#21. Renovating Your Inner Hotel Monday, July 5, 2021 Earth is a gigantic hotel... sort of. It is currently accommodating about eight billion guests. Some stay for a month. Others for a century. They all check out eventually. Then new guests fill the vacancies. Some of these folks are friendly to their host, conserving and recycling, inventing biodegradable materials, and devising innovative ways to reduce and reverse greenhouse gas emissions (that's us!). Other folks seem to take joy in the destruction of their lodgings. They check into a clean environment and immediately begin stuffing its soil, water, and sky with toxic trash (that's us, too!). Just like Earth's long roster of good and bad guests, our guts house heaps of helpful and harmful microorganisms. These include fungi, viruses, and bacteria. Collectively, these tenants are referred to as the "microbiome." Except, instead of eight billion organisms, each of us has more than a trillion, populated by hundreds of different bacterial species (Brody, 2020). It is only recently that we have begun to learn strategies to market our intestinal hotel to a more respectful class of lodgers. How might we accomplish this? Food matters most. Any change in your nutrition necessarily alters the diet of your microbiota. If you manipulate your dinner plate just right, you can feed your good bacteria while simultaneously starving the ones who smoke in bed. Okay, let's start tipping: Tip 1) Get some prebiotic fiber in your diet. When your friends in low places (microbiota living in the ileum and colon) are presented low-digestible carbohydrates, they produce short-chain fatty acids (SCFAs) as a byproduct of their fermentation. These SCFAs provide energy for the colon cells, enhance gut barrier function, reduce inflammation, and bolster immune function (Fukui et al., 2018; Venegas et al., 2019). Examples of prebiotic foods are asparagus, chicory root, dandelion greens, garlic, Jerusalem artichokes, leeks, and onions (Moshfegh et al., 1999). But transition gradually. Gluttonizing prebiotics too quickly (especially inulin) might make you feel like you're holding in an enema (Slavin, 2013). Tip 2) Avoid the types of meat you already know you should be avoiding. Like extra fatty cuts. And crunchy, charred slabs from the barbecue. And anything processed. Like those pink, tube-shaped mysteries that people ingest competitively. Or the spongy and slippery, sandwich-ready slices with words like "deli" or "lunch" in their title. All of these are best left packaged. For plenty of reasons. Your microbiome is just one more (Bultman, 2017; David et al., 2014; Sugimura, 2004). Tip 3) Mind your sweeteners. Sugar nourishes the wrong gut tenants, resulting in a proliferation of Proteobacteria and a decrease in Bacteriodes. This changing of the guard is followed by increased inflammation, worse gut barrier integrity, and dysregulated immune function (Satokari, 2020). Artificial sweeteners are preferable in many diets (and for many reasons), but they are unlikely to scoot clear through your digestive tract, mouth to toilet, unnoticed. Consequences such as reductions to Lactobacillus reuteri (Singh et al., 2017) make it advisable to keep excesses of all ingestible sweetness to a minimum.