Thursday, July 7, 2016

Resistant Starch (RS4) for Fat Loss & Exercise Performance

RS4 is still relatively difficult to come by. Options I know of are ActiStar® from Cargill and Fibersym® fom MGP. RS2 and RS3 alternatives are raw potato starch and, as previously discussed, banana starch or reheated starches. They'll have (presumably) very similar effects, but come directly from food.
You will probably remember the good old "Waxy Maize Reloaded" article from 4 years ago that caused quite a stir!? Well, I guess four years is a long time - more than enough to revisit the idea of designer resistant starches and their effect on your physique and performance. To do so, I've picked two recent studies from the South Dakota State University (Upadhyaya. 2016) and the Florida State University (Baur. 2016) that have one thing in common: they add to the hitherto still inadequate number of studies on resistant starch type 4 (RS4), one out of five forms of "resistant", i.e. (partly) undigestible, starches with significantly different chemical properties and corresponding functional differences such as their fermentability or their influence on the microbiota in the gut and their applicability as ergogenics in sports drinks and/or functional foods.
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To elucidate the effects on the gut microbiome and the production of health-relevant short-chain fatty acid (SCFA) production, of which the previously cited article about WM-HDP from 2012 explains how they affect GLP-1, glycemia and metabolism (read it), Upadhyaya et al. conducted an experiment with twenty individuals with signs of, but not fullly established metabolic syndrome (MetS).
Table 1: Overview of the study design (Upadhyaya. 2016).
With a total duration of 26 weeks that included two 12-week interventions periods, with one each for RS4 (30%, v/v in flour that is currently not available in supermarkets) and control flour (CF), and a two-week washout in between the interventions, the randomized cross-over study is one of the longest dietary interventions with any form of resistance starch I have read and thus also the one with the highest potential of yielding relevant insights into the long-term effects of RS-4 consumption. As previously pointed out, ...
"[...] all twenty participants who had signs of metabolic syndrome at baseline and submitted adequate stool samples at four data collection time points were included in the current investigation, which allowed for comparison of the gut microbial and SCFA profiles before and after the interventions and also between the endpoints of the RS4 and CF (control) interventions" (Upadhyaya. 2016). 
In view of the fact that adverse gastrointestinal side effects from the interventions were not evaluated in this cohort, we have to simply follow the scientists' reasoning that no bloating, belching or other unwanted sides would occur - an assumption that appears to be at least reasonable in view of the observations the scientists made in a previous study w/ similar design (Nichenametla. 2014).
The visible performance decrements in the low HMS group was sign. correlated with gastrointestinal distress (Baur. 2016).
What about performance? Those were evaluated by Daniel A. Baur in a study which investigated the metabolic and gastrointestinal effects of a hydrothermally-modified starch supplement (HMS) before and during cycling for ~3 h (1 h at 50% Wmax, 8 x 2-min intervals at 80% W max, and 10 maximal sprints) in 10 in male cyclists who underwent three nutritional interventions (crossover design): (1) a commercially available sucrose/glucose supplement (G) 30 min before (60 g carbohydrate) and every 15 min during exercise (60 g/h); (2) HMS consumed at the same time points before and during exercise in isocaloric amounts to G (Iso-HMS); and (3) HMS 30 min before (60 g carbohydrate) and every 60 min during exercise (30 g/h; Low HMS).

Interestingly enough, the supplement had no effects on sprint performance with Iso HMS vs. G, being identical and G and Iso HMS resultin in nothing but a "likely", yet small performance enhancement of 5.0% compared to the "low carb" = Low HMS trial.

What may  be considered a success, though, is the sign. increase in fat oxidation (31.6%+/-20.1%; very likely (Iso); 20.9%+/.16.1%; likely (Low)) and corresponding reduction in carbohydrate oxidation (19.2%+/-7.6%; most likely; 22.1%+/-12.9%; very likely) during exercise relative to the plain glucose trial (G). That the latter was dearly bought by increased during repeated sprints with ingestion of Iso HMS (17 scale units +/-18; likely) and Low HMS (18 +/-14; likely) that also explained the decreased performance with Low HMS vs. G (likely), future studies will have to either find ways to make HMS more gut friendly or test whether the repeated administration of HMS solves the issue by the means of intestinal adaptation - a corresponding study could also yield insights into whether the increased fatty oxidation would also trigger long-term mitochondrial growth that goes beyond what you'd see with regular Gatorade aka a sugar-containing workout beverage.
I know that you will probably me most interested in the effects on the subject's body composition. Therefore I plotted those in Figure 1 and postponed the presentation and discussion of the authors' actual research interest, the microbial composition of their subjects guts on a later paragraph.
Figure 1: Effects of control and RS4 diet on body composition and lipid variables (Updahyaya. 2016).
As you can see, the consumption of the RS4 diet had significant (beneficial) effects on the subjects' waist lines (~2% or 2 cm vs. baseline and control). In conjunctions with the beneficial effects on HDL (p = 0.001) and total cholesterol (p = 0.01), which were 10% higher and lower, respectively, after the RS4 vs. control diets, and a significant increase in adiponectin (p < 0.01), and none-significant improvements in fasting blood glucose (+5% and -4% vs. baseline in control and RS4, respectively) and HbA1c (-1% and -2% vs. baseline in control and RS4, respectively), there appears to be little doubt that the significant improvement in the firmicute to bacteriode ratio, which is frequently perceived as an indicator of a leaner phenotype (although the previously reported results are not always consistent | Fernandes. 2014) in the RS4 weeks, as well as specific results, such as ...
  • the previously observed increase of species from Clostridial cluster XIVa, but not cluster IV, that was triggered by RS4 supplementation of the diet; at the species level, RS4 consumption increased the abundance of Bifidobacterium adolescentis (90.5 fold, q= 0.087) and Parabacteroides distasonis (1180.2 fold, q< 0.001) but not Ruminococcus bromii (−3.2 fold, q > 0.05), Faecalibacterium prausnutzii (−1.2 fold, q > 0.05), or Dorea formicigenerans (1.1 fold, q> 0.05)
  • Timing Matters if You Want to Turn Regular into Resistant Starch | more
    a not previously observed RS4-induced increase in Christensenella minuta abundance (119.7 fold, q= 0.038, 97% query coverage, 88% identity and E< 0.001 in NCBI-BLAST) as well as in several OTUs in the family Ruminococcaceae and genus Bacteroides; at the species level, Bacteroides ovatus (37.6 fold, q= 0.087), Ruminococcus lactaris (2866.7 fold, q< 0.001), Eubacterium oxidoreducens (3.3× 105 fold, q< 0.001), Bacteroides xylanisolvens (47.8 fold, q= 0.037), and Bacteroides acidifaciens (92.4 fold, q= 0.038) were enriched after RS4 intervention
  • changes in the individual proportions of the SCFAs, butyric (69.5%, p= 0.03), propionic (50.2%), valeric (44.1%), isovaleric (20.3%), and hexanoic (19.2%) acids increased post intervention from baseline in the RS4 group (p< 0.05) but not in the CF group (data not shown)
  • correlations between significant changes in the gut microbiota composition induced by RS4 and altered SCFA level that were not observed after the control treatment
provide reasonable evidence for the use of RS4 as a food additive (in place of regular starches, obviously). In that, it is also important point out is that the changes in body composition, lipoproteins, glucose control and the bacterial composition of the subjects' microbiome occured in the absence of significant differences in macronutrient intake,... well, aside from the dietary fibre intake, which was obviously significantly higher in the RS4 group (p< 0.001). After all, RS4 is officially being classified as a prebiotic dietary fibre.
Figure 2: Differential gut microbial composition after RS4 intervention at the species level (left) and correlations with important metabolic outcomes from total cholesterol (TC) to adiponectin (right | Upadhyaya. 2016).
Overall, the average calories (~1,774 Kilocalories) consumed at baseline were estimated to come from carbohydrate (~49%), protein (~17%), and fat (~34%) - values you may criticize, but of which the authors rightly point out that they "fall within the Dietary Reference Intakes (DRI) for macronutrients, which are 45–65%, 10–35%, and 20–35% for carbohydrate, protein, and fat", respectively.
Is RS4 different from other prebiotics?It obviously is structurally different, so it is not 100% surprising that a previous parallel design study u-sing other prebiotics, na-mely inulin and oligofruc-tose, suggests that the ensuing improvement in metabolic functions and body composition are more pronounced with RS4 compared to other prebiotics.
Bottom line: In sum the two studies provide reasonable evidence for the addition of RS4 to your diet and/or functional foods. There is one thing you should keep in mind: the potential ergolytic effect that comes with the intestinal side effects in those who cannot handle the RS4-laden Gatorade alternative. Before you buy a few pounds of RS4 at the bulk-supplier of your trust, you should thus better test-drive your individual RS4 tolerance.

Since similar effects were not observed by Nichenametla and Updahyaya in their 2014 and 2016 studies, it is yet safe to assume that this effect may be exposure dependent with the use of  30% v/v RS4 in flour - a strategy that could also be employed in processed foods having no significant effect on the digestive health of the average customer, but a sign. effect on his waist circumference | Comment!
References:
  • Baur, Daniel A., et al. "Slow-Absorbing Modified Starch before and during Prolonged Cycling Increases Fat Oxidation and Gastrointestinal Distress without Changing Performance." Nutrients 8.7 (2016): 392.
  • Dewulf, Evelyne M., et al. "Insight into the prebiotic concept: lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women." Gut (2012): gutjnl-2012.
  • Fernandes, J., et al. "Adiposity, gut microbiota and faecal short chain fatty acids are linked in adult humans." Nutrition & diabetes 4.6 (2014): e121.
  • Nichenametla, Sailendra N., et al. "Resistant starch type 4‐enriched diet lowered blood cholesterols and improved body composition in a double blind controlled cross‐over intervention." Molecular nutrition & food research 58.6 (2014): 1365-1369.
  • Upadhyaya B, et al. "Impact of dietary resistant starch type 4 on human gut microbiota and immunometabolic functions." Sci Rep. 2016 Jun 30;6:28797. doi: 10.1038/srep28797.