Casein structures differently affect postprandial amino acid delivery through their intra-gastric clotting properties

We aimed to assess if casein structure affects its digestion and its subsequent amino acid delivery kinetic. Higher nitrogen levels were recovered in dialysates after in vitro digestions of sodium caseinate (SC, formed of small aggregates) compared to micellar casein (MC, native form of casein) and calcium caseinate (CC, intermediate structure). Likewise, plasma indispensable amino-acid concentration peak was higher after SC compared to MC or CC ingestion in healthy volunteers in a randomized, double blind, cross-over study. In pigs, gamma-scintigraphy using labelled meals revealed that SC was mainly localized in the proximal part of the stomach whereas MC was distributed in the whole gastric cavity. Caseins were found in both solid and liquid phases and partly hydrolyzed casein in the solid phase shortly after SC drink ingestion. These data support the concept of slow (MC) and rapid (SC) casein depending of casein structure, likely due to their intra-gastric clotting properties.

Protein intake and bone mineral density: Cross-sectional relationship and longitudinal effects in older adults

BACKGROUND

There are several mechanisms via which increased protein intake might maintain or improve bone mineral density (BMD), but current evidence for an association or effect is inconclusive. The objectives of this study were to investigate the association between dietary protein intake (total, plant and animal) with BMD (spine and total body) and the effects of protein supplementation on BMD.

METHODS

Individual data from four trials that included either (pre-)frail, undernourished or healthy older adults (aged ≥65 years) were combined. Dietary intake was assessed with food records (2, 3 or 7 days) and BMD with dual-energy X-ray absorptiometry (DXA). Associations and effects were assessed by adjusted linear mixed models.

RESULTS

A total of 1570 participants [57% women, median (inter-quartile range): age 71 (68-75) years] for which at least total protein intake and total body BMD were known were included in cross-sectional analyses. In fully adjusted models, total protein intake was associated with higher total body and spine BMD [beta (95% confidence interval): 0.0011 (0.0006-0.0015) and 0.0015 (0.0007-0.0023) g/cm² , respectively]. Animal protein intake was associated with higher total body and spine BMD as well [0.0011 (0.0007-0.0016) and 0.0017 (0.0010-0.0024) g/cm² , respectively]. Plant protein intake was associated with a lower total body and spine BMD [-0.0010 (-0.0020 to -0.0001) and -0.0019 (-0.0034 to -0.0004) g/cm² , respectively]. Associations were similar between sexes. Participants with a high ratio of animal to plant protein intake had higher BMD. In participants with an adequate calcium intake and sufficient serum 25(OH)D concentrations, the association between total protein intake with total body and spine BMD became stronger. Likewise, the association between animal protein intake with total body BMD was stronger. In the longitudinal analyses, 340 participants [58% women, median (inter-quartile range): age 75 (70-81) years] were included. Interventions of 12 or 24 weeks with protein supplementation or protein supplementation combined with resistance exercise did not lead to significant improvements in BMD.

CONCLUSIONS

An association between total and animal protein intake with higher BMD was found. In contrast, plant protein intake was associated with lower BMD. Research is warranted to further investigate the added value of dietary protein alongside calcium and vitamin D for BMD improvement, especially in osteopenic or osteoporotic individuals. Moreover, more research on the impact of a plant-based diet on bone health is needed.

Milk Polar Lipids Reduce Cholesterolemia by Decreasing Cholesterol Absorption in Humans (P06-041-19)

Objectives

Nutritional strategies can play a major role in the management of cholesterolemia, notably in postmenopausal women at risk of CVD. Interest has recently grown on the potential health benefits of milk polar lipids (MPL). We showed that isolipidic enrichment of the diet with MPL improved several lipid CV risk factors but underlying mechanisms remained unclear. We hypothesized that MPL reduce intestinal cholesterol absorption in humans.

Methods

We performed a double-blind randomized controlled trial in 58 postmenopausal women with fasting HDL-cholesterol < 1.6 mM. They were subjected to a 4-week dietary intervention with daily consumption of a cream-cheese containing 12 g of milk fat including either 0 g (control, n = 19), 3 g (n = 19) or 5 g (n = 20) of MPL. Before and after each intervention, blood lipids were measured in the whole cohort whereas fecal lipids and coprostanol were analyzed in a subgroup (n = 7–9 per group). A proof-of-concept mechanistic crossover study was also carried out in 4 ileostomized subjects who performed 8h-postprandial tests after consuming 0g-, 3g- or 5g-MPL enriched cheese labelled with 2H-cholesterol tracer. Plasma, chylomicrons and ileal efflux were analyzed.

Results

Milk fat enriched with 3 to 5 g MPL induced dose-response reductions in serum total cholesterol (up to −6.8% in 5 g group, p < 0.05), LDL-cholesterol (−8.7%, p < 0.05) and HDL/total-cholesterol ratio (p < 0.001), compared to the control that had no effect. Fecal excretion of coprostanol increased after MPL supplementation (p < 0.05, 3g- and 5g-MPL vs control), and the fecal coprostanol/cholesterol ratio was inversely correlated with serum total- and LDL-cholesterol after intervention (r = −0.5, p < 0.05). In ileostomized subjects, postprandial accumulation of 2H-cholesterol in plasma and chylomicrons was reduced after 3 to 5 g MPL consumption (p < 0.05, vs control). Both cholesterol and milk sphingomyelin increased in ileal efflux after MPL enriched cheeses (p < 0.05).

Conclusions

Present results suggest that milk polar lipids decrease cholesterol absorption in humans through interactions with sphingomyelin and by increasing conversion of cholesterol to coprostanol.

Funding Sources

ANR (French National Research Agency, VALOBAB project, ANR-11-ALID-007–01), PHRC-I (French Clinical Research Program, 14–007), CNIEL (French Dairy Interbranch Organization).

Impact of Eccentric or Concentric Training on Body Composition and Energy Expenditure

PURPOSE

To compare the effects of 8-wk eccentric (ECC) versus concentric (CON) training using downhill and uphill running in rats on whole body composition, bone mineral density (BMD), and energy expenditure.

METHODS

Animals were randomly assigned to one of the following groups: 1) control (CTRL), 2) +15% uphill-running slope (CON), 3) -15% downhill-running slope (ECC15), and 4) -30% downhill-running slope (ECC30). Those programs enabled to achieve conditions of isopower output for CON and ECC15 and of iso-oxygen uptake (V˙O2) for CON and ECC30. Trained rats ran 45 min at 15 m·min five times per week. Total body mass, fat body mass, and lean body mass (LBM) measured through EchoMRI™, and 24-h energy expenditure including basal metabolic rate (BMR) assessed using PhenoMaster/LabMaster™ cage system were obtained before and after training. At sacrifice, the right femur was collected for bone parameters analysis.

RESULTS

Although total body mass increased in all groups over the 8-wk period, almost no change occurred for fat body mass in exercised groups (CON, -4.8 ± 6.18 g; ECC15, 0.6 ± 3.32 g; ECC30, 2.6 ± 6.01 g). The gain in LBM was mainly seen for ECC15 (88.9 ± 6.85 g) and ECC30 (101.6 ± 11.07 g). ECC was also seen to positively affect BMD. An increase in BMR from baseline was seen in exercise groups (CON, 13.9 ± 4.13 kJ·d; ECC15, 11.6 ± 5.10 kJ·d; ECC30, 18.3 ± 4.33 kJ·d) but not in CTRL one. This difference disappeared when BMR was normalized for LBM.

CONCLUSIONS

Results indicate that for iso-V˙O2 training, the impact on LBM and BMD is enhanced with ECC as compared with CON, and that for isopower but lower V˙O2 ECC, an important stimulus for adaptation is still observed. This provides further insights for the use of ECC in populations with cardiorespiratory exercise limitations.

Changes in Dietary Intake and Adherence to the NU-AGE Diet Following a One-Year Dietary Intervention among European Older Adults-Results of the NU-AGE Randomized Trial

BACKGROUND

The Mediterranean Diet has been proposed as an effective strategy to reduce inflammaging, a chronic low grade inflammatory status, and thus, to slow down the aging process. We evaluated whether a Mediterranean-like dietary pattern specifically targeting dietary recommendations of people aged over 65 years (NU-AGE diet) could be effective to shift dietary intake of older adults towards a healthful diet.

METHODS

Adults aged 65⁻80 years across five EU-centers were randomly assigned to a NU-AGE diet group or control group. The diet group followed one year of NU-AGE dietary intervention specifying consumption of 15 food groups plus the use of a vitamin D supplement. Participants in the diet group received counselling and individually tailored dietary advice, food products and a vitamin D supplement. Dietary intake was assessed by means of seven-day food records at baseline and one-year follow-up. A continuous NU-AGE index (0⁻160 points) was developed to assess NU-AGE diet adherence.

RESULTS

In total 1296 participants were randomized and 1141 participants completed the intervention (571 intervention, 570 control). After one year, the diet group improved mean intake of 13 out of 16 NU-AGE dietary components (p < 0.05), with a significant increase in total NU-AGE index (difference in mean change = 21.3 ± 15.9 points, p < 0.01).

CONCLUSIONS

The NU-AGE dietary intervention, based on dietary recommendations for older adults, consisting of individual dietary counselling, free healthy foods and a vitamin D supplement, may be a feasible strategy to improve dietary intake in an aging European population.