|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.|
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).|
"[...] 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).|
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.
|Figure 1: Effects of control and RS4 diet on body composition and lipid variables (Updahyaya. 2016).|
- 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
- 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
|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).|
- 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.