With the rise and rise of low carb diets you might be surprised to learn about the growing popularity of Resistant Starch foods and supplements.
So what exactly is Resistant Starch and why is it suddenly so popular?
Read on to learn:
- What exactly is Resistant Starch
- Why it is so special
- What are the different types of Resistant Starch
- Where it is found
What exactly is Resistant Starch
Resistant starch is – as its name suggests, a type of starch – consisting of long chains of glucose. It can be found in various foods such as grains, potatoes, fruit and vegetables. However unlike most starchy foods which are broken down in our small intestines to sugars and quickly absorbed into our blood, resistant starches resist digestion and pass through our intestines to reach our colon undigested where they behave in a similar way to soluble fibre.
Along with plant fibre, it used to be a staple part of our diet – however the way we process cereals, grains and starchy vegetables in the food industry means the amount we consume has reduced significantly.
Why is Resistant Starch So Special?
Resistant Starch is special for a number of reasons:
1. It feeds our ‘Good’ gut bacteria
Resistant starch behaves in a similar way to soluble fibre – when it reaches our colon at the end of our large intestine it feeds our friendly gut bacteria – where it is fermented and broken down into short-chain fatty acids – such as butyrate resulting in some unique health benefits. It also has several beneficial effects on the colon.
By feeding and helping our good gut bacteria thrive – RS helps to promote a balanced gut -and increased diversity of gut bacteria – which in turn helps control the growth of pathogens and undersirable strains and species of bacteria associated with obesity, diabetes and chronic disease.
2. It helps us stay lean
We extract less energy from raw and unprocessed foods through digestion than we do from refined and processed foods – so while a plate of wholegrain and a plate processed foods may contain the same amount of calories, we digest and absorb fewer of the available calories from whole foods than we would from processed & refined foods.
As Resistant Starch is only partly digested, we typically extract half the number of calories of energy per gram than we do from other carbohydrates. What is more foods high in resistant starches tend to full us up more quickly leading us to eat less.
3. It increases insulin sensitivity
RS doesn’t digest into blood sugar, which means our bodies don’t release much insulin in response.
RS might also improve insulin sensitivity via alterations in fatty acid flux between muscle and fat cells. Some data indicate that ghrelin might increase with RS consumption, improving insulin sensitivity (this is counterintuitive since ghrelin drives appetite). RS may also lower blood fats (see above), which also improves insulin sensitivity.
Several studies show that it can improve insulin sensitivity, as in how well the body’s cells respond to insulin (24).Resistant starch is also very effective at lowering blood sugar levels after meals (25, 26, 27).
It also has a “second meal effect” – meaning that if you eat resistant starch with breakfast, it will also lower the blood sugar spike at lunch (28). The effect on glucose and insulin metabolism is very impressive. Some studies have found a 33-50% improvement in insulin sensitivity after 4 weeks of consuming 15-30 grams per day (29, 30).
The importance of insulin sensitivity cannot be stressed enough. Having low insulin sensitivity (insulin resistance) is believed to be a major causal factor in some of the world’s most serious diseases, including metabolic syndrome, type 2 diabetes, obesity, cardiovascular disease and Alzheimer’s Disease. By improving insulin sensitivity and lowering blood sugar, resistant starch may help you avoid chronic disease and may make you live both longer and better.
4. It helps lower blood cholesterol
RS may help to lower blood cholesterol and fats, while also decreasing the production of new fat cells (the latter has only been shown in rats). Also, since SCFAs can inhibit the breakdown of carbohydrates in the liver, RS can increase the amount of fat we use for energy.
5. It helps to treat leaky gut and irritable bowel syndrome
Butyrate, and other short-chain fatty acids produced by the fermentation of Resistant Starch in the colon have a remarkable effect on reducing intestinal permeability or ‘leaky gut’ and resulting symptoms of IBS and ulcerative colitis. Butyrate and other short-chain fatty acids play an important role in keeping our gut wall healthy and preventing unwanted pathogens or particles passing into our bloodstream – which is associated with inflammation, autoimmune responses and many diseases, including fatty liver, heart failure and autoimmune diseases such as allergies, asthma, MS and Parkinsons to name a few.
6. It helps reduce the risk of Colon Cancer
It reduces the pH level, potently reduces inflammation and intestinal permeability (leaky gut) leads to several beneficial changes that should lower the risk of colorectal cancer, which is the 4th most common cause of cancer death worldwide
What are the different types of Resistant Starch
Not all resistant starches are the same. There are 4 different types of resistant starch. The preparation method has a major effect on the ultimate amount of resistant starch in food.
For example, allowing a banana to ripen (turn yellow) will degrade the resistant starches and turn them into regular starches.
- Type 1
Found in grains, seeds and legumes and resists digestion because it is bound within the fibrous cell walls. Cannot be broken down by digestive enzymes
- Type 2
Intrinsically resistant to digestion and contains high amounts of amylose. Found in: fruits, potatoes, hi-maize RS products, corn, some legumes. Note: the more “raw” or “uncooked” a food is, the more RS it tends to have, since heat results in gelatinization of starch – making it more accessible to digestion.
- Type 3
In contrast to Type 2 Resistant Starches, Type 3 RS can be created when certain starchy foods such as pasta, potatoes and rice are cooked and cooled. Through this process the starch changes in composition, increasing its resistance to digestion. Studies have found that even when reheating previously cooked starchy foods the composition of resistant starch increases
- Type 4
Companies have isolated RS (usually from corn) to include it in processed foods (e.g., breads, crackers, etc.).This is not naturally occurring RS — it’s produced mostly via chemical modification, and it’s found in synthetic and commercialized RS products, such as “Hi-Maize Resistant Starch”.
How much Resistant Starch should you consume?
Resistant Starch is considered safe recommended for consumption of up to 40-45 grams per day. More than this might may result in discomfort or bloating, if your body and gut bacteria are not such quantities/
How we respond to RS varies by the type. One might notice more side effects when consuming RS3 (versus RS1, RS2, RS4). Our ability to ferment RS can increase over time, making it possible to adapt to a higher RS intake.
RS seems to be tolerated best when:
- It’s in solid food form (rather than liquid)
- It’s consumed as part of a mixed meal (rather than alone)
- Consumption is increased gradually over time (rather than a lot at once)
What are the best sources of Resistant Starch?
Here’s an idea how much RS is found in common foods. Note: these are average values and will vary.
Summary and recommendations
We absorb more energy (calories) from cooked and highly refined and processed carbohydrate dense foods. If we let machines and ovens do the digestion for us, we are left with highly digestible starches. Not good for glucose control, staying lean, or intestinal health.
Various cultures thrive and stay lean when eating whole unprocessed legumes, intact grains and starchy vegetables. RS may be one factor that enables this.
We might see some benefits from as little as 6-12 grams/day of RS, but closer to 20 grams/day might be ideal. This is easy to get if you eat plenty of whole plant foods.
More than 40 grams/day might cause digestive problems — especially if this RS comes from industrially produced RS products. In any case, we probably don’t get the same benefits of RS if it’s processed (i.e. an industrially created RS product) as we do from whole foods.