Hi all, long time no see!
As many of you know, I have a bit of an obsession with diet, fiber, and colon and digestive health. Over the years, I have come up with some hypotheses on the importance of diet and fiber in various conditions and new research is starting to crop up validating some these thoughts! It’s incredibly exciting and I can’t study this morning until I get some of this out!
The point: Dietary fiber is no-but-really crucial for health, including disease prevention and modulation, immunity strength, digestion and absorption of nutrients, and weight management.
What is fiber? Fiber is essentially a very complex carbohydrate that our body cannot digest. It passes from our mouths in the food we eat, to our stomachs, to our small intestines, and all the way to our large intestines/colon undigested. In the colon, it is broken down by our bacteria into various molecules and short chain fatty acids.
There are several sub-types of fiber, but all of these types are found only in certain types of foods. In order of fiber content (per calorie): vegetables, fruits, whole grains, nuts and seeds contain fiber. Meats and proteins, white grains and flour, sugar, and oils do not have fiber. A standard American diet is sorely lacking in fiber.
What does it do? SO MANY THINGS! In the stomach and intestines, it slows down the passage of food from one part of our digestion system to the next, which keeps us feeling more full for longer (good for weight control). By slowing the digestion of our meals, it also slows the absorption of sugar for better blood sugar control. In the colon, it clings to water to help poo glide right along and forms the bulk of feces to prevent constipation.
Perhaps most critically, it feeds the bacteria in our colon. This is huge because we have more bacteria in our colons then we have cells in our body, and they have a huge impact on our health. The bacteria eat the fiber that we cannot digest and break it down into many things, one of the most crucial things being short chain fatty acids, such as sodium butyrate. This fatty acid can diffuse right into our colon cells, and they use it as their main source of energy! This energy can go towards DNA replication for cell division, checking DNA for mistakes, and cell immunity to fight off infection. We need our colon cells to be healthy and to stick closely to each other, otherwise things we eat, including all the bad stuff like toxins and bad bacteria can squeeze between the cells and enter our systems and blood stream.
Thus, no fiber –> no short chain fatty acids –> starving colon cells –> decreased cell maintenance and replication –> potentially weakened barrier between the outside world (our intestinal tract) and our inner bodies and blood stream
Furthermore, starving colon bacteria start to eat protein if they can’t get any fiber. What protein is in our colon? Our mucus lining! Our intestines have a layer of mucus that lay over them which protects the delicate inner lining from the mass of bacteria as well as any toxins and crap that we eat.
Hungry bacteria –> starved of fiber from a low fiber diet –> resort to eating mucins (which are proteins) in our intestinal mucus layer –> thinner mucus layer –> colon lining more susceptible to the good bacteria, bad bacteria, toxins and crap that we eat –> in the context of unhealthy colon cells or gaps in between the cells, this could lead to these things entering our system –> inflammation –> potentially “leaky gut” and food allergies, IBD, auto-immunity, and a chronic inflammatory state (which predisposes to diseases and cancers).
The recent study (READ!!) that was released in the NYT this morning confirmed the low fiber = thinner mucus layer part of the theory. Taking it a bit further, I wonder if a low fiber diet also contributes to colon polyp or cancer development. If the destruction of the mucus layer leads to direct contact of the bacteria with the colonocytes, then the lining layer needs to up its defences to keep the bacteria out. This could manifest as making polyps, as if if they were a protective scab, or a perturbation of normal cell functioning, leading to chronic inflammation or decreased ability to repair the DNA mutations that accumulate in all cancers, including colon cancer. Another study has recently laid out that there IS in fact reasonably demonstrated inflammatory pathways being activated by direct contact of colon flora with the epithelial layer (in the absence of the mucin layer), so this seems reasonable.
What do I do about it? Eat fiber at every meal! Perhaps we have been focusing on the wrong parts of our diet this entire time. We obsess over calories and fat and grams of protein, but perhaps if we focus on getting fiber at every meal, everything else will more or less fall into place. If you are getting a healthy dose of fiber at each meal, you probably are not eating a ton of carbs or sugar, and calories are more likely at an appropriate level. When thinking about a meal, a simple approach would be: 1. Does this meal have enough fiber? 2. Am I getting enough protein? 3. Are there healthy fats and nutrients in the meal? (Since almost all foods rich in fiber are rich in nutrients, this shouldn’t be an issue.)
Another side note, it is interesting and sad that the healthcare system has been telling patients with Crohns and Ulcerative colitis to avoid fruits, vegetables, nuts and seeds all this time. Instead, these patients are told to eat simple white starches such as rice for their main food source. These are the very patients that need a healthy colon and we are completely starving their colon bacteria and intestinal cells with a fiber free diet. Understandably, fruits and veg are hard to digest for this very reason, and can certainly cause GI upset in people with and without IBD. A gradual increase in fiber is important in people who have previously not been eating fiber. Cooking fiber rich foods can help soften and pre-digest the food so it causes less GI upset. Steaming is great because it will maintain the nutrients and not add any potentially inflammatory molecules (like the black char that comes from grilling or high heat frying/baking). Blending is also an excellent way to make fruits and vegetables more digestible but still maintain the fiber content, such as for soups and smoothies.
Happy new year to you all and EAT YOUR VEG!