The dreaded flu season is in full swing!
Getting influenza, or the “flu”, is a miserable experience for anyone. Sudden fever, muscle aches, chills (1;2), cough, nasal congestion, and a sore throat can make you feel like you’ve been hit by a truck (2). Luckily, for many the flu will resolve on its own. But for some it can lead to serious complications (1;2), including inflammation of the heart or brain, pneumonia, or even death (1). Older adults (1), people living in nursing homes or long-term care, or people with weakened immune systems or certain chronic health conditions are especially at risk for these complications (2).
Regardless of the match between the flu vaccine and circulating flu viruses in any given year, the flu vaccine is the single best way to protect yourself against the flu (1;3;4). Among the general population, the flu shot can reduce flu risk by 40% to 60%, which helps prevent thousands of flu-related hospitalizations annually (5). Age also plays a role in determining the effectiveness of the flu shot. For example, while the vaccine reduces the likelihood of getting the flu by up to 90% in children, adolescents, and young adults, among older adults the risk of getting the flu is reduced by 30% to 40% (1;6).
But, what if there was a simple way to boost the effectiveness of the flu vaccine among older adults? Recent research explored whether prebiotic and probiotic supplementation could do just that (1). Probiotics—also referred to as “good” bacteria—are live bacteria that support overall health. Prebiotics, on the other hand, are substances that promote the growth of these beneficial bacteria (1;7). Both are found in food—oats, beans, and bananas are prebiotic foods, while kimchi, sauerkraut, and kombucha tea are probiotic foods (7).
So, does supplementation with these immune-boosters enhance the protection offered by the flu vaccine?
What the research tells us
A recent systematic review and meta-analysis found that taking prebiotic or probiotic supplements before a flu shot can improve the effectiveness of the vaccine. This review evaluated people who had taken probiotic supplements alone, prebiotics and probiotics together, or prebiotic supplements mixed with other substances like vitamins, minerals, oils, or fermented milk. Supplements were taken for at least two weeks, and up to 28 weeks before receiving flu vaccines designed to protect against the H1N1, H3N2, and B flu strains. Overall, people who took prebiotics or probiotics before receiving their flu shot had increased protection from certain strains of the flu compared to those who received a placebo. Specifically, healthy older adults who took the supplements over longer periods of time seemed to benefit the most.
These results are promising, but future research will be useful in determining the best combination of supplements, dose at which they need to be taken, and for how long in order to achieve the most benefit and to help further support the findings seen here (1). Clearer conclusions around side effects and safety are also needed.
So there you have it! The flu shot remains the best way to protect yourself against the flu, but supplementation with prebiotics or probiotics before getting the vaccine may be one way to boost its protective effects.