Getting the seasonal influenza vaccine is a scientifically-backed way to lower your risk of catching the flu. However, even the seasonal flu vaccine can’t guarantee you won’t develop a nasty case of influenza. Each year, vaccine developers try to target the flu virus strains that they think will circulate during the upcoming flu season. Sometimes they’re accurate in their predictions and other times the vaccine they develop misses the mark. If the vaccine doesn’t cover the right strains, your odds of developing influenza are higher than if they guessed the strains that will predominate and formulated the vaccine to match those strains.
Another problem that can lower the effectiveness of the flu shot is people have varying immune responses to the vaccine. In fact, there’s some evidence that being obese interferes with the body’s ability to respond to the vaccine. Timing is important too. If you get the vaccine too early in the year and influenza viruses make their debut later, your immunity from the vaccine may dwindle toward the end of the season and you may become susceptible to influenza viruses again. Health professionals usually recommend that people get their flu vaccination at the end of October before the flu season starts. It takes two weeks for the body to mount an immune response to the influenza vaccine. Therefore, getting vaccinated after your friends and family already have the flu might be too late. But there’s a balance too. If you get it too early, antibodies against the flu may drop before the flu season is over.
Are There Ways to Make the Flu Vaccine More Protective?
There’s a lot of talk about probiotics, friendly bacteria that make up your gut microbiome, and prebiotics, the fiber upon which they feed. In fact, more people are taking probiotic supplements these days to support and enhance gut and immune system balance. Many factors can disrupt a healthy gut microbiome, including diet and antibiotics. In fact, it can take up to a year for the gut microbiome to recover from a course of antibiotics.
Probiotics and prebiotics may have another health benefit. Some studies suggest that they may help the seasonal influenza vaccine work better. However, research looking at this issue is inconsistent. Some studies show benefits while others do not. When individual studies conflict, researchers sometimes use meta-analyses, an analysis of many studies to see if there is a link between two things. That’s what a group of researchers did. The researchers looked at 19 studies focusing on whether probiotics, prebiotics, or synbiotics (the combination of prebiotics and probiotics) boost the effectiveness of the flu vaccine.
What did the meta-analysis show? Supplementing with probiotics or prebiotics enhanced the protective response of the influenza vaccine by as much as 20%. Taking probiotics and prebiotics increased the number of protective antibodies in the blood. In theory, this should make the flu vaccine more effective since more antibodies mean more protection. The added protection from probiotics and prebiotics was strongest in healthy people and in those who supplemented longer term with either probiotics, prebiotics, or both. It didn’t appear that age was a factor in the response.
What Can We Conclude?
It might be beneficial to take a probiotic and prebiotic supplement a few weeks before and after getting the seasonal influenza vaccine. Unfortunately, no one knows what the ideal probiotic composition is for optimal protection. Probiotic supplements can vary in quality and viability. By the time a probiotic reaches store shelves, the friendly bacteria that were alive may have died or the formulation may not contain large enough quantities of the healthy bacteria. So, there’s no guarantee that the probiotic supplement you buy at the drug store or supplement store will be protective. But what about probiotics and prebiotics from food? There are few downsides to adding more probiotic and prebiotic-rich foods to your diet and they have other health benefits too.
Foods High in Probiotics and Prebiotics
If you want to go the food route, foods high in probiotics include yogurt with live and active cultures, kombucha, kefir, kimchi, tempeh, miso, sauerkraut, and other fermented vegetables. If you eat yogurt as a source of probiotics, look for one that says it contains active and live cultures. Also, choose a yogurt with as little added sugar as possible.
What about prebiotics? Prebiotics are the fiber-rich foods that healthy gut bacteria use for energy. Gut-friendly bacteria ferment fiber and produce short-chain fatty acids beneficial for the colon. In fact, studies show a diet high in prebiotics helps curb inflammation and may lower the risk of colon cancer. The best source of prebiotics are Jerusalem artichokes, garlic, dandelion greens, asparagus, leeks, chicory root, bananas, and onions. Some studies also show a diet rich in prebiotics boosts calcium absorption.
The Bottom Line
Protect yourself against influenza by getting the flu vaccine and by taking common-sense precautions like washing your hands and avoiding sick people. Across the globe, influenza kills between 250,000 and 500,000 people each year, a significant loss of life. Many more people fall seriously ill or are hospitalized. You’re at higher risk of getting very sick with the flu or dying if you’re over the age of 65, have chronic health problems, are pregnant, have a suppressed immune system or are taking medications that suppress immunity. Children under the age of 59 months are also at higher risk. If you work in a health care setting, you’re also more likely to be exposed to the flu.
If you fall into any of these categories, take precautions by getting a flu shot and take other commonsense precautions to lower your risk. Also, don’t assume because you got the influenza vaccine last year that you’re protected this year. The flu strains that circulate change from year to year. Therefore, you need to get the current vaccine yearly. So, make sure that it protects you and your family!
- World Health Organization. “Influenza Seasonal”
- com. “Can you boost your flu shot with prebiotics and probiotics?”
- Frei R, Akdis M, O’Mahony L. Prebiotics, probiotics, synbiotics, and the immune system: experimental data and clinical evidence. Curr Opin Gastroenterol. (2015)
- Harvard Health Publishing. “How to get more probiotics”
- Centers for Disease Prevention and Control. “Who Needs a Flu Vaccine and When”
- Mayo Clinic. “Flu shot: Your best bet for avoiding influenza”