Last week we spoke a bit about how prevalent diabetes is, and how that doctors are pretty good about diagnosing it and put patients onto treatment. The big problem is that treating diabetes with pharmaceuticals doesn’t get to the root cause of the disorder, and so the disease process continues, granted at a slower pace than if there was no treatment. Diabetes is particularly common amongst people of Asian descent but actually affects people of all ethnic origins. It is also happening at a younger age than in the past, riding on the back of the obesity epidemic.
ALSO READ : Turning the Tide – Can diabetes be reversed?
Physiology of carbohydrate metabolism
Carbohydrates are the main source of glucose, which is the actual fuel for the vast majority of cells in our bodies. It is particularly important for effective brain function, as well as muscle energy. The human brain averages around 1400 gms in mass but it consumes around 75 mg of glucose every minute – that is around 20% of our glucose intake.
Glucose is obtained from starchy foods – fruit, vegetables, grains, legumes, seeds, nuts and dairy products. It can be converted from proteins in meat as well in small amounts in the liver. In their natural form, carbohydrates are packaged in complex digestible units – polysaccharides – which are also surrounded by non-digestible starches called fibre. They are also accompanied by a vast array of phytochemicals, vitamins and minerals vital for a healthy body.
Our body is intricately designed with the ability to break down these complex sugars into glucose – a process that starts in the mouth and ends in the small intestine.
Once absorbed into the blood, glucose cannot naturally enter into the muscle and liver and brain cells without assistance. Vitally important for this important step is the presence of insulin. Special cells in the pancreas – the Islets of Langerhans (named after the German biologist who discovered them in 1869) – respond to rising levels of glucose in the blood, and secrete insulin into the blood stream. This insulin acts as a doorkeeper for the cells, and has a key which fits into a lock on the cell membrane called a receptor.
This key opens a “delivery hatch” through which glucose can enter the cell and be utilised in the “engine” (the mitochondria) of the cell to power multiple chemical processes.
With the advent of food processing, it is possible to extract the sugars from their natural foods and then add these directly to prepared foods for extra sweetening – hence table sugar, corn syrup, fructose, etc. The problem with these refined sugars is that their natural accompaniments – fibre, phytochemicals and minerals have almost all been stripped away. Fibre acts as a slow-release capsule, which governs the absorption of glucose into the blood stream to stop glucose spikes. If you take foods (like a sweet cool-drink, or a handful of sweets), that sugar will rapidly get into the blood stream. The pancreas then excretes a huge injection of insulin to help the entry into your cells, but often it overdoses. This leads to a sugar rush, followed by low sugar with feeling weak, sweaty and wobbly (called hypoglycaemia). That is unlikely if you confine your glucose intake to unrefined carbs – like fruits, starchy vegetables (as in potatoes, squash, turnips, sweet potatoes, etc), legumes (like beans, lentils chick-peas, etc) and whole grains (like maize on the cob, brown rice, oats, barley, whole-wheat, millet, sorghum, etc.).
In many traditional societies, up to 80% of food ingested is made up of complex starches (carbohydrates). These provide boundless energy for the normal function of the body. Starch rich natural foods usually have sufficient proteins and fats as well for the body’s needs, especially if a variety of foods is consumed. (I read about an experimenter – Andrew Flinders Taylor – who dramatically improved his poor health living on only various types of potatoes, and water (and Vit B12) every day for a year. Not the most interesting or sustainable diet, but shows the nutritional value of spuds!).
Now that you have a good idea of the physiology of carbohydrate and glucose metabolism, next week we will talk about diabetes mellitus – a disease of disturbed glucose metabolism.
Eat plenty of those healthful complex carbs, but cut way back on the processed carbs.
Dave Glass
Dr David Glass graduated from UCT in 1975. He spent the next 12 years working at a mission hospital in Lesotho, where much of his work involved health education and interventions to improve health, aside from the normal busy clinical work of an under-resourced mission hospital.
He returned to UCT in 1990 to specialise in obstetrics/gynaecology and then moved to the South Coast where he had the privilege of, amongst other things, ushering 7000 babies into the world. He no longer delivers babies but is still very clinically active in gynaecology.
An old passion, preventive health care, has now replaced the obstetrics side of his work. He is eager to share insights he has gathered over the years on how to prevent and reverse so many of the modern scourges of lifestyle – obesity, diabetes, ischaemic heart disease, high blood pressure, arthritis, common cancers, etc.
He is a family man, with a supportive wife, and two grown children, and four beautiful grandchildren. His hobbies include walking, cycling, vegetable gardening, bird-watching, travelling and writing. He is active in community health outreach and deeply involved in church activities. He enjoys teaching and sharing information.
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