December 2018

Ask the Nutritionist: Gut Bacteria

Why Are Gut Bacteria Important to Our Health?

Did you know that you have 10 times more microbes than human cells and that they weight about 4 pounds total! That means on a cellular level we are more microbial matter than human!

The types of bacteria that live within us, on our skin, in our guts, etc., are impacted by our method of delivery at birth, our diets, lifestyle, stress, antibiotic use, and illness. Before we are born we are squeaky clean, no microbes at all. But during delivery mom transfers her gut bacteria and breastfeeding continues to provide many more. The gut microbiome stabilizes into a more adult-like profile by age one. Therefore, this initial year can have a huge impact on our microbiome and health as an adult.

Some gut bacteria live in a symbiotic relationship with us, making essential nutrients for us to absorb (like vitamin K and B vitamins), they help us digest fibers and stimulate our nervous system. They can also support our gut barrier function and prevent pathogenic bacteria from calling our guts home.

However, some gut bacteria can be potentially harmful. If there is an imbalance of good vs. bad gut bacteria, also called dysbiosis, it can cause allergies, inflammatory bowel disease, irritable bowel syndrome, obesity, diabetes, depression, autism, cancer, and many other conditions. Some of the symptoms of dysbiosis include gas and bloating, diarrhea, constipation, and weight gain or difficulty losing weight. Therefore, gut bacteria play a vital role in human health and general well-being.

• Gut Bacteria and Gut Immune System: Good gut bacteria help resist the invasion of pathogenic bacteria and they can help protect us from developing food intolerances. Leaky gut, which is in part caused by poor bacterial diversity, is the main reason people develop food intolerances by activating an immune system response to consumed food proteins. Research has found that L. plantarum can help repair a leaky gut by restoring tight junctions in the gut lining, thereby reducing food intolerances and reducing GI inflammation (1).
• Gut Bacteria Benefit the Host: Good gut bacteria help maintain regular bowel movements, produce vitamins, transform bile acid and hormones, metabolize and destroy chemicals and toxins, and help absorb minerals. They also produce short-chain fatty acids in the colon, fueling our colon cells and reducing the risk of colon cancer (1).
• Gut Bacteria Can Impact Our Mood: Research finds gut dysbiosis is related to anxiety and depression. Did you know that more than 90 percent of your serotonin is made in your digestive tract? Therefore, establishing growth of good gut bacteria can alter neurotransmitter activity in the brain to improve these symptoms (2).
• Gut Bacteria and Insulin Resistance: Research has shown that obese individuals often present with an increase in Firmicutes and Actinobacteria and a decrease in Bacteroidetes species, while lean individuals present the opposite. This imbalance seems to increase leaky gut and the absorption of a toxic product called lipopolysaccharide (LPS) which stimulates an inflammatory cascade. This impairs insulin signaling and insulin sensitivity at the cellular receptor site. Consequentially, this leads to weight gain and blood sugar dysregulation (3).

Luckily, you can modulate the types of bacteria that call your GI tract home. Although everyone has a microbial blueprint, your dietary choices, lifestyle choices (stress management), and supplement choices can help encourage establishment of good gut bacteria. Incorporating a whole-foods diet rich in a variety of fruits and vegetables will not only support your gut bacteria but also help provide nutrients for optimal well-being.

Fiber & Prebiotics

Eating a whole-foods-based diet rich in fiber (fruits, vegetables, grains, beans, nuts, and seeds), can actively feed good gut bacteria and encourage their growth. Certain foods contain large amounts of prebiotics, which are indigestible carbohydrates that beneficial bacteria rapidly ferment for fuel. By eating more fiber and prebiotics you encourage beneficial bacteria to grow from the bottom up for lifelong benefits. Gradually increase the therapeutic foods listed below to avoid uncomfortable gas and bloating.

Raw Prebiotic Rich Vegetables: Onions, garlic, leeks, asparagus, artichoke, sunchokes, dandelion greens, and under-ripe bananas. Eating these vegetables raw will provide the largest amount of prebiotic punch.

Polyphenol Rich Foods: Red and purple fruits and veggies, flaxseed meal, chestnuts, hazelnuts, olive oil, red and black whole grains, green tea, dark cocoa, and herbs and spices are all rich sources of polyphenols (phytonutrients that beneficial bacteria feed on).

Mucilaginous Grains & Seeds: Mucilaginous seeds like chia and flaxseed, psyllium husk powder, and grains like oats provide a great fuel source for a beneficial bacteria called Akkermansia that is associated with a healthier metabolic status and a more diverse and healthy gut bacteria.

Resistant Starch: Found in cooked and cooled starchy foods like potatoes and rice, this starch is rapidly fermented by good bacteria and can help establish growth of Bifidobacterium species. Slightly under-ripe bananas are also rich in resistant starch as is green banana flour.

Fermented Foods

While prebiotics help provide the fuel for good gut bacteria, eating fermented foods can provide beneficial bacteria via food. However, decades of research shows you CANNOT repopulate the human gut with Lactobacilli and Bifidobacterium supplied by supplements or fermented foods. Colonization is only temporary and lasts only as long as you eat the food regularly. You must grow them from the bottom up using the prebiotic and fiber-rich foods mentioned above.

Nancy’s Plain Yogurt & Kefir: Researched bacterial strains are used in these yogurt and kefir products. Enjoy daily, mixed with one half of an under-ripe mashed banana sprinkled with chia or flaxseeds for added fiber. Some people may better tolerate goat yogurt and kefir.

Lacto-Fermented Veggies: Fermented sauerkraut, kimchi, and other veggies, available in the refrigerated section, have a “zing” to them when consumed for best probiotic benefits. Enjoy 2 tablespoons as a garnish on your savory meals.

Fermented Beverages: Kombucha, kvass, water kefir, and cultured coconut water can be tasty ways to get dairy-free probiotics. Good Belly makes cultured beverages and StraightShots that provide the strain L. plantarum 299v.

Limit Sugar & Refined Grains

Many pathogenic bacteria and yeasts thrive off simple carbohydrates such as sugar, white flour, and refined products. Try to avoid processed foods and sugar as much as possible and stick to a whole-foods diet by using the tips below.

• Choose only whole grain products and grains (brown rice, quinoa, whole wheat).
• Purchase locally made sourdough whole grain bread without added sugars and fillers.
• Use honey, maple syrup, or dates to sweeten dishes and beverages.
• Enjoy fresh fruit if craving sweets.
• Treat yourself with 1–2 squares of organic dark chocolate, which has limited sugar.
• Avoid sugar substitutes. Limited use of stevia or monk fruit are the only acceptable substitutes.

References:

1. Impacts of Gut Bacteria on Human Health and Diseases
2. The Gut-Brain Axis: The Missing Link in Depression
3. The Role of Gut Microbiota on Insulin Resistance

Get Selva's simple recipe for Steel Cut Oats that incorporates many of the dietary tips mentioned above. Perfect to enjoy after a workout, as a fiber-rich breakfast, or simply as a snack.

Have questions? Send them to [email protected]. Selva Wohlgemuth is a registered dietitian nutritionist. Learn more about her approach to general health and well-being at her Happy Belly Nutrition website, and see her recipes and other kitchen tips at Poppies and Papayas.