Are saturated fat really nasty?

Cette synthèse fait le point sur la relation entre les apports en acides gras saturés et le risque cardio- métabolique. Après un bref rappel biochimique, une petite note historique expose les fondements du dogme de leurs effets délétères. Ils reposent essentiellement sur des études écologiques et sur le lien entre acides gras saturés et élévation du cholestérol circulant. Or les preuves de l’absence de lien entre l’apport en acides gras saturés et le risque cardio-métabolique s’accumulent depuis des années. Nous passons en revue les études prospectives, les études de substitution, les études de prévention primaire et secondaire qui montrent que les acides gras saturés dans leur ensemble n’ont pas d’effet négatif sur ce risque. En revanche, un apport suffisant (mais non excessif) en acides gras polyinsaturés oméga-6 et oméga-3 est souhaitable. Nous évoquons brièvement les effets des acides gras saturés sur différents marqueurs et facteurs du risque cardio-métabolique. Au total il apparaît que c’est bien la source des acides gras saturés qui importe, ce qui pourrait rendre compte de certaines erreurs d’interprétation. Enfin l’équilibre global de tous les acides gras - et donc leur diversité - doit être considéré.This paper analyzes the relationship between the saturated fatty acids intake and the cardio-metabolic risk. After a short biochemical recall, a small historical note exhibits the basis of their deleterious effects. They rely on ecological studies and on the link between saturated fatty acids and high plasma level cholesterol. However the proven data on the lack of the relationship between saturated fatty acids and cardio-metabolic risk are actually numerous. We look at prospective studies, replacement studies, primary and secondary prevention trials, which show that globally saturated fatty acids have no harmful effect on that risk. But a sufficient intake (without excess) in omega-6 and omega-3 polyunsaturated fatty acids is necessary. We describe briefly the effects of the saturated fatty acids on some cardio-metabolic risk factors and markers. The saturated fatty acids food source is a key factor in this respect that could explain some misinterpretation errors: the global balance of all fatty acids must be considered

Nutritional requirements during ageing☆

Ageing is a physiological condition characterized by a decline of the adaptatives capacities and associated to a decrease of the lean mass. That one is due to a decrease of the post-prandial protein synthesis. It is why protein recommended allowances must be sufficient for a quantitative aspect (0.8–1.2 g/kg/d) and adapted for a qualitative point of view. Energy requirements do not decrease with age if the physical activity is unchanged: it is why the carbohydrate and lipid intakes must be similar to those of a younger adult. The quality of the carbohydrate intake and the distribution of the fatty acids are also important in order to avoid any deficiency. Concerning non-energetic nutrients, one must be particularly cautious for the vitamin D and calcium intakes. Behind nutrients there are foods and dietary patterns who have their own effects

Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep

Inheritance of the ovulation rate (OR) in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire) were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54) within ewe, with significant variability among ewes. High OR (≥ 4) were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47) and the mean OR varied considerably between families (from 1.24 to 1.78). Seven of the 12 BC families presented high-ovulating ewes (at least one record ≥ 4) and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2.2 standard deviations on the underlying scale

WHO draft guidelines on dietary saturated and trans fatty acids: time for a new approach?

The 2018 WHO draft guidelines on dietary saturated fatty acids and trans fatty acids recommend reducing total intake of saturated fat and replacing it with polyunsaturated and monounsaturated fatty acids. The recommendations fail to take into account considerable evidence that the health effects of saturated fat varies depending on the specific fatty acid and on the specific food source. Maintaining general advice to reduce total saturated fatty acids will work against the intentions of the guidelines and weaken their effect on chronic disease incidence and mortality. A food based translation of the recommendations for saturated fat intake would avoid unnecessary reduction or exclusion of foods that are key sources of important nutrients

French Roadmap for complex Systems 2008-2009

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of this roadmap is to foster the coordination of the complex systems community on focused topics and questions, as well as to present contributions and challenges in the complex systems sciences and complexity science to the public, political and industrial spheres

Litter Decomposition as an Indicator of Stream Ecosystem Functioning at Local-to-Continental Scales

RivFunction is a pan-European initiative that started in 2002 and was aimed at esta- blishing a novel functional-based approach to assessing the ecological status of rivers. Litter decomposition was chosen as the focal process because it plays a central role in stream ecosystems and is easy to study in the field. Impacts of two stressors that occur across the continent, nutrient pollution and modified riparian vegetation, were exam- ined at >200 paired sites in nine European ecoregions. In response to the former, decomposition was dramatically slowed at both extremes of a 1000-fold nutrient gra- dient, indicating nutrient limitation in unpolluted sites, highly variable responses across Europe in moderately impacted streams, and inhibition via associated toxic and addi- tional stressors in highly polluted streams. Riparian forest modification by clear cutting or replacement of natural vegetation by plantations (e.g. conifers, eucalyptus) or pasture produced similarly complex responses. Clear effects caused by specific riparian distur- bances were observed in regionally focused studies, but general trends across different types of riparian modifications were not apparent, in part possibly because of important indirect effects. Complementary field and laboratory experiments were undertaken to tease apart the mechanistic drivers of the continental scale field bioassays by addressing the influence of litter, fungal and detritivore diversity. These revealed generally weak and context-dependent effects on decomposition, suggesting high levels of redundancy (and hence potential insurance mechanisms that can mitigate a degree of species loss) within the food web. Reduced species richness consistently increased decomposition variability, if not the absolute rate. Further field studies were aimed at identifying impor- tant sources of this variability (e.g. litter quality, temporal variability) to help constrain ranges of predicted decomposition rates in different field situations. Thus, although many details still need to be resolved, litter decomposition holds considerable potential in some circumstances to capture impairment of stream ecosystem functioning. For instance, species traits associated with the body size and metabolic capacity of the con- sumers were often the main driver at local scales, and these were often translated into important determinants of otherwise apparently contingent effects at larger scales. Key insights gained from conducting continental scale studies included resolving the appar- ent paradox of inconsistent relationships between nutrients and decomposition rates, as the full complex multidimensional picture emerged from the large-scale dataset, of which only seemingly contradictory fragments had been seen previously

Continental-Scale Effects of Nutrient Pollution on Stream Ecosystem Functioning

Excessive nutrient loading is a major threat to aquatic ecosystems worldwide that leads to profound changes in aquatic biodiversity and biogeochemical processes. Systematic quantitative assessment of functional ecosystem measures for river networks is, however, lacking, especially at continental scales. Here, we narrow this gap by means of a pan-European field experiment on a fundamental ecosystem process—leaf-litter breakdown—in 100 streams across a greater than 1000-fold nutrient gradient. Dramatically slowed breakdown at both extremes of the gradient indicated strong nutrient limitation in unaffected systems, potential for strong stimulation in moderately altered systems, and inhibition in highly polluted streams. This large-scale response pattern emphasizes the need to complement established structural approaches (such as water chemistry, hydrogeomorphology, and biological diversity metrics) with functional measures (such as litter-breakdown rate, whole-system metabolism, and nutrient spiraling) for assessing ecosystem health