Can Dietary Fiber Rewrite Your Genetic Code to Combat Cancer?

In this episode of Daily Value, we take a look at how fiber fuels anti-cancer gene activity - emphasizing the role of short-chain fatty acids (SCFAs) produced during fiber fermentation. Drawing on new research PMID: 39789354) published in Nature Metabolism out of Stanford Medicine, we examine how fiber-derived metabolites influence gene activity to reduce cancer risk and promote overall health.

Discussion Points:

• The epigenetic role of SCFAs, such as butyrate and propionate, in activating anti-cancer genes and inhibiting harmful pathways.
• Insights from recent studies, including findings showing a 10% reduction in colorectal cancer risk for every 10-gram increase in daily fiber intake.
• Practical strategies to optimize fiber consumption, including food sources and supplementation options tailored for individual needs.

https://pubmed.ncbi.nlm.nih.gov/39789354/

Transcript

Speaker 0: 0:00

Can fiber really alter your DNA to fight cancer? Well, groundbreaking research out of Stanford Medicine says yes. Hello everyone, and welcome back to Daily Value. I'm William Wallace, and today we're focusing on a dietary component that mounting evidence suggests plays an important role in cancer prevention, and that is fiber. Drawing from recent high-quality studies and comprehensive reviews, we're going to uncover exactly how dietary fiber and, importantly, the metabolic byproducts of fiber metabolism, known as short-chain fatty acids, function as protective agents against multiple forms of cancer. One recent study that brought this topic on showed just how short-chain fatty acids like propionate and butyrate may be directly altering gene expression in cancer cells to exert their anti-cancer effects.

Speaker 0: 0:53

Fiber intake recommendations vary by region, but general guidelines suggest 25 grams per day for women and 38 grams per day for men. Unfortunately, most people fall far short of these targets. In the United States, the average daily fiber intake is only about 15 grams, while in Europe it's slightly higher, but still below recommended levels. This widespread deficiency highlights the importance of increasing fiber consumption to achieve its full health benefits, which include cancer prevention. As we'll get into, fiber is more than a single entity. It's a diverse group of plant-derived carbohydrates classified by their degree of polymerization and digestibility Non-digestible carbohydrates, dietary fiber that is, are divided into short-chain, also called low-molecular-weight fibers, and long-chain, also called high-molecular-weight fiber types. Low-molecular-weight fibers, like oligosaccharides and inulin, are rapidly fermentable and act as prebiotics in the gut, while high-molecular fibers, such as non-starch polysaccharides, provide bulk and are not fermented as rapidly. Through microbial fermentation, these fibers produce what are called short-chain fatty acids, potent epigenetic regulators that influence chromatin structure and gene activity. Now think of chromatin as a spool of thread where your DNA is the thread. It helps to pack long strands of DNA neatly into a cell's nucleus, depending on how tightly it's packed, genes can either be easily accessed and turned on, or tightly locked away and turned off.

Speaker 0: 2:37

Short-chain fatty acids like butyrate and propionate act as what are called acyl donors, meaning they provide chemical groups that modify histones, which are proteins around which DNA is wrapped. These modifications open up or close down access to certain genes, directly influencing their activity and playing a key role in cellular processes like growth and differentiation of cells. Now a study published just days ago in the journal Nature Metabolism looked at how fiber-derived short-chain fatty acids like propionate and deuterate influence gene activity in normal and cancerous cells. Particularly in colorectal cancer cells. Short-chain fatty acids were found to modify proteins called histones, which again help control how tightly DNA is packed and how accessible genes are for activation. These modifications were then mapped across the genome to identify their impact. What the researchers discovered was that short-chain fatty acids help make certain genes more active by loosening the structure of DNA in certain regions. This is especially important for genes that control cell growth and stress responses. Deuterates specifically blocked harmful processes in cancer cells by inhibiting enzymes called histone deacetylases. By inhibiting enzymes called histone deacetylases, this led to increased activation of anti-cancer genes and caused cancer cells to die while leaving healthy cells unaffected. The study showed that short-chain fatty acids influence major cancer-related pathways, which play a role in how cancer develops and spreads. The conclusion of the study was that dietary fiber, through its fermentation into short-chain fatty acids, can impact regulation and help reduce cancer risks by targeting specific cellular processes.

Speaker 0: 4:33

High levels of butyrate in the gut correlate with increased histone acylation and chromatin accessibility of anti-proliferative genes. In fact, an Umbrella meta-analysis published by Hu et al in 2023, so very recently found that for every 10 gram increase in daily fiber intake, the risk of colorectal cancer decreased by approximately 10%. Fiber's ability to reduce stool transit time and dilute carcinogenic or cancer-promoting substances in the colon may be another way that fiber protects against cancer, aside from short-chain fatty acid benefits that we just went over. The same review found that high fiber intake is linked to a 44% reduction in gastric cancer risk. Again, outside of the mechanisms outlined in this podcast, protection is thought to be due to fiber's ability to lower nitroso compounds, which are potent carcinogens formed in the stomach. The same review indicated a significant inverse relationship between fiber consumption and breast cancer risk, particularly in post-menopausal women. Increased fiber intake correlates with lower levels of harmful estrogen metabolites, which have been considered a major risk factor for breast cancer. Fiber has the ability to improve insulin sensitivity, which plays a role in reducing the risk of pancreatic cancer as well.

Speaker 0: 6:01

Understanding the mechanistic pathways linking dietary fiber and short-chain fatty acids to cancer prevention opens avenues for clinical and dietary interventions. Targeted fiber supplementation focusing on butyrogenic substances like resistant starches could enhance short-chain fatty acid production in people with low microbial diversity. It's also possible that leveraging microbiota-based therapies to increase the abundance of butyrate-producing bacteria may serve as an adjunct to conventional cancer treatments. Increasing butyrate-producing bacterial species that's something that I've touched on before in previous episodes and will actually deep dive on in the near future.

Speaker 0: 6:43

Short-chain fibers like inulin or other fructooligosaccharides found in onions, garlic and so on can be very efficient and quickly ferment in the gut. However, not everyone handles this rapid fermentation well, due to the rapid buildup of things like methane and hydrogen gas. For this reason, among a few others individuals who experience bloating or GI distress with these fiber types often people who would do well on a FODMAP protocol for a while they would likely respond better to longer chain fibers that ferment less rapidly. Cellulose is an example of a long chain fiber. This can be found in broccoli, green beans, oats and berries, resistant starch found in potatoes, rice, lentils and different beans, and then there's also lignans. These fibers can be found in flax seeds and sesame seeds. If you want to consider fiber supplements, psyllium husk has a good deal of data as a very beneficial long-chain fiber. This is the main active ingredient in the fiber supplement known as metamucil.

Speaker 0: 7:47

Fiber is not merely a dietary accessory. It can be a key player in the intricate interplay between diet, metabolism and epigenetics Through the production of short-chain fatty acids like propionate and butyrate. Through its fermentation, fiber exerts multifaceted anti-cancer effects, from enhancing chromatin accessibility to modulating anti-inflammatory pathways. By integrating high-fiber foods and targeted supplements into daily routines, we can also harness these epigenetic tools to mitigate cancer risk and promote overall health. Thank you for tuning in to Daily Value. If you found this episode insightful, please share it with people you think who may benefit. Until next time, stay healthy.