The Microbiome

What exactly is it and why should I care?

If you dig in to understanding probiotics and their benefits, you are bound to encounter the term “microbiome.” This term has recently gained currency in the scientific community because, in short, it’s an apt description. If your memory of high school biology is a bit rusty, a biome is a collection of plants and animals in a shared environment. Around the world there are numerous and distinct biomes, such as monsoon forest, arid desert, tree savanna, alpine tundra and more.
The “micro”, as you already guessed, puts this environment on a small scale. As The Economist stated, “in the nooks and crannies of every human being, and especially in his or her guts, dwells the microbiome: 100 trillion bacteria of several hundred species bearing 3 [million] non-human genes.” Most of those species come from four different groups, or phyla: Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria.
Most people have a decent understanding that there are beneficial bacteria, but most are probably not aware that we, as humans, are host to a whole civilization of them, in and on our bodies. They are also involved in bodily structures and processes. Digestion is a great example. Here’s a neat trick: Milk contains carbohydrates called glycans. As The Economist explains, they are “indigestible by any enzyme encoded in the 23,000 human genes. Only bacterial enzymes can do the job.”
Because of their impact on digestion, a proper balance of gut bacteria can aid in weight loss or weight maintenance. Scientific American reports “evidence indicates that gut bacteria alter the way we store fat, how we balance levels of glucose in the blood, and how we respond to hormones that make us feel hungry or full. The wrong mix of microbes, it seems, can help set the stage for obesity and diabetes from the moment of birth.”
To be clear, the microbiome isn’t the only factor in weight gain. That same article wisely concludes, “No one in the field believes that probiotics alone will win the war on obesity, but it seems that, along with exercising and eating right, we need to enlist our inner microbial army.”
Or maybe it’s all in your head. More and more scientists are referring to the connections between the brain and the gut, such as the book The Mind Gut Connection by Dr. Emeran Mayer, a UCLA professor. Just this month, an article in the American Journal of Gastroenterology reported that “preclinical and a few clinical studies have demonstrated the existence of a brain-gut-microbiome axis in which bacterial signals can modulate affective behavior, brain activity, and central gene expression profiles.”
Given the deep connections to health — both good and bad — the microbiome has, it’s important to maintain balance. The Economist reports: “A disrupted microbiome has been associated with a lengthening list of problems: obesity and its opposite, malnutrition; diabetes (both type-1 and type-2); atherosclerosis and heart disease; multiple sclerosis; asthma and eczema; liver disease; numerous diseases of the intestines, including bowel cancer; and autism. “
Clearly, what you don’t know, and what you can’t see, can hurt you, and that’s true of a microbiome that is out of balance.

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