“I will praise thee; for I am fearfully and wonderfully made: marvellous are Thy works.” Psalm 139:14
Our bodies, created by God, are fascinating in their complexity. As I do research for the many health articles I have written, I am more and more awed by the many trillions of tiny components that make up the human body that continually work in their perfect order to keep us alive, to allow us to perform a variety of tasks such as breathing, eating, moving, and even thinking. An organism this complex could only have been created by a superior being. Even now, science does not understand the whole workings of the human body. Throughout eternity, the redeemed will have the opportunity to learn more about the human body, the crowning glory of creation, created in the image of God.
Recent research has been made into learning more about a significant component of the human body known as the human microbiome. These studies have become possible because of advances in technology that allow scientists to map out the vast number of cells that live in our body that are not actually part of the structure of our body, yet coexist with human cells, and perform important functions. In fact, of all the cells in the human body, 90% are part of the human microbiome. For every human cell in the body, there are ten microbial cells. These cells are made up of more than 3 million genes; whereas human cell genes only number just over 20,000. Bacteria make up the largest part of the human microbiome, with anywhere from 75 trillion to 200 trillion individual organisms, and are 10–50 times smaller than human cells. The microbes contained in our intestines alone can weigh up to 2 kg (4 ½ pounds). Forty-thousand species of bacteria have been found in the human body. Most bacterial strains are either harmless or beneficial, with less than 100 species that can actually cause infectious diseases in humans.
Each of our human cells contains a set of instructions, telling it what function it must perform. This is known as the genome of a cell. Genomes are made of DNA. Bacteria also have genomes; therefore they also have a set of instructions telling them how to function. In fact, just the microbes in our gut contain 150 times more genes than are found in the entire human genome. Because of the vast number of microbial cells in the human body, and their impact on the healthy functioning of the body, we are all considered a blend of human and microbial traits.
Already as early as the mid-1880’s, discoveries have been made of bacteria inhabiting our bodies. An Austrian pediatrician, Theodor Escherich, discovered the bacteria known as Escherichia coli or E. coli. He found that the bacteria inhabited not only the intestines of children who had symptoms of an illness that causes diarrhea, but he also found that E. coli inhabited the intestines of healthy children, indicating that it may have a functional role in the human body. Most E. coli strains, naturally occurring in the intestinal tract of both humans and animals, are harmless; and, in fact, play an important role in the health of the individual. Vitamin K, which assists with blood clotting, preventing uncontrolled bleeding, is synthesized in the intestines by E.coli bacteria. These bacteria also are important members of the immune system, preventing harmful bacteria from growing in the intestine and causing illness. However, some E. coli strains can cause disease, such as food poisoning, urinary tract infections, traveller’s diarrhea, meningitis and pneumonia. You may have heard on many occasions of foods being recalled because of contamination with E. coli.
Since the 1800’s, many discoveries have been made regarding these organisms that live within the human body. However, only in the last few decades has research into the human microbiome been able to prove the crucial role that it plays in human health and disease. Current research on the human microbiome has become more sophisticated and more comprehensive, with the ability to identify the DNA and thus the function of the various microbes. This is crucial in determining the interactions between the microbiome and the “host” (the person) and being able to develop new therapies and treatments for disease.
The human microbiome or microbiota is a vast collection of microorganisms which include bacteria, archaea, protozoa, viruses, and fungi, living in and on our bodies. These microorganisms live everywhere including on our skin, inside our mouth, nose, genitalia, urinary tract, lung and the large (colon) and small intestine, coexisting alongside human cells. The biggest population of these microorganisms live in our intestines. They consist of 95% of all the microorganisms in our body. The collection of all these microbes form what is known as the human microbiome. A microbiome is defined as “the microorganisms contained in a particular environment (including the body or a part of the body)”. Micro is defined as “small.” The word “biome” denotes “community”. Therefore, we have an ecological community living inside of us, made up of various small organisms, sharing our body space. It is like a small world contained in our bodies. What is even more fascinating is that our collection of microbial cells is unique to each individual person, as unique as our DNA. Differences in the composition and function of the human microbiota are related to the location where one lives, age, sex, race, and the diet of the individual. The differences in our microbiome related to where we live and what we eat may explain why we develop diarrhea when we eat food or drink water when we travel to other countries, whereas people native to the country do not have a problem.
We are all born with a microbiome that develops into a diverse ecosystem as we develop and age. Our gut (gastro-intestinal system including stomach, intestines) begins to populate with bacteria at birth. The type of bacteria found in infants is influenced by genetics, the health of the parents, the delivery method, and being breast-fed vs bottle-fed. Babies born through the vaginal canal have healthy, beneficial gut microbiota, similar to that found in the mother. However, babies born via C-section have more pathogenic bacteria such as E.coli and Staphylococcus. These babies take longer to develop a healthy, beneficial gut microbiota. Then, as we grow, many factors determine the types of bacteria in the gut. Because many external factors determine the gut microbiome, our specific microbiome can change over time, depending on factors previously mentioned such as stress, where one lives, and especially our diet.
Despite the overwhelming amount of microbes in and on the human body, little was known about their role in health and disease. Many of the organisms had not been identified. In 2005, a largescale research study, known as the Human Microbiome Project (HMP) began. This project was an initiative of the United States NIH (National Institutes of Health) into the gut microbiome and its role in human health, to improve understanding of the microbial flora involved in human health and disease. Prior to that time, studies had mostly been done on the “harmful” bacteria in our gut.
The project is similar to the Human Genome Project which was started in 1999; the goal was to completely map out and understand all the genes which make up the genome of human beings. This project, concluded in 2003, determined that there are about 20,500 human genes, which are responsible for the set of “instructions” that all humans inherit to develop and function as a human being. This research also enabled scientists and doctors to determine the links between certain flaws in genes and their connection to inherited diseases. One of the benefits of the information gained from the Human Genome Project is that it provides a “textbook” for health care professionals to develop ways of treating, preventing, and curing diseases.
Some of the key functions of the human microbiome that have been discovered to this point are as follows: The human microbiota on our skin and in other areas where our body is exposed to the external environment, such as our lungs, urinary tract, and mouth act as a barrier, preventing harmful pathogens (disease-causing organisms) from entering into our body. The synthesis of certain vitamins occurs via organisms in the microbiome (Vitamin K, biotin). Serotonin, a chemical that is related to brain health and mood, is created by microorganisms in the intestines. The microbiome is also involved in the digestion and breakdown of the food we consume; regulating our metabolism and body weight. The microbiome is a vital component of
the development and maturation of the cells of the immune system. In fact, when the balance of the human microbiome is disrupted for any reason (dysbiosis), disease occurs. It has been determined that many human illnesses are connected to an imbalanced microbiome. These illnesses include infections such as bacterial vaginosis and urinary tract infections, liver diseases, inflammatory bowel disease, obesity, heart disease, certain cancers such as stomach and intestinal (colon) cancer, metabolic disorders such as diabetes, respiratory diseases, mental or psychological diseases, and autoimmune diseases such as multiple sclerosis and rheumatoid arthritis.
Because of the vital role that a healthy functioning microbiome plays in the overall health of a person, it has been suggested that it should be viewed conceptually as a newly discovered organ. We can live without some organs such as our spleen, appendix, gall bladder, and tonsils; however, we would not survive for very long without our body’s microbiome. It has also been proven that the more diverse the microbes are in one’s body, the lower one’s risk of allergies and disease. And, we can enrich our microbiome by various lifestyle choices, which we will learn about next month.
Some of the key findings from the HMP indicate that there is no one ideal “healthy gut”. Everybody’s gut is different. One third of our gut microbiota is common to most people, while two thirds are specific to each one of us. What is important is that the bacteria contained in the gut are able to function at their best, rather than having specific types and numbers of bacteria. The composition of the gut changes over time, as one’s health and diet changes. There are several things that we can do to help our gut microbiome become or remain healthy and balanced. The balance of our gut microbiome can be disrupted by several factors, and this can promote inflammation—a strong risk factor for physical and mental disorders. People with certain diseases often have a very different combination of bacteria in their intestines compared to healthy people. Researchers are working to determine the makeup of gut bacteria in healthy people. Therefore they would also be able to determine the combination of gut bacteria that can point to either a higher risk of disease or the actual presence of certain diseases. The key to gut microbiome health is not the presence or absence of any one particular type of bacteria, but rather the diversity of bacteria that it contains.
Joseph Petrosino, a researcher into the gut microbiome states, “If you have a wide array of bacteria that can break down lots of different food sources, produce lots of different molecules that help mature your immune system, and produce the molecules that your brain needs to function properly, you can see how that would potentially be a benefit over a less diverse gut microbiome.” In 2012, the HMP concluded that much of the diversity of the human microbiome in healthy people remains unexplained. Research continues.
Knowledge into the different species of organisms and their composition in the gut microbiome is increasing. However, still little is known why there is such a large variation across the world. Samples taken from different nations imply that there may exist a limited number of well-balanced gut microbiomes. For now, microbiome studies are still too new for scientists to determine whether certain bacteria might cause disease or whether disease might breed certain bacteria—or whether the relationship is something else altogether. For now, connections between a person’s bacterial composition and the presence of certain diseases can be determined. Regardless whether a cause-and-effect relationship exists, looking at the gut microbiome can help doctors diagnose certain diseases earlier and more accurately. The challenge in mapping out the human microbiome is the vast number of genes it contains. However, it is becoming more evident that there are links between the gut microbiome specifically and virtually every disease known to humankind.
“The mechanism of the human body cannot be fully understood; it presents mysteries that baffle the most intelligent. It is not as the result of a mechanism, which, once set in motion, continues its work, that the pulse beats, and breath follows breath. . . . The beating heart, the throbbing pulse, every nerve and muscle in the living organism, is kept in order and activity by the power of an ever-present God.
“The Creator of man has arranged the living machinery of our bodies. Every function is wonderfully and wisely made. And God has pledged Himself to keep this human machinery in healthful action if the human agent will obey His laws and cooperate with God. Every law governing the human machinery is to be considered just as truly divine in origin, in character, and in importance as the Word of God. Every careless, inattentive action, any abuse put upon the Lord’s wonderful mechanism, by disregarding His specified laws in the human habitation, is a violation of God’s law. We may behold and admire the work of God in the natural world, but the human habitation is the most wonderful.
“This living machinery is to be understood. Every part of its wonderful mechanism is to be carefully studied. “ –My Life Today, p. 127
NEXT MONTH:
HEALTH AND OUR MICROBIOME