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Un supplément de membrane du globule gras du lait pour prendre du muscle?

08/10/2015 | Etudes Compléments alimentaires et Etudes Anti-âge


Dietary milk fat globule membrane supplementation combined with regular exercise improves skeletal muscle strength in healthy adults: a randomized double-blind, placebo-controlled, crossover trial
Satoko Soga               Nutrition Journal 2015, 14:85

Our previous studies demonstrated that dietary supplementation with milk fat globule membrane (MFGM) combined with habitual exercise improved muscle strength by stimulating neuromuscular development in mice. This study aimed to demonstrate the beneficial effects of dietary MFGM supplementation plus regular exercise on muscle strength and neuromuscular function in healthy humans.

The study was designed as a randomized, double-blind, placebo-controlled, crossover trial. Fourteen Japanese adults aged 31–48 years took daily MFGM (1 g) or placebo tablets during the 4-week study period and attended a training program twice a week. Physical function tests and surface electromyography (EMG) were conducted at baseline and at the end of the study period.

The MFGM group had significantly greater leg extension strength than the placebo group after the 4-week study period. Surface EMG showed that the MFGM group had a significantly higher root mean square amplitude than the placebo group, which indicated that the MFGM group had higher motor unit activity.

Dietary MFGM supplementation combined with regular exercise improves skeletal muscle strength, which may be due to increased motor unit recruitment in healthy Japanese middle-aged adults.

Lutéine et Zéaxanthine protègent la vue

08/10/2015 | Etudes Anti-âge


Intakes of Lutein, Zeaxanthin, and Other Carotenoids and Age-Related Macular Degeneration During 2 Decades of Prospective Follow-up
Juan Wu                       JAMA Ophthalmol. Published online October 08, 2015.

Importance Despite strong biological plausibility, evidence from epidemiologic studies and clinical trials on the relations between intakes of lutein and zeaxanthin and age-related macular degeneration (AMD) has been inconsistent. The roles of other carotenoids are less thoroughly investigated.

Objective To investigate the associations between intakes of carotenoids and AMD.

Design, Setting, and Participants Prospective cohort study, with cohorts from the Nurses’ Health Study and the Health Professionals Follow-up Study in the United States. A total of 63 443 women and 38 603 men were followed up, from 1984 until May 31, 2010, in the Nurses’ Health Study and from 1986 until January 31, 2010, in the Health Professionals Follow-up Study. All participants were aged 50 years or older and were free of diagnosed AMD, diabetes mellitus, cardiovascular disease, and cancer at baseline.

Main Outcomes and Measures Predicted plasma carotenoid scores were computed directly from food intake, assessed by repeated food frequency questionnaires at baseline and follow-up, using validated regression models to account for bioavailability and reporting validity of different foods, and associations between predicted plasma carotenoid scores and AMD were determined.

Results We confirmed 1361 incident intermediate and 1118 advanced AMD cases (primarily neovascular AMD) with a visual acuity of 20/30 or worse by medical record review. Comparing extreme quintiles of predicted plasma lutein/zeaxanthin score, we found a risk reduction for advanced AMD of about 40% in both women and men (pooled relative risk comparing extreme quintiles = 0.59; 95% CI, 0.48-0.73; P for trend < .001). Predicted plasma carotenoid scores for other carotenoids, including β-cryptoxanthin, α-carotene, and β-carotene, were associated with a 25% to 35% lower risk of advanced AMD when comparing extreme quintiles. The relative risk comparing extreme quintiles for the predicted plasma total carotenoid index was 0.65 (95% CI, 0.53-0.80; P for trend < .001). We did not identify any associations of carotenoids, either as predicted plasma score or calculated intake, with intermediate AMD.

Conclusions and Relevance Higher intake of bioavailable lutein/zeaxanthin is associated with a long-term reduced risk of advanced AMD. Given that some other carotenoids are also associated with a lower risk, a public health strategy aimed at increasing dietary consumption of a wide variety of fruits and vegetables rich in carotenoids may reduce the incidence of advanced AMD.

Le glucagon augmente le métabolisme sans être thermogénique

08/10/2015 | Etudes sur les hormones et Etudes Perte de poids


Glucagon Increases Energy Expenditure Independently of Brown Adipose Tissue Activation in Humans
V. Salem       Diabetes, Obesity and Metabolism 2015 Vol. 17 Issue 10

Obesity is a global health concern. An ideal drug would inhibit appetite and elevate energy expenditure (EE), but no currently available medication can safely do this. Glucagon elevates EE in humans, but the mechanism remains unknown.

To investigate, for a given energy expenditure rise, the differential effects of glucagon infusion and cold exposure on brown adipose tissue (BAT) activation in humans.

Indirect calorimetry and supraclavicular thermography was performed in 11 healthy male volunteers before and after cold exposure, glucagon infusion (at 23°C) and vehicle infusion (at 23°C). All volunteers underwent 18F-FDG PET/CT scanning with cold exposure. Subjects with cold-induced BAT activation on 18F-FDG PET/CT (n=8) underwent a randomly allocated second 18F-FDG PET/CT scan (at 23°C) either with glucagon infusion (n=4) or vehicle infusion (n=4).

EE increased by 14% following cold exposure and by 15% post-glucagon infusion (50 ng/kg/min) (P<0.05 vs control for both). Cold exposure produced an increase in neck temperature (+0.44°C; P<0.001 vs control), but glucagon infusion did not alter neck temperature. In subjects with cold-induced increase in the metabolic activity of supraclavicular BAT on 18F-FDG PET/CT, a significant rise in metabolic activity of BAT following glucagon infusion was not detected. Cold exposure increased sympathetic activation, as measured by circulating norepinephrine levels, but glucagon infusion did not.

Glucagon increases energy expenditure to a similar magnitude compared to cold activation, but independently of BAT thermogenesis. This finding is of importance for the development of safe treatments of obesity through upregulation of energy expenditure.


Le sport modifie t’-il la sensibilité à la caféine?

04/10/2015 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge et Etudes sur les boosters sexuels et la sexualité


Regular physical activity attenuates the hypertensor effects of acute caffeine ingestion
Rogério N. Soares             Appl. Physiol. Nutr. Metab. Vol. 40, 2015   S62

The aim of this study was to evaluate whether regular physical activity
modifies cardiovascular system responses to acute caffeine ingestion.
Sixty subjects (19–50 years) underwent an interventional, quasi experimental
study. They were analysed according to physical activity
status: sedentary and physically active. To evaluate the influence of
caffeine consumption, they were also divided into four groups:
sedentary non-habitual light caffeine consumer (S),
sedentary habitual heavy caffeine consumer (SC)
, physically active non-habitual lightcaffeine consumer (A) and
physically active habitual heavy caffeine consumer (AC).

All groups had their cardiovascular parameters measured
before (basal) and 1 hour after caffeine ingestion (6 mg/kg of body

It was observed that 1 hour after caffeine ingestion the resting
heart rate (HR) from all subjects of the study decreased (p

< 0.05; 11%).
When comparing the subjects by physical activity status, it was observed

only sedentary subjects had their diastolic blood pressure
(DBP) increased
(p < 0.05). The basal and post DBP were lower in AC
than SC. Experimental groups showed differences in HR variation:
S (-6.9 ± 6.3 bpm) vs. A (-3.4 ± 6.5 bpm) (p < 0.05) and A (-3.4 ± 6.5 bpm)
vs. AC (-9.5 ± 7.9 bpm) (p < 0.05).

The regular practice of physical activity may protect against the hypertensor effects of caffeine ingestion.
However, its association with habitual caffeine consumption
may also make the cardiovascular system more sensitive to caffeine,
increasing bradycardia induced by acute caffeine ingestion.

Trop peu de repos entre les séries réduit-il la riposte anabolique?

03/10/2015 | Etudes Musculation


Short inter-set rest duration impairs resistance exercise-induced
rates of myofibrillar protein synthesis in young males

James McKendry         Appl. Physiol. Nutr. Metab. Vol. 40, 2015 pS41

Resistance exercise contractile variables can be manipulated to enhance
the muscle morphological response. Reducing the duration of
rest-recovery taken between sets of resistance exercise (≤1 min) influences
systemic concentrations of hormones thought to be critical for
muscle hypertrophy. However, local mechanisms activated through
the mechanical stress resistance exercise places on the muscle may act
as intrinsic ‘drivers’ of hypertrophy, irrespective of the endocrine

The aim of this study was to determine the acute muscle
anabolic response to a bout of resistance exercise performed with
contrasting inter-set rest durations. In a parallel designed study,
16 males completed 4 sets of bilateral leg press (LP) and knee extension
(KE) exercise at 75% of 1RM to momentary failure followed by ingestion
of 25g of whey protein.

Resistance exercise sets were interspersed by 1 min (1 M; n=8) or 5 min (5 M; n=8). Muscle biopsies of the vastus
lateralis were obtained at rest, 0, 4, 24 and 28 h postexercise during a
primed-continuous infusion of L-[ring-13C6] phenylalanine to determine
rates of myofibrillar protein synthesis (MPS) and anabolic signalling
in the ‘early’ (0-4 h) and ‘late’ (24-28 h) recovery phase. 1M induced
a greater elevation in plasma lactate and serum testosterone compared
with 5 M, with no difference between groups in serum growth
hormone response.

Total work volume (reps x sets x load) was 13%
lower for LP (P = 0.01) and 17% lower for KE (P = 0.029) in 1 M compared
with 5 M.

Rates of MPS increased above basal values by 80 and 150%
over 0-4 h post-exercise for 1 M and 5 M, respectively.
The rate of MPS
over 0-4 h post-exercise was significantly lower in 1 M compared with
5 M (0.040 ± 0.004 vs. 0.069 ± 0.007 %·h-1, respectively, P = 0.005). Rates
of MPS at 24-28 h post-exercise remained elevated above basal fasted
values for 1 M and 5 M (0.046 ± 0.007 and 0.046 ± 0.009 %·h-1, respectively,

P < 0.05) with no difference between groups. Immediately postexercise,
eEF2Thr56 phosphorylation was lower in 5Mcompared with
1 M (P <0.05).

In conclusion, short inter-set rest duration of 1 M impaired
resistance exerciseinduced myofibrillar protein synthesis compared
with rest-interval duration of 5 M
. We speculate that the
suppression in MPS in 1 M is notdue tothe reduction in total work, but
rather the intracellular metabolic ‘stress’ response (i.e. energy depletion),
which may have down-regulated protein translation through a
compromised anabolic signalling.

Le glutamate augmente le rebond glucidique

03/10/2015 | Etudes Compléments alimentaires et Etudes Perte de poids


Le glutamate augmente le rebond glucidique sans agir comme booster d’insuline

Glutamate increased glucose uptake in l6 myotubes in a concentration- and time-dependent manner that is mediated
Appl. Physiol. Nutr. Metab. Vol. 40, 2015 pS5   Tyler Barnes

Various in vivo studies have investigated the insulin response that is
elicited when glutamate is elevated in circulation or in a given tissue;
fewer studies have investigated the effects of glutamate on glucose
uptake and handling.

Work from our lab suggests that glutamate
ingestion in humans can attenuate rises in blood glucose following a
carbohydrate load (75 g of Trutol®) compared with administration of
a carbohydrate load alone; this attenuated rise in glucose, following
a combined carbohydrate and glutamate load, occurred in absence of
increases in serum insulin concentrations.

However, the underlying mechanisms have yet to be investigated. To elucidate the effects of
glutamate on glucose handling in skeletal muscle tissue, differentiated
rat L6 myocytes were treated with increasing doses of glutamate
for 1 hr and glucose uptake was assessed by the addition of
[3H]-2-Deoxyglucose in HBS for 10 min. Cells treated with 2 mM, 1 mM,
and 500 M glutamate significantly increased [3H]-2-DG uptake by
129 ± 7%, 123 ± 5%, and 121 ± 4%, respectively relative to the control
condition (P<0.05). To evaluate the effect of treatment time on glucose
uptake, cells were incubated with 2 mM of glutamate for various
times ranging from 0 to 120 minutes. Treating cells for 30 minutes
resulted in the greatest increase in [3H]-2-DG uptake versus the control
condition (143 ± 9%, P<0.001), while cells treated for 45 and 60 minutes
also significantly increased [3H]-2-DG uptake (125 ± 9% and 129 ± 7%,
respectively; P<0.05). To investigate select mechanisms by which glutamate
acts to increase glucose uptake, cells were treated with 2 mM of
glutamate for 30 minutes with either a PI3K inhibitor (LY294002), PKC
inhibitor (BMD I), or AMPK inhibitor (Compound C). Compound C
reduced glucose uptake in cells treated with glutamate to a similar
extent as the control condition (98 ± 2%), whereas cells treated with
LY294002 showed significantly greater uptake than the control (128 ±
5%, P<0.05).

Our findings suggest that when muscle cells are exposed
to increased glutamate concentrations, glucose uptake into these cells
is augmented through AMPK activation.
This study will provide a basis
for future animal and human studies exploring the interactions of
glutamate and glucose in skeletal muscle.

La digestibilité du gluten est réduite par la cuisson

03/10/2015 | Etudes sur les hormones et Etudes Perte de poids et Etudes Anti-âge


Digestibility of gluten proteins is reduced by baking and enhanced by starch digestion
Frances Smith           Molecular Nutrition & Food Research   Volume 59, Issue 10, pages 2034–2043, October 2015

Resistance of proteins to gastrointestinal digestion may play a role in determining immune-mediated adverse reactions to foods. However, digestion studies have largely been restricted to purified proteins and the impact of food processing and food matrices on protein digestibility is poorly understood.

Methods and results
Digestibility of a total gliadin fraction (TGF), flour (cv Hereward), and bread was assessed using in vitro batch digestion with simulated oral, gastric, and duodenal phases. Protein digestion was monitored by SDS-PAGE and immunoblotting using monoclonal antibodies specific for celiac-toxic sequences (QQSF, QPFP) and starch digestion by measuring undigested starch. Whereas the TGF was rapidly digested during the gastric phase the gluten proteins in bread were virtually undigested and digested rapidly during the duodenal phase only if amylase was included. Duodenal starch digestion was also slower in the absence of duodenal proteases.

The baking process reduces the digestibility of wheat gluten proteins, including those containing sequences active in celiac disease. Starch digestion affects the extent of protein digestion, probably because of gluten-starch complex formation during baking. Digestion studies using purified protein fractions alone are therefore not predictive of digestion in complex food matrices.

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