Anne Marie Roussel

Five‐Week Intake of Short‐Chain Fructo‐Oligosaccharides Increases Intestinal Absorption and Status of Magnesium in Postmenopausal Women

Fermentable carbohydrates have been shown to be nondigestible by human enzymes in the small intestine but are fermented extensively in the large bowel to short‐chain fatty acids (SCFAs), which can increase mineral absorption. It has been shown that feeding such carbohydrates including short‐chain fructo‐oligosaccharides (sc‐FOSs) increases intestinal magnesium (Mg) absorption in animals, but their beneficial impact on Mg absorption in humans still remains to be established. Therefore, this work aimed to investigate the effect of moderate daily doses of sc‐FOSs (10 g/day) on the intestinal absorption and status of Mg in postmenopausal women without hormone replacement therapy (HRT). Eleven healthy postmenopausal women aged 59 ± 6 years (mean ± SD) received for 5 weeks sc‐FOS or sucrose (placebo) treatments according to a randomized, double‐blind, crossover design separated by a washout period of at least 3 weeks. Subjects ingested 87.5 mg of stable isotope25Mg together with a fecal marker. Subsequently, feces were collected for 5–7 days. An inductively coupled plasma mass spectrometer (ICP/MS) was used for25Mg stable isotope measurements in feces, urine, and blood. Mg levels were assessed also at the beginning and at the end of each treatment in plasma, erythrocytes, and urine. These measurements allowed for the determination of net intestinal Mg absorption and Mg status. The results show that the addition of 10 g sc‐FOS to the diet increased Mg absorption by 12.3%, from 30.2 ± 5.0% (placebo treatment) to 33.9 ± 7.2% (sc‐FOS treatment; mean ± SD; p < 0.02). This increase in intestinal Mg absorption was accompanied by an increase in plasma25Mg level and led to a higher urinary25Mg excretion. This is the first time that such an effect is shown in humans. The overall conclusion of this work is that the ingestion of moderate doses of sc‐FOS did improve intestinal Mg absorption and status in postmenopausal women. Because of the important role of Mg in many cellular functions, such Mg absorption improvement may be particularly interesting when the dietary intake of Mg is limited.

Green tea increases anti-inflammatory tristetraprolin and decreases pro-inflammatory tumor necrosis factor mRNA levels in rats

BackgroundTristetraprolin (TTP/ZFP36) family proteins have anti-inflammatory activity by binding to and destabilizing pro-inflammatory mRNAs such as Tnf mRNA, and represent a potential therapeutic target for inflammation-related diseases. Tea has anti-inflammatory properties but the molecular mechanisms have not been completely elucidated. We hypothesized that TTP and/or its homologues might contribute to the beneficial effects of tea as an anti-inflammatory product.MethodsQuantitative real-time PCR was used to investigate the effects of green tea (0, 1, and 2 g solid extract/kg diet) on the expression of Ttp family genes (Ttp/Tis11/Zfp36, Zfp36l1/Tis11b, Zfp36l2/Tis11d, Zfp36l3), pro-inflammatory genes (Tnf, Csf2/Gm-csf, Ptgs2/Cox2), and Elavl1/Hua/Hur and Vegf genes in liver and muscle of rats fed a high-fructose diet known to induce insulin resistance, oxidative stress, inflammation, and TNF-alpha levels.ResultsTtp and Zfp36l1 mRNAs were the major forms in both liver and skeletal muscle. Ttp, Zfp36l1, and Zfp36l2 mRNA levels were more abundant in the liver than those in the muscle. Csf2/Gm-csf and Zfp36l3 mRNAs were undetectable in both tissues. Tea (1 g solid extract/kg diet) increased Ttp mRNA levels by 50–140% but Tnf mRNA levels decreased by 30% in both tissues, and Ptgs2/Cox2 mRNA levels decreased by 40% in the muscle. Tea (2 g solid extract/kg diet) increased Elavl1/Hua/Hur mRNA levels by 40% in the liver but did not affect any of the other mRNA levels in liver or muscle.ConclusionThese results show that tea can modulate Ttp mRNA levels in animals and suggest that a post-transcriptional mechanism through TTP could partially account for teas anti-inflammatory properties. The results also suggest that drinking adequate amounts of green tea may play a role in the prevention of inflammation-related diseases.

Zinc and insulin sensitivity

Many studies have shown that zinc deficiency could decrease the response to insulin. In genetically diabetic animals, a low zinc status has been observed, contrary to induced diabetic animals. The zinc status of human patients depends on the type of diabetes and the age. Zinc supplementation seems to have beneficial effects on glucose homeostasis. However, the mechanism of insulin resistance secondary to zinc depletion is yet unclear. More studies are therefore necessary to document better zinc metabolism in diabetes mellitus, and the antioxidant activity of zinc on the insulin receptor and the glucose transporter.

Cinnamon increases liver glycogen in an animal model of insulin resistance

The objective of this study was to determine the effects of cinnamon on glycogen synthesis, related gene expression, and protein levels in the muscle and liver using an animal model of insulin resistance, the high-fat/high-fructose (HF/HFr) diet-fed rat. Four groups of 22 male Wistar rats were fed for 12 weeks with (1) HF/HFr diet to induce insulin resistance, (2) HF/HFr diet containing 20 g cinnamon per kilogram of diet, (3) control diet, and (4) control diet containing 20 g cinnamon per kilogram of diet. In the liver, cinnamon added to the HF/HFr diet led to highly significant increases of liver glycogen. There were no significant changes in animals consuming the control diet plus cinnamon. In the liver, cinnamon also counteracted the decreases of the gene expressions due to the consumption of the HF/HFr diet for the insulin receptor, insulin receptor substrates 1 and 2, glucose transporters 1 and 2, and glycogen synthase 1. In muscle, the decreased expressions of these genes by the HF/HFr diet and glucose transporter 4 were also reversed by cinnamon. In addition, the overexpression of glycogen synthase 3β messenger RNA levels and protein observed in the muscle of HF/HFr fed rats was decreased in animals consuming cinnamon. These data demonstrate that, in insulin-resistant rats, cinnamon improves insulin sensitivity and enhances liver glycogen via regulating insulin signaling and glycogen synthesis. Changes due to cinnamon in control animals with normal insulin sensitivity were not significant.

Influence of Short-Chain Fructo-Oligosaccharides (sc-FOS) on Absorption of Cu, Zn, and Se in Healthy Postmenopausal Women

Objective: This study was carried out to evaluate the effect of short-chain fructooligosaccharides (sc-FOS) on the absorption of Cu, Zn, and Se among postmenopausal women who are potential candidates to subclinical trace element deficiencies. Design: A randomized double blind cross-over study. Setting: This study was carried out at the Human Nutrition Research Center, Clermont-Ferrand, France. Subjects: 11 postmenopausal women aged 53–70 y, not taking hormone replacement therapy were enrolled and completed the study. Interventions: Diets with 10 g/day sc-FOS or placebo were given for 5 weeks each in random order followed by a wash-out period of at least 3 weeks. At the end of each period, stable isotopes (3.19 mg 67Zn as ZnCl2, 2.06 mg 65Cu as CuCl2 and 52.3 μg 74Se as sodium selenite) and radiopaque pellets (as fecal excretion index) were administered during lunch. Stools were collected for the next 5–7 days. Isotopes were determined by ICP-MS (Cu and Zn) or GC-MS (Se). Results: Copper absorption was significantly enhanced (p = 0.042) by sc-FOS. No effect of sc-FOS was observed on Zn, and Se absorption. Conclusion: To our knowledge, this is the first study on the influence of sc-FOS on trace element metabolism. The observed increase in copper absorption may be of interest regarding daily copper requirements in menopausal women. However, the relevance of this observation remains to be established.

Age- and sex-dependent effects of long-term zinc supplementation on essential trace element status and lipid metabolism in European subjects: the Zenith Study.

Given the key role of Zn in many physiological functions, optimal Zn status could be a predictive parameter of successful ageing. However, the benefit of Zn supplementation is still a matter of debate since Zn supplementation has been reported to be associated with the alteration of Cu status and lipid metabolism. As part of the Zenith Project, the present study aimed to investigate, in free-living healthy European middle-aged and older subjects, the effect of Zn supplementation on the biochemical status of Zn, Fe and Cu and on lipid profile. Volunteers aged 55-70 (n 188) and 70-85 (n 199) years old participated in a double-blinded, randomised study and received a daily placebo, or Zn as 15 or 30 mg for 6 months. Zn supplementation did not significantly modify erythrocyte Zn levels or erythrocyte Cu,Zn-superoxide dismutase activity. But Zn supplementation at 15 or 30 mg/d for 6 months increased significantly serum Zn levels and Zn urinary excretion with no major adverse effects on Fe and Cu status or on lipid metabolism. However, Zn supplementation at 30 mg/d showed some age- and sex-dependent alterations in Fe status or lipid profile. Therefore, with respect to the key role of an optimal Zn status in successful ageing, Zn supplementation at 15 mg/d, when necessary, could be safely proposed regarding lipids and the risk of interaction with Fe and Cu.

Selenium and antioxidant vitamin and lipidoperoxidation levels in preaging French population

Selenium (Se) and antioxidant vitamins might play an important role in the etiology of free radical-related diseases and aging. In the Édude de vieillissement artériel (EVA) study, we have determined the plasma thiobarbituric acid reacting substances (TBARS) as an indicator of free radical-induced lipid peroxidation, plasma selenium and carotenoids, and erythrocyte vitamin E levels in 1389 subjects aged 59–71 years. We also looked for an association between these parameters and cardiovascular risk factors in early elderly. The results show that plasma TBARS were significantly increased in elderly in comparison with values reported in younger adults. However, plasma Se and carotenoids as well as erythrocyte vitamin E in elderly people are close to those reported in adult people. If plasma Se showed no difference between men and women, the three other parameters were significantly higher in women than in men. With regard with cardiovascular risk factors, plasma TBARS were highly positively correlated with total and low-density lipoprotein (LDL) cholesterol in men and women. Plasma carotenoids were also positively correlated with plasma total cholesterol and LDL cholesterol in both sexes. Finally, plasma TBARS were highly correlated with smoking and alcohol consumption. In conclusion, this part of the EVA study shows that some cardiovascular risk factors, like smoking and cholesterol level, are associated with high free radical-induced TBARS levels in the preaging population, although plasma Se and carotenoids as well as erythrocyte vitamin E levels in elderly people were close to those reported in adult younger people.

Hydroxyl radical formation and lipid peroxidation enhancement by chromium. In vitro study.

Chromium VI compounds have been shown to be carcinogenic in occupationally exposed humans, and to be genotoxic, mutagenic, and carcinogenic in a variety of experimental systems. In contrast, most chromium III compounds are relatively nontoxic, noncarcinogenic, and nonmutagenic. Reduction of Cr6+ leads to reactive intermediates, such as Cr5+, Cr4+, or other radical species. The molecular mechanism for the intracellular Cr6+ reduction has been the focus of recent studies, but the details are still not understood.Our study was initiated to compare the effect of Cr6+-hydroxyl radical formation and Cr6+-induced lipid peroxidation vs those of Cr3+. Electron spin responance measurements provide evidence for the formation of long-lived Cr5+ intermediates in the reduction of Cr6+ by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr6+. Hydrogen peroxide suppresses Cr5+ and enhances the formation of hydroxyl radical. Thus, Cr5+ intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction.Comparative effects of Cr6+ and Cr3+ on the development of lipid peroxidation were studied by using rat heart homogenate. Heart homogenate was incubated with different concentrations of Cr6+ compounds at 22°C for 60 min. Lipid peroxidation was determined as thiobarbituric acid reacting materiels (TBA-RM). The results confirm that Cr6+ induces lipid peroxidation in the rat heart homogenate. These observations might suggest a possible causative role of lipid peroxidation in Cr6+ toxicity. This enhancement of lipid peroxidation is modified by the addition of some metal chelators and antioxidants. Thus, strategies for combating Cr6+ toxicity should take into account the role of the hydroxy radicals, and hence, steps for blocking its chain propagation and preventing the formation of lipid peroxides.

ANTIOXIDANT SYSTEMS IN NORMAL AND PREECLAMPTIC ALGERIAN PREGNANT WOMEN

Preeclampsia affects 5 to 7% of all pregnancies and is one of the most common, yet least understood, disorder of pregnancy. It is also a leading cause of maternal and perinatal mortality worldwide. Damage from free radicals has been implicated in preeclampsia. This study was undertaken to investigate the relationship between the oxidative stress linked to preeclampsia and the possible antioxidant status modifications. We measured plasma thiobarbituric acid reactant (TBARs), Zn, Se, Vit A, E, and Beta-Carotenes and CuZnSOD, SeGPx erythrocytes, in 2 groups of pregnant Algerian women [40 preeclamptic = 27 moderate and 17 severe preeclampsia] compared to 40 normal pregnant women, We observed an increased in plasma TBARs which was significantly higher in women with preeclampsia [3.51 ± 0.45 vs 2.97. ± 0.38 μmol/l], but there were no significant differences into the preeclamptic group [3.55 ± 0.49 vs 3.42 ± 0.37μmol/l]. When adjusting to cholesterol, the peroxidation remained significantly increased [TBARs/Cholesterol ratio: 1.41 t 0.35 vs 1,18 t 0.26pmoi/I]. The plasma cholesterol was unchanged in the two groups [2.59 t 0.52 vs 2.59 ± 0.43 g/I]. Plasma triglycerides were higher in women with preeclampsia (3.33 t 1.00 vs 2.70 t 0.84gl1], especially in the severe prec1omposia [3.14 ± 1,06 vs 3,71± 0.793 We observed no difference in status concerning antioxidant [Zn, Se, Vit A, E. and Beta-Carotones] or in enzymatic antioxidants (CuZnSOD, SeGPX).

Is Zinc Essential to Modulate Insulin Sensitivity

Non insulin dependant diabetes mellitus (NIDDM) is a public health problem because of its growing prevalence in most of the countries and its subsequent complications. Prevalence of diabetes in developed countries is estimated to be 2–3%. Diabetic complications are a heterogeneous group of clinical disorders affecting microvascular (retina, kidney and peripheral nerves) and macrovascular system. Diabetic retinopathy is a leading cause of blindness in active population of developed countries. Epidemiological data suggest a strong relationship between the level of glycemia and the incidence and progression of the vascular diseases in individuals with insulin-dependent diabetes mellitus (IDDM) and NIDDM. The purpose of this review is to consider whether an essential trace element as zinc plays a role in the modulation of insulin activity. Actually, through the description of syndrome X, it is known that insulin resistance per se is correlated to vascular complications (Reaven et al., 1988). Therefore the importance of zinc in prediabetic states must be taken into account regarding its potential capacity to protect vascular tissues.