An advert persistently appears selling goat’s milk fermented with granules of a yeast-like product called kefir. It claims to “protect your immune system” and the advert details all the benefits to your gut microbes of so-called pro-biotics.
Trouble is, you can’t eat or drink something to “protect your immune system” and as far as I can tell from a search of the scientific literature there is no strong evidence based in human trials that suggests any benefits for healthy people whatsoever to eating or drinking probiotics to “balance” gut microbes either. Most of the so-called evidence comes from poorly designed, poorly controlled, and often downright biased tests. Moreover, there is growing evidence of detrimental effects of taking probiotics as outlined here.