By Dr. Colin Michie of AUC Medical School
Dr. Colin Michie has worked as a paediatrician in the United Kingdom, Africa, the Caribbean and the Middle East. He is specialised in nutrition, haematology and infectious diseases. Now the Associate Academic Dean for the American University of the Caribbean Medical School in St. Maarten, his enthusiasm is training medical students and healthcare teams to ensure they deliver better value health care.
Photographs of your family or friends show their distinctive appearances – why those ears? Which ancestor was so short? Is this not her mother’s calming smile? Despite similar genes, diets and habits, our individual bodies show great variation – no two are the same. You will know your own body reasonably well, but do you know what makes it up? Your health will depend on how your body is built. Some of your makeup is inherited; some is the result of the life you have led. Analysis of your body’s architecture might help improve your well-being. It is useful to use a system for this, looking at the molecules, then the cells and finally your tissues. Each requires particular scrutiny: Is all well, how can I improve or protect this part of me?
First, breaking down our bodies into its molecules shows how remarkably similar we are. Humans are 55-70% water by weight, with new-born infants or pregnant mothers having more water than older adults. Water is unique and crucial to almost all life forms on this planet. Even Members of Parliament are mostly water! By weight, about 18% of us is carbon, 3% nitrogen and 1.5 % calcium. Minerals such as sodium, chromium, zinc or magnesium account for about 6% of our total weight. These figures tell us that our tissues are not very different to those of most other mammals in terms of these elements.
Most body water is contained within cells as a carefully maintained salt solution. Fluids, such as blood, lymph, spinal fluid, bile and fluid in the eyes and inner ears, are all maintained in a precise balance of salts by molecular pumps on cell surfaces. Balances of even very small amounts of minerals are important. If we become short of iron, for instance, we become anaemic. Most iron, 2-4 grams, the weight of one or two US cents, is in the bloodstream. If we are short of iodine, our thyroid gland will not function well. Checking these micronutrients requires a blood test. If we are generally healthy and eat a reasonable diet, they are unlikely to be disordered. Perhaps it is useful to look at our bodies in terms of its cells.
All our tissues are built of cells surrounded by connective tissue scaffolding. Cells are built using instructions from the genes we were given by our parents. We have many different types of cells that grow and follow specific paths, such as cells in the brain that form connections, or cells in the bone marrow that make red and white cells for the blood. Several kilograms of our body are not human, but bacteria. Bacteria, viruses, fungi and protozoans can be found on our skins, in our mouth, ears, nose and in the gut. Some 1,200 types of bacteria can be identified in our mouths alone. There are approximately 10 times more bacterial than human cells in our bodies. By the time you have read this newspaper article, many of them will have multiplied and had children. This collection of organisms is called our microbiome.
Most of the organisms of our microbiome live in our bowel. They have a profound influence on our health. One crucial value of gut bacteria is that they make our vitamin K. We need this for our blood clotting. These bacteria also manufacture thiamine, riboflavin and B12, all vitamin B vitamins. Bowel organisms influence our efficiency at collecting food molecules and therefore our body weight. For infants, their new gut bacteria are supported by breast milk which provides crucial carbohydrates and other substances to help them develop. Some types of bowel bugs can predispose us to disorders such as rheumatoid arthritis or colitis. Bowel bacteria make methane and hydrogen, some of which pass through the blood and out in our breath.
If you wish to check the performance of your body’s cells, a blood test is useful. Tests are often used to check on the way our organs such as the liver or kidneys work, whether the heart, pancreas or bones are functioning normally. The bad news is that at present, we have few useful tests available to look at microbiome critters. An analysis of your breath gases is easy and can help make a diagnosis of lactose intolerance, for instance. This area is one of great research – you will have heard, for instance, that it is probably a good idea to feed your gut organisms well with prebiotics (found in fruits and plants). Sometimes, the addition of specific organisms, for instance those found in fermented foods such as live yoghurt or kimchi, will be useful after infectious diarrhoea and some types of bowel inflammation.
A third and practical way to look at bodies is anatomically. The reason for this is that globally, the most variable component of our human bodies is the proportion of fat. Obesity is increasingly common and is caused by too much fat. Being overweight is linked to mental health problems related to self-esteem, as well as physical ones that include hypertension, heart disease, blood lipid problems, sleeping and respiratory difficulties, joint disease, type 2 diabetes, infertility and gallstones. Fat in excess shortens our lifespan.
Continued in the next issue…
