The science
of your gut
According to recent studies by the National Institutes of Health's Human Microbiome Project, your gut's microbiome influences the overall health of your entire body. Much like the way bacteria convert milk into yogurt or cabbage into sauerkraut, the good bacteria in our intestines break down dietary fiber by fermenting it—this satisfies their needs and leaves behind organic acids that nourish and repair the cells of our body.
What exactly is the microbiome?
According to the University of Washington's Center for Ecogenetics and Environmental Health, your microbiome is the genetic material of all the microbes and microorganisms—bacteria, fungi, protozoa and viruses—that live on and inside the human body. Not generally recognized to exist until the late 1990s, it is essential for human development, immunity and nutrition. The microbiome makes up one or two percent of your overall body weight, meaning a 180-pound man is carrying about 2 pounds of bacteria around with him.
How to tell when your gut health
is out of whack
This army of microbes is a hardy but sensitive bunch. They react not just to what you eat and drink, but to the medications you take, the amount of sleep you get, how often you travel or get stressed at work—all of which can foster an environment that lets more of the bad bacteria to take over for a while. When that happens you'll likely first experience the typical intestinal symptoms: bloating, cramping, constipation or gas. Bad bacteria tend to produce more gas, so digestion issues are a pretty good signal that your gut doesn't have enough of the good kind.
Besides that, you may notice irritation on your skin. How? Shelby Keys, RD, a dietitian at Boston's Brigham and Women's Hospital explains it like this: One of the gut's primary roles is promoting health by generating immune responses, but a dysfunctional intestinal barrier could lead to inflammation that manifests in your external barrier—skin that's now suffering from rosacea, eczema or psoriasis.
Or you might just feel really rundown and tired. Your microbiome is responsible for much of the production of mood-enhancing chemicals (think dopamine and serotonin), so if your bacteria balance is off, your mood could feel equally off. And when your immune system is taxed, fighting the imbalance of the flora within your gut, you can feel like you're coming down with a cold or even flu-like symptoms.
Feed your gut,
but not too much
Stanford University's Justin Sonnenburg, a microbiologist focused on how diet impacts bacteria in the gut, recommends eating as many high-fiber fruits and vegetables and legumes as you can. If you don't give your body enough fiber, you're left with little to nourish our microbiome. But you want to spread out your meals. Eating sooner than every one-and-a-half to two hours can interfere with the body's cleansing waves known as peristalsis, says Keys. Preventing these cleansing waves can lead to an overgrowth of bacteria in the gut.
How do
probiotics help?
Here's where things get interesting. Probiotics are good bacteria that are either the same as or very similar to the bacteria that are already in your body. In a recent study published in Nutrients, researchers investigated probiotics' immune-boosting powers in yogurt. They found that the live bacteria interact with the microbes in our intestines to produce such vitamins as B6, B12 and K; while helping ward off bad bacteria such as E. coli and Salmonella. Probiotics may also enforce our intestines' natural barrier function, helping to keep viruses like the flu and common cold from getting through. And because they're such potent anti-inflammatories, probiotics have been shown to help clear up skin, reduce allergic reactions, as well as improve cholesterol levels and glucose metabolism.
