A mixture of milk and vegetable lipids in infant formula changes gut digestion, mucosal immunity and microbiota composition in neonatal piglets.

PURPOSE: Although composition of infant formula has been significantly improved during the last decade, major differences with the composition and structure of breast milk still remain and might affect nutrient digestion and gut biology. We hypothesized that the incorporation of dairy fat in infant formulas could modify their physiological impacts by making their composition closer to that of human milk. The effect of milk fat and milk fat globule membrane (MFGM) fragments in infant formulas on gut digestion, mucosal immunity and microbiota composition was evaluated. METHODS: Three formulas containing either (1) vegetable lipids stabilized only by proteins (V-P), (2) vegetable lipids stabilized by a mixture of proteins and MFGM fragments (V-M) and (3) a mixture of milk and vegetable lipids stabilized by a mixture of proteins and MFGM fragments (M-M) were automatically distributed to 42 newborn piglets until slaughter at postnatal day (PND) 7 or 28, and compared to a fourth group of sow's suckling piglets (SM) used as a breast-fed reference. RESULTS: At both PND, casein and ß-lactoglobulin digestion was reduced in M-M proximal jejunum and ileum contents compared to V-P and V-M ones leading to more numerous ß-Cn peptides in M-M contents. The IFNγ cytokine secretion of ConA-stimulated MLN cells from M-M piglets tended to be higher than in V-P ones at PND 7 and PND 28 and was closer to that of SM piglets. No dietary treatment effect was observed on IL-10 MLN cell secretion. Changes in faecal microbiota in M-M piglets resulted in an increase in Proteobacteria and Bacteroidetes and a decrease in Firmicutes phyla compared to V-P ones. M-M piglets showed higher abundances of Parabacteroides, Escherichia/Shigella and Klebsiella genus. CONCLUSIONS: The incorporation of both milk fat and MFGM fragments in infant formula modifies protein digestion, the dynamic of the immune system maturation and the faecal microbiota composition.

Fast digestive, leucine-rich, soluble milk proteins improve muscle protein anabolism, and mitochondrial function in undernourished old rats.

SCOPE: One strategy to manage malnutrition in older patients is to increase protein and energy intake. Here, we evaluate the influence of protein quality during refeeding on improvement in muscle protein and energy metabolism. METHODS AND RESULTS: Twenty-month-old male rats (n = 40) were fed 50% of their spontaneous intake for 12 weeks to induce malnutrition, then refed ad libitum with a standard diet enriched with casein or soluble milk proteins (22%) for 4 weeks. A 13C-valine was infused to measure muscle protein synthesis and expression of MuRF1, and MAFbx was measured to evaluate muscle proteolysis. mTOR pathway activation and mitochondrial function were assessed in muscle. Malnutrition was associated with a decrease in body weight, fat mass, and lean mass, particularly muscle mass. Malnutrition decreased muscle mTOR pathway activation and protein FSR associated with increased MuRF1 mRNA levels, and decreased mitochondrial function. The refeeding period partially restored fat mass and lean mass. Unlike the casein diet, the soluble milk protein diet improved muscle protein metabolism and mitochondrial function in old malnourished rats. CONCLUSIONS: These results suggest that providing better-quality proteins during refeeding may improve efficacy of renutrition in malnourished older patients.

Soluble Milk Protein Supplementation with Moderate Physical Activity Improves Locomotion Function in Aging Rats.

Aging is associated with a loss of muscle mass and functional capacity. Present study was designed to compare the impact of specific dairy proteins on muscular function with or without a low-intensity physical activity program on a treadmill in an aged rat model. We investigated the effects of nutritional supplementation, five days a week over a 2-month period with a slow digestible protein, casein or fast digestible proteins, whey or soluble milk protein, on strength and locomotor parameters in sedentary or active aged Wistar RjHan rats (17-19 months of age). An extensive gait analysis was performed before and after protein supplementation. After two months of protein administration and activity program, muscle force was evaluated using a grip test, spontaneous activity using an open-field and muscular mass by specific muscle sampling. When aged rats were supplemented with proteins without exercise, only minor effects of different diets on muscle mass and locomotion were observed: higher muscle mass in the casein group and improvement of stride frequencies with soluble milk protein. By contrast, supplementation with soluble milk protein just after physical activity was more effective at improving overall skeletal muscle function in old rats compared to casein. For active old rats supplemented with soluble milk protein, an increase in locomotor activity in the open field and an enhancement of static and dynamic gait parameters compared to active groups supplemented with casein or whey were observed without any differences in muscle mass and forelimb strength. These results suggest that consumption of soluble milk protein as a bolus immediately after a low intensity physical activity may be a suitable nutritional intervention to prevent decline in locomotion in aged rats and strengthen the interest to analyze the longitudinal aspect of locomotion in aged rodents.

Fast-digestive protein supplement for ten days overcomes muscle anabolic resistance in healthy elderly men.

BACKGROUND/OBJECTIVE: Adequate protein intake is crucial to maintain muscle protein content in elderly subjects, but quality of dietary proteins should be considered. The aim was to determine whether soluble milk protein offers an original strategy to increase muscle anabolism in elderly subjects via a synergistic effect of fast-digesting proteins together with a unique essential AA content. DESIGN: We investigated the effect of a 10-day adequate-protein (AP) or high-protein (HP) diet together with the protein source as caseins (CAS) or soluble milk proteins (PRO) on specific muscle protein fractional synthesis rates (FSRs) in healthy elderly men (71.8 ± 2.4 yr, n = 31). The isotopic study consisted of two periods of 4 h each: a post-absorptive and a postprandial period. The fed state was defined by consumption of either 15 g or 30 g of PRO or CAS, given fractionally every 20 min for 4 h. Soluble milk proteins are produced using a membrane process directly from pasteurized milk. MEASUREMENTS: Specific muscle protein FSRs were measured during both postabsorptive and postprandial period using a continuous infusion of l-[1-(13)C]leucine. RESULTS: FSR of sarcoplasmic muscle proteins and actin did not increase significantly in the postprandial state compared to postabsorptive state, whereas myosin FSR rate was increased by feeding whatever the protein source in HP groups (0.024 ± 0.005 vs 0.053 ± 0.011% h(-1), P < 0.05 and 0.026 ± 0.004 vs 0.050 ± 0.005% h(-1), P < 0.004 for PRO HP and CAS HP) but only with the PRO meal in the AP groups (0.031 ± 0.003 vs 0.062 ± 0.009% h(-1), P < 0.03 for PRO AP). Mitochondrial muscle protein FSR was also increased by feeding, irrespective of the protein quantity, but only in PRO meal groups (P < 0.02). CONCLUSION: Fast-digesting soluble milk proteins improved postprandial muscle protein synthesis, especially mitochondrial muscle proteins and myosin fractional synthesis rates, in elderly subjects.

Milk-soluble formula increases food intake and reduces Il6 expression in elderly rat hypothalami.

Malnutrition in the elderly is accompanied by several metabolic dysfunctions, especially alterations in energy homeostasis regulation and a loss of insulin responsiveness. Nutritional recommendations aim to enrich food with high protein and energy supplements, and protein composition and lipid quality have been widely studied. Despite the numerous studies that have examined attempts to overcome malnutrition in the elderly through such nutritional supplementation, it is still necessary to study the effects of a combination of protein, lipids, and vitamin D (VitD). This can be done in animal models of elderly malnutrition. In the present study, we investigated the effects of several diet formulae on insulin responsiveness, inflammation, and the hypothalamic expression of key genes that are involved in energy homeostasis control. To mimic elderly malnutrition in humans, elderly Wistar rats were food restricted (R, -50%) for 12 weeks and then refed for 4 weeks with one of four different isocaloric diets: a control diet; a diet where milk soluble protein (MSP) replaced casein; a blend of milk fat, rapeseed, and DHA (MRD); or a full formula (FF) diet that combined MSP and a blend of MRD (FF). All of the refeeding diets contained VitD. We concluded that: (i) food restriction led to the upregulation of insulin receptor in liver and adipose tissue accompanied by increased Tnfα in the hypothalamus; (ii) in all of the refed groups, refeeding led to similar body weight gain during the refeeding period; and (iii) refeeding with MSP and MRD diets induced higher food intake on the fourth week of refeeding, and this increase was associated with reduced hypothalamic interleukin 6 expression.

Four-month course of soluble milk proteins interacts with exercise to improve muscle strength and delay fatigue in elderly participants.

BACKGROUND: The benefit of protein supplementation on the adaptive response of muscle to exercise training in older people is controversial. OBJECTIVE: To investigate the independent and combined effects of a multicomponent exercise program with and without a milk-based nutritional supplement on muscle strength and mass, lower-extremity fatigue, and metabolic markers. DESIGN: A sample of 48 healthy sedentary men aged 60.8 ± 0.4 years were randomly assigned to a 16-week multicomponent exercise training program with a milk-based supplement containing, besides proteins [total milk proteins 4 or 10 g/day or soluble milk proteins rich in leucine (PRO) 10 g/day], carbohydrates and fat. Body composition, muscle mass and strength, and time to task failure, an index of muscle fatigue, were measured. Blood lipid, fibrinogen, creatine phosphokinase, glucose, insulin, C-reactive protein, interleukin-6, tumor necrosis factor-α soluble receptors, and endothelial markers were assessed. RESULTS: Body fat mass was reduced after the 4-month training program in groups receiving 10 g/day of protein supplementation (P < .01). The training program sustained with the daily 10 g/day PRO was associated with a significant increase in dominant fat free mass (+5.4%, P < .01) and in appendicular muscle mass (+4.5%, P < .01). Blood cholesterol was decreased in the trained group receiving 10 g/day PRO. The index of insulin resistance (homeostasis model assessment-insulin resistance) and blood creatine phosphokinase were reduced in the groups receiving 10 g/day PRO, irrespective of exercise. The inflammatory and endothelial markers were not different between the groups. Training caused a significant improvement (+10.6% to 19.4%, P < .01) in the maximal oxygen uptake. Increased maximum voluntary contraction force was seen in the trained groups receiving 10 g/day of proteins (about 3%, P < .05). Time to task failure was improved in the trained participants receiving a 10 g/day supplementation with PRO (P < .01). CONCLUSIONS: Soluble milk proteins rich in leucine improved time to muscle failure and increase in skeletal muscle mass and strength after prolonged multicomponent exercise training in healthy older men.

Effect on blood lipids of two daily servings of Camembert cheese. An intervention trial in mildly hypercholesterolemic subjects.

As a concentrated source of saturated fat, cheese consumption is considered to be associated with increased cholesterolemia and generally forbidden in dietary guidelines for adults with hypercholesterolemia. The aim of this study was to evaluate the impact of saturated fatty acids on lipid parameters and blood pressure with regards to different types of dairy products: Camembert and full-fat yoghurt. One-hundred and fifty-nine moderate hypercholesterolemic subjects without treatment were instructed to consume two full-fat yoghurts (2 × 125 g) per day for 3 weeks (run-in period) and then for a further period of 5 weeks, either two full-fat yoghurts or two 30 g servings of Camembert cheese per day. We observed that over the 5-week daily consumption of two servings of Camembert cheese, blood pressure and serum lipids did not change in moderate hypercholesterolemic subjects. These results suggest that fermented cheese such as Camembert could be consumed daily without affecting serum lipids or blood pressure.

"Fast proteins" with a unique essential amino acid content as an optimal nutrition in the elderly: growing evidence.

BACKGROUND & AIMS: Adequate protein intake is crucial to maintain body protein content in elderly subjects, but quality of dietary proteins should be also considered since amino acid composition and rate of protein digestion modulate amino acid availability. This study investigates whether the efficacy of optimal protein intake levels for protein retention in the elderly is influenced by protein quality. METHODS: We investigated the effect of a 10-day adequate-protein (AP) or high-protein (HP) diet together with the protein source as caseins (CAS) or soluble milk proteins (PRO) on whole-body (WB) protein synthesis (PS) and protein breakdown (PB) in 4 groups of healthy elderly men (mean ± SEM: 71.8 ± 24.4 yr). The study consisted of two periods of 4 h each: a post-absorptive period and a postprandial period. The fed state was defined by consumption every 20 min and for 4 h, of either 15 g or 30 g of PRO or CAS. Steady-state WB and splanchnic leucine kinetics were measured using a continuous infusion of L-[1-13C]leucine in the postabsorptive state and L-[1-13C]leucine infusion plus oral L-[5,5,5-2H3]leucine in the postprandial state. RESULTS: WB PS was stimulated by feeding only with HP diets, whereas WB PB corrected for splanchnic extraction showed a similar pattern of post-feeding decrease in all groups. Consequently, net leucine balance was greater in the postprandial state after HP meals than after AP meals, with PRO meals leading to a better postprandial leucine balance (3.63 ± 0.16 µmol kg FFM(-1) min(-1)vs. 2.77 ± 0.21 µmol kg FFM(-1) min(-1) for PRO HP and CAS HP, respectively; P = 0.005). CONCLUSION: Postprandial protein retention was better improved in elderly men by an increase in protein intake when the protein supplementation was provided as fast-digesting proteins that induce high leucine availability.

In vivo digestion of infant formula in piglets: protein digestion kinetics and release of bioactive peptides.

The first months of life correspond to a key period in human life where dramatic physiological changes (establishment of microbiota, development of the immune system, etc.) occur. In order to better control these changes it is necessary to understand the behaviour of food in the gastrointestinal tract of the newborn. Infant formula is the only food for the newborn when breast-feeding is impossible. The kinetics of digestion of milk proteins and the nature of the peptides liberated in the small intestine throughout infant formula digestion have never been extensively investigated so far and were therefore studied using the piglet as a model of the newborn child. Piglets were fed infant formula by an automatic delivery system during 28 d, and slaughtered 30, 90 and 210 min after the last meal. Contents of stomach, proximal and median jejunum and ileum were collected and characterised. The extent of ß-lactoglobulin (ß-lg), α-lactalbumin (α-la) and casein proteolysis was monitored by inhibition ELISA, SDS-PAGE, immunoblotting and MS. At 30 min after the last meal, caseins were shown to be extensively hydrolysed in the stomach. Nevertheless, peptides originating mainly from ß-caseins (from 509 to 2510 Da) were identified in the jejunum and ileum of the piglets. ß-Lg partially resisted gastric digestion but completely disappeared in the stomach after 210 min. α-La had a similar behaviour to that of ß-lg. Two large peptides (4276 and 2674 Da) generated from ß-lg were present in the ileum after 30 and 210 min and only one (2674 Da) after 90 min.

Detraining-induced alterations in metabolic and fitness markers after a multicomponent exercise-training program in older men.

The aim of the present study was to investigate the effects of a 8-week detraining period after a 16-week multicomponent training program including strength and aerobic exercises on the main determinants of aerobic fitness, muscle strength and some metabolic markers in 24 older subjects (60.2 ± 3.0 years). The oxygen uptake at the second ventilatory threshold (VO(2)V(T2)) and at the end of exercise (VO(2max)), maximum voluntary contraction force (MVC) of knee extensors and some metabolic indexes, i.e., insulin sensitivity, blood lipid profile, inflammatory cytokines, and endothelial function, were evaluated at baseline and after the training and detraining periods. The training program induced significant improvements in VO(2)V(T2) (16%, p < 0.05), VO(2max) (14%, p < 0.05), MVC (6.5%, p < 0.05), insulin sensitivity (16%, p < 0.05), and endothelial function (p < 0.05) but induced no significant change in lipid profile and inflammatory cytokines. Interestingly, VO(2)V(T2) and VO(2max) (mL·min(-1)·kg(-1)) scores remained significantly above pretraining values after the 8-week detraining period. However, the detraining period reversed MVC values, the insulin sensitivity and endothelial function to baseline levels. To conclude, the 8-week detraining partially reversed the major components of aerobic fitness but totally abolished the gains in muscle strength and some metabolic indexes after a 16-week multicomponent training program in older men. Taken as a whole, the results of this study emphasize the importance of exercise prescriptions for older subjects and the need not to interrupt exercise-training over a prolonged period.

Fate and effects of Camembert cheese micro-organisms in the human colonic microbiota of healthy volunteers after regular Camembert consumption.

The objective of this study was to determine i) if Camembert cheese micro-organisms could be detected in fecal samples after regular consumption by human subjects and ii) the consequence of this consumption on global metabolic activities of the host colonic microbiota. An open human protocol was designed where 12 healthy volunteers were included: a 2-week period of fermented products exclusion followed by a 4-weeks Camembert ingestion period where 2x40 g/day of Camembert cheese was consumed. Stools were collected from the volunteers before consumption, twice during the ingestion period (2nd and 4th week) and once after a wash out period of 2 weeks. During the consumption of Camembert cheese, high levels of Lactococcus lactis and Leuconostoc mesenteroides were measured in fecal samples using real-time quantitative PCR, reaching median values of 8.2 and 7.5 Log(10) genome equivalents/g of stool. For Ln. mesenteroides, persistence was observed 15 days after the end of Camembert consumption. The survival of Geotrichum candidum was also assessed and the fecal concentration reached a median level of 7.1 Log(10) CFU/g in stools. Except a decreasing trend of the nitrate reductase activity, no significant modification was shown in the metabolic activities during this study.

Increased availability of leucine with leucine-rich whey proteins improves postprandial muscle protein synthesis in aging rats.

OBJECTIVE: We previously found that aging was characterized by a decreased sensitivity of muscle protein synthesis to leucine and that a free leucine-supplemented diet corrected this defect in old rats and elderly humans. The present experiment was undertaken to evaluate the efficiency of selected leucine-rich proteins to stimulate postprandial muscle protein synthesis in old rats to optimize nutritional protein support in the elderly. METHODS: Sixty rats (22 mo old) received an experimental meal for the first hour of feeding and a standard diet for the rest of the day for 30 d. Experimental meals contained milk proteins that differed in leucine content: beta-lactoglobulin (14.5% leucine), Prolacta (13.4%), alpha-lactalbumin (10.9%), and casein (10%). As a control, a fifth group was added that received herring flour protein (7.3% leucine). Muscle protein synthesis was determined in vivo in the postprandial state at the end of the 30-d nutritional period using the flooding dose method (1-(13)C phenylalanine). RESULTS: Leucine intake and plasma leucine concentrations were significantly increased in rats fed meals containing the leucine-rich proteins (i.e., beta-lactoglobulin and Prolacta). As previously observed with free leucine-supplemented meals, postprandial muscle protein synthesis was significantly improved in rats fed the meals containing the leucine-rich proteins. Interestingly, the beneficial effect was maintained after the 30-d supplementation. CONCLUSION: The results indicated that leucine-rich proteins were efficient in improving muscle protein synthesis in old rats. Thus, nutritional supplements containing such proteins may be efficient in preventing sarcopenia in the elderly and would represent a safe and optimized nutritional strategy. However, further experiments are necessary to determine the duration of such nutritional support to obtain a significant protein gain in muscle.