Metabolic adaptations to HFHS overfeeding: how whole body and tissues postprandial metabolic flexibility adapt in Yucatan mini-pigs.

PURPOSE: In the present study, we aimed to metabolically characterize the postprandial adaptations of the major tissues involved in energy, lipids and amino acids metabolisms in mini-pigs. METHOD: Mini-pigs were fed on high-fat-high-sucrose (HFHS) diet for 2 months and several tissues explored for metabolic analyses. Further, the urine metabolome was followed over the time to picture the metabolic adaptations occurring at the whole body level following overfeeding. RESULTS: After 2 months of HFHS consumption, mini-pigs displayed an obese phenotype characterized by high circulating insulin, triglycerides and cholesterol levels. At the tissue level, a general (muscle, adipose tissue, intestine) reduction in the capacity to phosphorylate glucose was observed. This was also supported by the enhanced hepatic gluconeogenesis potential, despite the concomitant normoglycaemia, suggesting that the high circulating insulin levels would be enough to maintain glucose homoeostasis. The HFHS feeding also resulted in a reduced capacity of two other pathways: the de novo lipogenesis, and the branched-chain amino acids transamination. Finally, the follow-up of the urine metabolome over the time allowed determining breaking points in the metabolic trajectory of the animals. CONCLUSIONS: Several features confirmed the pertinence of the animal model, including increased body weight, adiposity and porcine obesity index. At the metabolic level, we observed a perturbed glucose and amino acid metabolism, known to be related to the onset of the obesity. The urine metabolome analyses revealed several metabolic pathways potentially involved in the obesity onset, including TCA (citrate, pantothenic acid), amino acids catabolism (cysteine, threonine, leucine).

Iron absorption in dysmetabolic iron overload syndrome is decreased and correlates with increased plasma hepcidin.

BACKGROUND/AIMS: The dysmetabolic iron overload syndrome (DIOS) is a common disorder but its origin remains unclear. METHODS: A case-control study was conducted to compare intestinal absorption of iron in 16 men with DIOS (age 53 +/- 11 years, serum ferritin 750 +/- 372 microg/l, hepatic iron 78 +/- 25 micromol/g) and in 32 age-matched controls with normal body iron stores (16 overweight subjects and 16 lean subjects). Intestinal absorption was calculated as the area under the curve (AUC) of 58Fe administered orally and correlated with plasma hepcidin and with insulin resistance parameters including HOMA. RESULTS: Intestinal iron absorption was lower in DIOS (AUC = 22.4 +/- 15.9 microg/l/h) compared to both overweight controls (AUC = 40.5 +/- 29.4 microg/l/h, p=0.04) and to lean controls (AUC = 102.5 +/- 113.5 microg/l/h, p < 0.01). There was an inverse correlation between intestinal iron absorption and plasma hepcidin (r = -0.61, p < 0.001), HOMA (r = -0.35, p = 0.01) and C reactive protein (r = -0.52, p < 0.001). CONCLUSIONS: In overweight subjects with normal iron stores, iron absorption is decreased through hepcidin upregulation. In patients with DIOS, this decrease is more pronounced due to an additional effect of iron excess on circulating hepcidin levels.

Digestive stability of xanthophylls exceeds that of carotenes as studied in a dynamic in vitro gastrointestinal system.

Epidemiological studies have suggested that high consumption of tomato products is associated with a lower risk for chronic diseases. To exert their health effect, the phytochemicals of tomatoes have to be bioavailable and therefore it implies their stability through the digestion process. Here, we assessed the digestive stability of the red-pigmented lycopene and other carotenoids brought in nutritional quantity within different food matrixes, using the TNO gastrointestinal tract model (TIM). This multicompartmental dynamic system accurately reproduces the main parameters of gastric and small intestinal digestion in human. In vitro digestions of a standard meal containing red tomato (RT), yellow tomato (devoid of lycopene), or lycopene beadlets were performed. Zeaxanthin and lutein were stable throughout artificial digestions, whereas beta-carotene and all-trans lycopene were degraded (approximately 30 and 20% loss at the end of digestion, respectively) in the jejunal and ileal compartments. The recovery of beta-carotene in the digesta of the RT meal was significantly lower than that in the yellow one, showing a food matrix effect. In the same way, until 180 min of digestion, the recovery percentages of all-trans lycopene from RT were significantly lower than those issued from the supplement. Isomeric conformation also influenced the stability of carotenoids, 5-cis lycopene being the most stable isomer followed by all-trans and 9-cis. No trans-cis isomerization of lycopene occurred in the TIM. By using a relevant dynamic in vitro system, this study allowed us to gain further insight into the parameters influencing the digestive stability of carotenoids, and therefore their bioavailability, in humans.

The effect of aging on intestinal absorption and status of calcium, magnesium, zinc, and copper in rats: a stable isotope study.

Many investigators have reported changes in mineral status with age but conflicting observations were done concerning mineral absorption. This study was conducted to clarify the effect of aging on intestinal absorption and status of minerals, using a stable isotope approach. To do so, 40 rats of different ages: 9, 22, 44, and 88 weeks were fed with a semi-purified diet for a total of 30 days. At the beginning of the 4th week, the rats received a stable isotope solution containing (44)Ca, (25)Mg, (67)Zn, and (65)Cu. Individual feces and urine were then collected during 4 consecutive days in order to measure stable isotopes by inductively coupled plasma/mass spectrometry (ICP/MS) and blood and tissues were sampled for mineral status determination. Intestinal absorption of (44)Ca and (67)Zn considerably decreased with age, whereas intestinal (25)Mg absorption decreased only moderately and intestinal (65)Cu absorption was unaffected. Plasma and bone calcium (Ca) were not modified with age whereas urinary Ca excretion considerably increased. Plasma and erythrocyte magnesium (Mg) levels were unaffected with age whereas urinary Mg excretion and Mg bone level decreased. Plasma zinc (Zn) level decreased and bone Zn level increased with age whereas red blood cell and liver Zn level and urinary Zn excretion remained unchanged. Plasma Cu level increased with age whereas liver and bone Cu levels and urinary Cu excretion remained unchanged. These results show that the effect of aging on the intestinal mineral absorption and status differ largely according to the mineral considered. Further studies are required under different nutritional conditions to explore the underlying mechanisms during aging and to adjust a better nutrition of the elderly.

Long-term moderate zinc supplementation increases exchangeable zinc pool masses in late-middle-aged men: the Zenith Study.

BACKGROUND: Zinc supplementation may be beneficial for health. Assessing exchangeable zinc pools may be a useful approach to evaluate zinc status. OBJECTIVE: We evaluated the effects of long-term supplementation with 2 moderate doses of zinc on the mass of exchangeable zinc pools. DESIGN: Three groups of healthy, late-middle-aged men (n = 16 per group) participated in a stable-isotope zinc kinetic study after 6 mo of daily supplementation with 0 (placebo), 15, or 30 mg Zn. At the end of the supplementation period, each subject received an intravenous injection of 0.89 mg (70)Zn, and the plasma zinc disappearance curve was monitored for the next 10 d. Two approaches were used to determine the characteristics of the exchangeable zinc pools: 1) formal 3-compartmental modeling and 2) a simplified determination of the total mass of the rapidly exchangeable zinc pool (EZP). RESULTS: In the placebo group, the exchangeable zinc pool masses for the 3 considered pools were as follows: 2.15, 12.7, and 100.5 mg Zn. The rapidly exchangeable zinc pool mass in the placebo group was 143 mg Zn. Zinc supplementation significantly increased the exchangeable zinc pool masses regardless of the approach used to determine these pools. In addition, these data confirm that exchangeable zinc pool masses correlate positively with total zinc intake and negatively with subject age and do not correlate with plasma zinc concentrations. CONCLUSION: Our data show that long-term supplementation with 2 moderate doses of zinc is an efficient way to increase exchangeable zinc pool masses in late-middle-aged men.

Evaluation of magnesium fluxes in rat erythrocytes using a stable isotope of magnesium.

The mechanisms that maintain intracellular Mg concentration at physiologic levels are not fully understood. In this work, we described for the first time, a new method using 25Mg stable isotopes, that allows simultaneous determination of Mg2+ efflux and Mg2+ influx in non-loaded cells at physiological levels of extracellular Mg. Erythrocytes from rats were suspended as a 10% suspension in NaCl medium or choline medium. The erythrocyte suspension was incubated at 37C, and aliquots of the cell suspension were centrifuged at the beginning of the incubation and after 60 and 120 min. The quantification of 24Mg, 25Mg and 26Mg in supernatants and in erythrocytes were determined by ICP/MS. Simultaneous Mg2+ efflux and Mg2+ influx were calculated from the intra-extracellular distribution of the three isotopes. By this new approach we characterized Mg2+ influx and Mg2+ efflux at 0.4 mM extracellular Mg in both NaCl and choline Cl medium. Mg2+ efflux and Mg2+ influx were largely inhibited by amiloride in NaCl medium and by cinchonine in choline Cl medium. Apparent velocity and LineWeaver-Burk kinetics showed that Mg2+ influx is different from Mg2+ efflux suggesting the involvement of two distinct transport mechanisms. Moreover, modifying extracellular Mg concentrations, to mimic hypo- or hyper-magnesaemia, we showed that Mg2+ efflux and Mg2+ influx increased with extracellular Mg up to 0.8 mM, the physiologic concentration of total extracellular Mg. Our data demonstrate that Mg2+ fluxes are directly related to the levels of extracellular Mg and that in physiological conditions, Na-dependent and Na-independent Mg2+ efflux counterbalance Mg influx to maintain constant intracellular Mg level.

Lycopene but not lutein nor zeaxanthin decreases in serum and lipoproteins in age-related macular degeneration patients.

BACKGROUND: Epidemiological studies have established that a low serum concentration of carotenoids was associated with risk of Age-Related Macular Degeneration (ARMD). The aim of this study was to determine carotenoid levels in serum and in different lipoprotein fractions in patients diagnosed for ARMD and in matched control group. METHOD: Thirty-four ARMD patients and 21 control subjects from Brest area (France) have been included to this study. Lipoproteins have been separated from serum by gradient density ultracentrifugation. We measured concentration of carotenoids and tocopherols in serum and in different lipoprotein fractions by HPLC. RESULTS: No difference was observed between ARMD patients and control subjects in total serum carotenoids. Individual carotenoid levels showed that only lycopene was decreased significantly in serum, LDL and HDL fractions in patients (P<0.05). Concentrations in serum and lipoparticle fractions of lutein and zeaxanthin, the major pigments present in macula were not modified between both groups. CONCLUSIONS: Lycopene, as liposoluble antioxidant nutrient, is the only carotenoid altered in ARMD patients. It cannot be excluded that this effect is related to different dietary habits, but we hypothesise that lower lycopene status could result also from specific antioxidant protection of lutein and zeaxanthin by lycopene.

Dietary inulin intake and age can significantly affect intestinal absorption of calcium and magnesium in rats: a stable isotope approach.

BACKGROUND: previous studies have shown that non-digestible inulin-type fructan intake can increase intestinal mineral absorption in both humans and animals. However, this stimulatory effect on intestinal absorption may depend on experimental conditions such as duration of fermentable fiber intake, mineral diet levels and animals' physiological status, in particular their age. OBJECTIVES: the aim of this study was to determine the effect of inulin intake on Ca and Mg absorption in rats at different age stages. METHODS: eighty male Wistar rats of four different ages (2, 5, 10 and 20 months) were randomized into either a control group or a group receiving 3.75% inulin in their diet for 4 days and then 7.5% inulin for three weeks. The animals were fed fresh food and water ad libitum for the duration of the experiment. Intestinal absorption of Ca and Mg was determined by fecal monitoring using stable isotopic tracers. Ca and Mg status was also assessed. RESULTS: absorption of Ca and Mg was significantly lower in the aged rats (10 and 20 mo) than in the young and adult rat groups. As expected, inulin intake increased Ca and Mg absorption in all four rat groups. However, inulin had a numerically greater effect on Ca absorption in aged rats than in younger rats whereas its effect on Mg absorption remained similar across all four rat age groups. CONCLUSION: the extent of the stimulatory effect of inulin on absorption of Ca may differ according to animal ages. Further studies are required to explore this effect over longer inulin intake periods, and to confirm these results in humans.

Stable isotopes in studies of intestinal absorption, exchangeable pools and mineral status: the example of magnesium.

Magnesium (Mg) is a biologically essential mineral and Mg deficiency is known to lead to severe biochemical and symptomatic disorders. Radioactive isotopes and, more recently, stable isotopes have been used as research tools to determine intestinal Mg absorption in humans and animals under different nutritional and physiological conditions. Mg isotopes are given orally or orally plus intravenously and analysed in faeces and/or in plasma and urine in order to calculate intestinal Mg absorption and possibly endogenous Mg excretion. Mg isotopes have been used to assess exchangeable pools of Mg under nutritional and physiopathological conditions. Mg isotopes are given intravenously and are analysed in plasma and urine to calculate the size and half-life of the various Mg exchangeable pools. More recently, in vitro isotopic tests have been developed to study the need of cells for Mg in different nutritional and genetic conditions. Whole blood is incubated with Mg isotopes and isotopic blood cell enrichment is measured, which reflects the avidity of cells for Mg and thus its initial status. This paper is a report on the use of stable Mg isotopes and their advantages in these different fields of Mg absorption and metabolism. The studies available have clearly demonstrated that stable isotopes provide a useful research tool for determining intestinal Mg absorption, and represent a precious research tool for the study of Mg metabolism and the assessment of Mg status.

Differential effects of lycopene consumed in tomato paste and lycopene in the form of a purified extract on target genes of cancer prostatic cells.

BACKGROUND: Prospective studies indicate that tomato consumers are protected against prostate cancer. Lycopene has been hypothesized to be responsible for tomato health benefits. OBJECTIVE: Our aim was to differentiate the effects of tomato matrix from those of lycopene by using lycopene-rich red tomatoes, lycopene-free yellow tomatoes, and purified lycopene. DESIGN: Thirty healthy men (aged 50-70 y old) were randomly assigned to 2 groups after a 2-wk washout period. In a crossover design, each group consumed yellow and red tomato paste (200 g/d, which provided 0 and 16 mg lycopene, respectively) as part of their regular diet for 1 wk separated by 2 wk of washout. Then, in a parallel design, the first group underwent supplementation with purified lycopene (16 mg/d) for 1 wk, whereas the second group received a placebo. Sera collected before and after the interventions were incubated with lymph node cancer prostate cells to measure the expression of 45 target genes. RESULTS: Circulating lycopene concentration increased only after consumption of red tomato paste and purified lycopene. Lipid profile, antioxidant status, prostate-specific antigen, and insulin-like growth factor I were not modified by consumption of tomato pastes and lycopene. We observed significant up-regulation of IGFBP-3 and Bax:Bcl-2 ratio and down-regulation of cyclin-D1, p53, and Nrf-2 after cell incubation with sera from men who consumed red tomato paste when compared with sera collected after the first washout period, with intermediate values for yellow tomato paste consumption. Cell incubation with sera from men who consumed purified lycopene led to significant up-regulation of IGFBP-3, c-fos, and uPAR compared with sera collected after placebo consumption. CONCLUSION: Dietary lycopene can affect gene expression whether or not it is included in its food matrix. This trial was registered by the French Health Ministry at http://www.sante-sports.gouv.fr as 2006-A00396-45.

Comparison of lycopene and tomato effects on biomarkers of oxidative stress in vitamin E deficient rats.

BACKGROUND: Cohort studies suggested that individuals with higher intake of tomatoes and tomato products have a lower risk of degenerative diseases. Lycopene, an antioxidant and antiproliferative carotenoid, has been hypothesized to be responsible for the health benefits of tomatoes. However, studies demonstrated a higher potential of tomatoes compared to lycopene to reduce oxidative stress or carcinogenesis. AIM OF THE STUDY: Our study aimed at distinguishing lycopene effect from that of tomato on oxidative stress, by using yellow tomato, a tomato variety devoid of lycopene. METHODS: Effects of feeding with none (control), 16% freeze-dried yellow tomato (YT), 16% freeze-dried red tomato (RT) or 0.05% lycopene beadlets (LB) were compared in a rat model with mild oxidative stress induced by low vitamin E diet (LVED). Four groups of 10 rats were fed ad libitum for 6 weeks. Physiological parameters such as ingesta, body, spleen and liver weights, cholesterol and triglycerides (TG) levels were assessed. Lycopene and vitamin E concentrations and oxidative stress biomarkers were measured in the plasma and/or liver and/or heart tissue of the rats. RESULTS: RT, YT, and LB had no effect on rats' ingesta, body and spleen weights. RT, YT and LB had no effect on plasma cholesterol concentration. RT decreased TG level compared to control, YT and LB (P < 0.05). Rats fed RT or LB accumulated lycopene in plasma in contrast with rats fed YT. Heart level of thiobarbituric reactive species (TBARS) in rats fed RT or YT was lower than that in the control and the LB fed rats (P < 0.05). Despite similar concentrations of lycopene in plasma and liver, rats fed LB showed a significantly higher heart level of TBARS than rats fed tomatoes. RT increased erythrocyte superoxide dismutase (eSOD) activity compared with LB and nitric oxide (NO) level compared with control and LB. LB decreased ferric reducing ability of plasma (FRAP) level compared with control, RT and LB (P < 0.05). CONCLUSION: Our study showed for the first time that tomatoes, containing or not containing lycopene, have a higher potential than lycopene to attenuate and or to reverse oxidative stress-related parameters in a mild oxidative stress context.