Thanksgiving Microbes: Gut-Healthy Foods for the Holidays
Fruits and Vegetables. Source.
The role of microbes in the healthy human gut might be just as complex as the political discourse over the Thanksgiving holiday. In addition to the unique personalities at the dinner table, every person's own gut microbiome varies from the beginning to the end of the digestive tract. However, scientists and dietitians have noticed some common links between the diets and gut microbiota of healthy humans. Such effects can be augmented by certain foods and popular ingredients.
While these food choices have shown to benefit some patients in clinical studies, the microbiome is an emerging field—some people may respond differently or not at all to dietary modifications. However, based on supporting studies, these five foods have been linked to gut-healthy changes in the human microbiome. As Thanksgiving 2017 draws near, we celebrate and give thanks for the beneficial effects of microbes in our gut health. Bon appetit!
Garlic and Leeks
Easily included in soups and main courses, garlic and leeks are thought to increase concentration of Actinobacteria in our guts. Actinobacteria are aerobic, gram-positive bacteria that promote a healthy immune system and produce acetate to protect against some pathogenic infections. In this way, Actinobacteria contribute to the vast array of beneficial microbial effects of the colonized human gut, such as immune system development, defense against infections, and synthesis of vitamins. Additionally, high-fiber dietary components like leeks stimulate fermentation leading to an increase in bacterial mass and therefore have a healthy stool-bulking effect.
Artichokes and Asparagus
A healthy gut microbiome helps us fight against chronic inflammation and serious illnesses. Specific foods such as Jerusalem artichokes, asparagus, garlic, soybeans and chicory, ingested over an extended period, might promote a protective mucosal barrier against harmful, pathogenic bacteria. Artichokes and asparagus are rich in inulin, a naturally occurring polysaccharide that increases fecal Bifidobacterium, a bacterial species that’s particularly suited to survive in the human gut. Increased levels of gut Bifidobacterium are thought to have a number of healthful effects, such as improved colon regularity, competitive exclusion of undesirable bacterial species, and may play a role in prevention of inflammatory bowel disease and colon cancer.
Kefir and Raw Dandelion greens
These two ingredients are examples of prebiotics, which are thought to stimulate the growth and metabolic activity of beneficial species and to improve the health and wellbeing of the host. Selectively fermented ingredients support a healthy microbiome by resisting digestion in the small intestine. Instead of being digested in the small intestine, prebiotics ferment in the colon. This mechanism supports the production of beneficial short-chain fatty acids that promote the growth of healthy gut bacterial species such as Bifidobacterium, Lactobacillus, F. prausnitzii, A. muciniphila, and Rominococcus bromii. Kefir provides a particularly inviting environment for healthy gut bacteria. Due to the acidic nature of fermented products, kefir causes acid-resistant species of bacteria to proliferate later on in the digestive tract, influencing parts of the intestine that are particularly apt at absorbing important nutrients. Dandelion greens are delicious tossed into a salad or cooked down into a Thanksgiving Day breakfast omelet. How do you include kefir to a meal? Bake it into biscuits!
Almonds, Pistachios, and Red Berries
Studies have also shown that almonds and pistachios lead to increased levels of butyrate, a type of fatty acid that helps your gut work most efficiently. Butyrate-producing bacteria such as Faecalibacterium prausnitzii and Eubacterium rectale also compete against gram-negative carbohydrate-utilizing bacteria (such as Bacteroides spp.), and are involved in the maintenance of colonic mucosal health. Bacteroides induce a response in the human body that coats the bacteria with a surface protein (surface immunoglobulin A), allowing the bacteria to be more resistant to degradation by bacterial proteases. These mechanisms may keep the body from uptaking the bacteria and inducing a systemic immune response. Red berries containing anthocyanins have been shown to increase the amount of gut-healthy Bifidobacterium spp. and Lactobacillus acidophilus.
How do whole grains support a healthy gut microbiome? Along with a balanced, vegetable-based diet, whole grains induce a more diverse microbial population by increasing protective species and decreasing deleterious inflammation. Additionally, whole grains provide other healthful ingredients such as phytochemicals, phenolic compounds, lignans, and phytic acid. While whole grains should not be an excuse to gorge on that fifth dinner roll, thoughtful inclusion of whole grains supports a healthy gut by increasing satiety, supporting healthy blood sugar levels, as well as providing fiber, selenium, magnesium, and potassium. According to the American Heart Association, whole grains contain the entire grain: the bran, germ, and endosperm. Whole grains include oats, rye, barley, brown rice, popcorn, corn, bulgur, millet, quinoa, and others.
Many of the foods that support healthy gut microbiomes also help combat chronic diseases such as diabetes, inflammatory bowel disease, and colon cancer. While cultivating your favorite Thanksgiving meal traditions, take steps toward health promotion and disease prevention this holiday. Have a wonderful holiday, and enjoy the science behind the menu.
- “Which foods can improve your gut bacteria?” BBC. http://www.bbc.com/news/health-38800977
- “Can We Eat Our Way To A Healthier Microbiome? It's Complicated.” NPR. https://www.npr.org/sections/thesalt/2013/11/08/243929866/can-we-eat-our-way-to-a-healthier-microbiome-its-complicated