The So-Called Simple Carbohydrates

By Sherri Shafer

The monosaccharides and disaccharides illustrated here are considered simple carbohydrates (sugars). There are naturally occurring sugars in many foods. Fruits, milk, and yogurt are examples of foods that contain natural sugars.

Carbohydrate chemical structure.

Take a closer look at the carbohydrate building blocks, the single sugars. Sugar molecules are made out of carbon, hydrogen, and oxygen, which can be assembled to form glucose, fructose, or galactose. Those are the three monosaccharide single sugars. The single sugars can decide to partner up with each other, form a loving bond, and become disaccharides.

The sugars.

Going au naturel with glucose, fructose, and lactose

All fruits have natural sugar. Fruits contain both glucose and fructose. In fact, fruit is 100 percent sugar. There’s no protein or fat in fruit. Avocados and tomatoes are considered fruits if you ask a botanist. However, when considering the actual composition of those foods in terms of calories, carbs, and the effect on blood sugar, tomatoes get shipped off to the “vegetable” group and avocados are relegated to the “fat” group because they are more similar in composition to the items in those respective food groups. Vegetables also contain glucose and fructose, but in lower amounts than fruit.

While fructose is a natural sugar, high-fructose corn syrup is not. The latter is made in mass quantities and added to foods during manufacturing. Fruit has positive nutritional benefits and is part of a balanced diet. High-fructose corn syrup does not offer any nutritional benefits.

Lactose is the natural sugar in milk. It is a disaccharide, or double sugar. Lactose is digested in the intestine as lactase enzymes clip apart the double sugar into its two single sugars, glucose and galactose. Only single units of sugar are absorbed into the bloodstream.

Some people do not have enough of the enzyme to properly break down lactose. If you are unable to digest milk, then you are likely lactose intolerant. People who are lactose intolerant feel gassy and bloated or crampy (or have diarrhea) after consuming milk (and sometimes other dairy products). One solution is to buy lactose-free milk. Lactose-free milk has the enzyme pre-added to the milk. The double sugar, lactose, breaks down into the individual sugars, glucose and galactose, before you even drink it. The carton will say 100 percent lactose-free milk, but keep in mind the actual amount of sugar is exactly the same as normal milk — it just contains single sugars instead of the double sugar. Another work-around on lactose intolerance is to use a nondairy milk substitute.

If you are lactose intolerant, you may still be able to tolerate cheese. That’s because cheese is basically carbohydrate-free. Cheese is made from the protein and the fat from milk, but it has no (or only trace amounts of) lactose. Some people who are lactose intolerant seem to tolerate yogurt fairly well too. The lactase enzyme needed to digest lactose sugar is also available in tablets and liquid drops, so you can take it as needed when you have a serving of dairy.

Finding other forms of sugar: Sucrose, maltose, honey, and syrups

Sucrose is the fancy name for white sugar. It is a disaccharide (double sugar) that is made from glucose paired with fructose. When you digest it, which occurs in the intestine, the two sugars break apart and are individually absorbed into the bloodstream.

Maltose consists of two glucose molecules joined together. Maltose results when starches are being broken down into sugars. The maltose can quickly split into individual glucose sugars. Maltose and malted grains are used for making alcoholic beverages. Maltose and other sugars can be converted to alcohol by yeast during the fermentation process.

Honey is composed of fructose, glucose, several oligosaccharides, and water. Oligosaccharides are chains of three to nine monosaccharide sugars, whereas polysaccharides have ten or more sugar molecules in the chain. The bees add enzymes to the honey when they produce it, so most of the sugars exist in monosaccharide form. Honey is slightly sweeter tasting than sugar, so you may achieve the same sweetness when using a smaller portion.

Syrups may be of the naturally occurring variety, such as pure maple syrup. Many other types of syrups are manufactured, often out of high-fructose corn syrup. Maple syrup is high in natural sucrose but also has traces of fructose and glucose.

Spotting simple carbs in the grocery aisles

When looking at Nutrition Facts food labels, the grams of sugar are indented and listed under the total carbohydrates. All the sugars discussed thus far in this chapter are lumped together and called “sugar.” That means the natural sugars in fruit and milk get counted as sugar on the food label. It’s more informative when carb counting to look at the total grams of carbohydrate on Nutrition Facts labels. The sugars are already included in the total carbs. If you’ve been looking only at the grams of sugar, you’ve been missing the big picture. The starches eventually break down into simple sugars during digestion, so keep your eye on the total carbohydrate counts.

Look to the perimeter once you’re inside the supermarket, as that is where you typically find the healthy foods that contain natural sugars. Fresh fruits and vegetables and reduced-fat dairy products such as milk and yogurt are considered to be part of a well-balanced and healthy diet. Those are real foods with real nutrition. Fruits, vegetables, and reduced-fat dairy products contain important vitamins and minerals and offer health benefits.

On the other hand, many not-so-healthy foods are loaded with added sugars in the form of sweets and treats, such as cookies, pastries, ice creams, and candy. Use caution when steering your grocery cart down those aisles. Excessive intake of desserts can end up piling on the carbs and the calories. Use caution at the checkout stand too, as the store is making one last attempt to sell you candy.