Your gut has three-and-a-half to four-and-a-half pounds of bacteria, which is about equivalent to the size of your liver!  There are more bacterial cells in your body than there are human cells, ten times more, actually.  And only recently research has been showing what these little bugs do and what kind of role they play in our health.

New research shows that an unhealthy gut may be the source of seemingly unrelated physical and mental disorders, like diabetes, heart disease, Alzheimer's and mood disorders. There is some scientific evidence of this already that is taking health practitioners in a whole new direction. If you don't have a correct balance of friendly bacteria in your gut, your metabolism is affected, which could make you gain weight and develop metabolic and immunological diseases. These bacteria even produce vitamins your body needs to stay healthy, such as vitamins K and B6.

Our modern diet contains less fermented food than before.  For most people, the processed and cooked food does not provide enough of the friendly bacteria from diet alone, so choosing a supplement is important.  You need more than yogurt to do it, so look for supplements that contain different strains, and make sure they have Acidophilius and Bifidobacterium, as these are the most common types.  Choose a supplement that has at least 1 CFU (CFU stands for "colony forming units") per serving.  Look for enteric coating - a special protective coating that allows more of them to make it past the digestive acids in your stomach and into the gut.

As science struggles to make sense of these new findings, allow me to go on a limb here and say that this information has been available to humanity for the past several thousand years - Ayurveda has been telling us that our gut and what they called "humours" or "doshas" inside our bodies are the sources of imbalance and disease.  I believe that Ayurveda is talking about the same thing, only using a different language.  Think of it this way: you have an environment inside you, populated by bacteria of different species, in different numbers and therefore different proportions of one bacteria to another.  Various types of microbes accumulate everywhere in and on the human body.  Some of them perform specific useful functions, such as development and regulation of the immune system, produce beneficial compounds that the body cannot produce on its own, and other tasks.  Others produce toxins that poison us.  Some are even capable of creating a certain mood or mental state in us!  It all depends on the kind of environment you create for them - do good bacteria want to live in you, or bad bacteria? 

Antibiotics are largely to blame, but there is more to this than that.  The environment inside us is fostered through the foods we eat and lifestyle choices we make.  You create the conditions in your body, and based on those conditions  you will have the types of residents that prefer them.  Just like lions and giraffes live in Africa, and polar bears in Antarctica, good bacteria lives in moderate climes of your gut, and bad bacteria will call home extreme conditions that are created by improper diet.

When we are born we inherit a lot of our bacteria from the parents, especially the mother.  The dramatic increase in the rate of deliveries by cesarian section limits the transfer of these bacteria from the mother to the child.  Fewer children in families also means that children don't inherit a lot of these bacteria from their older siblings.  Cleaner water and living conditions also have contributed to a more sterile environment and reduction of the variety of bacteria we are exposed to.

How does it relate to Ayurveda?

Vata Dosha is a type of gut environment that creates favorable conditions for bacteria that cause anxiety, fear, inability to concentrate, memory problems, constipation, gas, irregular appetite, and poor nutrient absorption and other signs of having too much wind in the body.  The Vata-aggravating bacteria accumulates in the large intestine, from there the poisons spread to joints and bones and other weak places in the body.  This type of gut environment is created by eating raw, dry, cold foods, such as salads, popcorn, chips, oil-free and fat-free foods (by vegetarian diet that does not contain enough complete protein and good oil) and by keeping an irregular daily routine, staying up late, watching too much TV.  Coffee, smoking and other stimulants such as drugs or over-exercising are also major contributing factors.  Cold, dry and windy weather makes Vata worse.  Vata aggravation is reduced by mild exercise that includes stretching (Vata causes stiffness of joints and muscles), regular routine and sufficient sleep, and by Vata-pacifying diet - warm, heavy, oily, nourishing foods.  Oil massage and warm bath also help.  One of the best ways to reduce Vata is a moisturizing enema.

Pitta Dosha is a type of environment that is created by spicy, oily or greasy food, by eating too many sweets, by overindulgence in alcohol, by driving oneself too hard at work and being too competitive and selfish.  It causes inflammation in the body, burning sensations, acid reflux, acne, liver and kidney damage, vision problems, anger bordering on rage, severe headaches and other manifestations of having too much heat and fire in the system.  Too much Pitta causes one to sweat and produces strong body odor.  It accumulates in the small intestine, from which it can then spread to blood, lymph, organ of vision, sebaceous glands and other parts of the body, causing inflammation.  Hot and humid weather makes Pitta worse.  Pitta is best balanced by diet rich in green, leafy vegetables, by eating less of red meat, grilled and spicy foods, and by consuming ghee (clarified butter) and small amounts of lean protein.  Moderate Yoga practice that produces mild sweating is indicated so the toxins can be removed through the skin.

Kapha Dosha is a type of environment that is created by diet rich in fatty, sweet, and cold foods (think ice cream), and laziness.  It accumulates in the stomach.  When too much of it is accumulated, Kapha becomes aggravated.  The individual becomes depressed, lethargic, gains weight, suffers from allergies, respiratory illnesses.  All sorts of mucus and phlegm form in the body, especially in the chest, throat, head, pancreas, stomach, lymph, fat, nose and tongue.  Cold and damp weather makes Kapha worse.  Kapha is best expelled upwards through the nose and throat by vigorous and heating Yoga practices and Pranayama (think Sun Salutes and Kapalabhati), by eating small meals with lots of roughage and fiber, by adding spices and reducing dairy.  Vegetarian diet with lots of spices is best suited to a Kapha Dosha.

Now, what is important to note here is that all of these elements: air (Vata), fire (Pitta) and water (Kapha) are necessary for health. When it is in just the right amounts Vata gives us creativity, flashes of brilliance, light and joy.  When Pitta is balanced, it gives us enthusiasm, courage, leadership qualities and charisma.  When Kapha is balanced it gives us good immunity, radiant health, steadiness, fills our hearts with love and peace.  It is when there is too much of one that we have a problem.  It becomes Vata Dosha when there is too much of the element, and Dosha means "that which is out of balance."  In and of themselves these "humors" are not bad, but when they accumulate and become aggravated - that's when we have a problem. High Vata results in the mind loosing connection with the body.  The body then begins to emaciate, decay and waste away.  High Pitta results in too much internal heat and infections.  High Kapha results in excess weight, slow metabolism, looseness of limbs and lethargic state.   By modifying our diet and lifestyle we can change the internal environment in our bodies and make it less favorable for the accumulation and aggravation of these "humors."

For more information about the microbiome, read the article in Scientific American, Volume 306, number 6 for June 2012.