It's been too easy, what with study after study for over 30 years showing that RS has profound effects on the gut biome and health of the habitual user. Let's take a look at this latest study and see if we should all immediately halt the use of RS2.
Too long? Don't wanna read? : RS2, as found in raw potato starch, banana flour, and Hi-Maize corn starch is a great prebiotic and can be used as a supplement for fiber in a healthy diet!
From Sept 2015 (full text, please read!): The effect of dietary resistant starch type 2 on the microbiota and markers of gut inflammation in rural Malawi children
In this study, researchers were examining ways to reduce the massive stomach inflammation common in 18 undernourished, stunted growth, 3-5 year old Malawi children. They gave the kids 2TBS of RS2 per day for 2-4 weeks and concluded that it just did not help.
The reason these researchers chose RS2 as an intervention? In their words:
Resistant starch (RS) type 2 is present in cereals, tubers, legumes, and fruits. In animal models, consumption of RS improves gut integrity and absorption of nutrients and reduces T cell infiltration of the mucosa. In humans, the consumption of RS changes the composition of the microbiota and promotes the microbial fermentative production of short-chain fatty acids (SCFA), which putatively reduce gastrointestinal inflammation. RS also improves symptoms and reduces pathology in inflammatory bowel disease. In addition, RS meets the criteria for safety, durability, and availability as a dietary intervention to reduce EED [chronic gut inflammation]. Administration of an RS during an acute attack of diarrhea reduces duration of diarrhea in adults with cholera and children. These data compel an examination of RS as an agent to reduce EED.
Indeed, RS2 has been shown to do some seemingly miraculous things that all emanate from the gut.
Why, then, did it not help these young children, severely malnourished, with EED (chronic gut inflammation)?
The intervention diet consisted of "spiking" the kids normal food with about 2TBS of Hi-Maize corn starch (HAMS). A "mandasis" is a donut-like food, these kids typically eat one per week.
During the intervention, the kids were given two mandasis per day for two weeks. They must have been in heaven!
Mandasis ingredients (in case you would like to eat these):
Form dough into ball and fry in soybean oil.
Yum, yum. These sound delicious, although I prefer not to deep-fry my sugar and flour.
The Results (Were they Bad?)
All of the kids had an increase in Lactobacillus, which is normally considered the gold-standard for children's gut health. However, certain markers for gut inflammation did not decrease. Fecal Calprotectin was used as the marker for inflammation. This marker increased slightly, but was "not accompanied by any clinical manifestations."
Changes seen in the gut flora, short-chain fatty acid, pH, and all that were present. Some deemed "good" some deemed "bad." The researchers admit many, many limitations to their study:
Limitations of this study are that fecal sampling on either the habitual diet or after the addition of RS were made at a single point in time. Perhaps a more complete picture of the changes could be seen for a series of samples collected from each subject. No placebo arm was included, so that any temporal changes that occurred during the 4-week study were not controlled for natural changes in the gut microbial composition in this age group. A limitation of the data analyses was that the microbiome before and after consumption of RS was compared with LEfSe, a software that does not account for the paired nature of the specimens. This results in a loss of statistical power to detect differences.
If you ask me, this study is more about WHEAT than resistant starch! These kids' normal diet?:
The children consumed a plant based, predominantly maize diet, with an animal source food.
The "animal source food" was less than 4g per day! These kids were eating almost nothing but CORN prior to the donut orgy the researchers brought to town.
More than likely, these kids were already on a high RS diet, yet severely malnourished and starving for animal nutrients. It's well-known that the corn served in these areas is often as "stale maize porridge" high in RS and normally protective of gut problems for the rural Africans who can manage to stave off malnutrition.
Bottom line, this study replaced a bit of corn with a LOT of flour. Fried in oil, no less.
This study was designed to test an RS intervention on severely malnourished, stunted pre-schoolers. The researchers did a terrible job feeding these kids during the intervention diet. The intervention proved to be not helpful in reducing markers of inflammation.
RS is a great prebiotic! Use Hi-Maize or Raw Potato Starch as a supplement if you feel you need more fermentable fiber in your diet. Just please, not like this: