A new study unlocks a major benefit of resistant starch in the development of digestive tract cancers.

Researchers looked at the benefits of resistant starch in individuals with Lynch Syndrome. Lynch Syndrome is a hereditary condition that increases the risk of cancers of the digestive tract.

People with Lynch Syndrome have a defect in genes that repair DNA. This causes them to have an increased risk of many cancers, including those in the gut, bladder, brain, reproductive tract and skin.

Furthermore, they tend to see earlier onset of cancer, often before they’re 50.

Benefit of resistant starch revealed in new study!!!

In this newly published study, researchers looked at the use of aspirin and/or resistant starch daily for up to 4 years. Previously published results showed 600mg of aspirin daily for 2 years reduced the risk of developing colorectal cancer over the following 10 years by 44%.

In the newly published results, resistant starch, a form of dietary fiber, didn’t have a significant effect on colorectal cancer risk. But, resistant starch did substantially lower the risk for non-colorectal cancers, particularly those in the upper gut(Stomach, duodenum, and pancreas).

All in all resistant starch lowered non-colorectal cancer risk over the 10 year follow-up by 46%. The daily dose of resistant starch used in the study was 30g. Foods high in resistance starch include:

• Underripe bananas (Type used in study)
• Plantains
• Cooked and cooled potatoes
• Beans, peas, lentils
• Oats

How does it work?

Our diet plays an important role in the health of our gut. However, it’s not just what we do with our food, it’s also what our microbiome does with it.

Various factors within our diet can increase our risk for cancers of the digestive tract. Excess fermentation of dietary protein by members of our microbiome create byproducts such as ammonia, p-cresol, and hydrogen sulfide which can damage DNA and increase inflammation.

Higher levels of dietary fat increase the production of secondary bile acids. More fat causes greater recirculation of bile acids, which allows more exposure to bacteria that convert them to secondary bile acids. These bile acids can freely enter our cells, create oxidative stress, increase inflammation, and damage DNA.

On the other hand, delivering fermentable carbohydrates such as resistant starch tends to decrease DNA damage and inflammation. In fact, multiple mechanistic studies in animal models(Check this one and this one) show that resistant starch abolishes the negative effects of a western diet by increasing short chain fatty acid production.

https://www.gastrojournal.org/article/S0016-5085%2819%2941369-3/fulltext

In this way, the primary benefit of resistant starch for cancers of the gut likely resides in its ability to negate the cancer-promoting effects of other things we eat.

Conclusion

The result of this study are pretty impressive. Though there was no benefit in colorectal cancer risk for consuming resistant starch, it did reduce cancers elsewhere in the gut. This may be due to an interaction effect between greater susceptibility to DNA damage in the colon and decreased repair in those with Lynch Syndrome.

This study alone doesn’t support the idea that resistant starch will benefit healthy individuals. However, taken together with other human outcome data, each 10g increase in dietary fiber, including resistant starch, lowers colorectal cancer risk by 10%.

As such, it’s a good idea to include resistant starch and other types of dietary fiber in your diet to reduce your risk of cancers of the digestive tract.