Is it a good idea to include more carbs in our diets? – If its resistant starch it may well be…
When we talk about carbohydrates, we are often referring to foods high in starch (although non-starchy fruit and vegetables are carbohydrates too). Carbohydrates are a key source of energy for the human body and are broken down to glucose by digestion ready to be used as fuel. Carbohydrates high in starch include grains such as wheat and rice and the foods made from them, bread, cereal, pasta and noodles etc, as well as starchy vegetables like potatoes and pulses such as peas, chickpeas or lentils (which by the way, do not count towards your daily portions of fruit and vegetables).
As its name implies, resistant starch is resistant to digestion in our small intestine. It is found naturally in some foods like unripe bananas and raw potatoes, and cooked pulses have some starch trapped within undigestible parts. However, a third type of resistant starch can be formed by simple food processing.
By processing I do not mean just a factory made ready meal. Simple at home cooking and then cooling causes first the gelatinisation of starch, then the recrystallisation in a different, less digestible way. This remains the case even on re-heating, a phenomena found in cooked and cooled rice, potatoes and pasta. It also occurs after longer term storage of baked bakery items like bread, which is why it becomes hard when stale.
Should we be interested in forming resistant starch especially as it is indigestible? In some cases, it could be helpful e.g. where there is an abundance of calories but not enough fibre in the diet. Despite not being digested, fibre is well known for its health benefits and we should aim for 30 grams of it per day. Resistant starch acts like soluble fibre in the body and it has been shown to slow the rise in blood sugar levels after eating, improve insulin sensitivity and lower cholesterol, which may result in benefits for individuals with diabetes, obesity, heart disease or Alzheimer’s.
Another important role for resistant starch is as food for our friendly gut bacteria (known as our gut microbiota) which is found mainly in the colon. We are learning more and more about how important they are for human health, with studies suggesting they influence diverse health issues such as IBS, mood, hormones, inflammation, immunity and, of particular interest to me, autoimmunity.
One way they contribute to our health is by producing compounds called short chain fatty acids (SCFAs). Butyrate is a SCFA particularly beneficial for colon health and could protect against inflammatory autoimmune diseases like ulcerative colitis, or colon cancer. Other SCFAs like propionate act in the liver to regulate appetite and glucose production, while acetate is used to make cholesterol and other fats.
Therefore eating resistant starch could help develop beneficial gut bacteria and produce more of the key SCFAs.
There is still uncertainty about which types and amounts of resistant starch may have effects, and different people (and their different microbiomes) will respond differently. Supplements of raw potato starch have been produced as an instant shot of resistant starch and food manufacturers are investigating how they can use resistant starch in many of their products.
I always recommend a food first approach to health and consuming your rice, potatoes and pasta cooked and then cooled could be an easy way to add to the fibre in your diet. A word of caution though, always ensure that cooked food is refrigerated and in particular, that rice is cooled rapidly after cooking (e.g. by rinsing in cold running water) to avoid unhealthy bacteria multiplying and producing toxins, then refrigerate for up to 3 days before eating. No point trying to increase your resistant starch intake whilst at the same time giving yourself an upset stomach!
If you would like to discuss your gut health and whether nutritional therapy could support your health goals, contact me for a free exploratory call.
Bello-Perez, L.A., Flores-Silva, E., Agama-Acevedo, J. and Tovar, J., 2021. Starches, resistant starches, the gut microflora and human health
Fasano, A., 2020. All disease begins in the (leaky) gut: Role of zonulin-mediated gut permeability in the pathogenesis of some chronic inflammatory diseases.
Johnston, K.L., Thomas, E.L., Bell, J.D., Frost, G.S. and Robertson, M.D., 2010. Resistant starch improves insulin sensitivity in metabolic syndrome.
MA, Z., N, S., PM, M., M, T., V, G., JL, W., H, S., KD, R., DH, M. and K, L., 2012. Butyrate suppresses colonic inflammation through HDAC1-dependent Fas upregulation and Fas-mediated apoptosis of T cells.
Valdes, A.M., 2018. Role of the gut microbiota in nutrition and health.