Part 4: Fiber and Food: Based on the book “Metabolical”
The fiber in food is perhaps the most important nutrient for health, because it single handedly protects the liver and feeds the gut in six different ways: Both kinds of fiber together form a gel on the inside of the duodenum to reduce the rate of absorption of monosaccharides and disaccharides, as well as slow the breakdown of starches. Reduced absorption means reduced transport to the liver, thus preventing the liver from turning excess energy into fat—in turn preventing liver insulin resistance. The reduction in the rate of absorption also reduces the glycemic excursion in the blood, keeping the insulin response down, and reducing energy deposition into fat tissue. There are two flavors of bacteria that live in your gut: the white hat and the black hat bacteria—and it’s a daily struggle to see which will prevail. The white hat bacteria (e.g., Bacteroides) need more energy to survive and grow in order to battle the black hat bacteria (e.g., Firmicutes). Thankfully, the good bacteria can proliferate and maintain a balanced intestinal ecosystem, but need a greater and more robust supply chain to ward off the bad guys. What’s that supply chain made of? Fiber—both types. The fiber transits the food through the intestine faster, generating the satiety signal (the gut hormone peptide YY3–36, which is released into the bloodstream and goes to the brain) sooner, thus reducing second portions. Soluble fiber is metabolized by gut bacteria into short-chain fatty acids like butyrate. They uniquely feed the microbiome of the colon (large intestine) and are absorbed into the bloodstream where they are anti-inflammatory as well as suppress insulin secretion from the pancreas. Insoluble fiber acts as a mild abrasive in the lumen of the colon, which dislodges and sluffs old dead cells, thus reducing cancer risk. There are three inherent myths about carbohydrates that play a role as to whether they’re causative of, or preventative against disease: Sugar vs. starch. Sugars are monosaccharides and disaccharides (one or two molecules), while starch is a complex polymer (many molecules). Sugars either have one bond or no bonds to break, so they’re digested and absorbed quickly in the duodenum, especially when they’ve been liberated from a food matrix, as they often are (e.g., soda, fruit juice, alcohol). Starch has more bonds to break, and is digested and absorbed slower. All of this adds up to a more rapid and higher insulin response with sugar, which drives weight gain. Type of starch (the two “Amys”): But “a starch is not a starch.” There are two kinds of starch: amylose (brown foods including beans, lentils, and legumes; carbs that are digested and absorbed slowly) and amylopectin (white foods including wheat, pasta, rice, and potatoes; carbs that are digested and absorbed rapidly). Amylose is better for you, as it’s a string of glucoses with two ends; therefore, only two enzymes at a time can chew it up, resulting in slow digestion and absorption. Amylopectin is more like a tree of glucoses, with lots of branch points. Many more enzymes can chew it up at once, releasing glucose more rapidly, which is more likely to be absorbed early, flood the liver, and generate a bigger insulin response. Carbs are rarely ingested in isolation. A slice of white bread is straight glucose. But Real Food is glucose plus protein plus fat plus fiber. Those other macronutrients, or lack thereof, influence the glucose’s absorption in the intestine, the insulin response that follows, and risk for weight gain. The important parameter is glycemic load (GL). GL is different from glycemic index (GI)—how much food do you have to eat to get the 50 grams of carbohydrate? GL takes into account the beneficial effect of fiber. A good example is carrots, which are high-GI (lots of carbohydrate) but low-GL (even more fiber). More fiber means a larger portion, because there’s less digestible carbohydrate. You can turn any high-GI food into a low-GL food by eating it with its original fiber. Real Food is by definition low-GL. Protein. Your kidneys have a limited capacity to excrete the metabolic by-products of protein metabolism, and overexcretion can cause kidney damage. Therefore, protein quality is as important as protein quantity. For example, eggs and beans both contain protein, but are very different in quality. You have a spectrum of macronutrient compositions to choose from, from one end to the other: vegan, Ornish, flexitarian, pescatarian, Japanese, Mediterranean, low-carb, paleo, keto. They all work, if you’re eating Real Food. Real Food is low-sugar and high-fiber, which lowers insulin; it protects the liver and feeds the gut. The caveat is that each of us has different genetic predispositions, intestinal microbiota, and livers, so it’s likely that there are specific diets that will work better for some and not for others. Fats. Omega-3s are fish oil, not snake oil. Omega-3s might just be the healthiest thing you can put in your mouth. There are two kinds—docosahexaenoic (DHA) and eicosapentaenoic acids (EPA)—both of which reduce the inflammatory response in the fat cell and prevent the release of free fatty acids. This keeps them from hitting the liver, where they would be packaged into triglyceride. What’s in our processed foods? The ultra-processed food industry adds chemicals at various points. They may add it to the animal while it’s maturing to prevent infection, or they may add it to the plant while it’s growing to prevent infestation. They may also add chemicals to the food during processing for flavor, color, texture, and/or preservation. In any case, when they add it to the animal or plant or food, they add it to you as well. Many of these chemicals act directly on those eight subcellular pathologies to increase your burden of chronic disease. Natural Flavors. Did you ever wonder what a “natural” or “artificial” flavor was? Aside from salt, sugar, and water, natural or artificial flavor is the most commonly listed item, appearing on one out of seven food ingredient lists on the Nutrition Facts label. But what are they exactly? They’re chemicals, and the company doesn’t have to tell you what’s in it, and the FDA doesn’t require them to. Since most flavors are nonpolar, it usually means there’s an emulsifier (e.g., polysorbate 80), a solvent (e.g., propylene glycol), and a preservative (e.g., butylated hydroxyanisole; BHA), although it could be several of one hundred different items. The companies that make flavors also make fragrances. In general, the dose is small, so disease is unlikely—unless you have an allergy. But we don’t know for sure. Emulsifiers. Lecithin (chocolate), polysorbate 80 (shortening), carboxymethylcellulose (salad dressing), and carrageenan (ice cream) are added to foods to maintain food consistency upon storage. After all, who wants clumpy ice cream? These molecules have one polar end and another nonpolar end, so they’re able to bind fat and water together to keep them from separating. However, emulsifiers are also detergents, and can strip away the mucin layer that sits on top of and protects intestinal epithelial cells from the bacteria, thus predisposing individuals to intestinal disease, food allergy, or leaky gut. Thus far, however, the FDA states they haven’t found cause for human concern.
