20 Jul, 2021
Explaining our hesitation and ultimate decision on including resistant starches in our Acceptable Ingredients list
At Certified Ketogenic, we believe in the mandate "First, Do No Harm" when it comes to our recommendations. We wait for peer reviewed studies to be available on new sweeteners, and we update our certification specifications when human trials have been conducted to our satisfaction, such as with the sweetener allulose.
Resistant starches, like the sweetener allulose, seemed too good to be true when they were first recommended as a way to improve insulin sensitivity. Why would potato starch be okay if a baked potato is not? If eating starch breaks those molecules down to form glucose, why would a green banana be any different than a ripe one? And if we at Certified Ketogenic approved potato starch, did that risk opening the floodgates on a range of products that squeaked by with the help of resistant starches but in such quantities, or through improper preparation, that their quality might be less than ideal for the ketogenic diet and lifestyle?
We believe that the ketogenic diet and lifestyle, when well-formed, promotes health as well as weight-loss. Often we find that when someone says 'the keto diet doesn't work'—if we are able to take a peek under the hood at what these judgements were based on—the diet itself did not adhere to true ketogenic guidelines. Thanks to industry adoption of the keto buzzword, popularity easily outpaces education. Many practitioners fall prey to believing that "If It Fits Your Macros" approaches, prepared foods made with rice or potato flours or coconut or agave sugars, or asparatame-laden diet sodas can be part of a successful keto diet. No wonder people blame the diet when their success is short-lived, unsustainable, or otherwise fails to live up to the hype.
Resistant starch is one that resists being digested, passing through the small intestine unchanged and only beginning to ferment (feed our gut microbiome) in the colon. Like insoluble fiber, studies show that resistant starches have a minimal impact on your blood glucose levels. The classification of resistant starch mandates how it should be prepared in order to take advantage of its molecular structure.
- Type 1 is contained within its cell structure in its 'raw' form (e.g., legumes, seeds, and grains). When processed or milled, it can be converted to glucose like normal starch.
- Type 2 has a molecular structure that is harder for digestive enzymes to access (e.g., unripe bananas, raw potatoes, and lentils). When prepared with heat, it becomes a normal starch that can be easily converted to glucose.
- Type 3 are produced when certain foods (e.g., rice and potatoes) are heated to a paste (gelatinized) and then cooled (retrogradized) before eating. Heating them again does not negate the effect.
- Type 4 is an artificial resistant starch created using chemical processes to create a starch molecule that is resistant to digestion.
- Type 5 starches are manufactured by heating and cooling certain starches in combination with certain fats, creating molecules that are more resistant to digestion.
Our product review process now evaluates the type of starch based on which category it is and how it is treated to make the products in question. We won’t approve a product if they’ve been prepared in a way that negates the included starches’ beneficial structures.
Please note this analysis specifically refers to starches in foods only, not to the whole food which may contain so many natural sugars and/or carbs as to offset the potential benefit of any naturally occurring resistant starch to a ketogenic diet and lifestyle.
Having made this decision, though, we wish to remind ketogenic dieters that not all fiber has a null effect on your blood sugar and 'net' carbs may allow you to lull yourself into a false sense of having 'followed the guidelines.' If you choose to introduce resistant starches into your keto diet and lifestyle, we recommend keeping a food log, tracking total as well as net carbs, and be prepared to adjust if you find things are having a negative overall impact on your path to ketogenic success. As with any new food, introduce these supplemental starches slowly into your diet to minimize digestive discomfort as you acclimate to the food(s).
A non-exhaustive collection of research on this subject:
- Short-Chain Fatty Acids and Human Colonic Function: Roles of Resistant Starch and Nonstarch Polysaccharides - Topping, Clifton - July 2001
- Consumption of Both Resistant Starch and β-Glucan Improves Postprandial Plasma Glucose and Insulin in Women - Behall, Scholfield, Hallfrisch, Liljeberg-Elmståhl - May 2006
- Resistant Starch—A Review - Sajilata, Singhal, Kulkarni - November 2006
- Sources and intake of resistant starch in the Chinese diet - Chen, Liu, Qin, Meng, Zhang, Wang, Xu - February 2010
- Resistant starch improves insulin sensitivity in metabolic syndrome - Johnston, Thomas, Bell, Frost, Robertson - April 2010
- Starch with High Amylose and Low in Vitro Digestibility Increases Short-Chain Fatty Acid Absorption, Reduces Peak Insulin Secretion, and Modulates Incretin Secretion in Pigs - Regmi, van Kempen, Matte, Zijlstra - January 2011
- Resistant Starch from High-Amylose Maize Increases Insulin Sensitivity in Overweight and Obese Men - Maki, Pelkman, Finocchiaro, Kelley, Lawless, Schild, Rains - February 2012
- Insulin-sensitizing effects on muscle and adipose tissue after dietary fiber intake in men and women with metabolic syndrome - Robertson, Wright, Loizon, Debard, Vidal, Shojaee-Moradie, Russell-Jones, Umpleby - June 2012
- Resistant starch: a promising dietary agent for the prevention/treatment of inflammatory bowel disease and bowel cancer - Higgins, Brown - March 2013
- Starch Retrogradation: A Comprehensive Review - Wang, Li, Copeland, Niu, Wang - July 2015
- Effects of Arabinoxylan and Resistant Starch on Intestinal Microbiota and Short-Chain Fatty Acids in Subjects with Metabolic Syndrome: A Randomised Crossover Study -
Hald, Schioldan, Moore, Dige, Lærke, Agnholt, Knudsen, Hermansen, Marco, Gregersen, Dahlerup - July 2016
- Health effects of resistant starch - Lockyer, Nugent - January 2017
- Usual Dietary Intake of Resistant Starch in US Adults from NHANES 2015–2016 - Miketinas, Shankar, Maiya, Patterson - October 2020