Influence of sourdough prefermentation, of steam cooking suppression and of decreased sucrose content during wheat flakes processing on the plasma glucose and insulin responses and satiety of healthy subjects.

BACKGROUND: Ready-to-eat breakfast cereals (RTE-BC) are eaten more and more frequently by both adults and adolescents, but their nutritional quality is far from satisfactory: they often contained too much sugars and lead to a high glycemic index (GI) which generally contributes to a more rapid return of the feeling of hunger favouring nibbling in the morning. OBJECTIVE: To reduce the GI and to improve the nutritional quality of standard wheat flakes (SWF) by adding a sourdough prefermentation step, suppressing steam cooking and decreasing the sucrose content (MWF, modified wheat flake). METHODS: Eleven healthy male volunteers were randomly given, at three separate times, SWF, MWF, and white-wheat bread (WWB, reference food). Plasma glucose, insulin and ghrelin concentrations were measured. The feeling of hunger was evaluated using a subjective rating scale. Starch structure of SWF and MWF was characterised by scanning electron microscopy. RESULTS: GI of MWF (83 +/- 7) was 12% lower than that of SWF (94 +/- 9) at 90 min but the effect was not significant. Insulinaemic index of MWF was significantly lower than that of SWF at 90 min (78 +/- 6 vs 98 +/- 8). Hunger feelings were lower following MWF consumption and were positively correlated (r = 0.98; P < 0.05) with plasma ghrelin concentrations, for which there was no significant difference between SWF and MWF. Starch granules of SWF were fully gelatinised unlike those of MWF. CONCLUSION: Despite its relatively high GI, MWF could provide health benefits by improving the management of hunger feeling in the morning and by moderately improving insulin economy, which could be of interest for type 2 diabetic subjects. GI is not, therefore, the sole parameter reflecting the nutritional quality of cereal products.

Orally administered isoflavones are present as glucuronides in the human prostate.

Better knowledge of the bioavailability and metabolism of isoflavones in prostate tissue is needed to further investigate their mechanisms of action in the context of prostate cancer prevention. A total of 12 men with benign prostatic hyperplasia received soy extract supplementation (3 Evestrel capsules, providing a total of 112.5 mg isoflavones aglycone eq/day) for 3 days before prostate surgery. Blood and prostate tissues were sampled and metabolites were identified using electrospray ionization liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) and chemically synthesized standards of glucuronidated isoflavones. The main metabolites were the same in prostate tissue and in plasma, namely, 2 monoglucuronides of daidzein and 2 monoglucuronides of genistein. Concentrations of total isoflavones measured in prostate reached 1.05 +/- 0.62 nmol/g tissue (range 0.30-2.23) at the time of sampling, 12 h after the last isoflavone supplementation. At that time point, prostate concentrations were lower than plasma concentrations in all volunteers: 0.47 nmol/g vs. 0.66 microM for daidzein and 0.58 nmol/g vs. 0.78 microM for genistein. Isoflavone mechanisms of action should thus be investigated in in vitro cell studies using physiological conditions, intracellular concentrations below 5 nmol/g and no intracellular deconjugation of the monoglucuronide metabolites.

Lipid metabolism and antioxidant status in sucrose vs. potato-fed rats.

OBJECTIVE: Consumption of high levels of simple carbohydrates is associated with several metabolic disorders in humans and in laboratory animals, including symptoms of an early stage of metabolic syndrome (syndrome X). This disorder has several cardiovascular risk factors, such as hypertriglyceridemia, and is associated with an increase in oxidative stress. In contrast to sucrose, potato, a source of complex carbohydrates and antioxidant micronutrients, was thought to improve lipid metabolism and antioxidant protection. METHODS: We investigated the effects of diets containing i) complex dietary carbohydrates and antioxidant micronutrients (potato Solanum tuberosum L.), ii) complex carbohydrates (starch) and iii) a simple carbohydrate (sucrose) on lipid metabolism and antioxidant status in rats. RESULTS: An increase in short chain fatty acid (SCFA) pools was observed in the cecum of rats fed a potato-based diet, resulting from an increase in all SCFAs, especially propionate (+360%, P < 0.0001). Feeding rats a potato-based diet for 3 weeks led to a decrease in cholesterol (-37%, potato vs. control and -32%, potato vs. sucrose) and triglycerides (-31%, potato vs. control and -43%, potato vs. sucrose) concentrations in triglyceride-rich lipoproteins (TGRLP) fractions. The antioxidant status was decreased by sucrose consumption and improved by potato consumption. CONCLUSIONS: Our present results suggest that consumption of complex carbohydrates (provided as cooked potatoes), in combination with different antioxidant micronutrients, may enhance the antioxidant defences and improve lipid metabolism, when compared with starch (complex carbohydrates) and to sucrose consumption (source of simple sugar). These effects limit oxidative stress and reduce the risk of developing the associated degenerative diseases, including cardiovascular disease, and could have potential in cardiovascular disease prevention.

Wheat germ supplementation of a low vitamin E diet in rats affords effective antioxidant protection in tissues.

BACKGROUND: Oxidative stress is implicated in the etiology of many diseases, but most of clinical trials failed to demonstrate beneficial effects of antioxidant supplementation. METHODS: In the present experiment, we assessed the mean-term effect of wheat germ supplementation, as a dietary source of vitamin E, on antioxidant protection in rat. RESULTS: Feeding rats a 20% wheat germ diet significantly increased plasma and liver vitamin E levels, compared to the low vitamin E basal diet. Concurrently, wheat germ diet consumption strongly decreased the susceptibility of heart and liver lipids to oxidation, as well as the plasma. Wheat germ feeding did not change triglycerides (TG) nor total cholesterol concentrations in plasma or liver, resulting in higher vitamin E/TG ratio compared to controls. Similar results were found with a diet in which wheat germ oil provided the same amount of vitamin E. CONCLUSIONS: Wheat germ appears thus very effective to improve antioxidant defense status, especially in tissues, irrespective of modifications of lipids status.

Parameters controlling the glycaemic response to breads.

Bread is one of the most widely consumed staple foods worldwide. White-wheat bread, largely consumed in France, is made from highly refined flour, which leads to a low nutrient density. Due to a highly porous structure and gelatinised starch, it is easily broken down during digestion, leading to a rapid increase of glucose released into the bloodstream. Low glycaemic responses are considered favourable to health, especially against a background of diabetes. Literature reports show that selection of raw material is an essential factor in decreasing the glycaemic index (GI) of white bread. There are two means of decreasing the rate of starch degradation: either (i) slowing gastric emptying rate and/or glucose diffusion-absorption through the intestinal mucosa, which can be achieved by incorporating soluble fibre or organic acid in bread, or (ii) limiting starch accessibility to alpha-amylase by using high-amylose cereal varieties and/or incorporating intact cereal grains. Studies on cereal products show that preservation of the food structure during digestion seems to be a more important GI-reducing factor than the degree of starch crystallinity or the presence of soluble fibre. Thus, we should look to produce bread with a more compact food structure or higher density, which is the case in leavened wholewheat bread or bread with intact cereal grains. The baking process should also be improved to achieve this goal, by using, for example, a reduced kneading time or less yeast than usual.

Influence of dietary antioxidants on polyphenol intestinal absorption and metabolism in rats.

The ingestion of complex foodstuff implicates the simultaneous presence along the digestive tract of several antioxidants micronutrients. This work aimed to determine if the interactions that may occur at the digestive level between polyphenols and other antioxidant micronutrients may modulate the fate of polyphenols in the splanchnic area. This study was conducted in a rat in situ intestinal perfusion model. Polyphenols (gallic and caffeic acids, catechin, and naringenin) were perfused with or without an antioxidant cocktail. For gallic acid, a significant reduction (-20%) of its net transfer through the brush border associated with a drastic decrease of its intestinal secretion of conjugates (-90%) was observed. By contrast, the transfer of catechin through the brush border increased (18%) and the secretion of its conjugates was twice in the presence of the antioxidants. Perfused polyphenols largely differed in their respective biliary secretion, but these fluxes were not modified by the presence of the antioxidant cocktail. Finally, the simultaneous presence in the small intestine of polyphenols and other dietary antioxidants never affects polyphenol splanchnic metabolism but may modify their intestinal transport without noticeable consequence on their final availability for peripheral tissues.

Wheat lipoxygenase activity induces greater loss of carotenoids than vitamin E during breadmaking.

The current study was undertaken to provide solutions to optimize the unsaponifiable antioxidants content of bread. We report a complete description of changes in wheat carotenoids and vitamin E content from grain to bread and highlight the most important processing steps affecting their level in wheat bread. Major carotenoids losses occurred during kneading. A close correlation (r(2) = 0.97; P = 0.05) was found between carotenoid pigment losses and lipoxygenase (LOX) activity, both parameters depending on wheat genotype. The use of wheat species exhibiting high carotenoid contents and low LOX activity was shown to preserve significant carotenoid level in the bread. No relation was found between vitamin E losses during doughmaking and LOX activity. In addition, moderate kneading resulted in higher vitamin E retention in comparison with carotenoids (12% and 66% losses, respectively). It is concluded that carotenoids are more susceptible to oxidation by endogenous lipoxygenase than vitamin E during breadmaking. This study showed that bread nutritional quality, in terms of antioxidant content, could be improved by selecting suitable cereal genotypes, if this potential is preserved by milling and baking processes.

Fermentable carbohydrate supplementation alters nitrogen excretion in chronic renal failure.

BACKGROUND: Considerable attention has been given to the impact of nutrition on kidney disease. Most dietary attempts to treat chronic renal failure (CRF) and to decrease uremia use a protein restriction. An alternative dietetic approach based on fermentable carbohydrate (FC) supplementation of the diet could lead to the same urea-lowering effect by increasing urea nitrogen (N) excretion in stool, with a concomitant decrease of the total N quantity excreted in urine. METHODS: In the present prospective study, the impact of FC (40 g/d) on uremia and on N excretion routes was investigated during 5 weeks in nine CRF patients in the presence of a moderated restrictive protein diet (0.8 g/kg/d). Patients were their own controls and were treated by the cross-over method after randomization (5 weeks with FC versus 5 weeks without FC). RESULTS: Feeding FC significantly increased the quantity of N excreted in stool from 2.1 +/- 0.8 to 3.2 +/- 1.1 g/d (+51%) (P < .01) and decreased, in parallel, the urinary N excretion from 9.4 +/- 1.7 to 8.3 +/- 1.4 g/d (-12%) (P < .01). The total N quantities excreted by the two routes were unchanged by the FC, which shows that the FC was efficient to shift N excretion from the urinary route toward the digestive route. As a result of the increase of urea transfer into the colon, the plasma urea concentration was significantly decreased from 26.1 +/- 8.7 to 20.2 +/- 8.2 mmol/L (-23%) (P < .05). CONCLUSIONS: These results show the same beneficial effects in CRF as those obtained with a restrictive protein diet without its nutritional drawbacks. This should be confirmed by other prospective works over a longer duration and a larger number of patients to study the effects of FC on CRF progression and on CRF terminal stage tolerance.

Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies.

Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases is emerging. Bioavailability differs greatly from one polyphenol to another, so that the most abundant polyphenols in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Mean values for the maximal plasma concentration, the time to reach the maximal plasma concentration, the area under the plasma concentration-time curve, the elimination half-life, and the relative urinary excretion were calculated for 18 major polyphenols. We used data from 97 studies that investigated the kinetics and extent of polyphenol absorption among adults, after ingestion of a single dose of polyphenol provided as pure compound, plant extract, or whole food/beverage. The metabolites present in blood, resulting from digestive and hepatic activity, usually differ from the native compounds. The nature of the known metabolites is described when data are available. The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L with an intake of 50 mg aglycone equivalents, and the relative urinary excretion ranged from 0.3% to 43% of the ingested dose, depending on the polyphenol. Gallic acid and isoflavones are the most well-absorbed polyphenols, followed by catechins, flavanones, and quercetin glucosides, but with different kinetics. The least well-absorbed polyphenols are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data are still too limited for assessment of hydroxycinnamic acids and other polyphenols. These data may be useful for the design and interpretation of intervention studies investigating the health effects of polyphenols.

Co-administration of quercetin and catechin in rats alters their absorption but not their metabolism.

Quercetin and catechin are among the major flavonoids in plant foods and their intake has been associated to a risk reduction in several degenerative diseases. The aim of the present study was to bring data on the bioavailability of quercetin and catechin when administered simultaneously. The study was performed on rats adapted to diets containing (i) 0.25% quercetin, or (ii) 0.25% catechin, or (iii) 0.25% quercetin+0.25% catechin. Quercetin, catechin and their metabolites were determined in plasma, urine and liver by HPLC with UV or coulometric detection. When quercetin and catechin were fed in association, their respective plasma concentration significantly decreased (-35% and -28% respectively), whereas the urinary and hepatic concentrations were only affected for quercetin (-36%). These data may be explained by a competitive interaction between quercetin and catechin at the digestive level, leading to a reduction of the intestinal absorption of quercetin and a possible delaying of catechin absorption over time. The simultaneous administration of quercetin and catechin had no effect on the formation of their glucurono and sulfo conjugates, indicating the absence of competition between quercetin and catechin for the corresponding conjugative enzymes.

Moderate decrease of pH by sourdough fermentation is sufficient to reduce phytate content of whole wheat flour through endogenous phytase activity.

Whole wheat bread is an important source of minerals but also contains considerable amounts of phytic acid, which is known to impair their absorption. An in vitro trial was performed to assess the effect of a moderate drop of the dough pH (around 5.5) by way of sourdough fermentation or by exogenous organic acid addition on phytate hydrolysis. It was shown that a slight acidification of the dough (pH 5.5) with either sourdough or lactic acid addition allowed a significant phytate breakdown (70% of the initial flour content compared to 40% without any leavening agent or acidification). This result highlights the predominance of wheat phytase activity over sourdough microflora phytase activity during moderate sourdough fermentation and shows that a slight drop of the pH (pH value around 5.5) is sufficient to reduce significantly the phytate content of a wholemeal flour. Mg "bioaccessibility"of whole wheat dough was improved by direct solubilization of the cation and by phytate hydrolysis.

Blackberry anthocyanins are mainly recovered from urine as methylated and glucuronidated conjugates in humans.

The consumption of anthocyanins has been shown to prevent certain chronic diseases. However, anthocyanin metabolism has not yet been fully elucidated. The aim of this study was to evaluate anthocyanin urinary excretion in humans receiving a meal containing blackberries and to identify possible metabolites in urine. Five healthy volunteers were fed 200 g of blackberries (960 mumol of anthocyanins). Urine samples were collected and rapidly treated by solid-phase extraction. Anthocyanin metabolites were identified and quantified by HPLC-ESI-MS-MS and HPLC with UV-vis detection, respectively. In addition to native cyanidin 3-glucoside, several other anthocyanin metabolites were identified in the urine: methylated glycosides, glucuronides of anthocyanidins and anthocyanins, a sulfoconjugate of cyanidin, and anthocyanidins. Total urinary excretion of blackberry anthocyanin metabolites was 0.160 +/- 0.020% (n = 5) of the amount of anthocyanins ingested. Monoglucuronides of anthocyanidins represented >60% of this excretion. Urinary excretion of anthocyanins was maximal between 2 and 4 h after the meal, but continued during the 24 h of the experiment. This study highlighted the influence of aglycon structure on anthocyanin urinary excretion. It demonstrated that anthocyanins are not only methylated but also glucuroconjugated and sulfoconjugated in humans and that the main metabolites of blackberry anthocyanins in human urine were anthocyanidin monoglucuronides.

Anthocyanin metabolism in rats and their distribution to digestive area, kidney, and brain.

Anthocyanins are present in human diet due to their wide occurrence in fruits and beverages. They possess antioxidant activities and could be involved in several health effects. The aim of this study was to investigate anthocyanin metabolism and distribution in the digestive area organs (stomach, jejunum and liver) and kidney, as well as a target tissue (brain) in rats fed with a blackberry (Rubus fruticosus L.) anthocyanin-enriched diet for 15 days. Identification and quantification of anthocyanin metabolites was carried out by HPLC-ESI-MS-MS and HPLC-DAD, respectively. The stomach exhibited only native blackberry anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-pentose), while in other organs (jejunum, liver, and kidney) native and methylated anthocyanins as well as conjugated anthocyanidins (cyanidin and peonidin monoglucuronides) were identified. Proportions of anthocyanin derivatives differed according to the organ considered, with the liver presenting the highest proportion of methylated forms. Jejunum and plasma also contained aglycone forms. In the brain, total anthocyanin content (blackberry anthocyanins and peonidin 3-O-glucoside) reached 0.25 +/- 0.05 nmol/g of tissue (n = 6). The urinary excretion of total anthocyanins was low (0.19 +/- 0.02% of the ingested amount). Thus, organs of the digestive area indicated a metabolic pathway of anthocyanins with enzymatic conversions (methylation and/or glucurono-conjugation). Moreover, following consumption of an anthocyanin-rich diet, anthocyanins enter the brain.

Caffeic acid inhibits oxidative Stress and reduces hypercholesterolemia induced by iron overload in rats.

The effects of caffeic acid, a major phenolic compound of the diet, on oxidative stress and cholesterolemia are studied in rats submitted to oxidative stress by iron overload. Male Wistar rats were fed semi-synthetic diets containing regular (50 mg/kg diet) or high (2000 mg/kg) doses of iron with and without caffeic acid (6460 mg/kg) for 4 weeks. The high doses of iron induced an increase of lipid oxidation in the liver, as measured by thiobarbituric acid-reactive substances (TBARS), and an increase of cholesterolemia. Caffeic acid fully prevented the pro-oxidant effects of high iron doses (p < 0.001). It also reduced lipid peroxidation in rats fed the low iron dose (p < 0.05). Caffeic acid also increased vitamin E levels in plasma (2.74 micromol/L to 4.09 micromol/L for normal diet; p < 0.001; 2.78 micromol/L to 4.94 micromol/L for iron supplemented diet p < 0.001). Iron-induced hypercholesterolemia was inhibited by caffeic acid (1.07 g/L to 0.82 g/L; p < 0.001). These results demonstrate the antioxidative capacity of caffeic acid, a highly bioavailable polyphenol, in an in vivo model of oxidative stress.

Metabolism of dietary procyanidins in rats.

Procyanidins are major dietary polyphenols made of elementary flavan-3-ol (epi)catechin units. They have antioxidant properties and may contribute to health benefits in humans, but little is known about their metabolic fate. We compared here the metabolism of procyanidin dimer B3, trimer C2, and polymer isolated from willow tree catkins to that of catechin monomer in rats. These compounds were administered in the rat diet (0.1%, w/w) for 5 d and their metabolites estimated in 24 h urine. In rats fed procyanidins, neither parent compound nor catechin derivatives could be detected in contrast to animals fed catechin monomer, which excreted large amounts of catechin and its 3'-O-methylated form (25.7 +/- 0.6%). On the other hand, 16 metabolites of microbial origin were detected and identified as phenylvaleric, phenylpropionic, phenylacetic, and benzoic acid derivatives. Their total yields significantly decreased from the catechin monomer (10.6 +/- 1.1%) to the procyanidin dimer (6.5 +/- 0.2%), trimer (0.7 +/- 0.1%), and polymer (0.5 +/- 0.1%). Therefore, the degree of procyanidin polymerization has a major impact on their fate in the body characterized by a poor absorption through the gut barrier and a limited metabolism by the intestinal microflora as compared to catechin. This will have to be considered to explain the health effects of procyanidins. The contribution of their microbial metabolites should also be further investigated.

Polyphenols: food sources and bioavailability.

Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases such as cancer and cardiovascular diseases is emerging. The health effects of polyphenols depend on the amount consumed and on their bioavailability. In this article, the nature and contents of the various polyphenols present in food sources and the influence of agricultural practices and industrial processes are reviewed. Estimates of dietary intakes are given for each class of polyphenols. The bioavailability of polyphenols is also reviewed, with particular focus on intestinal absorption and the influence of chemical structure (eg, glycosylation, esterification, and polymerization), food matrix, and excretion back into the intestinal lumen. Information on the role of microflora in the catabolism of polyphenols and the production of some active metabolites is presented. Mechanisms of intestinal and hepatic conjugation (methylation, glucuronidation, sulfation), plasma transport, and elimination in bile and urine are also described. Pharmacokinetic data for the various polyphenols are compared. Studies on the identification of circulating metabolites, cellular uptake, intracellular metabolism with possible deconjugation, biological properties of the conjugated metabolites, and specific accumulation in some target tissues are discussed. Finally, bioavailability appears to differ greatly between the various polyphenols, and the most abundant polyphenols in our diet are not necessarily those that have the best bioavailability profile. A thorough knowledge of the bioavailability of the hundreds of dietary polyphenols will help us to identify those that are most likely to exert protective health effects.

Cocoa procyanidins are stable during gastric transit in humans.

BACKGROUND: Polyphenolic procyanidins are abundant flavonoid polymers in Western diets. In vitro biological activity has been reported for these compounds, but activity in vivo depends on the amount and chemical nature of the flavonoids reaching the gastrointestinal tract. Degradation of procyanidins under simulated gastric conditions at pH 2.0 has been reported in vitro. OBJECTIVE: The objective was to examine whether depolymerization of procyanidins occurs in the stomach of human subjects in vivo. DESIGN: After an overnight fast, 6 healthy subjects (3 men and 3 women) consumed 500 mL of a cocoa beverage containing 733 mg procyanidin polymers and 351 mg structurally related flavanol monomers. With the use of a nasogastric tube, stomach contents were collected every 10 min after beverage ingestion until the stomach was emptied. Flavanols and procyanidins (up to pentamers) were quantified by normal and reversed-phase HPLC. RESULTS: In all subjects, gastric transit lasted approximately 50-60 min. No change in the HPLC profile of procyanidins was observed during this period, showing that procyanidins were remarkably stable in the stomach environment. CONCLUSION: The results suggest that most ingested procyanidins reach the small intestine intact and are available for absorption or metabolism.

Chocolate intake increases urinary excretion of polyphenol-derived phenolic acids in healthy human subjects.

BACKGROUND: Proanthocyanidins, the most abundant polyphenols in chocolate, are not depolymerized in the stomach and reach the small intestine intact, where they are hardly absorbed because of their high molecular weight. In vitro and in vivo studies using pure compounds as substrates suggest that proanthocyanidins and the related catechin monomers may be degraded into more bioavailable low-molecular-weight phenolic acids by the microflora in the colon. OBJECTIVE: The aim of the study was to estimate the amounts of phenolic acids formed by the microflora and excreted in the urine of human subjects after consumption of polyphenol-rich chocolate. DESIGN: After consumption of a polyphenol-free diet for 2 d and a subsequent overnight fast, 11 healthy subjects (7 men and 4 women) consumed 80 g chocolate containing 439 mg proanthocyanidins and 147 mg catechin monomers. All urine was collected during the 24 h before chocolate consumption and at 3, 6, 9, 24, and 48 h after chocolate consumption. Aromatic acids were identified in urine by gas chromatography-mass spectrometry and were quantified by HPLC-electrospray ionization tandem mass spectrometry. RESULTS: Chocolate intake increased the urinary excretion of the 6 following phenolic acids: m-hydroxyphenylpropionic acid, ferulic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxyphenylacetic acid, vanillic acid, and m-hydroxybenzoic acid. CONCLUSION: The antioxidant and biological effects of chocolate may be explained not solely by the established absorption of catechin monomers but also by the absorption of microbial phenolic acid metabolites.

Health effect of vegetable-based diet: lettuce consumption improves cholesterol metabolism and antioxidant status in the rat.

BACKGROUND & AIMS: It is often assumed that fruits and vegetables contribute to protect against degenerative pathologies such as cardiovascular diseases. Besides epidemiological observations, scientific evidences for their mechanism of action are scarce. In the present study, we investigated the mean term and post-prandial effects of lettuce ingestion on lipid metabolism and antioxidant protection in the rat. RESULTS: Feeding rats a 20% lettuce diet for 3 weeks resulted in a decrease cholesterol LDL/HDL ratio and a marked decrease of liver cholesterol levels (-41%). Concurrently, fecal total steroid excretion increased (+44%) and apparent absorption of dietary cholesterol was significantly depressed (-37%) by the lettuce diet. Lettuce diet also displayed an improvement of vitamin E/TG ratio in plasma and limited lipid peroxidation in heart as evidenced by TBARS. In post-prandial experiment, lettuce intake significantly increased both ascorbic acid and alpha-tocopherol plasma levels which contribute to improve plasma antioxidant capacity within 2 h of consumption. Other lipid-soluble antioxidants (lutein and vitamin E) may also improve the plasma antioxidant capacity. CONCLUSION: Lettuce consumption increases the total cholesterol end-products excretion and improves antioxidant status due to the richness in antioxidants (vitamins C, E and carotenoids). In our model, lettuce clearly shows a beneficial effect on lipid metabolism and on tissue oxidation. Therefore regular consumption of lettuce should contribute to improve protection against cardiovascular diseases.

Novel liquid chromatography-electrospray ionization mass spectrometry method for the quantification in human urine of microbial aromatic acid metabolites derived from dietary polyphenols.

An HPLC-ESI-MS-MS method was developed to quantify in human urine fourteen aromatic acids known as metabolites of dietary polyphenols. These metabolites were determined simultaneously in a single 20-min chromatographic analysis with multiple reaction monitoring detection. The inter- and intra-day precisions, calculated from quality control samples were 8.8 and 5.3%, respectively, and the mean accuracy was 2.3%. The method was tested on urine samples collected from one healthy volunteer who consumed a polyphenol-rich diet for 3 days. Increased levels of several aromatic acid metabolites were observed, demonstrating that the method can be used to detect changes in the excretion of microbial metabolites induced by the consumption of polyphenol-containing foods in humans.