Most people understand that sugar is awful for health. Sugar rots teeth, raises blood sugar and thereby insulin, causes insulin resistance, leads to accumulation of visceral (deep abdominal) fat, and leads to increased body-wide inflammation. We know that sugar, along with the amylopectin A carbohydrate unique to wheat and grains, are the factors that provoke formation of small LDL particles that cause heart disease. We also know that sugar fuels the process of de novo lipogenesis in the liver, the process that converts sugar to triglycerides that, in turn, are released into the bloodstream as very low-density lipoprotein, or VLDL, particles that cause heart disease, as well as some triglycerides that become trapped in the liver and cause fatty liver. We know that rises in blood sugar from sugar consumption increase the process of glycation, the irreversible modification of the body’s proteins, a process that leads to heart disease, cataracts, kidney disease, and dementia. So many modern health conditions have sugar as their root cause.
But did you know that sugar is also a major determinant of bowel flora composition? And it doesn’t take much. A few days of sugar indulgence, such as having a few too many margaritas during your Caribbean vacation, or a couple cans of soda every day, are all it takes to provoke massive shifts in bowel flora composition.
A few days of sugar consumption are enough to:
- Decrease microbial diversity–i.e., loss or reduction of beneficial species
- Cause proliferation of unhealthy bacterial species–especially species of Enterobacteriaceae such as E. coli and Shigella.
- Increase intestinal permeability–therefore “exporting” microbial breakdown products to other parts of the body, so-called “endotoxemia” that causes inflammation throughout the body in places such as skin, joints, arteries, prostate, breast, and brain.
- Cause even previously healthy people to develop symptomatic small intestinal bacterial overgrowth, SIBO, experiencing effects such as bloating, abdominal discomfort, and diarrhea
- Allow proliferation of fungal species, such as Candida albicans, and strengthen their biofilm (via production of biofilm exopolysaccharide) that makes fungi less susceptible to an immune response or antifungal agents.
The disruption of bowel flora composition–dysbiosis–that develops from sugar consumption is not fully reversible, since many beneficial species are simply lost. Restoration of a healthy diet without sugars and with the addition of prebiotic fibers cannot therefore restore microbial species that have been lost, no more than lots of water and fertilizer will not yield tomatoes in your garden after you planted seeds for zucchini.
In other words, sugar consumption not only yields direct effects such as high blood sugar and weight gain, but also exerts indirect effects via disruptions of microbiome composition that, even without ongoing sugar intake, perpetuate weight gain, inflammation, and insulin resistance.
While you cannot go back in time to fully undo the harm inflicted during your Caribbean vacation, or your diet of sugary sodas and ramen noodles during college, or the quart of ice cream you eat when stressed, you can at least begin to chart your course back to a healthier microbiome. I liken these efforts to having a backyard garden in springtime:
- Prepare the “soil”–Begin with sugar avoidance, but then go farther, as we do in the Wheat Belly lifestyle. (If you are just starting out, a good place to start is the Wheat Belly Revised & Expanded Edition that contains the updated program) Filter your drinking water, avoid emulsifying agents, avoid synthetic sweeteners like aspartame, choose organic foods without herbicide or pesticide residues whenever possible, get off stomach acid-blocking drugs, non-steroidal anti-inflammatory drugs, and statins.
- Plant the “seeds”–The seeds for your microbiome are a high-potency multi-species probiotic and daily consumption of fermented foods.
- “Water” and “fertilize” your garden–Include prebiotic fibers with every meal. Prebiotic fibers are metabolized by bacteria to yield metabolites that are beneficial to both intestinal and to metabolic health with effects such as reduced blood sugar, reduced insulin resistance, reduced blood pressure, improved mental health.