*The information within this article is not directed at COVID-19, and is referring to the current research conducted on probiotics in relation to URTI such as coughs and colds.
Coughs, colds not only can leave us feeling drained and wiped out but can be disruptive and affecting our overall quality of life. Whilst many factors can affect the normal functioning of the immune system, stress, nutritional deficiencies, excess alcohol consumption, age, lack of sleep and a lack of exercise can all contribute to weakened immunity.
An often overlooked area for the immune function is the health of our gut, yet as many as 70% of our immune cells lie within the gut. Our gut microbiota is made up of trillions of bacteria, and weighs as much as a bag of potatoes, 1-2kg worth in fact! Our microbiota plays a role with the normal functioning of the immune system, and a shift in the balance of ‘good’ and ‘bad’ bacteria may affect our immune response. Many lifestyle factors can disrupt the delicate balance of our microbiota, including antibiotic use, stress, age, and low fibre diets to name just a few.
What are probiotics?
The World Health Organisation defines probiotics as ‘live microorganisms which when administered in adequate amounts confers a benefit on the host’. There is more and more emerging research investigating the use of probiotics for modulating immunity.
What does the research say?
A large Cochrane review concluded that probiotics were more effective than placebo in reducing the number of participants experiencing episodes of acute Upper Respiratory Tract Infections (URTI) such as coughs and colds by about 47%. What’s more, the authors concluded that probiotics can probably reduce the duration of coughs and colds by approximately 2 days (1).
However, it’s important to note that probiotics work in a strain-specific way, meaning that not all probiotics will have these immune-modulating effects. This is why it is important to check that the strains included in the probiotic you are reaching for have been researched for the health outcome you are trying to achieve. There has been numerous research conducted on probiotic strains such as Lactobacillus rhamnosusGG, which is a robust strain, and has a high survival rate thought the stomach, with good adhesion to the gut cell walls. In fact, the effects of this well-known probiotics strain have been examined in over 800 studies! L. rhamnosushas shown to modulate pro-inflammatory and anti-inflammatory cytokines, which are a group of proteins made by the immune system which act as chemical messengers. Further research has shown that this strain is effective in reducing the number, severity and duration of respiratory tract infections in children (2,3).
Subsequent research has shown that children taking a combination of Bifidobacterium lactisand Bifidobacterium bifidum with a little vitamin C each day for 6 months, experienced fewer coughs and colds. if infection occurred symptoms occurred, symptoms were reduced and they took fewer sick days off school (4). A subsequent randomised, placebo-controlled trial showed that B. bifidumcould reduce the occurrence of upper respiratory infections in healthy but ‘academically stressed’ students (5).
Whilst there are a whole host of areas to be mindful of when it comes to immune function such as genetics, sleep, exercise and a nourishing diet, there may also be a role for supporting the health of our gut! Probiotics may be beneficial to immunity and could be considered an adjunctive option to support to give our body and our immune system the best chance to do its job.