A starch supplement may reduce the risk of certain hereditary cancers

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Resistant starch is found in foods such as cereals, bananas and rice. Hiroshi Watanabe/Getty Images
  • An international trial has found that resistant starches may help protect people at high risk for hereditary cancers.
  • The decades-long study also reported that resistant starch supplementation reduced cancers in this group by more than 60%.
  • The protective effect of these starches lasted at least 10 years after supplement use was stopped.
  • Nevertheless, some experts are hesitant to recommend supplements and suggest eating whole plant foods to ward off cancer.

Resistant starches (RS) are carbohydrates that pass undigested through the small intestine and are digested or fermented in the large intestine.

They are present in plant-based foods including beans, oats, breakfast cereals, rice, cooked and cooled pasta, peas, and lightly green bananas.

RS is one of the dietary fibers known to reduce the risk of colorectal cancer and many other non-communicable diseases.

Researchers from Newcastle University and the University of Leeds in the UK found that an RS powder supplement may help prevent cancer in people with Lynch syndrome.

Experts conducted a multinational trial called CAPP2 involving nearly 1,000 people with Lynch syndrome. They gave participants a 30g dose of RS for an average of two years.

Supplementation did not affect colorectal cancers as expected. However, unexpectedly, its protective potential was most apparent in the upper digestive tract, where cancers are aggressive and usually not detected early.

These findings appear in Cancer prevention research.

Lynch syndrome, an inherited disease, predisposes people to colon cancer, gastric cancer, and several other cancers.

Medical News Today speak with Dr. Anton Bilchiksurgical oncologist and director of the division of general surgery at Providence Saint John’s Health Center and chief of medicine at Saint John’s Cancer Institute in Santa Monica, California.

Dr. Bilchik, who was not involved in the study, shared that LS is caused by a genetic mutation that prevents DNA from correcting itself as efficiently as it should after cell division, which can lead to lead to cancer. It occurs in about 1% of patients with colorectal cancer.

The United Kingdom National Institute for Health and Care Excellence (NICE) recommends people with LS take aspirin daily for at least two years to help prevent colorectal cancer.

so far, prophylactic surgery removal of non-cancerous organs or glands was considered the only preventive measure against LS-related cancers outside of the colon.

The CAPP2 trial analyzed the long-term effects of aspirin and RS on the development of cancer in patients with Lynch syndrome.

Earlier to research during the trial found that aspirin reduced colorectal cancer by 50%.

A total of 463 participants took 30g of RS daily for up to four years, and 455 subjects took a placebo.

The dose used was equivalent to the daily consumption of a slightly unripe banana. Bananas at this stage resist breakdown in the small intestine, reaching the large intestine and feeding the microbiome there.

The researchers planned a 10-year follow-up and studied data from the UK’s National Cancer Registry over 20 years.

They found no difference in the number of colorectal cancer cases. However, fewer participants receiving the supplement developed non-colorectal LS cancers compared to those taking the placebo.

The study noted, “The reduction in LS cancers from non-colorectal cancer was detectable in the first 10 years and continued over the following decade.”

RS supplementation over an average of 25 months did not reduce the risk of colorectal cancer in LS patients, the team found.

They reported: “Dietary supplementation with RS for this limited time period does not mimic the apparently protective effect of diets high in [dietary fiber] against colorectal cancer in the general population.

Surprisingly, participants taking RS were 60% less likely to be diagnosed with non-colorectal LS cancers.

The protective effect was most evident with upper gastrointestinal cancers, including cancers of the stomach, bile duct, pancreas and duodenum. The researchers found five cancers in five RS participants versus 21 cancers in 17 of the control group.

Currently, researchers are conducting another multinational trial involving more than 1,800 people with Lynch syndrome. The CaPP3 study aims to find out if smaller doses of aspirin can help reduce the risk of cancer.

The authors of the present study have not yet determined exactly how RS reduces the risk of upper gastrointestinal cancer. However, they are certain that the gut microbiota plays a role.

Gastrointestinal microbes produce a short-chain fatty acid called butyrate while decomposing RS. This compound helps to stop cancer cell growth and could induce cancer cell death.

According to Dr. Bilchik, one theory is that an increase in butyrate may help reduce upper gastrointestinal cancers.

The study authors believe that the effect of RS on bile acids may also help explain the reduced cancer risk of LS.

An unrelated 2022 Advancing science article reported that interactions between bile acids and the gut microbiome may be associated with the development of gastrointestinal cancer.

Dr Bilchik wondered how the British researchers had come to use 30g of RS in the study. He said such a number is “very difficult for people to interpret” in real life.

The surgeon also noted that the study does not establish causation.

Overall, he found this research “very exciting, as the leading causes of death in Lynch syndrome patients are upper gastrointestinal cancers. So these can be reduced [with RS]and it is significant.

The implications are impressive since these cancers are more difficult to diagnose and overcome than other LS cancers.

Dr Bilchik expressed concern that taking RS or probiotic supplements “could disrupt what already exists in our bodies to protect us against cancer”.

He praised the current study for supporting “abundant evidence that high-fiber diets reduce the risk of colorectal cancer.”

Dr Michael Gregerdoctor, author and clinical nutritionist who was also not involved in the study, encourages the consumption of whole foods rather than supplements to fight and beat cancer.

In a recent NutritionFacts.org podcastDr. Greger said:

“Foods contain many thousands of substances that lead to a large number of possible interactions, but much of the nutritional science has long been directed [toward] the impact of unique food components.

“Yes, this type of ‘reductionist’ approach can reveal the role of individual nutrients or foods in the development of disease, but let’s think about what would be the optimal research strategy to study the effects of bioactive natural plant compounds on disease prevention,” he added.

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