With the 2014-15 flu season coming, you may decide to forgo most of those 10 easy ways to boost your immune system naturally we discussed previously and, instead, go straight for a flu vaccine.

Unfortunately, you’ve probably also heard from some of your vaccinated and angry friends and family members coming down with the flu anyway. If you decide to get a flu shot, you’ll want to consider taking a vaccine-boosting probiotic too, based on recent research.

Lactobacillus improves flu shot response

The trick to making many vaccines work is much more than the inclusion of key antigens to help them recognize and attack diseases later on. Actually, many of these molecules aren’t able to provoke strong immune responses at all, according to the National Cancer Institute.

What’s just as important are the inclusion of adjuvants, substances that enhance the ability of vaccines to trigger protection against infection. Adjuvants work by activating the immune system, thus enabling antigens (pathogenic ingredients that provoke an immune response) in vaccines to stimulate long-term protection, according to the National Institute of Allergy and Infectious Diseases.

A 2011 study published in the European Journal of Clinical Nutrition showed how probiotic bacteria — a proprietary strain of Lactobacillus — would be effective as an adjuvant of a live-attenuated flu vaccine in a double-blind study.

During the study, all patients received a flu shot, then a placebo or Lactobacillus twice a day for four weeks. For the H3N2 strain of flu, 84 percent of patients who were given Lactobacillus had a protective amount of the vaccine in their bodies 28 days later, compared to 55 percent who were given a placebo.

Take a probiotic with your flu shot

A more recent study in the journal Immunity that linked vaccines to the health of your gut microbiota — not depleted by antibiotics — may dictate how effective a flu shot may be.

The roots of this study date back to similar research in 2011 that monitored the response of healthy patients to the flu shot. Scientists discovered a link between the response of antibodies to the vaccine and the expression of the Toll-like receptor 5 (TLR5) gene.

This gene stimulates a healthy immune response by detecting flagellin, a component of tail-like appendages used by bacteria in the body, including the gut, to help them move.

The latest study took the next step by comparing the immune response of these three groups of mice to a flu shot to a vaccinated control group of germy mice: Genetically modified animals that lacked the TLR5 gene, germ-free mice and those that had spent four weeks drinking antibiotic-laced water.

A week after being inoculated, all three groups experienced up to an eightfold reduction of vaccine-specific antibodies in their blood compared to the vaccinated, germy control group, according to Science. However, blood antibody levels appeared to rebound within four weeks in all groups, but dropped again 85 days later among genetically-manipulated mice.

(It’s also important to remember, compared to normal, germy mice, the bodies of animals raised in a sterile environment — too clean for their own good health via the hygiene hypothesis — also produced fewer antibodies.)

In another test, mice given the polio vaccine (made of viral molecules but, like the flu vaccine, not an active virus) produced fewer beneficial antibodies too, suggesting “weaker” vaccines lacking active adjuvants require more help from bacterial signaling, according to Science.

“These results demonstrate an important role for gut bacteria in shaping immunity to vaccination, and raise the possibility that the microbiome could be harnessed to modulate vaccine efficacy,” says Dr. Bali Pulendran from Emory University.

These studies underscore how important it is to take a multi-species probiotic like EndoMune Advanced Probiotic and EndoMune Advanced Junior (for kids) to boost your immune system, especially if you’re considering getting a flu shot.