The nutrition research spotlight is on the gut and its role as the second brain. This refers to the fact that there are continuous messages being sent from the gut to the brain and vise-versa. Traditionally, Western medicine has focused on the gut and the brain as separate entities but research over the last decade has brought to life the interconnectedness of the gut-brain axis.
The Gut Microbiome
The gut microbiome is home to trillions of bacteria in our gastrointestinal tract that begin developing from the moment we are born. Comparatively the amount of bacteria in the stomach is significantly lower; however, the bacterial load increases exponentially through the digestive system with the highest amount of bacteria being found in the colon (1). Gut bacteria is influenced by the types of food we eat, antibiotic use, probiotic use, stress, alcohol intake, cigarette smoking, and sleep deprivation. This bacteria can also vary depending on vaginal birth vs. cesarean-section and breastfeeding vs. bottle feeding. Gut microbiota metabolites stimulate cells (enteroendocrine cells) throughout the gastrointestinal tract. These cells contain nutrient receptors and have an important role in controlling appetite, insulin secretion, hormone release and motility. Research to date demonstrates that dietary intake plays an incredibly important role in gut bacteria composition (2). Diets that are high in fiber, antioxidants, and plant-based nutrients contribute to a balanced and healthy gut microbiome. Conversely diets rich in processed foods, red meat, and saturated fat can contribute to dybiosis, bacterial and fungal overgrowth. It has been found that 50% of the variation of gut microbiota has been related to dietary changes and major changes in diet during adulthood can modify the gut microbiota in a matter of days (3).
What is Dysbiosis and Why Should I Care?
Dysbiosis is an imbalance in the gut microbiota and has been linked to inflammatory bowel diseases (IBD), irritable bowel syndrome (IBS), obesity, diabetes, cardiovascular disease, neurocognitive disorders, depression, and cancer (4). In short, the food we regularly consume either protects or promotes the development of many gastrointestinal disorders and chronic disease.
As previously mentioned, dietary intake can greatly alter the gut microbiota. Simultaneously, the gut microbiota determine what you are capable of extracting from dietary intake (3). The gut forms part of the enteric nervous system (a division of the autonomic nervous system). The vagus nerve is majorly involved in the bidirectional communication between the gastrointestinal and nervous systems. This communication system is involved in homeostasis, hormonal and immunological signaling. In other words, everything you eat plays a part in maintaining a healthy balance in you brain and gut and can alter your hormone release as well as your immune system.
What Should I Eat for Optimal Gut Health?
WHOLE FOODS- plenty of fruits and vegetables. Limit your intake of high-fructose corn syrup and other added sugars that are commonly found in processed and packaged snack foods. Make sure you’re incorporating daily omega-3 sources into your food choices such as fish and nuts. Soluble fiber will help feed short chain fatty acids (which are the primary fuel source for cells in your colon). You can find soluble fiber in legumes, ground flax seeds, oats, chia seeds, Brussel sprouts, avocado, and sweet potatoes to name a few. The research involving fermented foods and gut health is still in its infancy but to date studies have shown that consuming these foods may offer digestion benefits. Examples of fermented foods include kefir, kombucha, yogurt, sauerkraut, tempeh, and kimchi.