Health and Nutrition

Understanding the Carbohydrate Puzzle

Gregg Carroll - Thursday, February 07, 2013

Obesity in the United States has become a major epidemic, and according to a report published in the Journal of American Medical Association (JAMA), at any given time 45% of women and 30% of men are trying to lose weight. With so many people trying to shed pounds, there are a multitude of programs that claim to be successful in losing weight. One option is a low-carbohydrate diet, which has become a recent trend advocated by weight-loss books. While weight loss is possible on a low carbohydrate diet, the results are not long lasting, and indicate that carbohydrates are not the only source of weight gain.

Companies and individuals cashing in on the weight-loss trend have demonized carbohydrates, creating a notion that carbohydrates are bad for your health. On the other hand, clinical studies and medical establishments recommend a high carbohydrate, low calorie diet for sustained weight loss. Clearly there is a gap in the common understanding on carbohydrates. There is a huge difference between whole carbohydrates and refined carbohydrates. Not all carbohydrates are the same.

Are All Carbs the Same?

A statement for health professionals from the American Heart Association recommends the following dietary guidelines for Americans, “Consume a diet low in (refined) sugar and high in unrefined carbohydrates.”

Carbohydrates are our body's primary and most preferred fuel source. So how could our body's chief fuel source be harmful to our health? The difference is in the type of carbohydrates we consume. To differentiate between carbohydrates, it is necessary to understand different carbohydrate types and their influence on our bodies.

What is a Carbohydrate?

Sucrose, also known as table sugar, is a common disaccharide. It is composed of two monosaccharides: D-glucose (left) and D-fructose (right).

Carbohydrates are produced exclusively by plants through photosynthesis as carbondioxide and water combine to form a carbohydrate. They are a plant's storage form of energy, and because of this, they produce different types of carbohydrates for different requirements. The simplest form are called monosaccharides (“saccharide” means sugar), and the complex form of carbohydrates are called polysaccharides. Regardless of the type of carbohydrate, all break down into sugar, carbon, and water. One gram of carbohydrate reulsts in 4 calories.

Types of Carbohydrates and Their Structure

Type Structure Example Food Source
Monosaccharides Glucose, fructose
(one sugar molecule)
Table sugar, honey, processed foods, refined flour, white bread, chips, cakes, sweets, fruit juices, etc.
Disaccharides Made of two monosaccharides
(two sugar molecules)
Sucrose – beets, cane sugars, maple syrup
Lactose - Milk and milk products
Oligosaccharides Made of 3–10 monosaccharides
(more than 2 sugar molecules)
Cabbage, broccoli sprouts, whole grains, beans, etc.
Polysaccharides Made of very long chains of hundreds or thousands of monosaccharides (either straight or branched) Cellulose, starch, pectin
Cellulose is present in spinach, seeds, apples,and most fruits and vegetables.
Pectin is present in nuts, oats, beans.

The time taken for carbohydrate to be digested (broken down) and release glucose (sugar) after consumption is a crucial factor in raising blood-glucose levels. The slower the breakdown, the steadier the rise in glucose level. The faster the breakdown of the carbohydrate, the quicker the rush of glucose into the blood stream, characterized by a high peak level and a quick drop. The rate at which consumed food raises blood sugar is determined by the factors of glycemic index and glycemic load. It should be noted that our bodies perform better if our blood glucose levels are kept at a relative constant.

Glycemic Index and Glycemic Load

Glycemic index (GI) is a numerical measure that shows the ability of a given food to raise the blood-glucose level. It indicates how fast a carbohydrate is digested and released as sugar into the blood stream. The GI measure only takes into account the quality of carbohydrates, while the amount of carbohydrate, and other factors such as fiber and water in the food, and portion size consumed are not. Because of this limitation, a measure called glycemic load was introduced.

Glycemic load (GL) is a numerical measurement which indicates the ability of an actual portion size of carbohydrate-rich food to raise blood glucose levels. The glycemic load places emphasis on the quantity and quality of carbohydrates. GL is a better indicator of how a carbohydrate-rich food will influence an increase in blood sugar. Consuming foods with high GL raises the blood glucose level at a faster rate. To arrive at GL, GI and the number of carbohydrates in the food are both taken into consideration:

GL = GI / 100 x net carbohydrate

Glycemic Index and Glycemic Load of Different Foods

Food Serving Size Glycemic Index Glycemic Load
Apple (regular) 120 gram 39 6
Apple juice 250 ml
(1 cup)
44 30
Watermelon 1 cup 72 3
Whole wheat flour (whole grain) 1 cup
(120 g)
292 40
White wheat (refined) flour 1 cup
(120 g)
280 66
Oat bran (raw) 1 ounce
(28 g)
55 5
Instant oats (quick cooking) 1 ounce
(28 g)
60 + 7 11

How to Differentiate a Wholesome Carbohydrate from Refined?

The healthiest carbohydrates are natural, wholesome, and are always bound to fiber components. Examples include whole grains, nuts, seeds, fruits and vegetables. A wholesome carbohydrate becomes a sugar when the nutritional components of natural carbohydrates are lost during the refining process, altering the texture and colour of a natural food. A perfect example is refined flour, originally from a whole grain, stripped of its essential nutrients leaving simple sugars. It is the refined sugar and not the whole carbohydrate that is the culprit.

The “Whole” Story About the Grains

Whole grains are the complete seed of a plant composed of bran, endosperm, and germ. The bran is the outer layer, rich in antioxidants, vitamins and fiber. The endosperm is the starchy part that is the food supply for the germ. The germ is what sprouts into a new plant, and it is rich in B vitamins, healthy fats, and protein. Any whole grain will contain all the three parts, but during the process of refining, the bran and germ are removed leaving only the starchy endosperm.

Before the invention of iron rollers, stone grinders were used to convert whole grains into flour, which retained the fiber, essential fats and many other nutrients, but left an unappealing white color. Once iron rollers replaced stone grinders, the bran and germ were easily removed and crushed the starchy endosperm, resulting in a product of white flour that lacked fiber and 17 key nutrients of whole grains. Consequently, refined grains have a higher glycemic load (66) than whole grains (40). Grains in their natural form have a lower glycemic index because it takes longer for our digestive enzymes to reach the starch inside whole grains, slowing down the conversion of starch into sugar. The carbohydrate (sugar) in whole grains exist in a complex matrix of dense nutrients that include vitamins, minerals and fiber. A whole grain is composed of both soluble and insoluble fiber which has a crucial role in influencing the glycemic load index. This is the primary factor behind the low GL of the whole grains compared to processed ones.

Dr. Andrew Weil demystifies the carbohydrate puzzle in his book Eating Well for Optimal Health. In it, he explains that if we are able to chew on grains or see grains in our food products, it is an assurance that they are natural whole grains with a low GI ranking. Examples are wild rice, barley, wheat berries (spelt), and millet. The more your jaw has to work, the better. But when grains are pulverized into flour, whether whole or not, their surface area expands dramatically, providing a huge, starchy surface area on which enzymes can work. Consequently, the conversion to sugar happens very quickly. Consuming more natural and less processed grains is key in consuming low GL foods. Note the difference between the glycemic load values of natural oats with bran and instant oats (processed) in the GI and GL table.

The best way to stay on a healthy track is to ask yourself if the food you're eating is wholesome, unprocessed, and provides calories along with nutrients like vitamins, minerals, antioxidants and phytonutrients. Clearly, carbohydrates are not the villain, but the refining and processing techniques which turn naturally nourishing carbohydrates into empty calories and deprives us of their inherent nutrients.

Carbohydrates, if eaten in the context of a food that naturally provides fiber, vitamins, minerals, antioxidants and phytonutrients, are certainly healthy. The real culprits are the processed, refined and manufactured foods which are digested quickly and increase blood glucose level quickly. Cutting back on such processed carbohydrates helps weight loss. Consuming the wrong kind of carbohydrates is the primary cause for obesity epidemic and other health disorders.

It seems prudent to distinguish between refined carbohydrates and whole grain carbohydrates for making the right dietary choices. There are plenty of tools available online to estimate the glycemic load of various foods, easing our goal of choosing the right carbohydrates to enjoy the maximum health benefits.

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