It is very exciting whenever a study has good results in preventing cancer, especially if this is from simply eating certain foods. This recently occurred in a large study of people with a high hereditary susceptibility to certain cancers, called Lynch syndrome.
The study found that just eating some resistant starch (e.g., the amount in a green tipped banana) daily was enough to cut the incidence of upper GI cancers (e.g., pancreatic, bile duct, stomach, and duodenal cancers) by 60% over the next ten years. These are fabulous results.
However, it did not have an effect on the incidence of colorectal cancer and endometrial cancer.
In the well-done study (conducted in England, Wales, and Finland), people were randomly assigned to either a group that ate 30 grams of resistant starch daily or a placebo daily for up to 4 years. Then they were all followed for up to a further 10 years, and a portion up to 20 years. [Note: the researchers said the 30 g daily was equivalent to one slightly green banana]
Resistant starch is a type of dietary fiber found in foods such as slightly green bananas, potatoes, whole grains, beans, chickpeas, lentils, and seeds. Resistant starch is not digested in the small intestine, but is fermented by gut microbes to produce beneficial short-chain fatty acids, such as butyrate, in the colon (large bowel).
Bottom line: Eat a variety of fiber rich foods (whole grains, legumes, fruits, vegetables, seeds, and nuts) daily, including foods that provide resistant starch. Your gut microbes and health will thank you!
A trial in people with high hereditary risk of a wide range of cancers has shown a major preventive effect from resistant starch, found in a wide range of foods such as oats, breakfast cereal, cooked and cooled pasta or rice, peas and beans and slightly green bananas.
An international trial -- known as CAPP2 -- involved almost 1000 patients with Lynch syndrome from around the world and revealed that a regular dose of resistant starch, also known as fermentable fiber, taken for an average of two years, did not affect cancers in the bowel but did reduce cancers in other parts of the body by more than half. This effect was particularly pronounced for upper gastrointestinal cancers including oesophageal, gastric, biliary tract, pancreatic and duodenum cancers.
The astonishing effect was seen to last for 10 years after stopping taking the supplement.
The study, led by experts at the Universities of Newcastle and Leeds, published today in Cancer Prevention Research, a journal of the American Association for Cancer Research, is a planned double blind 10 year follow-up, supplemented with comprehensive national cancer registry data for up to 20 years in 369 of the participants.
Previous research published as part of the same trial, revealed that aspirin reduced cancer of the large bowel by 50%.
"We found that resistant starch reduces a range of cancers by over 60%. The effect was most obvious in the upper part of the gut," explained Professor John Mathers, professor of Human Nutrition at Newcastle University. "This is important as cancers of the upper GI tract are difficult to diagnose and often are not caught early on.
"Resistant starch can be taken as a powder supplement and is found naturally in peas, beans, oats and other starchy foods. The dose used in the trial is equivalent to eating a daily banana; before they become too ripe and soft, the starch in bananas resists breakdown and reaches the bowel where it can change the type of bacteria that live there.
Between 1999 and 2005, nearly 1000 participants began either taking resistant starch in a powder form every day for two years or aspirin or a placebo.
At the end of the treatment stage, there was no overall difference between those who had taken resistant starch or aspirin and those who had not. However, the research team anticipated a longer-term effect and designed the study for further follow-up.
In the period of follow-up, there were just 5 new cases of upper GI cancers among the 463 participants who had taken the resistant starch compared with 21 among the 455 who were on the placebo.