Ready for three truths and a lie: science and nutrition edition? This format allows for both facts and fables to be covered, which is especially important with media constantly highlighting questionable research conducted on complex topics such as the microbiome. But let’s back up. What’s the microbiome? Does the microbiome contribute to overall health? Are there certain foods that support a microbiome? Should I avoid specific foods if I want a healthy microbiome? All valid questions that will be answered in this article. Let’s begin.
Truth No. 1: The microbiome is a community of about 100 trillion cells.
Think that only things like the national debt reaches a figure in the trillions? Well, the microbiome fits this bill, too — and then some. These cells can be found all over your body, ranging from the armpit to the belly button to the oral cavity. The largest microbial community resides in the gastrointestinal tract — you may have heard it referenced as “the microbiome,” “the microbiota” or “the microflora.” Not surprisingly, the microbiome is comprised of microbes, which are microorganisms that include all types of bacteria as well as other microorganisms like viruses. Microbes can be divided into classes based on different characteristics of bacteria. Recent research has shown that three predominant microbial phyla (or groups) promote a “healthy” microbiome: Bacteroidetes, Actinobacteria and Firmicutes.
Truth No. 2: We are just learning about the impact of the microbiome on health.
Although microbes have long been associated with infection and disease, the microbiome also contributes to positive health effects. Research has shown that the microbiome contributes to human health by aiding in digestion, providing energy and nutrients, outcompeting harmful bacteria and training the immune system. On the flipside, altered microbiome profiles have been associated with obesity, inflammatory bowel conditions, cancer and cardiovascular disease, and we are only just beginning to understand these associations.
Truth No. 3: Eating foods such as prebiotics and probiotics support a healthy microbiome.
Prebiotics were first defined in 1995 as “a nondigestible food ingredient that beneficially affects the host by selectively stimulating the growth of one or a limited number of bacterial species in the colon, and thus improves health.” Simply put, prebiotics are “food” for the microbiome. Prebiotics are composed of carbohydrate polymers (i.e. more complex carbs) that cannot be digested. Since these carbohydrates cannot be digested, the gut microbiome instead uses them for energy and nutrients. Inulin, polydextrose, fructooligosaccharides and galactooligosaccharides are examples of prebiotics.
Inulin, FOS and GOS are naturally occurring carbohydrates found in foods such as bananas, honey, leeks, onions and garlic. In addition, many fortified foods and beverages contain prebiotics to aid in digestion. More broadly speaking, prebiotics are specific types of fiber, so getting prebiotics from fiber is a great strategy to support a healthy gut. Certain studies have shown that 2 to 30 grams/day of prebiotics offer gut-promoting effects.
However, since this range is large and it is difficult to parse out the specific dose of a prebiotic in certain foods, aiming for total fiber amounts may be a better strategy to reap the benefits of prebiotics. Microbial ecologist Dr. Jens Walter, an associate professor at the University of Alberta, agrees and suggests focusing on “foods rich in dietary fiber (such as fruits, vegetables, whole grains, beans, nuts, cereals, etc.), or food products enriched in fiber through the addition of fiber-rich raw materials or added fiber.” Dr. Walter adds that fiber is “fermented by the gut microbiota to products with beneficial physiological and immunological attributes, which is considered to have a highly positive effect on the gut microbiota and health.” Unsure how much fiber to add to your diet? Leading scientific bodies such as the the Institute of Medicine recommends that women consume 25 grams of fiber and men consume 38 grams of fiber each day.
Probiotics contain microbiome-promoting bacteria including Bifidobacterium, Streptococcus and Lactobacillus, which are types commonly found in dairy products. However, not all bacteria present in fermented milk products or yogurt have a probiotic effect. For this reason, in order to be classified as a probiotic, the specific strains must exhibit clinical health benefits and contain more than 10 organisms/grams at the end of manufacturing.
Naturally fermented foods contain the highest amounts of live active cultures. These foods include yogurt, buttermilk, kefir, kombucha, kimchi, sauerkraut, miso and tempeh. While all these foods contain live cultures, to be classified as a “probiotic,” the live cultures must have documented health benefits. This is important since many products are labelled as containing “live active cultures,” but may not have a sufficient quantity of probiotics. Studies have shown that probiotics are able to survive transit through the intestinal tract. However, there remains confusion regarding the dose and duration of probiotics required to achieve the desired effect. Additionally, for those who prefer not to consume probiotics in the form of food, probiotic supplements offer a potential solution and have been shown to also support a healthy microbiome. However, consuming probiotics from food sources have an added benefit since these foods may also contain the key nutrients needed to promote optimal health.
Lie: Low-calorie sweeteners negatively impact the microbiome.
You may have heard or read about studies “linking” low-calorie sweeteners and negative alterations to the microbiome. Media stories on such complex topics don’t always do the best job of explaining the design, results and limitations of scientific studies. They tell and sell a story based on one study, often devoting little time to the wealth of accepted literature that may say otherwise. The overwhelming majority of media stories about the role of low-calorie sweeteners on the microbiome point to scientific studies performed in animal models, rather than clinical trials (the gold standard). To date, there are no published studies that assess the relationship and impact of low-calorie sweeteners on the microbiome in humans.
Stories and headlines have vilified low-calorie sweeteners as yet another “thing” to avoid. However, low-calorie sweeteners are safe ingredients added to foods and beverages to provide sweetness without adding a significant amount of calories. In reducing calorie content, low-calorie sweeteners can also play an important role for those simultaneously seeking weight management and a certain level of sweetness in their diets. Low-calorie sweeteners have a long history of safe use in a variety of foods and beverages, ranging from diet soft drinks to reduced-calorie juices to table-top sweeteners. They are some of the most studied and reviewed food ingredients in the world today and have passed rigorous safety assessments from governing bodies like the European Food Safety Authority and U.S. Food and Drug Administration. In the U.S., the most common and popular low-calorie sweeteners permitted for use in foods and beverages today are:
— Acesulfame potassium (ace-K)
— Neotame
— Saccharin
Now that we have covered facts and fables about the microbiome, it should be easy to look for ways to support a healthy microbiome. Don’t let the myths and misinformation about the microbiome bog you down, but rather, stick to the science to support a healthy gut!
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3 Truths and a Lie About the Microbiome originally appeared on usnews.com
