The Willingness to Modify Portion Sizes or Eat New Protein Foods Largely Depends on the Dietary Pattern of Protein Intake

International audiencePromoting a more balanced animal/plant dietary protein ratio by changing portion sizes or introducing new foods is a promising means to improve diet quality, but little is known about the willingness of individuals to adopt such changes. Our objective was to assess the willingness to adopt dietary changes by these means. In a French cross-sectional study in 2018 (n = 2055), we analyzed the association between the willingness to eat smaller or larger portions or to introduce non-consumed protein foods and the current dietary patterns of individuals and their socio-demographic characteristics. These modifications had previously been identified as improving the nutrient adequacy of diets. Participants were more willing to eat smaller portion sizes than to introduce new foods and to eat larger portion sizes. The willingness for any modification varied depending on the food groups concerned. Participants were also more willing to eat larger portions and less willing to eat smaller portions when they were the most frequent consumers of the foods concerned. Participants were more willing to eat a new food if it was consumed in large quantities by individuals with a similar dietary pattern. This study underlines the importance of accounting for individual food habits when issuing nutritional recommendations

Les signatures isotopiques naturelles des modulations nutritionnelles et physiopathologiques du métabolisme protéique et énergétique

Conférence invitée pour la journée d'animation scientifique du CRNH Auvergne, Clermont-Ferrand (France

Modélisation multi-compartimentale, dynamique, mécaniste et intégrative, des différents flux métaboliques azotés intra- et inter-organes dans l'organisme, et de leurs modulations

Conférence au Séminaire "Modélisation et Alimentation" du métaprogramme DID'IT de l'INRA, Paris, France

Diet-animal fractionation of nitrogen stable isotopes reflects the efficiency of nitrogen assimilation in ruminants

The natural abundance of 15N in animal proteins (δ15Nanimal) is greater than that in the diet consumed by the animals (δ15Ndiet), with a discrimination factor (Δ15N = δ15Nanimal- δ15Ndiet) that is known to vary according to nutritional conditions. The objectives of the present study were to test the hypothesis that Δ15N variations depend on the efficiency of nitrogen utilisation (ENU) in growing beef cattle, and to identify some of the physiological mechanisms responsible for this N isotopic fractionation in ruminants. Thus, we performed the regression of the Δ15N of plasma proteins obtained from thirty-five finishing beef cattle fed standard and non-conventional diets against different feed efficiency indices, including ENU. We also performed the regression of the Δ15N of different ruminant N pools (plasma and milk proteins, urine and faeces) against different splanchnic N fluxes obtained from multi-catheterised lactating dairy cows. The Δ15N of plasma proteins was negatively correlated with feed efficiency indices in beef cattle, especially ENU (body protein gain/N intake) and efficiency of metabolisable protein (MP) utilisation (body protein gain/MP intake). Although Δ15N obtained from different N pools in dairy cows were all negatively correlated with ENU, the highest correlation was found when Δ15N was calculated from plasma proteins. Δ15N showed no correlation with urea-N recycling or rumen NH3 absorption, but exhibited a strong correlation with liver urea synthesis and splanchnic amino acid metabolism, which points to a dominant role of splanchnic tissues in the present N isotopic fractionation study

Isotopic and modeling investigation of long-term protein turnover in rat tissues

Poupin N, Huneau J, Mariotti F, Tome D, Bos C, Fouillet H. Isotopic and modeling investigation of long-term protein turnover in rat tissues. Am J Physiol Regul Integr Comp Physiol 304: R218-R231, 2013. First published November 7, 2012; doi:10.1152/ajpregu.00310.2012.-Fractional synthesis rates (FSR) of tissue proteins (P) are usually measured using labeled amino acid (AA) tracer methods over short periods of time under acute, particular conditions. By combining the long-term and non-steady-state N-15 labeling of AA and P tissue fractions with compartmental modeling, we have developed a new isotopic approach to investigate the degree of compartmentation of P turnover in tissues and to estimate long-term FSR values under sustained and averaged nutritional and physiological conditions. We measured the rise-to-plateau kinetics of nitrogen isotopic enrichments (delta N-15) in the AA and P fractions of various tissues in rats for 2 mo following a slight increase in diet delta N-15. Using these delta N-15 kinetics and a numerical method based on a two-compartment model, we determined reliable FSR estimates for tissues in which P turnover is adequately represented by such a simple precursor-product model. This was the case for kidney, liver, plasma, and muscle, where FSR estimates were 103, 101, 58, and 11%/day, respectively. Conversely, we identified tissues, namely, skin and small intestine, where P turnover proved to be too complex to be represented by a simple two-compartment model, evidencing the higher level of subcompartmentation of the P and/or AA metabolism in these tissues. The present results support the value of this new approach in gaining cognitive and practical insights into tissue P turnover and propose new and integrated FSR values over all individual precursor AA and all diurnal variations in P kinetics

Profil de consommation protéique et attitudes vis-à-vis des protéines animales des végétariens, flexitariens et omnivores d’une population représentative française

International audienc

La sensibilité à l'induction de l'obésité et du syndrome métabolique par un régime gras et sucré s'accompagne d'une efficacité protéique accrue dans le foie et diminuée dans le muscle

International audienceIntroduction et but de l’étude : Il existe une forte variabilité interindividuelle de réponse à une alimentation trop grasse etsucrée : chez les individus les moins aptes à gérer cet excès chronique d'énergie, elle favorise le développement d'uneobésité (O) parfois associée à un syndrome métabolique (SM), avec des altérations du métabolisme énergétique maisaussi probablement du métabolisme protéique qui sont encore mal connues. Cette étude visait à mieux identifier lavariabilité de réponse à un régime gras et sucré ainsi que les différences métaboliques entre individus sensibles etrésistants à l'O et au SM, en utilisant des biomarqueurs isotopiques des orientations préférentielles du métabolismeprotéique, les abondances naturelles en 15N (δ15N) des tissus.Matériel et méthodes : 36 rats Wistar mâles, de poids initialement similaires, ont été nourris avec un régime riche enlipides et sucres, suivis pour leurs consommation et gain de poids pendant 4 mois puis euthanasiés pour mesurerparamètres biochimiques, composition corporelle et δ15N des protéines tissulaires par spectrométrie de masse à ratioisotopique. Nous avons discriminé les rats selon leur sensibilité à l'O et au SM par une classification non supervisée(proc cluster sous SAS), sur la base de 2 indicateurs d'O (poids et adiposité viscérale) et de 2 indicateurs de SM (HOMAIRet triglycérides hépatiques). Nous avons calculé le Zscore global d'O et de SM (ZOSM) comme la moyenne des Zscoresde ces 4 indicateurs, puis analysé les corrélations entre ZOSM, efficacités protéiques tissulaires (protéines tissulaires /protéines ingérées) et δ15N tissulaires.Résultats et Analyse statistique : La classification a distingué 3 groupes de rats : résistants à l'O et au SM (R, n=12),sensibles à l'O mais résistants au SM (O, n=12), ou sensibles à l'O et au SM (OSM, n=12). Les rats R, O et SM avaientles caractéristiques suivantes (moyennes ± écart-types, significativement différentes si elles portent des lettresdifférentes) : poids de 542 ± 42a, 620 ± 44b et 670 ± 33c g ; adiposité viscérale de 6,9 ± 0,5a, 8,3 ± 0,3b et 8,6 ± 0,7b % ;HOMA-IR de 7,1 ± 3,4a, 10,0 ± 5,7a et 21,7 ± 7,3b μg·mmol·L-2 ; triglycérides hépatiques de 57 ± 14a, 62 ± 20a et 101 ± 13b μmol·g-1 ; efficacités protéiques de 2,37 ± 0,20a, 2,41 ± 0,31ab et 2,62 ± 0,18b % dans le foie, 0,53 ± 0,08a, 0,49 ± 0,04aet 0,43 ± 0,04b % dans le muscle gastrocnémien, et 0,19 ± 0,02a, 0,17 ± 0,02ab et 0,16 ± 0,02b % dans le muscle tibialis.Le ZOSM était corrélé (P<0,01) positivement à l'efficacité protéique du foie (R=0,54) et négativement à celles des musclesgastrocnémien (R=-0,48) et tibialis (R=-0,45), et négativement au δ15N des protéines du foie (R=-0,47), érythrocytes (R=-0,43) et poils (R=-0,49).Conclusion : Dans ce modèle, la sensibilité à l'O et au SM concerne 2/3 de la population, avec 1/3 en O saine et 1/3 enO avec SM. Chez les individus sensibles, l'efficacité d'utilisation anabolique des protéines alimentaires est plus grandedans le foie mais plus faible dans certains muscles, et la plus grande efficacité anabolique hépatique est liée à unemoindre orientation catabolique des acides aminés dont attestent les plus faibles δ15N du foie et d'autres pools plusaccessibles (érythrocytes, poils).Conflits d’intérêts: Aucun conflit à déclare

Development and evaluation of a new dietary index assessing nutrient security by aggregating probabilistic estimates of the risk of nutrient deficiency in two French adult populations

International audienceAlthough micronutrient deficiencies affect 2 billion people worldwide, no index focuses on measuring the risk of overt nutrient deficiency. We aimed to develop an index that could capture the nutrient dimension of nutritional security, a nutrient security index (named SecDiet), and evaluate its apparent validity. The SecDiet (range: 0–1) is based on the square-weighted average of the probabilities that the intake of twelve critical nutrients exceeds the threshold value associated with a risk of overt deficiency. Using adult populations from a French representative survey (INCA3, n 1774) and a large cohort (NutriNet-Santé, n 104 382), the content and construct validity of the SecDiet was evaluated by estimating associations of the SecDiet with its components and with relevant socio-demographic characteristics. The SecDiet was high in the overall population (0·93 (SD 0·09) in INCA3) and markedly skewed towards 1 (i.e. lower risk of insufficient intake). It correlated positively with its twelve components (r 0·17–0·78, all P < 0·001). The SecDiet was associated with monthly income (P = 0·002), perception of financial situation, professional situation, food insufficiency and security statuses (all P < 0·001) in the INCA3 population and with monthly income, professional situation and level of education (all P < 0·001) in the NutriNet-Santé population. Unlike a broader nutrient-based quality index taken as comparison, the SecDiet mean decreased and the tail of its distribution notably extended downwards in at-risk sub-populations, thus revealing its specific sensitivity. The SecDiet could be used to screen sub-groups or study the determinants of nutrient insecurity in large population surveys

Self-declared attitudes and beliefs regarding protein sources are a good prediction of the degree of transition to a low-meat diet in France

International audienceMeat consumption in Western countries is declining and, while the proportion of strict vegetarians remains low, intermediate diets such as flexitarianism have been developing in recent years. Our objectives were to identify the different levels of transition towards low-meat diets, characterize how these diets differ in terms of food intake, and identify whether attitudes and beliefs can explain these degrees of transition. In a representative survey of the French adult population conducted in 2018 (n = 2055), participants declared whether they followed a particular diet and completed a food frequency questionnaire on 29 food sources of protein and a questionnaire on their attitudes and beliefs regarding protein sources. We identified four dietary types based on these declarative data: vegetarians, flexitarians, pro-flexitarians and omnivores. The theory of planned behavior was used to predict meat intake and intentions to reduce meat intake. The sample contained 2.5% vegetarians, 6.3% flexitarians, 18.2% pro-flexitarians and 72.9% omnivores. The diet groups displayed specific dietary profiles and attitudinal scores. Compared with omnivores, pro-flexitarians consumed less red meat, more vegetables and legumes and were much more in agreement about the environmental impacts of meat. Compared with pro-flexitarians, flexitarians consumed less red meat and processed meat, and agreed much more about the health impacts of meat. Finally, versus flexitarians, vegetarians consumed almost no meat but far more legumes, nuts and seeds, and were much more sensitive to animal welfare issues. Attitudes, social norms and perceived behavioral control (PBC) predicted intentions to reduce meat consumption but attitude was the most important predictor. Intentions and PBC were both predictive of meat consumption. The dietary type related to the level of meat intake could be predicted by self-declared attitudes and beliefs regarding protein sources