THE ROLE OF THE GUT MICROBIOME IN OUR RECOVERY FROM INJURY AND DISEASE
It has been well documented that nutrition is key to assisting with improving the rate and quality of recovery from injury. Recent evidence indicates that the interaction between the gut microbiome and a person’s diet has important effects on bone, muscle and joints. Specialized nutrients are required in times of injury and disease to assist with the production of new tissue and enhance the body’s natural healing responses. The microbes in our gut have a strong impact on how these nutrients are processed thus impacting on our recovery from disease and injury. So, the answer is ‘yes’ when questioning “is there a diet that can help my condition?”.
The gut microbiome is made up of 100 trillion bacteria within the gastrointestinal tract consisting of 1000 different microbial species. These colonise in the colon. The intestinal immune system protects against pathogens while avoiding harmful immune responses towards allergens from food and the microbiota. The gut microbes can be considered as organisms living in synergy with humans. They have evolved over time to undertake many metabolic functions that impact on our health. The analysis of gut microbiome has resulted in the ability to classify and sequence the many different bacteria and compare the composition to various health traits. Their role in regulation of fatty acid metabolism, immunity and inflammation demonstrates their importance to humans recovering from injury, post-surgery or managing disease.
The gut microbiome plays a role in the development and progression of obesity. Studies have shown that humans with lower diversity and dysbiosis are more prone to obesity. Several studies have also highlighted the key role of the microbiome in insulin resistance and inflammatory pathways. People with depression have been found to have a less diverse microbiota with trials in psychobiotics in the early stages of demonstrating improvements in this cohort.
The gut microbiome has been indicated to play an important role in skeletal muscle composition and metabolism. Animal studies have indicated that muscle mass and function is increased in healthy mice that have been supplemented with the bacterium L. plantarum. This indicates that targeting the gut microbiota can be used to modulate muscle mass. Increasing muscle mass is a goal in strength training or rehabilitation after injury or surgery. Age, gender and genetic background are among the factors that affect the rate and total amount of gains in lean muscle mass. A good gut microbe profile can be achieved by eating a fibre rich diet, taking probiotic supplements and avoiding medication that kill good gut microbes which will ultimately improve the profile of skeletal muscles. To-date two randomized controlled trials have shown athletes on probiotics have demonstrated improvements in performance. Improvements in exhaustion and grip strength have also been shown in the over 65-year age group during a 13-week period on probiotics indicating the importance of their use in this age group.
The gut microbiome has been shown in animal studies to play a role in promoting bone formation and suppressing bone resorption which impacts on bone remodelling and protects from bone loss. A recent trial involving 75-80 year-old women demonstrated results that indicate bone remodelling in animal studies are also relevant to humans and can be influenced by probiotic supplementation. In addition, the gut microbiome composition influences the absorption of key vitamins and minerals such as calcium, magnesium and vitamin D all of which are crucial to bone metabolism.
Studies involving inflammatory forms of arthritis such as rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis have demonstrated changes in gut microbiome compared to controls. Cartilage metabolism is also influenced by the gut microbiome.
Recent trials have demonstrated that taking a probiotic may reduce the frequency and severity of migraine attacks by up to 45%. Emerging evidence indicates that the gut microbiome impacts on brain health and function. Low mood and anxiety along with neurological condition such as migraine can benefit from ingesting certain live microbes. Studies have identified certain strains of bacteria showing promising results in treating anxiety with lower levels of the hormone cortisol found in participants saliva. Tryptophan, a building block of the hormone serotonin required for normal sleep and mood comes from our diets but also our gut. This field of research into psychobiotics demonstrates the link between the gut and the brain along the vagus nerve and the production of fatty acids that get into our bloodstream.
The animal studies critiqued for this synopsis on the benefits of gut microbiome all indicate its beneficial impact on bone, muscle and joint metabolism. There are no routine clinical tests to assess a human’s microbiome composition. However, the clinical trials of probotic intervention very promisingly suggest that targeting the gut microbiome can have substantial effects on muscle, bone and joint health. It is well worth combining rehabilitation with a highly diverse gut microbiome to promote better outcomes for patients ranging from athletes, to post surgery to the frail elderly.
Professor Ted Dinan reflects on our modern stressful lifestyles and identifies an issue more with our reduced biological capacity to deal with stress being down to our lack of diversity in our gut microbiota. Processed foods decrease this diversity as they are low in fibre and high in saturated fats, sugar and salt. Many fibre rich foods are a source of prebiotics which act as food for friendly gut bacteria.
Eating a diet including fermented foods such as yoghurt, kefir, kombucha and sauerkraut enhances the microbe diversity in the gut. These foods act as prebiotics or foods that feed probiotics and can stimulate the growth of many different strains of good gut bacteria. The overall resounding advice is to follow a Mediterranean style diet rich in fruit and vegetables and plenty of fermented foods.
Heathy Food Guide 2019 reporting on Professor Ted Dinan, Psychiatrist UCC.
The Psychobiotic Revolution: Mood, food and the new science of the gut connection.
In Touch Physio First Spring 2019: The role of the gut microbiome in musculoskeletal rehabilitation