Examine publishes rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies each month, available to all Examine Members. Click here to learn more or log in.
Study under review: Positive effects of resistant starch supplementation on bowel function in healthy adults: a systematic review and meta-analysis of randomized controlled trials
Introduction
Resistant starch has become a popular topic over the last decade for its proposed health benefits as a fiber and for its potential as a functional food ingredient. As the name alludes, resistant starch is defined as a portion of starch that cannot be digested by human enzymes (it resists digestion), instead entering the large intestine to feed the microbiome.
There are currently five known types of resistant starch (shown in Table 1), which are briefly summarized in the table below and addressed in more detail in the FAQ section. All resistant starches act as a prebiotic fiber (which feeds the microbiome) and have been shown to facilitate a diverse and healthy microbiome. Additionally, resistant starch has been shown to increase the production of short-chain fatty acids within the colon, which may have anti-cancer effects and promote the growth of healthy colon tissue.
| Designation | Description | Example |
|---|---|---|
| Resistant starch type-I | Physically inaccessible starch | Coarsely ground or whole-kernel cereal grains |
| Resistant starch type-II | Native (uncooked) amylose starch | Raw potatoes or green bananas |
| Resistant starch type-III | Retrograde starch | Cooked and cooled starchy foods such as potatoes or rice |
| Resistant starch type-IV | Chemically modified starch | Various synthetic starches; not found in nature |
| Resistant starch type-V | Amylose-lipid complex | High-amylose starches cooked in the presence of fat, such as stir-fried rice |
Composition, consistency, frequency, and weight of bowel movements have been proposed as key indicators of bowel function and digestive health. Despite a logical basis to suggest that consuming resistant starch would benefit bowel function, data from healthy humans is scarce and conflicting. For instance, two studies[1] have shown that resistant starch supplementation significantly increases fecal weight while another[2] reported a non-significant decrease.
To consolidate the currently available evidence, the current study performed a meta-analysis investigating how resistant starch supplementation affects bowel function in healthy adults.
Resistant starch is a type of fiber that has been suggested to have numerous health benefits for the gut and systemically. The current study was a meta-analysis of human trials investigating how resistant starch supplementation impacted bowel function.
Who and what was studied?
What were the findings?
What does the study really tell us?
The big picture
Frequently Asked Questions
What should I know?
Other Articles in Issue #27 (January 2017)
-
Low-carbing for endurance: the oxygen problem
You might have seen more low-carb endurance athletes popping up in the past few years. This trial tested a ketogenic diet in world-class athletes, compared to two different carb regimens.
-
Can giving infants egg powder prevent allergies?
We've previously covered ground-breaking research on preventing peanut allergies in infants. This new study takes the same basic idea, and tests it with egg introduction and development of allergies.
-
Boost your immune system with … fiber?
Eat your veggies: the oldest dietary advice in the book. But what happens when you don't eat veggies, or any fiber? This rodent study looks into what might happen to your gut.
-
Interview: Melanie Jay MD, MS
Everyone knows obesity is a major public health issue, but what are the best ways for primary care doctors to treat it? Melanie is a researcher who studies these issues in depth.
-
A non-traditional use for probiotics: illness in athletes
With the gut being so important for immune health, it's no surprise that trials are starting to look at probiotics for common illnesses. This one looked at a probiotic blend to help combat colds and related conditions.
-
Milking more benefit from dairy: A2 milk and glutathione
We’ve written about A2 milk before, comparing it to A1/A2 milk for GI symptoms. Turns out that the powerful antioxidant glutathione may also be affected by which milk you drink
-
Interview: Deanna Busteed MS, RDN, CSSD
As a performance nutritionist at a large university, Deanna tells us about practical aspects of implementing nutrition advice for athletes.
