|It's not just about more protein it's about significantly more protein and - possibly - also about whey!|
... but I do also know that the beneficial metabolic effects of high protein intakes appear to be even more, not less pronounced in human beings and will thus not mention 500x that the assumption that we'd see similar benefits in men and women would obviously require experimental confirmation... alright?
Now that we are clear, dear non-dams and non-bucks...
... you are probably already drooling at the sought of reading yet another "high protein is good for you" study. Don't worry I am not going keep you on the tenderhooks longer than absolutely necessary. What is necessary, though is a very brief summary of the study design, which was designed to elucidate the effects macronutrient quality and composition on energy balance and the gut microbia - probably two of the hottest topics in today's discussions on the health and fitness bulletin boards of this world.
As the Irish researcher point out, their goal was to investigate how changes to protein quality (casein versus whey protein isolate; WPI) and the protein to carbohydrate (P/C) ratio within a high fat diet (HFD) impacts on the aforementioned parameters. The questions the experiment was supposed to answer were thus:
- Protein Quality ➲ Would adding whey protein on top of an obesogenic high fat rodent diet yield to a different weight and microbiota response than casein protein?
- Protein Quantity ➲ Would diets with 20%, 30% or 40% of the total energy intake from protein have different effects on body weight and microbiota in the rodents?
As it turned out, the analysis of issues related to question #2, i.e. "Would diets with 20%, 30% or 40% of the total energy intake from protein have different effects on body weight and microbiota in the rodents?" did produce the more intriguing results, though.
|Figure 1: Weight gain, fat and lean mass, as well as energy intake and respiratory exchange ratio (RER) after 21-weeks on diets with different amounts of whey protein in them (McAllan. 2014),|
|Figure 2: Adipose tissue mRNA expression of selected genes (McAllan. 2014)|
- reduce the plasma leptin and liver triacylglycerold levels, and...
- attenuate the reduction in adipose FASN mRNA
"[...]microbiota in the HFD-20% WPI group clustering closely with HFD controls, although WPI specifically increased Lactobacillaceae/Lactobacillus and decreased Clostridiaceae / Clostridiumin HFD-fed mice." (McAllan. 2014)To understand the potential implications of these changes we will have to take a closer look at the recent evidence linking Clostridiaceae and Lactobacillaceae to the diabesity epidemic:
Lactobacillus reuteri has anti-breast-cancer effects as well (Lakritz. 2014).
- lactobacilli, above all those of the reuteri type, have recently been used in several studies for their anti-obesogenic (Million. 2013a, b), anti-autoimmune (Forsberg. 2013), anti-caries (Stensson. 2013), anti-helicobacter plyori (Francavilla. 2013), pro-vitamin-D (Jones. 2013), and a whole host of other beneficial effects; for other types of lacutobacilli researchers have observed that they exert similar anti-obesity effects that may be mediated by the intestinal productino of the anti-obesity isomer of CLA, i.e. trans‐10, cis‐12‐conjugated linoleic acid (Lee. 2007)
High protein, low carb - What does it do?
|Table 1: Plasma amino acid levels (mmol/L); blue bars to the right indicate sign. inter-group difference (McAllan. 2014)|
"[...]the highest ratio [40% of the total energy intake from protein] reduced HFD-induced weight gain, fat mass and plasma triacylglycerol, non-esterified fatty acids, glucose and leptin levels, while it increased lean mass and oxygen consumption." (McAllan. 2014)As the scientists point out, similar effects were observed on adipose mRNA expression, where the highest ratio of protein to carbohydrates reduced HFD-associated expression of UCP-2 (a protein that has the fat stores eat themselves up), the inflammatory marker TNF-alpha and CD68 a gylcoprotein that messes with LDL cholesterol.
On the other hand, the (really) high protein diet increased the diet-associated expression of the b3-adrenergic recepto (b3-AR), lipoprotein lipase, a water soluble enzyme that hydrolyzes triglycerides in lipoproteins, such as those found in chylomicrons and very low-density lipoproteins (VLDL), as well as the expression of insulin receptors and the glucose transporters GLUT4 - all of which should be old acquaintances of loyal SuppVersity readers.
- Duca, Frank A., et al. "Replication of obesity and associated signaling pathways through transfer of microbiota from obese prone rat." Diabetes (2014): DB_131526.
- Forsberg, Anna, et al. "Pre‐and post‐natal Lactobacillus reuteri supplementation decreases allergen responsiveness in infancy." Clinical & Experimental Allergy 43.4 (2013): 434-442.
- Jones, Mitchell L., Christopher J. Martoni, and Satya Prakash. "Oral Supplementation With Probiotic L. reuteri NCIMB 30242 Increases Mean Circulating 25-Hydroxyvitamin D: A Post Hoc Analysis of a Randomized Controlled Trial." The Journal of Clinical Endocrinology & Metabolism 98.7 (2013): 2944-2951.
- Lakritz, Jessica R., et al. "Beneficial bacteria stimulate host immune cells to counteract dietary and genetic predisposition to mammary cancer in mice." International Journal of Cancer (2014).
- Lee, K., et al. "Antiobesity effect of trans‐10, cis‐12‐conjugated linoleic acid‐producing Lactobacillus plantarum PL62 on diet‐induced obese mice." Journal of applied microbiology 103.4 (2007): 1140-1146.
- McAllan, Liam, et al. "Protein Quality and the Protein to Carbohydrate Ratio within a High Fat Diet Influences Energy Balance and the Gut Microbiota In C57BL/6J Mice." PLOS ONE 9.2 (2014): e88904.
- Million, M., et al. "Correlation between body mass index and gut concentrations of Lactobacillus reuteri, Bifidobacterium animalis, Methanobrevibacter smithii and Escherichia coli." International Journal of Obesity (2013a).
- Million, Matthieu, and Didier Raoult. "The role of the manipulation of the gut microbiota in obesity." Current infectious disease reports 15.1 (2013b): 25-30.
- Stensson, Malin, et al. "Oral Administration of Lactobacillus reuteri during the First Year of Life Reduces Caries Prevalence in the Primary Dentition at 9 Years of Age." Caries research 48.2 (2013): 111-117.
- Weigle, David S., et al. "A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations." The American journal of clinical nutrition 82.1 (2005): 41-48.