasma and milk for about 2 wk. The results could not confirm a release of BC by bovine adipose tissue, but the level of underfeeding was moderate in this trial. The concentration of BC explained 58 and 40% of variation in CI of plasma and milk, respectively. These CI appear to be valuable tools for diet traceability (i.e., silage vs. hay).

The Medi-RIVAGE study (Mediterranean Diet, Cardiovascular Risks and Gene Polymorphisms): rationale, recruitment, design, dietary intervention and baseline characteristics of participants.

OBJECTIVE: To report the rationale, recruitment, design, dietary intervention and baseline characteristics of participants in the Medi-RIVAGE study (Mediterranean Diet, Cardiovascular Risks and Gene Polymorphisms). DESIGN: A randomised, parallel trial comparing a new nutritional programme with a conventional programme. SETTING: Centre for Detection and Prevention of Arteriosclerosis, Timone University Hospital, Marseille, France, and collaborating teams. SUBJECTS: Two hundred and twelve male and female volunteers with at least one cardiovascular risk factor. INTERVENTION: A Mediterranean-type diet characterised mainly by the quality of fatty acids, amount of fish, vegetable foodstuffs and fibre was proposed and compared with a usually prescribed, low-fat/cholesterol diet. Body mass index, fasting lipids and lipoproteins, apolipoproteins, glucose, insulin and homocysteine were the main outcome measures. Gene polymorphisms of interest were determined. RESULTS: Characteristics of men in the two arms were comparable with regard to sociodemographic variables, and clinical and biological cardiovascular risk factors. There were few differences between the groups of women (cholesterol-related parameters, P<0.05). There was no difference between arms in allelic distribution of the gene polymorphisms studied. Saturated fat and protein intakes were high while carbohydrate and fibre intakes were low, but with no difference between arms. Overall, the nutritional markers were comparable in both arms with few exceptions. Correlations between nutritional intakes and plasma nutrient levels ranged from 0.19 (beta-carotene) to 0.47 (folate). CONCLUSIONS: The comparability of the two arms is notable and warrants a low risk of biases. Current diet departs from the traditional Mediterranean one. The assessment of nutritional intake is validated by correlations obtained between dietary intake and relevant biomarkers. This will be important to estimate participant compliance and to analyse intervention data.

Persistence of carotenoid pigments in the blood of concentrate-finished grazing sheep: its significance for the traceability of grass-feeding.

Carotenoid pigments are good biomarkers of grass feeding in sheep. However, grazing lambs are often stall-finished because of grass shortage. We investigated the nature of the carotenoids present in sheep blood and their persistence in this tissue. Four treatments were compared: 1) feeding a concentrate-based diet (n = 10 lambs), 2) grazing followed by a long stall-finishing period (n = 10), 3) grazing followed by a short stall-finishing period (n = 10), and 4) grazing to slaughter weight (n = 10). The concentrate supply was regulated to have similar average daily gain for all treatments. The 40 lambs were allocated to either the grazing or the stall treatments on the basis of their birth date, birth weight, and body weight. The 30 grazing lambs were further allocated to long-stall, short-stall, or grass treatment on the basis of their body weight and plasma carotenoid content. Plasma content of total carotenoids was measured by spectrophotometry during the grazing and the stall periods for all lambs and at slaughter weight for the eight heaviest lambs of each treatment. Analysis of the nature and the concentration of individual carotenoids was performed by HPLC on pasture and stall diets and on blood of grazing lambs. The carotenoid content of the stall diet was 2 to 3% that of the pasture diet. Lutein, zeaxanthin, and beta-carotene accounted for 43 to 58%, 3 to 17%, and 0 to 7% of total plasma carotenoids in grazing lambs, respectively. Two unknown polar carotenoids, expressed in lutein equivalent, accounted for 10 to 22% and 0 to 9% of total carotenoids. Plasma carotenoid content during the grazing and the finishing periods varied among animals (P < 0.001). At slaughter weight, plasma carotenoid content was higher for grass-fed than for stall-fed, long-stall finished, or short-stall finished lambs (P < 0.001), and reliably distinguished grass-fed lambs from all the others. Plasma carotenoid content decreased exponentially with the interval from starting on the stall diet (P < 0.005). The deceleration parameter of the model increased linearly with lamb average daily gain during the stall-finishing period, suggesting that the turnover of carotenoids in the blood may depend on the level of intake of the stall-finishing diet. After 4 to 13 d on the stall diet, depending on the initial plasma carotenoid concentration, plasma carotenoid concentration of previously grazed, stall-finished lambs fell to the values of lambs fed a concentrate diet without grazing. Such a low persistence is of interest for discriminating grazing lambs from stall-finished grazing lambs.

Simple method for clinical determination of 13 carotenoids in human plasma using an isocratic high-performance liquid chromatographic method.

We report a reversed-phase high-performance liquid chromatography method which resolves 13 identified carotenoids and nine unknown carotenoids from human plasma. A Nucleosil C18 column and a Vydac C18 column in series are used with an isocratic solvent system of acetonitrile-methanol containing 50 mM acetate ammonium-dichloromethane-water (70:15:10:5, v/v/v/v) as mobile phase at a flow-rate of 2 ml/min. The intra-day (4.5-8.3%) and inter-day (1.3-12.7%) coefficients of variation are suitable for routine clinical determinations.

Processing of vitamin A and E in the human gastrointestinal tract.

We aimed to provide basic data on the processing of vitamin A and E in the human gastrointestinal tract and to assess whether the size of emulsion fat globules affects the bioavailability of these vitamins. Eight healthy men received intragastrically two lipid formulas differing in their fat-globule median diameter (0.7 vs. 10. 1 microm. Formulas provided 28 mg vitamin A as retinyl palmitate and 440 mg vitamin E as all-rac alpha-tocopherol. Vitamins were measured in gastric and duodenal aspirates, as well as in chylomicrons, during the postprandial period. The gastric emptying rate of lipids and vitamin A and E was similar. The free retinol/total vitamin A ratio was not significantly modified in the stomach, whereas it was dramatically increased in the duodenum. The proportion of ingested lipid and vitamins was very similar in the duodenal content. The chylomicron response of lipids and vitamins was not significantly different between the two emulsions. Our main conclusions are as follows: 1) there is no significant metabolism of vitamin A and E in the human stomach, 2) the enzyme(s) present in the duodenal lumen is significantly involved in the hydrolysis of retinyl esters, and 3) the size of emulsion fat globules has no major effect on the overall absorption of vitamin A and E.

[Measurement of carotenoids by high pressure liquid chromatography: from difficulties to solutions]. / Dosage des caroténoïdes par chromatographie liquide haute performance: des difficultés aux solutions.

The measurement of serum carotenoids by HPLC has been largely improved during the last 10 years. However these techniques still require much time and skills, and direct application of published methods is rarely satisfying. We report here the difficulties that we met to transfer some HPLC methods described in the literature to our laboratories. We propose some solution to overcome the problems that we have encountered, our experience will perhaps help out other biologists. We reported also some results obtained in healthy populations.

Effect of vitamin A status at the end of term pregnancy on the saturation of retinol binding protein with retinol.

BACKGROUND: Vitamin A (retinol), which is required for normal fetal development and successful gestation, circulates in the blood bound to a specific protein, the retinol binding protein (RBP). Little is known about the transport and metabolism of this complex protein or about retinol status during normal human pregnancy. OBJECTIVE: The aim of this study was to assess retinol status and transport modalities of retinol in well-nourished women with normal pregnancies, a population poorly investigated compared with pathologic and malnourished pregnant women. DESIGN: The maternal blood and cord blood concentrations of retinol, vitamin E, beta-carotene, RBP, and transthyretin of pregnant French women at term (n = 27) were measured and compared with values from a nonpregnant control group (n = 27). In addition, holo-RBP (retinol bound), apo-RBP (retinol free), and total protein were assessed in both groups to enable the hemodilution occurring during pregnancy to be taken into consideration and to evaluate the extent of saturation of RBP with retinol. RESULTS: Healthy pregnant women at term had normal serum circulatory amounts of retinol, vitamin E, binding proteins, and beta-carotene. However, they had less binding of retinol to RBP (holo-RBP: 49.9% in pregnant women, 54.0% in cord blood, and 77.5% in the control group). CONCLUSION: The results of this study suggest that retinol homeostasis and transport are modified during normal human pregnancy.

Age-related changes in plasma lycopene concentrations, but not in vitamin E, are associated with fat mass.

The aim of the present study was to assess the influence of age on plasma concentration of alpha-tocopherol, retinol and carotenoids with a special attention paid to natural differences in body composition. Forty healthy subjects were recruited: twenty were less than 35 years old and twenty above 60 years old. Males and females were equally represented in each age group. Subjects were kept in energy balance and received controlled diets for 36 h. Fat mass and fat-free mass were determined with the (18)0-enriched water dilution technique. Plasma vitamins A and E, and carotenoid levels were determined after 12 h fasting and were shown to be similar in women and men. Plasma alpha-tocopherol concentration increased with age (+44 % elderly v. young), and correlated with % fat mass and plasma cholesterol. After adjustment for plasma cholesterol, the effect of age and % fat mass disappeared. In contrast, plasma lycopene level was 2-fold lower in the elderly than in the young group, and was inversely correlated with fat mass. When lycopene values were adjusted for fat mass, the effect of age disappeared. These results suggest that plasma levels of vitamin E and lycopene differed in the two age groups and that differences in plasma cholesterol and fat mass might participate in such an effect. Short-term vitamin intake did not appear to influence plasma vitamin concentrations.

[Carotenoids: 2. Diseases and supplementation studies]. / Les caroténoïdes: 2. Pathologie et études de supplémentation.

Inverse correlations have been found in most studies on the relationship between dietary intake and plasma concentrations of carotenoids on one side and degenerative diseases such as cancer and cardiovascular diseases on the other side. Protective effects of carotenoids have been found for pathologies of the retina and the skin. Concentrations of these molecules in blood are lower in digestive pathologies and HIV. Short- and long-term toxicity of carotenoids was found to be low. In combination with the beneficial effects found for diets rich in carotenoids, this has initiated trials with relatively high doses of carotenoid supplements. In the study in Linxian (China) in a rural population with poor nutritional status, supplementation with beta-carotene, zinc, selenium and vitamin E lowered total mortality and mortality from stomach cancer. Other studies (ATBC, Caret.) on well-fed subjects did not show beneficial effects on mortality from cancer and cardiovascular diseases. On the contrary, higher mortality and lung cancer incidence was found in supplemented subjects that were also exposed to asbestos and cigarette smoke. In these studies, doses of supplemental beta-carotene were high and varied from 20 to 50 mg/day. One still ongoing study, called Suvimax, doses subjects for eight years with a cocktail of vitamins and minerals including 6 mg per day of beta-carotene. This supplementation with physiologically seen more "normal" doses might give clarity on the question if beta-carotene is the protective factor in fruits and vegetables.

[Carotenoids: 1. Metabolism and physiology]. / Les caroténoïdes: I. Métabolisme et physiologie.

Carotenoids are a family of pigments with at least 600 members. They derive from lycopene after steps of cyclisation, dehydrogenation and oxidation. It is their chemical structure that determines their physiochemical properties and, in part, their biological activities. About 50 carotenoids can be found in human diet and about 20 of them have been found in plasma and tissues. There is no RDA (Recommended Daily Allowance) for carotenoids. Quantities of carotenoids in diet are difficult to estimate, partly because methods used for the establishment of food composition tables were not specific and sensitive enough. Also, given values do not always take into account variations due to season and region of culture. Absorption of beta-carotene in humans has been the subject of numerous studies but only very little is known about other carotenoids. In general, absorption depends on bioavailability from the food matrix and solubility in micelles. After absorption through passive diffusion, carotenoids follow the chylomicrons metabolism. They are taken up by the liver and released in the blood stream in lipoproteins (VLDL). Carotenoids with no-substituted beta-ionone cycles (alpha and beta-carotene and beta-cryptoxanthin) have provitamin A activity. Highest activity has been found for all-trans beta-carotene. Not all steps of vitamin A biosynthesis and metabolism of other carotenoids have been clarified yet. Besides their provitamin A activity, carotenoids have numerous biological functions. They are efficient scavengers of free radicals, particularly of 1O2. In vitro they have been shown to protect LDL. However, results in vivo are inconsistent. Other functions include enhancement of gap junctions, immunomodulation and regulation of enzyme activity involved in carcinogenesis.

Low and high responders to pharmacological doses of beta-carotene: proportion in the population, mechanisms involved and consequences on beta-carotene metabolism.

The aim of this study was to assess the interindividual variability of chylomicron beta-carotene response to a pharmacological load of beta-carotene in the population, to identify the mechanisms responsible for this variability, and to evaluate its consequences on beta-carotene status and metabolism. The variability, as estimated by the 3-h chylomicron beta-carotene response to 120 mg beta-carotene in 79 healthy male volunteers, was high (CV = 61%), but it was unimodal and all the subjects had detectable chylomicron beta-carotene. In 16 subjects randomly selected among the 79, the interindividual variability of the triglyceride-adjusted chylomicron (beta-carotene + retinyl palmitate) response (0-12.5 h area under the curve) was high (CV = 54%), suggesting that there is a high interindividual variability in the efficiency of intestinal absorption of beta-carotene. The chylomicron beta-carotene response was correlated (r = 0.50, P < 0.05) with the chylomicron triglyceride response. The beta-carotene status, as assessed by beta-carotene concentration in buccal mucosal cells, was correlated (r = 0.73, P < 0.05) with the triglyceride-adjusted chylomicron beta-carotene response, i.e., with the ability to respond to beta-carotene. The triglyceride-adjusted chylomicron retinyl-palmitate response was correlated (r = 0.55, P < 0.05) with the triglyceride-adjusted chylomicron beta-carotene response. Plasma all-trans retinoic acid slightly, but significantly, increased (+40%) 3 h after the beta-carotene load, but this increase was not related to the triglyceride-adjusted beta-carotene response. In conclusion, the ability to respond to beta-carotene is highly variable, but there is probably a very small proportion of true non-responders to pharmacological doses of beta-carotene in the healthy population. This variability is apparently mainly due to interindividual differences in the efficiency of intestinal absorption of beta-carotene and in chylomicron metabolism. The ability to respond to beta-carotene can affect the beta-carotene status and the provitamin A activity of beta-carotene, but it has apparently no effect on the amount of retinoic acid appearing in the plasma after the ingestion of a pharmacological dose of beta-carotene.

The bioavailability of alpha- and beta-carotene is affected by gut microflora in the rat.

The present study examined whether the intestinal microflora could affect the bioavailability and vitamin A activity of dietary alpha- and beta-carotene in the rat. In the first set of experiments, we used conventional, germ-free (axenic), and human-flora-associated (heteroxenic) rats. In a second series, conventional rats were treated with either an antibiotic mixture or a potent inhibitor of gastric secretion (Omeprazole). All animals were first depleted of vitamin A over 4 weeks and then were fed on a sterilized diet supplemented with 14 mg beta-carotene and 3 mg alpha-carotene/kg for 2 weeks. In both experiments, a reduction in the intestinal microflora resulted in an increased storage of beta-carotene, alpha-carotene and vitamin A in the liver. Neither the nature of the metabolism of the intestinal microflora (aerobic or anaerobic) nor treatment with omeprazole, to modify intestinal pH, induced a significant effect on the measured variables. When incubated with 15 mumol beta-carotene/l for 72 h, neither the anaerobic nor the aerobic sub-fractions obtained from rat or human faeces contributed to beta-carotene degradation or to vitamin A synthesis. These findings suggest that reduction in gut microflora results in a better utilization of alpha- and beta-carotene by rats, although bacteria do not have a direct effect on the bioavailability of these pigments.

Chylomicron beta-carotene and retinyl palmitate responses are dramatically diminished when men ingest beta-carotene with medium-chain rather than long-chain triglycerides.

The effect of the ingestion of beta-carotene with medium-chain triglycerides (MCT) or long-chain triglycerides (LCT) on the bioavailability and the provitamin A activity of beta-carotene was investigated in humans. Sixteen healthy young men ingested, on two different days, a test meal containing 120 mg beta-carotene incorporated into 40 g LCT (LCT meal) or 40 g MCT (MCT meal). This meal was followed 6 h later by a beta-carotene-free meal containing 40 g LCT. Chylomicron beta-carotene, retinyl palmitate and triglycerides were measured every hour for 12.5 h after the first meal. No significant increase in chylomicron triglycerides was detected for the 6 h after the MCT meal intake, whereas a significant increase in chylomicron triglycerides was observed after the LCT meal intake. The chylomicron beta-carotene and retinyl palmitate responses to the MCT meal (0-6 h area under the curves, AUC) were significantly (P < 0.05) lower [AUC = 68.1 +/- 26.8 and 43. 4 +/- 10.4 nmol/(L.h), for beta-carotene and retinyl palmitate, respectively] than those obtained after the LCT meal [301.4 +/- 64.0 and 166.0 +/- 29.0 nmol/(L.h), respectively]. The chylomicron beta-carotene and retinyl palmitate responses obtained after the beta-carotene-free meal (6-12.5 h AUC) were also significantly lower when the first meal provided MCT rather than LCT. The chylomicron (retinyl palmitate/beta-carotene) ratios were constant during the postprandial periods, whatever the meal ingested. We conclude that the chylomicron beta-carotene response is markedly diminished when beta-carotene is absorbed with MCT instead of LCT. This phenomenon is apparently due to the lack of secretion of chylomicrons in response to MCT; however, a lower intestinal absorption of beta-carotene or a higher transport of beta-carotene via the portal way in the presence of MCT cannot be ruled out. Finally, the data obtained show that MCT do not affect the rate of intestinal conversion of beta-carotene into vitamin A.

Oxidative stress status and antioxidant status are apparently not related to carotenoid status in healthy subjects.

Several lines of evidence suggest that carotenoids may have a beneficial effect on health as a result of their antioxidant properties. In addition to beta-carotene, five other carotenoids are recovered in noticeable amounts from human plasma and tissues. Although the effect of beta-carotene on in vivo lipid peroxidation has been documented, few data are available on the effects of the other carotenoids. We evaluated the ability of the main human carotenoids to reduce lipid peroxidation by determining the correlations between plasma carotenoid concentration and plasma antioxidant capacity (in 79 healthy volunteers) and between carotenoid status and breath pentane excretion (in a subgroup of 24 subjects). Carotenoid intake was assessed by means of a 3-day food recall. Carotenoid status was evaluated by measurement of beta-carotene, lycopene, lutein/zeaxanthin, and alpha-carotene in plasma and buccal mucosal cells. Antioxidant status was evaluated by measurement of the total antioxidant capacity of the plasma. Oxidative stress status was evaluated by breath pentane measurements. Food recall data and the carotenoid concentrations in plasma and buccal mucosal cells showed that the subjects had normal carotenoid intake and normal carotenoid status. The total antioxidant capacity of the plasma was not related to the concentration of any specific carotenoid. The level of expired air pentane was not related to the carotenoid status of the subjects. These results show that normal concentrations of carotenoids in plasma and tissues are not correlated with these clinical markers of antioxidant and oxidative stress status.

Comparison of the postprandial plasma vitamin A response in young and older adults.

To assess the influence of age on vitamin A intestinal and liver metabolism in humans, the postprandial plasma concentrations of intestinal-originated vitamin A, i.e., retinyl esters, and liver-originated vitamin A, i.e., retinol, were compared in eight young (20-30 years old) and eight elderly (64-72 years old) healthy men. Plasma and chylomicron retinyl esters and retinol concentrations were measured for up to 24 h following the intake of a test meal that contained 23,300 RE retinyl palmitate. The chylomicron retinyl palmitate response (area under the curve) was not significantly different between the two groups, but its peak was slightly delayed (1 h) in the elderly men. The proportion of the different retinyl esters secreted in the chylomicrons was not significantly different between the two groups. The postprandial plasma retinol concentration did not change in the young participants, whereas it significantly increased in the elderly. These results suggest that vitamin A intestinal absorption and retinol intestinal esterification processes are not markedly modified in the elderly, whereas the chylomicron clearance and the regulation of postprandial plasma retinol concentration are apparently altered in these subjects.

Diet, antioxidant status, and smoking habits in French men.

The aim of this study was to assess the association between smoking, food consumption, and antioxidant vitamin intake and plasma indexes of oxidative stress and antioxidant defenses in French adults. Food and nutrient intakes of 459 healthy men aged 23-57 y were estimated by the diet history method and analyzed by smoking status. Plasma alpha-tocopherol, ascorbic acid, and carotenoids were measured as antioxidants and malondialdehyde, protein Schiff bases, and autoantibodies against malondialdehyde-protein adducts as oxidative stress indexes. Smokers ate less fruit and vegetables than nonsmokers, leading to lower vitamin E, vitamin C, and carotene intakes, even after adjustment for age, education, and marital status. Unlike vitamin E, plasma ascorbic acid and beta-carotene concentrations were reduced in smokers compared with nonsmokers and were inversely related to cigarette consumption. This difference remained significant after adjustment for alcohol and dietary intakes. Among the measured oxidative stress indexes, only Schiff base concentration was positively related to the number of cigarettes smoked. In our sample of French men, smoking had an adverse effect on antioxidant status; vitamin intakes were reduced in smokers and plasma antioxidant indexes were altered independently of dietary intakes. As in other countries, in France smokers require particular attention in terms of public health intervention.

Postprandial chylomicron and plasma vitamin E responses in healthy older subjects compared with younger ones.

The effect of ageing on vitamin E bioavailability in humans was assessed by comparing chylomicron and plasma alpha-tocopherol postprandial concentrations after a dose of vitamin E (432 or 937 IU as d1-alpha-tocopherol acetate), in eight young (20-30 years old) and eight healthy elderly men (64-72 years old). The fasting plasma alpha-tocopherol concentration was significantly higher in the elderly (33 +/- 2 mumol L-1) than in the young (22 +/- 2 mumol L-1). In both groups, the plasma and chylomicron alpha-tocopherol postprandial concentrations were significantly, approximately twofold, higher after the 937-IU meal than after the 432-IU meal. For both test meals, the chylomicron alpha-tocopherol areas under the curve were significantly lower in the elderly than in the young subjects: 98.9 +/- 16.5 (young group) vs. 55.3 +/- 7.8 (elderly group) mumol L-1 h for the 937-IU test meal and 60.4 +/- 14.1 (young group) vs. 26.0 +/- 7.6 (elderly group) mumol L-1 h for the 432-IU test meal, whereas the plasma alpha-tocopherol area under the curve was significantly higher in elderly than in young subjects: 337.56 +/- 16.11 (937-IU test meal) vs. 159.81 +/- 35.55 (432-IU test meal) mumol L-1 h in the young group and 709.55 +/- 69.33 (937-IU test meal) vs. 436.39 +/- 41.08 (432-IU test meal) mumol L-1 h in the elderly group. We concluded that (a) the amount of vitamin E appearing in plasma is proportional to the dose ingested (up to 937 IU); (b) the intestinal absorption of vitamin E is not increased, even possibly decreased, in the elderly; and (c) the amount of vitamin E transported by non-chylomicron lipoproteins is apparently higher in the elderly. This suggests that vitamin E postprandial transport is affected by ageing, mainly as the consequence of age-related modifications of lipoprotein metabolism.

Dietary triglycerides, up to 40 g/meal, do not affect preformed vitamin A bioavailability in humans.

OBJECTIVE: Assessing the effect of the dose of dietary triglycerides on preformed vitamin A (retinyl esters) bioavailability in humans. DESIGN: Four test meals containing 15,000 RE retinyl-palmitate and either 0, 15, 30 or 40 g added triglycerides were ingested by eight healthy volunteers, at different days and in a randomized order. SETTING: The study was done in the Hospital Sainte Marguerite, Marseille, France. SUBJECTS: Eight healthy male volunteers were recruited by advertisement. INTERVENTION: Blood samples were collected every hour for seven hours after the test meals intake. Serum and chylomicron (Svedberg flotation unit > 1000) were prepared by centrifugation and retinyl esters were measured by HPLC. RESULTS: The serum retinyl ester response was not significantly lower after the intake of the meal without added triglycerides (7944 +/- 3262 nmol/L h) than after the intake of the fat meals (10012 +/- 2182, 7869 +/- 3157 and 10777 +/- 2067 nmol/L h for the 15, 30 and 40 g-fat meal, respectively), indicating that the serum retinyl ester response was not related to the amount of meal triglycerides. Chylomicron retinyl linoleate response stepwise increased when the amount of meal triglycerides increased while retinyl palmitate and retinyl stearate responses reached a maximum since 15 g triglycerides. Postprandial serum retinol concentration did not change whatever the meal ingested. CONCLUSIONS: (i) a significant amount of preformed vitamin A is apparently absorbed when ingested with trace amount of meal triglycerides only; (ii) meal triglycerides, up to 40 g/meal, do not increase preformed vitamin A bioavailability; (iii) the retinyl ester pattern recovered in the chylomicrons, and probably the esterification process of retinol, is affected by the amount of meal triglycerides; (iv) postprandial retinol homeostasis is not affected by dietary triglycerides.