Resistant starch diet induces change in the swine microbiome and a predominance of beneficial bacterial populations
In this study, researchers compared the prebiotic effect of alginates and RS3. Alginates are a class of fiber derived from certain seaweed that are shown to be beneficial. The RS3 was from tapioca, as found in a product called ActiStar, used by food manufacturers to increase fiber contents in food. It's made my repeatedly heating and cooling tapioca starch in a controlled fashion until the starch has retrograded (crystallized) turning into RS3...I doubt you could make this at home, and it does not seem to be readily available for consumer purchase.
What the study found was that the gut bacteria of the pigs fed RS3 were of a much favorable profile over pigs fed alginate or a control diet, although alginate did have some good effect.
In conclusion, RS exhibited the strongest structural variation compared to ALG, which is likely resultant from the contrasting physicochemical properties of these dietary fibers. The increase in relative abundance of Lachnospiraceae-, Prevotella -and Ruminococcus - affiliated phylotypes in RS pigs can be considered as desirable traits given the reputation of these groups in fiber degradation and production of short chain fatty acids. Moreover, resistant starch and to a lesser extent alginate, influenced the imputed functionality of predicted metagenomes and correlation between bacterial phylotypes and PCWCs.
PCWCs are Plant Cell Wall Components, and what the researchers saw was that the pigs fed RS were better able to utilize all of the parts of the plant, ie. diverse fibers like cellulose, pectin, and xylan. The takeaway from this paper is that once again, RS3 is shown to be a great prebiotic. While we may not have access to ActiStar, we can get ample RS3 just by pre-cooking, then cooling, our beans, rice, and potatoes. Eat them with corn tortillas for bonus points!
Green banana flour
Resistant starch: a functional food that prevents DNA damage and chemical carcinogenesis.
This paper is from a university in Brazil examining the effects of RS on cancer causing foods. Brazil seems to have plenty of both (RS and cancer) and hope they can use one to fight the other.
Here we see researchers giving rats a chemical that is nearly guaranteed to cause cancer. The rats are injected with 1,2-dimethylhydrazine, a chemical with the sole purpose of causing cancer in lab animals.
Some of the rats injected with this powerful carcinogen were fed green banana flour and others regular rat food. As you can guess, the rats getting the green banana flour fared much better. The researchers were actually very surprised at how much better, though.
A reminder of what RS is all about, (from the paper):
Studies suggest that diets containing prebiotics such as resistant starch plays a significant role in preventing colorectal cancer due to the high potential antigenotoxic, antimutagenic, and anticarcinogenic activities of these compounds. According to Champ and Faisant (1996), resistant starch is the starch fraction that provides no glucose to the body. However, resistant starch is fermented in the large intestine mainly to produce gases and short-chain fatty acids. The activities of resistant starch, as well as the effects observed in this study, are attributable to these characteristics.
This is maybe the first paper I've seen where they looked for the ability of RS to lessen a carcinogen's effect. Chemical carcinogens, such as pesticides and industrial contaminates that may find there way into our food supply, have shown to damage DNA (genotoxicity), mutate cells (mutagenicity), and cause cancer (carcinogenicity). The chemical they gave these rats is known to interact with DNA to cause cancer.
...we concluded that green banana flour may be an important food compound with cancer-preventing activity. Thus, including green banana flour in the daily diet of the general population could prevent genome damage associated with cancer development or even prevent cancer development. Even if cancer is already present in the body, the continual intake of this food supplement could be beneficial.
The researchers gave several reasons why green banana flour works so well, and mainly attribute the effects to the RS content, such as improved pH, more butyrate, and more rapid cell turnover in a healthy gut. They concluded their study with:
In carcinogenesis, resistant starch is believed to reduce the incidence of cancer biomarkers and improve disease prognosis by minimizing the number of biomarkers that develop into tumors. Thus, resistant starch has therapeutic properties that could be exploited in human dietary applications.
Unlike the first study that used RS3 from tapioca (ActiStarc), this research used a much more achievable RS source. The simply took green bananas, dipped them in hypochlorite and citric acid, then sliced 1cm thick and dried in an oven at 122 deg F (50C) for 72 hours. After drying, they ground the dried bananas into a flour.
This is easily do-able at home. The hypochlorite and citric acid steps are unneeded, these steps are used to disinfect and prevent oxidation...it was probably just done to provide a pure sample to the lab rats. I have been making a similar thing for several years now. I take very green plantain bananas and slice them thinly and air dry in the sun or in a very low heat oven. If you heat them above about 135 degrees, you will destroy the RS, so keep the heat low. A fan directed at them works great, too.
I just eat the dried plantains like crackers. They are crunchy and sort of tasteless, but good for mindless eating.
Here's some pictures of my green plaintains:
See? Too easy! Now you know how to do it and that they are good for you, so what's your excuse? And also remember to cool those starches after you cook them for maximum RS3.