Dietary guidelines : Carbohydrates

What are the different types of carbohydrate?

Simple carbohydrates

Monosaccharides: Glucose and fructose (fruit and vegetables), galactose (milk), xylose (found in wood and cellulose of some plants)

Disaccharides: sucrose (table sugar), lactose (milk), maltose (from starch), trehalose (often added to ice-cream)

Sucrose (disaccharide) consists of glucose and fructose.

Lactose (disaccharide) consists of glucose and galactose

Simple carbohydrates are sugars. They consist of just one or two molecules. They provide a rapid source of energy, but you soon feel hungry again.

Foods containing lots of simple carbohydrates are white bread, lollies, and cakes.

Complex carbohydrates

Oligosaccharides: maltodextrins (produced from starch and used as a food additive).

Polysaccharides: starch present in potato, maize, rice other cereals, cellulose,

Starch is the storage form of glucose found in plants.

Complex carbohydrates consist of long chains of sugar molecules.

Complex carbs are wholegrains and foods that still have their fiber. They tend to fill you up for longer, and they are considered more healthful, as they contain more vitamins, minerals, and fiber.

Starches consist of those glucose molecules, joined together in large clusters. Still-larger arrays of glucose molecules make up indigestible dietary fiber, molecules of cellulose or hemicellulose. The atomic bonds in cellulose molecules are so strong that your stomach can't break them down. Starches are less stubborn and can be digested to some degree but not always completely.

There is another way of classifying carbohydrates:

Bad carbs

Bad carbs are sucrose (table sugar) and refined wheat.

Healthy carbs  

Fruits, vegetables, legumes, dairy milk, cheese and yogurt, nuts and seeds.

Whole grain such as wheat, rye, barley, rice, quinoa, amaranth, buckwheat, millet, maize, sorghum and oats. 

Most of these foods also contain protein, oil, fibre, vitamins and minerals, , phytonutrients.

How many carbohydrates are needed each day?

Women need 1,600-2,400 calories per day.

Men need 2,000-3,000 calories per day.

Experts have said adults should consume 45-65% of calorie intake as carbohydrates. With only 10% from sugars.

The brain needs carbohydrates, specifically glucose, because neurons cannot burn fat

Athletes need more carbs to replace glycogen used during exercise. Up to 70%

Calculate 45-65% of your daily calorie intake and then divide by four to get grams of carbs.

For example:

2,000 calorie diet

900-1300 calories from carbs

225-325 grams of carbs

Does cooking or processing alter the carb?

When eating starch (polysaccharides) alpha-amylase break down the starch to glucose which is then absorbed. Starch varies. There are different types. The amount of glucose absorbed varies.  If it is cooked more is absorbed. If it contains fiber less is absorbed. If the fruit is riper more is absorbed. If the grain is turned into flour more is absorbed.

When cooked starch molecules undergo gelation. They absorb steam from their own moisture or the cooking liquid, swell and then burst. They are then more digestible.

Raw starches are not as easily absorbed. They travel further down the colon where they encounter anaerobic bacteria.  These bacteria breakdown some of the carbs and cause flatulence. Some bacteria will pass undigested through the intestine.  Some of the carbs are absorbed further down the intestine.

Resistant starch isn’t absorbed on its passage through your colon. It feeds some bacteria in your intestine which is a good thing. It provides all of fiber’s benefits.

Processing starch

Whole grains are often milled into flour. If the flour is sifted then fibre, protein, oil, vitamins, minerals and phytonutrients are often discarded decreasing its nutritional value.

The advantage of processing whole grain wheat to make plain white flour is the bread or cakes made will be lighter and fluffier. The disadvantage is they will not be as healthy.

Whole grain flakes are readily available.

How can carbohydrates lead to diabetes?

Eat carbohydrate.

The digestive system breaks down the complex carbs to glucose.

Glucose is absorbed enters the blood stream. (Blood sugar increases).

Beta cells in pancreas release insulin.

Insulin lowers the blood sugar level by making cells absorb glucose for energy.

When blood sugar drops to a low level alpha cells in pancreas release glucagon.

Glucagon makes liver release glycogen releasing glucose needed by the brain.

If you eat too much carbohydrate.

Blood glucose increases rapidly.

Cells need more insulin to react. This is insulin resistance.

Pancreas has to produce more insulin. Eventually it wears out and can cease altogether.

The glycemic index

Carbohydrates enter the bloodstream as glucose at different rates.

Carbohydrates that raise blood sugar quickly are said to be high on the glycemic index.

High-GI carbs enter the bloodstream quickly as glucose.

Carbohydrates that have a gentle effect on blood sugar levels have a lower GI score.

Low-GI carbs take longer to digest and break down and enter the blood stream.

Low GI foods: whole grains, fruit, vegetables, legumes

The Bottom Line

I will attempt to eat natural, unprocessed, unrefined carbs such as wholegrains, legumes, vegetables and fruit.  

I will attempt to avoid refined carbs such as table sugar and white flour. 

No fruit juice. If I want orange juice I will eat an orange.

I will cook plants to make the food more palatable. Cooking is not a big negative or positive.