Dietary calcium impairs tomato lycopene bioavailability in healthy humans.

Lycopene (LYC) bioavailability is relatively low and highly variable, because of the influence of several factors. Recent in vitro data have suggested that dietary Ca can impair LYC micellarisation, but there is no evidence whether this can lead to decreased LYC absorption efficiency in humans. Our objective was to assess whether a nutritional dose of Ca impairs dietary LYC bioavailability and to study the mechanism(s) involved. First, in a randomised, two-way cross-over study, ten healthy adults consumed either a test meal that provided 19-mg (all-E)-LYC from tomato paste or the same meal plus 500-mg calcium carbonate as a supplement. Plasma LYC concentration was measured at regular time intervals over 7 h postprandially. In a second approach, an in vitro digestion model was used to assess the effect of increasing Ca doses on LYC micellarisation and on the size and zeta potential of the mixed micelles produced during digestion of a complex food matrix. LYC bioavailability was diminished by 83 % following the addition of Ca in the test meal. In vitro, Ca affected neither LYC micellarisation nor mixed micelle size but it decreased the absolute value of their charge by 39 %. In conclusion, a nutritional dose of Ca can impair dietary LYC bioavailability in healthy humans. This inhibition could be due to the fact that Ca diminishes the electrical charge of micelles. These results call for a thorough assessment of the effects of Ca, or other divalent minerals, on the bioavailability of other carotenoids and lipophilic micronutrients.

A gene variation (rs12691) in the CCAT/enhancer binding protein α modulates glucose metabolism in metabolic syndrome.

BACKGROUND AND AIMS: CCAAT/enhancer-binding protein alpha (CEBPA) is a transcription factor involved in adipogenesis and energy homeostasis. Caloric restriction reduces CEBPA protein expression in patients with metabolic syndrome (MetS). A previous report linked rs12691 SNP in CEBPA to altered concentration of fasting triglycerides. Our objective was to assess the effects of rs12691 in glucose metabolism in Metabolic Syndrome (MetS) patients. METHODS AND RESULTS: Glucose metabolism was assessed by static (glucose, insulin, adiponectin, leptin and resistin plasma concentrations) and dynamic (disposition index, insulin sensitivity index, HOMA-IR and acute insulin response to glucose) indices, performed at baseline and after 12 weeks of 4 dietary interventions (high saturated fatty acid (SFA), high monounsaturated fatty acid (MUFA), low-fat and low-fat-high-n3 polyunsaturated fatty acid (PUFA)) in 486 subjects with MetS. Carriers of the minor A allele of rs12691 had altered disposition index (p = 0.0003), lower acute insulin response (p = 0.005) and a lower insulin sensitivity index (p = 0.025) indicating a lower insulin sensitivity and a lower insulin secretion, at baseline and at the end of the diets. Furthermore, A allele carriers displayed lower HDL concentration. CONCLUSION: The presence of the A allele of rs12691 influences glucose metabolism of MetS patients.

Increased levels of microparticles originating from endothelial cells, platelets and erythrocytes in subjects with metabolic syndrome: relationship with oxidative stress.

BACKGROUND AND AIMS: The Metabolic Syndrome (MetS) is associated with increased cardiovascular risk. Circulating microparticles (MP) are involved in the pathogenesis of atherothrombotic disorders and are raised in individual with CVD. We measured their level and cellular origin in subjects with MetS and analyzed their associations with 1/anthropometric and biological parameters of MetS, 2/inflammation and oxidative stress markers. METHODS AND RESULTS: Eighty-eight subjects with the MetS according to the NCEP-ATPIII definition were enrolled in a bicentric study and compared to 27 healthy controls. AnnexinV-positive MP (TMP), MP derived from platelets (PMP), erythrocytes (ErMP), endothelial cells (EMP), leukocytes (LMP) and granulocytes (PNMP) were determined by flow cytometry. MetS subjects had significantly higher counts/µl of TMP (730.6±49.7 vs 352.8±35.6), PMP (416.0±43.8 vs 250.5±23.5), ErMP (243.8±22.1 vs 73.6±19.6) and EMP (7.8±0.8 vs 4.0±1.0) compared with controls. LMP and PNMP were not statistically different between groups. Multivariate analysis demonstrated that each criterion for the MetS influenced the number of TMP. Waist girth was a significant determinant of PMP and EMP level and blood pressure was correlated with EMP level. Glycemia positively correlated with PMP level whereas dyslipidemia influenced EMP and ErMP levels. Interestingly, the oxidative stress markers, plasma glutathione peroxydase and urinary 8-iso-prostaglandin F(2) α, independently influenced TMP and PMP levels whereas inflammatory markers did not, irrespective of MP type. CONCLUSION: Increased levels of TMP, PMP, ErMP and EMP are associated with individual metabolic abnormalities of MetS and oxidative stress. Whether MP assessment may represent a marker for risk stratification or a target for pharmacological intervention deserves further investigation.

Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaén and Córdoba (Spain) 2008.

Olive oil (OO) is the most representative food of the traditional Mediterranean Diet (MedDiet). Increasing evidence suggests that monounsaturated fatty acids (MUFA) as a nutrient, OO as a food, and the MedDiet as a food pattern are associated with a decreased risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes and hypertension. A MedDiet rich in OO and OO per se has been shown to improve cardiovascular risk factors, such as lipid profiles, blood pressure, postprandial hyperlipidemia, endothelial dysfunction, oxidative stress, and antithrombotic profiles. Some of these beneficial effects can be attributed to the OO minor components. Therefore, the definition of the MedDiet should include OO. Phenolic compounds in OO have shown antioxidant and anti-inflammatory properties, prevent lipoperoxidation, induce favorable changes of lipid profile, improve endothelial function, and disclose antithrombotic properties. Observational studies from Mediterranean cohorts have suggested that dietary MUFA may be protective against age-related cognitive decline and Alzheimer's disease. Recent studies consistently support the concept that the OO-rich MedDiet is compatible with healthier aging and increased longevity. In countries where the population adheres to the MedDiet, such as Spain, Greece and Italy, and OO is the principal source of fat, rates of cancer incidence are lower than in northern European countries. Experimental and human cellular studies have provided new evidence on the potential protective effect of OO on cancer. Furthermore, results of case-control and cohort studies suggest that MUFA intake including OO is associated with a reduction in cancer risk (mainly breast, colorectal and prostate cancers).

The anionic peptide fraction is present on the gallbladder apical epithelium and favours biliary cholesterol absorption.

BACKGROUND/AIMS: We investigated (a) in vitro and in vivo the changes of biliary mass of the anionic peptide fraction, apolipoproteinA-I, immunoglobulin-A, albumin and cholesterol over time in the excluded gallbladder and (b) in vivo the localization in the gallbladder epithelium of the anionic peptide fraction and cholesterol absorbed from bile. METHODS: Native bile was substituted with pig bile containing radiolabeled cholesterol in the in vitro isolated intra-arterially perfused pig gallbladder (n=9) and in vivo in anestethized pigs with excluded gallbladders (n=6). The amount of cholesterol (scintillation counting) and proteins (enzyme-linked immunosorbent assay) in gallbladder bile were measured over time. The localization of the anionic peptide fraction and cholesterol absorbed from bile in the gallbladder epithelium was studied in vivo by immunohistochemistry and fluoro-phospho-imager analysis. RESULTS: The rate of biliary cholesterol disappeared from bile was a function of the initial concentration and of the biliary mass changes over time of the anionic peptide fraction, but not of that of the other biliary proteins. The anionic peptide fraction colocalized with biliary cholesterol absorbed by the gallbladder on the apical side of gallbladder epithelial cells. CONCLUSIONS: These data indirectly suggest that biliary anionic peptide fraction could favour biliary cholesterol absorption by the gallbladder epithelium.

Effect of the main dietary antioxidants (carotenoids, gamma-tocopherol, polyphenols, and vitamin C) on alpha-tocopherol absorption.

OBJECTIVE: (R,R,R)-alpha-tocopherol is a fat-soluble antioxidant vitamin generally ingested with other dietary antioxidants. The objective of this study was to assess whether the main dietary antioxidant classes, that is carotenoids, polyphenols, vitamin C and gamma-tocopherol, affect the intestinal absorption of alpha-tocopherol. METHODS, DESIGN AND SUBJECTS: We evaluated first the effect of different combinations of antioxidants on (R,R,R)-alpha-tocopherol absorption by a human intestinal cell line (Caco-2 clone TC7). Then we compared the effect of two doses of a dietary antioxidant (lutein) on the postprandial chylomicron alpha-tocopherol responses to an alpha-tocopherol-rich meal. Eight healthy men ate two similar meals in a random order at a 1 month interval. The meals contained 24 mg alpha-tocopherol in sunflower oil plus either 18 or 36 mg lutein. Blood samples were collected during the postprandial periods to compare chylomicron alpha-tocopherol responses. RESULTS: A mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene, beta-carotene and lutein) significantly impaired alpha-tocopherol absorption in Caco-2 cells (P<0.001 and P<0.0001, respectively). The inhibitory effect of gamma-tocopherol was close to significance (P=0.055). In contrast, vitamin C had no significant effect (P=0.158). Naringenin was the only polyphenol that significantly impaired alpha-tocopherol absorption. Postprandial alpha-tocopherol response was weakest at the highest dose of lutein (616+/-280 nmol/l h vs 1001+/-287 nmol/l h). The observed extent of reduction (-38%, P=0.069) supported the inhibitory effect of carotenoids observed in the Caco-2 experiments. CONCLUSION: Naringenin, carotenoids and probably gamma-tocopherol can impair alpha-tocopherol absorption whereas vitamin C and phenolic acids have no effect.

International conference on the healthy effect of virgin olive oil.

1. Ageing represents a great concern in developed countries because the number of people involved and the pathologies related with it, like atherosclerosis, morbus Parkinson, Alzheimer's disease, vascular dementia, cognitive decline, diabetes and cancer. 2. Epidemiological studies suggest that a Mediterranean diet (which is rich in virgin olive oil) decreases the risk of cardiovascular disease. 3. The Mediterranean diet, rich in virgin olive oil, improves the major risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile. Endothelial function, inflammation and oxidative stress are also positively modulated. Some of these effects are attributed to minor components of virgin olive oil. Therefore, the definition of the Mediterranean diet should include virgin olive oil. 4. Different observational studies conducted in humans have shown that the intake of monounsaturated fat may be protective against age-related cognitive decline and Alzheimer's disease. 5. Microconstituents from virgin olive oil are bioavailable in humans and have shown antioxidant properties and capacity to improve endothelial function. Furthermore they are also able to modify the haemostasis, showing antithrombotic properties. 6. In countries where the populations fulfilled a typical Mediterranean diet, such as Spain, Greece and Italy, where virgin olive oil is the principal source of fat, cancer incidence rates are lower than in northern European countries. 7. The protective effect of virgin olive oil can be most important in the first decades of life, which suggests that the dietetic benefit of virgin olive oil intake should be initiated before puberty, and maintained through life. 8. The more recent studies consistently support that the Mediterranean diet, based in virgin olive oil, is compatible with a healthier ageing and increased longevity. However, despite the significant advances of the recent years, the final proof about the specific mechanisms and contributing role of the different components of virgin olive oil to its beneficial effects requires further investigations.

Flavonoids in food and natural antioxidants in wine.

Plant foodstuffs are an important source of a wide variety of flavonoids with protective properties on low-density lipoprotein oxidation as shown in vitro and in some human and animal experiments. Increasing information is available concerning the absorption and pharmacokinetics of these molecules, but their long-term protective effect on coronary heart disease still needs further investigation.

Method for simultaneous measurements of traces of heptadeuterated cholesterol and cholesterol by gas chromatography-mass spectrometry: application in humans.

An assay was developed to quantify deuterated cholesterol (used as a tracer) and cholesterol using gas chromatography-mass spectrometry. Ergosterol and epicoprostanol were used as internal standards. Deuterated cholesterol was quantified by comparing its peak area to that of epicoprostanol and cholesterol to ergosterol. The mean absolute recovery in spiked serum was 99.96%; the precision was in the range 0.16-10.9% and accuracy 90.4-100%; the limit of detection in plasma was 3x10(-5) mmol l(-1). Using two internal standards, the method described herein seems particularly suitable for application in humans i.e., measuring traces of deuterated cholesterol (range: 0-6.26 x 10(-4) mmol l(-1)) along with natural cholesterol (range: 0.065-4.42 mmol l(-1)) in human plasma and lipid fractions postprandially.

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.

Postprandial studies on dietary cholesterol in human subjects using stable isotopes and gas chromatography-mass spectrometry analysis.

We hypothesized that intestinal absorption and postprandial re-secretion of dietary cholesterol may be a particularly complex process in humans. To test this hypothesis, we used deuterium-enriched cholesterol to specifically label meal cholesterol and developed an improved method for quantitative measurement of traces of deuterated cholesterol as well as cholesterol with reference to two different internal standards by gas chromatography-mass spectrometry (GC-MS) measurement. In the first study, a group of healthy subjects ingested a single test meal containing deuterated cholesterol with a 7 h postprandial follow-up. In the second one, a group of healthy subjects ingested a first test meal containing deuterated cholesterol and a follow-up was performed during three consecutive test meals and later until 72 h. The most striking observations were that the occurrence of dietary cholesterol in chylomicrons is not concomitant to triglycerides and is very low after a single meal while most dietary cholesterol is re-secreted in chylomicrons after a second, and even a third, fat test meal. The data obtained show that the re-secretion of dietary cholesterol from the small intestine is a slow and complex process in humans.

Effects of moderate amounts of emulsified dietary fat on postprandial lipemia and lipoproteins in normolipidemic adults.

Eight normolipidemic males ingested a meal containing either 42 g fat or 31 g fat in the form of emulsions (9.0 and 9.2 m2) and a fixed amount of retinyl palmitate. Fasting and postmeal blood samples were obtained for 7 h. Serum and chylomicron triglyceride responses were related to the amount of fat ingested and peaked after 2-3 h. The chylomicron retinyl palmitate response was lower (P < or = 0.05) with the 31-g fat supply. After the 42-g fat intake, but not after the 31-g fat intake, serum free cholesterol and phospholipids increased and esterified cholesterol decreased postprandially. Significantly different responses were observed after both meals for low-density-lipoprotein (LDL) free cholesterol, very-low-density-lipoprotein (VLDL) and LDL esterified cholesterol, and high-density-lipoprotein (HDL) phospholipids. These data show that ingesting 31 g instead of 42 g fat in a meal reduces postmeal lipoprotein variations and suggest that a threshold level of dietary fat should be overcome to promote significant postprandial changes in lipoprotein particles.

Influence of acute injection of chloroquine on the biliary secretion of lipids and lysosomal enzyme on rats.

Phospholipids and cholesterol combine with a protein fraction (IgA and an acid polypeptide) in bile to form the bile lipoprotein complex. We wished to determine whether lysosomes participated only on IgA secretion or if their secretory role also involved the lipid components of the bile complex. This aspect was studied with a single acute injection of chloroquine, a lysosomotropic drug. The results show that a nonnegligible quantity of IgA travels through the lysosomes. In addition, phospholipid and cholesterol levels undergo a significant (P less than 0.05) decrease 1 hr after injection before increasing to normal levels. In contrast to the total inhibition of protein secretion (beta-glucuronidase, acid phosphatase), a transitory decrease of the secretion of bile lipids takes place that suggest secretory mechanisms involving organelles other than lysosomes.

Immunohistochemical localization of the apoproteins of the bile lipoprotein complex in the human intestine.

The human bile lipoprotein complex includes an apoprotein fraction of IgA fragments and an acidic polypeptide tightly bound to bile cholesterol and phosphatidylcholines. The fate of the intestinal bile lipoprotein complex was immunohistochemically studied. Its localization in the human duodenum is consistent with selective capture or synthesis. The result of both might be the presence of bile apoprotein in the bloodstream. These two mechanisms may explain the cross-reaction between the lipoprotein complex apoprotein and the high density lipoprotein.

Possible roles of bile lipids and colipase in lipase adsorption.

The adsorption isotherms of bile salts, phospholipids, and cholesterol were determined with siliconized glass beads. It was observed that the molar fractions of cholesterol, phospholipid, and bile polypeptide fractions increased simultaneously and considerably on the surface of the beads in comparison to the corresponding fractions found in bile. The composition of the adsorbed film is approximately 1 cholesterol: 2 phospholipid: 3 bile salt molecules. The performed complex of lipase, colipase, and bile lipids behaves as an entity which determines lipase adsorption. The modification of the interface quality of a lipid substrate by a detergent is not perse the reason for the lack of lipase adsorption. A model is proposed according to which lipolysis under physiological conditions would occur in two steps requiring two cofactors. Colipase would be necessary for the formation of the lipase-bile lipoprotein complex, and bile lipids would be required to direct the adsorption of this lipolytic entity toward the emulsified substrate.

Zone electrophoresis study of the bile lipoprotein complex.

Sucrose gradient column electrophoresis was performed with human hepatic and gallbladder bile. It is shown that bile phosphatidylcholines exhibit a more rapid anodic mobility than do bile salts and serum albumin. This high mobility of bile phosphatidylcholines is not due to the negatively charged lipids which are present in bile, i.e. bile salts or free fatty acids. It is demonstrated that phosphatidylcholines are associated with anionic polypeptides. Electrophoresis of reassociations between these purified polypeptides and dilaurylphosphatidylcholine showed that these anionic polypeptides are primarily responsible for the high anodic mobility of the bile lipoprotein complex. This work describes a procedure for the purification of the bile lipoprotein complex which can be useful for the study of other kinds of lipid-polypeptide associations.