You've probably heard the term "healthy gut". Media and the food industry have been rolling the term around with vague definition, at best, and it's usually strategically referenced alongside food products like yogurts and probiotic supplements and a number of other products touted to keep your gut "healthy"--even "happy".
Gut health is important. We've always known this. But what we are only beginning to learn through scientific research that is driving the media hype are the astounding mechanisms through which this mysterious healthy gut is attained. The driving forces behind these mechanisms: hundreds of trillions of microbes!
In our age of excellent sanitation and antibacterials--of pocket-sized Purell, handy Lysol wipes, and our conveniently packaged "Z-pack" broad-spectrum antibiotics from our MD, you might think of bacteria in your body as harmful, or at least undesirable. Indeed, some bacteria--and the focus of the microbes in the body has been bacteria, though fungi and viruses dwell inside you too--are pathogenic. Bacteria like Clostridium difficile, Salmonella, and Escherichia coli O157:H7 are some examples of microorganisms that can wreak havoc or even be fatal when they take up residence and multiply in a human intestine--NOT a happy, healthy gut! It is with good reason we practice thorough personal hygiene and food sanitation to avoid serious illness caused by these and many other bacteria.
But all bacteria are not "bad" bacteria! We have inside us a complex ecosystem of enormous diversity of bacteria, residing peacefully without our awareness. With their diversity within species, it is estimated we have 2 million different genes from these microorganisms. In contrast, humans have a "mere" 23,000 genes from our human DNA. This means that ~99% of the genes in our body are not really OURS, and ~90% of our cells aren't human.
The NIH-funded Human Microbiome Project has gone about the insanely challenging task of uncovering exactly which bacteria are common to healthy persons. It is evident that the guts of healthy persons have rather different ecosystems than unhealthy persons, such as those with autoimmune diseases like Crohn's disease. Even obesity itself is related to differences in gut inhabitants compared to their lower-BMI controls.
Comparing differing taxa of the gut might be interesting for a microbiologist. But why should YOU care about your microbiome?
The microorganisms in your body are not separate and distinct from your body. They vitally interact with your body in many ways. So important is your microbiome that you should think of it as a vital organ of organisms!
1. Your microbiome educates your immune system. Your adaptive immunity--how your body learns to fight pathogens and leave harmless or helpful microorganisms alone--comes from signaling from bacteria, mostly in your gut. Your microbiome is integral to your immune system!
2. Your microbiome affects your mind. The gut-brain connection is under-appreciated in nutrition of mental health. Did you know that in biblical times, saying "I love you with all of my heart" was more literally said "I love you with all of my bowels"?! Emotions, alertness, mood--they are all influenced by your gut microbiota.
3. Your microbiome is your super metabolizer. The bacteria in your gut break down drugs and toxins, akin to the vital organ that your liver is. Your colon, where most of your gut bacteria reside, also receives the "indigestible" food waste that YOUR own cells can't break down and -voila!- metabolizes this too, making many beneficial products, such as short-chain fatty acids, Vitamin K, and antimicrobials to keep their own colony safe--not to mention feeding themselves!
Microbiome research is only in its infancy, but we already know that this organ of organisms is critical to our health and may be important in the etiology of autoimmune diseases like Crohn's disease, psoriasis, asthma, insulin-dependent diabetes, and food allergies, and it also might play a large role in development of obesity. I look forward to more posts on these amazing microorganisms!
Meanwhile, what can YOU do to have a helpful microbiome?
Besides following your prudent doctor's advice to take antibiotics only when necessary, the best way to promote a thriving microbiome is to eat whole, unprocessed foods! The polysaccharides, polyphenols, lignans, isoflavones, fructans in fruits, vegetables, and whole grains are wonderful nourishment for your friendly bacteria, ensuring a happy, healthy gut!