Starch is one of the most abundant foods in the world and has been a primary food component in every diet known to man and beast. As our food is processed, however, the starch in our diets became more easily digestible and contains much less resistant starch and dietary fiber.
Most raw starch in plants resists digestion because the plant cell walls and/or hulls slows down the enzymes digesting the starch. This type of starch is known as “resistant starch”, (abbreviated as RS). Once you cook plants, however, the plant structure breaks down and the starch becomes rapidly digestible – it will break down to glucose very quickly in your digestive tract. For instance, foods that are highly processed (think instant oats) will turn into glucose very quickly, but steel cut oats (which need to be cooked for 20 minutes) contain much more resistant starch and are digested more slowly.
Resistant starch does not release glucose. It is eaten by the good bacteria in the large intestine. Historically, we thought that not much happened in the large intestine, but recently, we have discovered that the bacteria in our gut contributes not only to healthy digestion, but also to our immune system, brain function and every other aspect of our metabolism. If we are not feeding them fermentable fibers like resistant starch, they are starving and trigger can be harmful effects. If, however, you eat resistant starch and other types of fermentable fibers, the short-chain fatty acids produced by the bacteria are used as energy and trigger improvements in the same important metabolic pathways.
Here are the top 27 Science-Based Health Benefits of Resistant Starch:
1. Improved regularity
Resistant starch increases regularity. On average, every gram of resistant starch consumed increased fecal output by 1.1 gram, primarily from increased bacteria.Wheat bran or psyllium increase bulking by 3 or 4 grams/gram of fiber consumed, primarily because these fibers work by absorbing water. They are not fermented or are minimally fermented and they do not feed the good bacteria. If you only want regularity, use wheat bran or psyllium, but if you want the metabolism benefits, you need resistant starch.
2. Helps keep colon tissue healthy
Resistant starch helped to heal intestinal inflammation and leaky gut in animal models. Reference Reference
Resistant starch fermentation in the large intestine increases the short-chain fatty acid butyrate, which is the preferred food for healthy colon cells. Reference
Butyrate has a regulatory role in fluid transport, mucosal inflammation and oxidative status, reinforcing the epithelial defense barrier and modulating intestinal motility. Lack of butyrate may contribute to the development of colitis and/or colorectal cancer. Reference
Resistant starch also reduced ammonia and phenolic compounds, which are potentially harmful byproducts of protein fermentation. Reference
3. Prebiotic – promotes healthy and balanced gut microbiome
Resistant starch is broken down in the large intestine by a wide variety of bacteria. Many type of beneficial bacteria are increased, including Bifidobacteria, Lactobacillus, Ruminococcus, Faecalibacterium prausnitzii and others. Reference
4. Low calories
Resistant starch delivered an average of 2.8 kilocalories/gram in healthy people and even less in people with insulin resistance. Digestible starch and sugar delivers 4.0 kilocalories/gram. Reference
5. Low glycemic response
Resistant starch does not release glucose in the small intestine and does not contribute to the glycemic response of foods. When it substitutes for flour in foods, the glycemic response of that food is reduced. Reference
6. Improves insulin sensitivity & reduces risk of developing type 2 diabetes
Fifteen to thirty grams of resistant starch/day increases insulin sensitivity in both men and women, especially in people with low insulin sensitivity (also called insulin resistance). Reference
Loss of insulin sensitivity is the major biomarker for the development of type 2 diabetes. Increasing insulin sensitivity helps to reverse prediabetes.
7. Increases glucose uptake into muscles
Forty grams of resistant starch/day increased glucose uptake into muscles by 65% in insulin resistant adults. This was a direct result of increased insulin sensitivity. Reference
8. Helps burn fat and shifts metabolism to help you lose weight
Forty grams of resistant starch/day also reduced circulating non-esterified fatty acids (NEFA), reduced triglyceride storage in muscle, increased uptake of SCFAs into both muscle and adipose tissue, and increased fat oxidation. Reference
One study found that only 5 grams of resistant starch/day significantly increased fat oxidation (measured by Respiratory Quotient) in healthy adults. Reference
9. Improves first phase insulin response
Forty grams of resistant starch/day increased first-phase insulin release in overweight adults at risk of developing type 2 diabetes. Reference
Loss of first-phase insulin secretion is a defect in the development of type 2 diabetes.
10. Reduces triglycerides
Several studies have reported reduction in triglycerides in healthy adults and in adults with type 2 diabetes. Reference
11. Improves endothelial function
In patients with insulin resistance, or newly diagnosed type 2 diabetes, resistant starch improved endothelial function, as measured by RH-PAT index (a measure of peripheral microvascular endothelial function), and serum total nitric oxide. This may assist in preventing atheriosclerosis beyond improved blood sugar control. Reference
12. Reduces fat deposits in the liver
Animal studies show that resistant starch modulates lipid metabolism in the liver by decreasing fatty acid synthesis and increasing lipid oxidation, as well as improving other aspects of liver dyslipidemia. Reference
13. Stops diarrhea
Resistant starch helped to reduce diarrhea when given to individuals with diarrhea from cholera, rotavirus and other diarrheal diseases. Reference
14. Helps treat people with glycogen storage disease
People with glycogen-storage disease have a genetic mutation that interferes with the production of glucose from glycogen. Consequently, they require a consistent consumption or infusion of glucose to maintain normal metabolism. This is particularly problematic throughout the night. Raw cornstarch contains a significant percentage of slowly-digestible and resistant starch and has been shown to help maintain normal blood glucose levels in infants and adults with glycogen storage disease. It helps them get them through the night without having to wake up and eat. Reference
15. Helps protect probiotics through digestion so that they reach the colon
Resistant starch helps to protect probiotic bacteria, such that they reach the large intestine in greater numbers and higher viability than probiotics delivered without resistant starch. Reference
16. Increases mineral absorption and promotes healthy bones, especially during weight cycling
Resistant starch increased calcium and iron absorption compared with a digestible starch in animals. Reference
In addition, resistant starch increased femur bone mineral density and femur bone mineral content as well as increased femur calcium and magnesium concentrations in animals that had repeatedly gained and lost weight. Reference
17. Helps to reduce hunger within a few hours
18. Helps to reduce hunger the next day
Resistant starch delivered in breads for dinner, increased satiety the next day in healthy adults. The authors suggested that resistant starch’s fermentation effects would likely be the primary driver for this delayed benefit, as satiety hormones generated in the intestines were also increased. Reference
19. Improves glycemic control in newborn babies when consumed by the prediabetic pregnant mothers
When pregnant rats with an increased risk of diabetes were fed resistant starch, the mothers had better glycemic control including improved insulin sensitivity and improved pancreatic beta-cell density. In addition, the offspring had lower fasting glucose levels, which suggests reduced risk for developing type 2 diabetes in their lifetime. Reference
20. Helps protect the eyes and may reduce the development of macular degeneration
Three animal studies have shown that resistant starch reduced the development of retinal lesions and other advanced glycation end (AGE) products that precede age-related macular degeneration. Reference
. The controls in these studies were high glycemic starch.
21. Helps kidney health and function
Resistant starch lowered indoxyl sulfate and possibly p-cresol in the blood of dialysis patients with Chronic Kidney Disease. Reference
These compounds are bound to plasma proteins and are not cleared by dialysis but build up to toxic levels in the blood. Resistant starch’s bacteria-promoting fermentation (which requires nitrogen) in the large intestine provides an alternative mechanism to dispose of nitrogen without requiring processing by the kidneys. Animal studies have also shown this benefit. Reference
In addition, resistant starch lowered inflammation and oxidative biomarkers in hemodialysis patients, further confirming improved kidney health. Iranian Reference, Brazilian Reference A good 2017 review article on this topic was published by Koh and Rowling in Nutrition Reviews.
22. Improves Vitamin D metabolism in the kidneys
Two animal studies have shown that resistant starch protected the kidneys from diabetes-related damage and increased the re-absorption of Vitamin D within the kidneys, significantly increasing serum levels of Vitamin D (25-hydroxycholecalciferol). Reference
23. May reduce the risk of some types of cancer
A recent study switched the diets of South Africans, who consume a lot of resistant starch and low fat, with black African Americans living in Pennsylvania, for two weeks. After adding resistant starch and reducing fat, the African Americans had significantly lower mucosal biomarkers for cancer risk and improvements in microbiota and pathways known to affect cancer risk. The South Africans had exactly the opposite effects after eating a typical American diet, with increased risk of colorectal cancer. Reference
24. May help to manage some gastrointestinal diseases
Foods naturally rich in resistant starch were found to be beneficial in individuals with ulcerative colitis. Reference
One study found that the combination of wheat bran and resistant starch tended to normalize gut transit in adults with ulcerative colitis. However, the abnormal functioning of the gut microbiota in these individuals was not corrected in this 8-week study. Reference
25. RS is anti-aging and has potential for improving healthspan
Resistant starch shifted the microbiota of old mice to look like that of younger mice (and humans): i.e., more diverse and increased levels of beneficial bacteria. In addition, resistant starch improved motor coordination of old mice and restored appetite and nutrient sensing behavior commonly reduced in the elderly. Reference
26. Helps protect offspring against the development of asthma when consumed by their pregnant mothers
A high resistant starch diet fed to pregnant mice protected the offspring against developing allergic airways disease (AAD), a model for human asthma, later in life. It was suggested that resistant starch’s fermentation, producing high levels of the short-chain fatty acid, acetate, imprinted on the fetal lung cells, enhancing the number of T-regulatory cells and reducing the expression of certain genes linked to both human asthma and mouse AAD. Reference
27. Increases H2 gas, which functions as an antioxidant
Resistant starch reduced oxidative stress in people with prediabetes or newly diagnosed type 2 diabetes. Reference
In addition, resistant starch prevented liver damage caused by oxidative stress in animals. Reference
Resistant starch is insoluble and is slowly fermented in the large intestines. Some people experience mild gas and flatulence after adding resistant starch to their diet (especially as a supplement). It is recommended that you ramp up addition of resistant starch in your diet, beginning with lower doses and increasing over time to give yourself time to adjust. The gas effect may go away as the microbiota shifts to more beneficial bacteria. There have not been reports of other types of digestive side effects. Tolerance studies have also showed that people could consume up to 45 grams of resistant starch/day before the increase in gas was statistically significant.
Everybody can benefit from increased resistant starch from either food sources or supplements. Lower levels will assist in increasing regularity and maintaining health. If, however, you want an improvement in a specific health condition, doses of 20 grams or more/day are generally needed, which are really difficult to get through food sources. For these purposes, supplementation may be more effective.
Under-ripe bananas, beans and intact whole grains are relatively good food sources of resistant starch. Barilla’s High Fiber White Pasta is also a good option, with 6 grams of fiber (about 4 grams comes from RS) per serving. For more food options, click here.
Several supplements are also available, which can be blended into smoothies, mixed into oatmeal or sprinkled onto cereal. RS Complete, made with green banana resistant starch and resistant potato starch, is a great product and is available from Dr. Alan Christianson. MS Prebiotic sells raw potato starch. Bob’s Red Mill also sells raw potato starch but does not certify or claim how much resistant starch is in this product. Hi-maize resistant corn starch is available from King Arthur Flour or from Honeyville Grain.
I use green banana resistant starch because it has the highest levels of resistant starch, is a whole food and less processed. Hi-maize is also useful because it can replace a portion of flour in baked goods without losing its resistance – it gets baked into every cookie, pancake, cake or muffin that I have made for years. I’m not going to stop eating baked goods, especially if they are better-for-you versions of my favorite recipes.
However you choose to add resistant starch to your diet and for whatever reason, it’s all good!
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