Healthy Metabolism

Resistant starch has many benefits – it’s hard to break it down and isolate just one benefit.  There is an entire cascade of effects – you cannot stop with just one. Depending upon the underlying metabolic condition, individuals may experience different benefits following consumption of resistant starch.  The good news is that with resistant starch, you get any or all of these benefits.  Here is a breakdown of this cascade into understandable pieces:

  1. Resistant starch is low glycemic. It does not break down in the small intestine into glucose and does not trigger a release of insulin.  People following Paleo or Ketogenic diets often stop here and don’t realize the more powerful metabolic benefits behind resistant starch.
  2. Resistant starch is prebiotic. It feeds the microbiome and shifts the entire microbiome toward a healthier balance.  It seems to be initially broken down by Ruminococcus bromii, but the fragments then feed lots of beneficial bacteria, including Bifidobacterium, Akkermansia muciniphila, Faecalibacterium prausnitzii and Lactobacillus.  Unlike probiotics, which may change one bacteria, resistant starch changes the entire microbiome. Animal studies suggest that resistant starch helps return the microbiota of aged mice to a profile more similar to younger animals (Tachon FEMSME 2013, Zhou MNFR 2013).
  3. Resistant starch’s fermentation produces a lot of butyrate, the preferred food for healthy colon cells (Cummings AJCN 2001). Butyrate also is a cellular mediator which regulates gene expression, cell differentiation, gut tissue development and function, oxidative stress reduction and immune modulation (Canani WJG 2011). Butyrate also causes the absorption of sodium in the large intestine, which causes the absorption of water by osmotic pressure. This is the likely mechanism for resistant starch’s ability to stop diarrhea (Binder ARP 2010).The high ratio of the production of butyrate (versus propionate and acetate) likely differentiates resistant starch from other fibers. Sugar-based soluble fermentable fibers (inulin, FOS, and GOS) produce the most acetate and the least amount of butyrate. Consequently, they may not generate the same benefits. I do not believe in generic health benefits of “prebiotic” fibers, as different fibers may produce different health effects. Physiologically, we need different types of dietary fibers for different reasons – just like vitamins, which also serve different roles within the body
  4. Resistant starch’s fermentation strengthens the intestinal gut barrier. This is hugely important as a leaky gut is emerging as one of the problems in many different health conditions, ranging from intestinal to autoimmune and inflammatory diseases.Animal studies have shown that resistant starch helps maintain a healthy mucus layer (which protects the intestinal cells (Toden NC 2005), heals intestinal ulcerations (in a rat model of colitis, Le Leu DDS 2013, Moreau BJN 2003) and stops translocations of probiotic bacteria and reduced mortality (in a mouse model of lupus, Zegarra-Ruiz CHM 2019). Maintaining a strong intestinal gut barrier is critical to healthy and an integral part of healthy metabolism.’
  5. Resistant starch’s fermentation changes the expression of more than 200 genes in the large intestine. Some of these genes are involved in intestinal function (contractions, regularity, etc.) but some are involved in metabolism (Keenan JNN 2012). For instance, resistant starch changes the production of GLP-1 and PYY, hormones involved in insulin sensitivity and satiety. To date, twenty clinical studies have been published showing that resistant starch improves insulin sensitivity, especially in prediabetics and people with insulin resistance. (See post on FDA’s health claim.) This is a classic example of nutrigenomics, (the study of the interaction of nutrition and genes).
  6. Resistant starch improves metabolism. The FDA has already approved a qualified health claim that resistant corn starch improves insulin sensitivity and reduces the risk of type 2 diabetes.  Insulin is major hormone that controls metabolism – it assists in metabolizing carbohydrates and storing glucose for energy in cells. It also stimulates the creation and storage of glycogen from glucose and stops the breakdown of fat in adipose/fatty tissue. This causes the buildup of triglycerides in the fat cells and other tissues. Insulin also helps amino acids from protein to enter cells. When people are insulin resistant, it can be difficult to build muscle mass. Finally, insulin makes cells more receptive to potassium, magnesium and phosphate. These electrolytes are important for conducting electricity within the body, which impacts muscle function, blood pH and water content. Maintaining insulin sensitivity is really important for a healthy metabolism.Studies have also shown improved health in conditions known to be associated with insulin resistance and type 2 diabetes: glycemia-related advanced macular degeneration (eye health, Rowan GM 2018), kidney health (Sirich CJASN 2014, Esgalhado FF 2018, Koh NR 2017) , and pancreatic release of insulin (Bodinham PLoS One 2012).In addition, resistant starch has been shown to reduce blood pressure (Izar A 2018, Tavares da Silva NH 2014), reduce inflammation (Esgalhado FF 2018, Khosroshahi HI 2018) and may impact immune status of the bone marrow, and help maintain healthy bones (Tousen N 2019). The mechanisms for all of these metabolic benefits are not always clear, but resistant starch consumption has been shown to be beneficial in all of these important metabolic ways.

As stated before, resistant starch delivers an entire cascade of benefits.  Everyone I know could use more resistant starch in their diet for one reason or another. Half of Americans are either diabetic or prediabetic and need improved insulin sensitivity. Everybody else I know is experiencing some sort of intestinal dysfunction or imbalance. And for the rest of the population, they just want to stay healthy as they get older. Which category are you?