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Sugar Confusion

  • By Monique Ryan
  • Published Sep. 9, 2011
  • Updated Oct. 12, 2012 at 12:52 PM EST

Dear Monique,

I am thinking of eliminating sugar from my diet, but can’t find anything to replace my energy drink or gel with, have you come across any products that fit the bill?
Soured on Sweets

Dear Soured,
There seems to be a lot of confusion regarding the best types of carbohydrates that should be consumed during exercise with some sports nutrition products promoted as containing “complex carbohydrates” versus the “simple carbohydrates,” often also referred to as sugars. But classifying a carbohydrate as simple or complex really doesn’t provide the complete picture regarding a carbohydrate source. There are also distinct differences regarding the type of carbohydrate sources you should include in your daily diet versus what you should consume while training.

Classifying Carbohydrates
Carbohydrate can vary widely in their structure, sweetness, and effecton our health.
Simple carbohydrates, which are often called “sugars,” consist of one or two molecules, while complex carbohydrate are composed of several to thousands of molecules. Monosaccharides are one molecule carbohydrates and include glucose, fructose (found in fruit), and galactose and are the easiest to digest. Glucose is the carbohydrate utilized by the cells in your body, and the other monosaccharides can be converted to glucose. We actually obtain most of the monosaccarides in our diet from the breakdown of disaccharides, which are two carbohydrate molecules. An exception would be fructose which in found in fresh fruits, but also in a variety of processed foods as high-fructose corn syrup.

Disaccharides include table sugar or sucrose (glucose + fructose), lactose the sugar found in milk (glucose + galactose), and maltose (glucose+ glucose). These “simple” carbohydrates are also relatively easy to digest. Complex carbohydrates that contain three to ten carbohydrate molecules are oligosaccharides and include many manufactured carbohydrates such as maltodextrin (found in some sports drinks) and corn syrup (found in processed foods). Oligosaccharides also include carbohydrates like rafinnose and stachyose that are found in nutrient rich foods such as legumes.

Other complex carbohydrates or polysaccharides are composed of over ten and often hundreds of glucose molecules joined together, and include amylose and amylopectin. Most of the carbohydrates found in the plant world are in the form of polysaccharides, but not all complex carbohydrates are unprocessed, whole food sources. Glucose polymers, which are made commercially from starch and are also technically complex carbohydrates, can be found ina number of sports drinks and carbohydrate gels.

Indigestible carbohydrates are commonly referred to as fiber and include cellulose, hemicellulose, gums, and pectins, and are very important for gastrointestinal tract health and disease prevention. So you can see that there are many types of carbohydrates. As an endurance athlete, you can include a variety of carbohydrate sources in your daily diet, and at various times.

For your health and fuel recovery you can emphasizecarbohydrate sources from whole grains, fruits, vegetables, skim milk products, and incorporate a variety of these foods in your diet for the different nutrients they provide. Athletes also have a wide variety of sports drinks, gels, bars, and recovery drinks to choose from, all containing different carbohydrate sources from monosaccahrides, disaccharides, and polysaccahrides such as maltodextrinor glucose polymers.
Daily Diet Carbohydrates
Of course you want to emphasize whole foods and nutritious carbohydrates such as whole grains, fruits, and vegetables in your daily training diet. Skim dairy products and soy milk also add carbohydrate to your diet. Incorporating these foods into meals and snacks help you meet two of the most important purposes of your training diet. These carbohydrate sources effectively replenish muscle glycogen stores between training sessions and also provide a variety of vitamins, minerals, and phytochemicals that contribute to keeping your body healthy and immune system strong. Of course, when you eat real foods in the hours before training, you also have to consider your tolerances to specific food choices. Easily digested carbohydrates also make good recovery foods immediately after training.
For many of us sugar is contained in foods that we view as treats, and it is currently estimated that Americans consume over 60 pounds of sugar yearly. Depending on your food choices, sugar in your diet is either added sugar, which is simply sugar added to food, or naturally occurring sugars. The key to smart sugar consumption in your daily diet is to downplay the nonnutritive added sugars and incorporate food sources of natural sugars.

Natural sugar sources include the fructose found in fruits and lactose found in milk, foods that provide a nice variety of vitamins and minerals. Added sugars are low in nutritional value and particularly prevalentin processed foods is high fructose corn syrup, which is sweeter than fructose.

So how much sugar in your daily diet is too much? It depends who you ask. The World Health Organization recommends that no more than 10 percent of your daily total calories comes from sugar, considerably less than the National Academy of Science recommendation of 25-percent of total caloric intake.

As an endurance athlete, you can often consume a substantial number of calories to meet your training energy needs, so 10 percent from sugar leaves rooms for treats. If your daily energy intake is at 3,000 calories, then 300 calories from sugar should not crowd out plenty of healthful foods from your diet.When trying to minimize the added sugar in your daily diet keep in mind that the Nutrition Facts label does not distinguish between added sugars and natural sugars in foods, as only the “total sugars” are listed. Check the ingredient list of foods to look for added sugars which can include terms such as cane syrup, corn syrup, brown rice syrup, high fructose cornsyrup, maltodexrin, and sucrose.
Training Diet Carbohydrates
In contrast to your daily diet, the carbohydrates you consume during training must be palatable during exercise, easy to digest, and well tolerated, with performance being your primary consideration. These carbohydrates must effectively provide fuel for your exercising muscles and maintain blood glucose levels as your training continues to deplete your liver and muscle glycogen stores during longer or high intensity training sessions. Food and drinks also taste differently when you are exercising, so it is best to determine what product tastes best to you when you are exercising. Carbohydrates commonly seen on labels of sports drinks include fructose, glucose, maltodextrin, glucose polymers, and other assorted carbohydrates.

Technically fructose is a simple sugar and a glucose polymer is a complex carbohydrate, so is one a sugar and the other not? Clearly you won’t be consuming a bowl of granola during training, you probably won’t eat an apple during interval training on your bike, pull a muffin out of your back pocket during the season’s A race, or chomp on an ear of corn during training. What you need for top performance is a sport drink containing a carbohydrate that will quickly empty from your stomach and be easily absorbed through your small intestine.

Keeping the carbohydrate concentration of a sports drink at 6 to 8 percent ensures that a drink can easily empty from your stomach. Having a sports drink that has two different carbohydrate sources, such as both glucose and fructose, also maximizes the potential of the drink to be absorbed through the small intestine. The sodium in sports drinks also facilitates absorption of fluid across the small intestine. Obviously water provides no carbohydrates or electrolytes, while carbohydrate free drinks only provide fluid (and maybe electrolytes)- offering no performance benefit when fuel stores runlow.

Of course in our daily diet, the hormone insulin is secreted in response to our blood glucose levels. In fact when you are not exercising, a small amount of insulin is constantly being secreted even when blood glucose levels are in the normal range, so that there is a steady flow of glucose into your brain cells and muscles. In your daily diet, food, particularly carbohydrate intake, will trigger a specific output of insulin with some foods resulting in a higher insulin output than others.

During exercise, insulin release is blunted and it is important to maintain blood glucose levels during training and competition. Your most important consideration for carbohydrate consumption during exercise is to find a sports drink that you tolerate, like, and can drink steadily to offset fluid and fuel depletion. Gels, which are much more concentrated in carbohydrates, also raise blood glucose levels and must be consumed with water to prevent any gastrointestinal discomfort during exercise. You should also keep in mind that once you have reached a certain level of dehydration, fluids and gels take longer to empty from your stomach, so drink steadily from the start.

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