According to Digestive Wellness, there’s a total of one hundred trillion bacteria live together in our digestive system, in either symbiotic or antagonistic rela tionships. That’s ten times more intestinal bacteria than cells in our body. Their total weight is about four pounds-the size of the liver. They have many functions and act like a symbiotic organ to protect our health. Eighty percent of the dry weight of our stool is composed of gut bacteria, and half of that is still alive. Gut flora accounts for half of the volume of the contents of the large intestine.
We have four hundred to five hundred types of bacteria in our digestive systems, each of which has many types of strains. This variety may seem overwhelming, but twenty types make up three-quarters of the total. The most common are bacteroides, bifidobacteria, eubacterium, fusobacteria, lactobacillus, peptococ- caceae, ruminococcus, and streptococcus. Most of these bacteria are anaerobic, meaning they do not need oxygen to thrive; some are aerobic and do need oxygen for survival. A third group produces lactic acid and can be either aerobic or anaerobic. Lactic acid-producing bacteria help acidify the intestinal tract and protect us from overgrowth of harmful bacteria.
Billions of bacteria inhabit our mouths. While the stomach has few because of its high acid content that prohibits their growth, the small intestine has many billions of bacteria. The overwhelming majority of intestinal flora reside in the colon-trillions and trillions. Each day, we produce several ounces of these microbes and eliminate several ounces in stool. These bacteria manufacture substances that raise or lower our risk of disease and cancer, the effect of drugs, immune competence, nutritional status, and rate of aging. Some of these bacteria cause acute or chronic illness. Other bacteria cause illness in people who are genetically susceptible but no problems in other people.
Another group of bacteria offers us protective and nutritive properties. These friendly bacteria are called intestinal flora, pro-biotics, or eubiotics. The last two terms mean “healthful to life.” The term probiotics is commonly used to refer to supplemental use of these bacteria in powder or capsule form. It was coined in 1965 by researchers Lilly and Stillwell to mean organisms that promote life of microorganisms, in opposition to antibiotics, which kill microorganisms. The two most important groups of flora are the lactobacilli, found mainly in the small intestine, and bifidobacteria, found primarily in the colon. These bacteria live symbiotically within us in a mutually beneficial relationship that has evolved to enhance our health and theirs.
The bacteria within us live at about 98.6° Fahrenheit and thrive on the constant nourishment we provide in a warm, dark, moist environment. We allow them to inhabit us because they give us valuable preventive and therapeutic benefits.
Where did these trillions of bacteria come from? Up until birth, we receive predigested food from our mothers and are born with a sterile digestive tract. The trip down the birth canal initi ates us into the world of microbes that thrive everywhere. Babies are exposed to bacteria in breast milk and formula and when sucking on nipples, fingers, and toes. With every breath and touch, bacteria enter the body to colonize on the skin and mucous membranes. In no time, every conceivable space in the colon is occupied by microbes. Within the first few days of life, colonization of E. coli and streptococcus occurs. Within a week of birth, bifidobacteria, bacteroides, and Clostridium are established in bottle-fed babies. Breast-fed infants have increased numbers of lactobacillus and bifidobacteria species.
The microbes set up homogeneous neighborhoods that push out competing microbes trying to break into their territories. This normally happens in a predictable way, and once established, the colonies flourish. When babies are unable to properly colonize friendly flora, they become irritable and colicky and have gas pains and eczema in their diaper area. Babies who don’t develop the right balance of beneficial bacteria are more susceptible to allergy, asthma, and eczema. The colonization patterns we set up in infancy continue to prevail throughout our entire lifetime.