Resistant starches (RS) are carbohydrates that pass undetected through the small intestine and are digested, or fermented, in the large intestine.
Beans, oats, breakfast cereals, rice, cooked and cooled pasta, peas, and somewhat unripe bananas are all included in plant-based foods.
RS is a component of dietary fiber that is known to lower the risk of colorectal cancer and other non-communicable illnesses.
Researchers at Newcastle University and the University of Leeds in the United Kingdom discovered that a RS powder supplement might help prevent cancer in people with Lynch syndrome.
CAPP2 is a multi-national study that involved over 1,000 people with Lynch syndrome. They administered a 30g dose of RS to each participant for an average of two years.
As predicted, the supplementation did not affect colorectal cancers. However, unexpectedly, its protective potential was most apparent in the upper digestive tract, where cancers are aggressive and are not usually caught early.
These findings have appeared in Cancer Prevention Research.
What is Lynch syndrome?
Lynch syndrome, an inherited illness, is known to individuals who are predisposed to colon cancer, gastric cancer, and several other illnesses.
Dr. Anton Bilchik, a surgical oncologist and division chair of general surgery at Providence Saint Johns Health Center and the chief of medicine at Saint Johns Cancer Institute in Santa Monica, CA, spoke with Medical News Today.
Dr. Bilchik, who was not involved in the study, explained that LS is caused by a genetic mutation that prevents the DNA from being able to repair itself as efficiently as it should after cell division, which may cause cancer. It affects about 1% of colorectal cancer patients.
The National Institute for Health and Care Excellence (NICE) of the United Kingdom advises that people with LS take aspirin daily for at least two years to help prevent colorectal cancer.
Prophylactic surgery to remove noncancerous organs or glands was considered as the sole preventive measure against LS-related cancers outside the colon until now.
One unripe banana a day
The CAPP2 study investigated the long-term effects of aspirin and RS on cancer onset in Lynch syndrome patients.
Aspirin reduced colorectal cancer by 50%, according to earlier research during the study.
For up to four years, a total of 463 participants took 30 g of RS daily, and 455 participants took a placebo.
The amount used was equivalent to eating one slightly unripe banana per day. Bananas at this stage resist breakdown in the small intestine before reaching the large intestine and feeding the microbiome there.
Over 20 years, the researchers planned a 10-year follow-up and investigated data from the National Cancer Registry in the United Kingdom.
Although no difference in colorectal cancer cases were found, less participants receiving the supplement developed non-colorectal LS cancers than those taking the placebo.
The reduction in noncolorectal cancer LS cancers was detectable in the first ten years, and continued in the next ten years, according to the study.
Certain cancers are protected from protection.
The study concluded that RS supplementation over an average of 25 months did not decrease colorectal cancer risk in LS patients.
According to the authors, diets rich in [dietary fiber] against colorectal cancer in the general population are not adequately supplemented with RS for this short time period.
Surprisingly, participants who took RS were 60% less likely to be diagnosed with non-colorectal LS cancers.
Lower GI cancers included stomach, bile duct, pancreatic, and duodenal cancers, and the protective effect was most apparent among participants in the study. Five cancers were identified in five participants in the study, compared to 21 cancers in 17 of the control group.
The researchers are currently leading a massive research that involves over 1,800 people with Lynch syndrome. The CaPP3 study aims to determine whether or not smaller dosages of aspirin can help reduce cancer risk.
How may RS may reduce cancer risk?
The authors of the present study have yet to define how RS reduces upper GI cancer risk. However, they are certain that the gut microbiota plays a role.
While breaking down RS, gastrointestinal microbes release a short-chain fatty acid called butyrate. This compound helps stop the growth of cancer cells and might induce cancer cell death.
According to Dr. Bilchik, an increase in butyrate might aid in the reduction of upper GI cancers.
The authors of the research believe that the RSs effect on bile acids may also explain the decreased likelihood of LS cancer.
An unrelated 2022 Advance Science paper suggested that interactions between bile acids and the gut microbiome may be associated with the development of GI cancer.
The findings have their drawbacks.
Dr. Bilchik questioned how the researchers in the United Kingdom came to terms with the inclusion of 30 grams of RS in the study. He noted that such a figure is very difficult to interpret in real life.
The surgeon has also noted that the study does not establish causality.
He found this study very interesting, because the majority of Lynch syndrome patients die of upper gastrointestinal cancers. These can be managed [with RS], and that is significant.
The implications are staggering, since these cancers are much more difficult to diagnose and conquer than other LS cancers.
Supplements vs. food choices
Dr. Bilchik expressed worry that taking RS or probiotic supplements might disrupt what already exists in our body to protect us against cancer.
He applauded the current paper for proving that a large number of studies demonstrate that high fiber diets reduce the likelihood of getting colorectal cancer.
Dr. Michael Greger, a physician, author, and clinical nutritionist who was also not involved in the research, encourages the consumption of whole foods over supplements to combat and battle cancer.
Dr. Greger stated in a recent NutritionFacts.org podcast that:
Despite the fact that foods contain tens of thousands of substances that may be involved in a large number of possible interactions, much of nutritional research has long focused on the impact of individual dietary components.
Yes, this kind of reductionist approach can reveal the role of individual nutrients or foods in the development of illness, but let's think about what the best research strategy might be to investigate the effects of bioactive natural plant compounds on disease prevention, added.