Why is resistant starch such an interesting dietary ingredient?
It is said to be a natural prebiotic, which means that it boosts the growth and richness of your intestinal microbiota. It also protects the colon against cancer, nourishes the intestinal cells, reduces the risk of inflammation in this area, and lowers blood sugar and ‘bad’ cholesterol levels.
A healthy intestine means a healthy and strong body so obviously resistant starch is an ingredient that you should include in your everyday diet. But before we get into that, just a few words about its sources.
Resistant starch varieties and types
Starch is a complex carbohydrate, one of the key components of your diet. It occurs in cereal products and vegetables: potatoes, sweet potatoes, legumes, but curiously enough, only after these are cooled and/or refrigerated. ‘Regular’ starch is digested in the small intestine and then broken down into glucose, whereas resistant starch is not affected by digestive enzymes.
There are four types of resistant starch:
- physically unreachable starch (RS1)
Occurring in whole or partly milled grains and in cooked legumes, it is surrounded by other substances that block the access of digestive enzymes.
- raw starch grains (RS2)
Escaping digestion due to its structure, it is found in raw products such as potatoes, cereals and unripe bananas.
- retrograded starch grains (RS3)
First cooked and then cooled, this type of starch takes a crystalline form. It is found in cooked and then cooled starchy foods (such as potatoes).
- chemically obtained starch (RS4)
With its structure modified by chemical processes, it is present in thickeners, etc.
Benefits of resistant starch
As mentioned above, resistant starch has a highly beneficial effect on the intestinal microbiome and reduces the risk of colorectal cancer and inflammation. It also regulates the frequency of bowel movements and helps with constipation.
In addition, starch has a great effect on immunity (for which intestines are crucial), reduces the risk of gall bladder stones, enhances the absorption of calcium and iron, slows down the absorption of glucose into the blood, lowers the glycemic index of products (if cooled), and as a result of lower insulin secretion, reduces body fat.
How much resistant starch should be eaten per day?
An average of 6 g per meal, with a maximum of 14 g throughout the day.
What influences the formation of resistant starch?
It all depends on its structure: amylose turns into resistant starch quickly and at higher temperatures, whereas amylopectin is slightly more resistant and needs lower temperatures. What does it mean? Different foods cooked and cooled in the same way will have their GI reduced in different ways.
The formation of resistant starch depends on various processes: cooling, but also prolonged heating. Resistant starch can also be found in stale bread.
This being the case, what cooked products should be eaten cooled? Certainly potatoes and legumes, which should first be left to cool completely and then put in a fridge. When it comes to cereal products, cooling them to room temperature will be enough.
Resistant starch in products
g/100 g | Glycemic index
- Buckwheat 1.8 | 51
- White bread 1.2 | 69
- Wholemeal bread 1.0 | 72
- Brown rice 1.7 | 66
- White rice 1.2 | 72
- White spaghetti pasta 1.1 | 50
- Corn flakes 3.2 | 80
- Oatmeal 0.2 | 49
- Broad beans 1.2 | 79
- Potatoes 1.3 | 80
- Sweet potatoes 0.7 | 48
- Corn 0.3 | 59
- Cooked beans 1.2 | 40
- Cooked lentils 3.4 | 29
Resistant starch in athletes’ diet – does it make sense?
Professional athletes tend to avoid dietary fiber and resistant starch so as to make the digestive process as light as possible and reduce bodily distress during exercise. On the other hand, the high-protein diets they tend to use may have an adverse effect on the gut microbiota, which means that the diet of professional sportspersons must be constantly monitored by nutritionists.
However, if you train as an amateur, both fibre and resistant starch can only benefit your health (unless there are any dietary contraindications, which you should consult with a specialist).
Resistant starch and losing weight
Finally, you will probably find this interesting: a scientific study has found that combining resistant starch and protein accelerates fat oxidation and enhances the feeling of fullness. This was tested on a group of 70 women who were served pancakes with the addition of resistant starch. So if you care about your body shape or want to lose weight, this topic is something that should grab your attention. All the more so that lowering the GI of food products is crucially important when you are on a weight loss diet.
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References:
1. Birt DF, Boylston T, Hendrich S, Jane JL, Hollis J, Li L, McClelland J, Moore S, Phillips GJ, Rowling M, Schalinske K, Scott MP, Whitley EM. Resistant starch: promise for improving human health. Adv Nutr. 2013 Nov 6;4(6):587-601. doi: 10.3945/an.113.004325. PMID: 24228189; PMCID: PMC3823506.
2. Jang LG, Choi G, Kim SW, Kim BY, Lee S, Park H. The combination of sport and sport-specific diet is associated with characteristics of gut microbiota: an observational study. J Int Soc Sports Nutr. 2019 May 3;16(1):21. doi: 10.1186/s12970-019-0290-y. PMID: 31053143; PMCID: PMC6500072.
3. Gentile CL, Ward E, Holst JJ, Astrup A, Ormsbee MJ, Connelly S, Arciero PJ. Resistant starch and protein intake enhances fat oxidation and feelings of fullness in lean and overweight/obese women. Nutr J. 2015 Oct 29;14:113. doi: 10.1186/s12937-015-0104-2. PMID: 26514213; PMCID: PMC4627411.