|Only dairy, not soy-based lasagna will help you build muscle.|
Ah, and obviously to investigate if middle aged men with MetS display a resistance of anabolic signalling to mixed meal ingestion compared with healthy control.
The latter already tells you that the subjects of Petra Grans study were obese. Twenty 40–60 year-old men who were recruited from newspaper, poster, and flyer advertisements to participate.
The subjects were classified as having MetS based on the International Diabetes Federation criteria which means they were abdominally obese (waist circumference≥94 cm) and had two of the following health issues: raised serum triglycerides (≥1.7 mmol/l), reduced serum HDL cholesterol (<1.03 mmol/l), impaired fasting glycaemia (fasting plasma glucose≥5.6 mmol/l) or raised blood pressure (systolic blood pressure≥130 mmHg or diastolic blood pressure≥85 mmHg).
A cohort of age and height matched healthy controls, without MetS were also included and subjects from both groups were randomly assigned to consume either a breakfast meal (had to be consumed withing 15 minutes) comprised of dairy-derived protein or void of dairy-derived proteins (replaced with the same level of soy based protein).
The test breakfast meals consisted of cheese, butter, and full cream milk with white bread toast (dairy breakfast) and the second meal contained soy cheese analogue, soy beverage, a soy spread, and white bread toast and contained the same amount of protein (31 g) with similar carbohydrate content.
"The interval between the two test meals was at least four weeks. To prevent possible differences between subjects at baseline from their previous meal the night prior to the study day, subjects were provided with a controlled meal for dinner. The meal consisted of a pre-packaged lasagna and fruit yogurt providing a total of 2462 kJ as 20% fat, 18% protein and 62% carbohydrates. Subjects were asked to eat only the provided food and nothing else." (Gran. 2014)
Table 1: Amino acid composition of the test meals (Gran. 2014)
Based on previous research you would expect that...
... switching from dairy to soy, will reduce the anabolic response to the meal. What really happened, however was that the pro-anabolic proteins mTOR (Ser448) and the ribosomal protein S6 increased only after the ingestion of the dairy, not after the consumption of the soy meal.
|Figure 1: Activation of mTOR, p70S6K and S6 during the postprandial period in human skeletal muscle (Gran. 2014)|
"[...] P70S6K is the primary readout used to assess the activity of the mTOR pathway (Drummond. 2009; Bodine. 2001); the lack of change in P70S6K phosphorylation after mixed-meal consumption in men with MetS is similar to the anabolic resistance induced by periods of inactivity (Glover. 2008; Breen. 2013) and is observed in older adults (Cuthbertson. 2005; Burd. 2013). Although protein synthesis was not directly measured in this study signalling deficits have been shown to underlie ageing induced anabolic resistance (Cuthbertson. 2005)." (Gran. 2014)Now, the guys in the study at hand were not exactly old enough for age to be the determining factor, here. Rather than that, research by Villareal, et al. (2012) indicates that eating a clean, energy reduced diet - which was obviously not what the subjects consumed before the experiment in the study at hand - can restore / increase the protein anabolic response in subjects with metabolic syndrome. The non-existent increase in p70S6k in the study at hand could, as Gran et al. highlight, be evidence of this obesity / diet induced resistance to protein-induced skeletal muscle anabolism.
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