Cut Sick Days with a Healthy Gut
by Ashleigh Feltham,  Accredited Practising Dietitian and Accredited Nutritionist.

Most of us don’t have time to get sick. A busy life coupled with stress can wreak havoc on your immune system. There are a number of strategies that you can implement to help get your immune system functioning at its best. This includes taking time for self-care; and prioritising sleep, exercise and diet.

Diet plays a major role in promoting optimal immune system function, and fibre is the star. Prebiotic fibre can cut your risk of getting sick, and the number of days with symptoms if you do get sick. Specifically, we take a look at upper respiratory tract infections and gastrointestinal illnesses.

In the digestion process, prebiotic fibre passes through the small intestine undigested and then moves through to the large intestine. Here it becomes the fuel source for the health promoting microbes in your gut. When gut microbes feed on prebiotic fibre, they release short-chain fatty acids, which in turn move to different parts of the body to promote their health and function.

Around 70-80% of your immune system is in your gut. It makes sense to look after your gut if you want to be well and healthy. A healthy gut microbiome supports homeostasis in the body for good health. If it is off balance, pathogens can enter your body and lead to illness.

A double-blind study on 33 elite rugby players analysed the potential effects of prebiotic fibre on upper respiratory tract infection symptoms, gastrointestinal symptoms and markers of immune function. These participants were randomly assigned oligolactose, a prebiotic fibre, or a placebo for 24 weeks.

Participants completed daily and weekly questionnaires for self-reported gastrointestinal and upper respiratory symptoms. Blood samples were collected to determine levels of inflammation markers and saliva samples for antibodies, which are the first line of defence for the upper respiratory system.

Participants that took prebiotic fibre had two fewer days of the symptoms of upper respiratory tract infection compared to those taking the placebo. Gastrointestinal symptoms and severity as well as the frequency of illness were also lower in this group.

The ability of the immune system to respond appropriately to pathogens was greater in the group taking prebiotic fibre. Antibodies were 42% higher compared to participants taking a placebo. No differences in levels of inflammation markers were found.

The role of your gut in keeping your immune system functioning optimally is clear. To keep your health-promoting microbes healthy and thriving, aim to add a variety of plant-based foods to your diet. These plant-based foods are the key source of prebiotic fibre.

Adults need 25-38g of fibre each day. A healthy goal is 30 different plant foods each week, such as wholegrains, legumes, nuts, seeds, fruit and vegetables.

Take home message:

Include enough prebiotic fibre in your diet each day to boost your immune system function and cut your sick days. Your gut microbes are a team you need on your side.

References:

1. Wu HJ, Wu E. The role of gut microbiota in immune homeostasis and autoimmunity. Gut Microbes. 2012 Jan-Feb;3(1):4-14. doi: 10.4161/gmic.19320. Epub 2012 Jan 1. PMID: 22356853; PMCID: PMC3337124.
2. Parker C, Hunter KA, Johnson MA, Sharpe GR, Gibson GR, Walton GE, Poveda C, Cousins B, Williams NC. Effects of 24-week prebiotic intervention on self-reported upper respiratory symptoms, gastrointestinal symptoms, and markers of immunity in elite rugby union players. Eur J Sport Sci. 2023 Nov;23(11):2232-2239. doi: 10.1080/17461391.2023.2216657. Epub 2023 Jun 18. PMID: 37331347.
3. Matsuzaki K, Sugimoto N, Islam R, Hossain ME, Sumiyoshi E, Katakura M, Shido O. Salivary Immunoglobulin A Secretion and Polymeric Ig Receptor Expression in the Submandibular Glands Are Enhanced in Heat-Acclimated Rats. Int J Mol Sci. 2020 Jan 27;21(3):815. doi: 10.3390/ijms21030815. PMID: 32012687; PMCID: PMC7037029.
4. Wiertsema SP, van Bergenhenegouwen J, Garssen J, Knippels LMJ. The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies. Nutrients. 2021 Mar 9;13(3):886. doi: 10.3390/nu13030886. PMID: 33803407; PMCID: PMC8001875.