Carbohydrate (carbs) are mainly a source of energy. They are made by photosynthesis in plants and are the main source of energy in nature’s plant foods; fruits, vegetables, grains, legumes and tubers. Three main carbohydrates are starches, sugars and fibre.
- Starches: found mainly in grains. Also in the starchy vegetables; potato, pumpkin, carrot and peas.
- Sugars: refined sugar and honey are concentrated forms, also in most fruits and some vegetables.
- Fibre: the indigestible part of the plant foods. It may be insoluble and useful as roughage, moving the intestinal contents fast enough to prevent re-absorption of toxins and excess cholesterol. Soluble fibre (found in onions, leeks, garlic, asparagus, Jerusalem artichoke and in the water from boiled rice, oats or barley) becomes a food to nourish beneficial gut bacteria.
The simplest and best way to think of carb food is that they are either grain or fruit and vegetables.
Carbohydrates provide energy and are also needed for protein and fat metabolism. They help growth of body tissue and have compounds that help lubricate the joints. Some carb foods are high in fibre which is essential for bulking the intestinal contents and keeping them moving through the digestive tract, aiding in the elimination of wastes and toxins before they can be re-absorbed.
In this age of refined foods we often hear of “complex carbohydrates”. This is a useful description but it doesn’t mean very much. Carbs are either fibre rich or they are not. They may also be full of nutrition (nutrient dense) such as green vegetables or they may be full of energy (energy dense) such as starchy foods & grain. Grain is 2/3 carbohydrate, most of this is starch. The idea of eating “complex” carbs is good; we should eat unrefined, unprocessed, unpackaged foods as much as possible. Which really means ample vegetables and minimal grain. Modern broadacre agriculture combined with advertising has brought energy dense carbs to dominate much of our diet. One powerful part of this promotion is the United States Department of Agriculture (USDA) Food Pyramid which rests on a foundation of starchy foods. Good nutrition requires nutrient dense foods, for carbohydrate this means vegetables (which can be grown in our own gardens!)
Another important aspect of carbs to our body is providing special sugars such as glucosamine (for joints), xylose, fucose, mannose, etc, which seem to be part of the building blocks for our antibodies and thus vital for immunity and vibrant health. These special sugars are available to us from eating a variety of “picked ripe” fruits, they are also in the immune stimulating herbs e.g. astragalus.
Carbohydrates cause insulin secretion to the bloodstream. Insulin is a powerful hormone with a number of functions, mainly in regulating energy and metabolism. Its most important function of maintaining low glucose levels becomes a problem if there is a lot of glucose!
GLYCEMIC INDEX / GLYCEMIC LOAD
After a meal, the carbs we’ve eaten are digested down into glucose (either in the intestine or liver) and enter the bloodstream, causing insulin to be secreted from the pancreas, immediately beginning conversion of glucose to fat for storage and connecting to receptors on cells so glucose may enter for energy.
The cell’s requirements for energy fuel is capped at the energy demand of the moment, so the speed and amount of glucose entering the blood becomes a measure of how much excess blood sugar will be turned to fat. It’s also a measure of how much stress is put onto insulin secretion and its ability to connect with cell receptors.
“Glycemic index” (GI) is a tool for calculating how quickly a food causes blood sugars to rise and “glycemic load” is the effect of a whole meal. Glycemic index its determined in a laboratory. Volunteers are given a glass of water with pure glucose added and a range of finger prick blood tests taken over two hours. The peak blood sugar reading is given a value of 100. This procedure is repeated with a food and the peak reading is the glycemic index, as a percentage of the pure glucose value. Interestingly, starches like potato have a higher GI than sugar.
Carbs with a high glycemic index cause blood sugar stress. But a portion of high GI foods in a meal with fat and protein will have much less effect because the meal has a lower glycemic load.
Reading Glycemic Index values.
Glycemic index is a measure of how fast a carb food turns into glucose. Pure glucose is given the number 100, and all foods are a proportion of this number.
High GI is any food rated over 75
- Most starches are high (especially the baked and fried vegetables and grains)
Medium GI is from 55 to 75
- Most sugars are medium (sugar & dry fruit higher, with fresh fruit at the lower values)
Low GI is below 55
- Most wholesome nutrient and fibre dense foods are low, such as meats, green vegetables, legumes & pulses.