Sugars: exposed

Sugar is confusing-- there are so many types and so much marketing for those types. It is naturally found in fruits, dairy, and some vegetables/grains-- which are part of a healthy diet-- but it often gets a bad rap!! 

Types of sugar

The controversy stems from the fact that the majority of the intake in the American diet is not from these natural sugars but from “added sugars.”  These are sugars that are added to foods during processing, preparation, or upon consumption to sweeten the flavor of food and drink. They may be also added to foods to help with preservation, texture, body, and appearance. There are many kinds of added sugars, including white sugar, brown sugar, corn sugar, honey, syrup, and current studies indicate that these typically make up about 15-20% of a person’s total caloric intake! Because of this high intake, recent government guidelines, as well as those from the American Diabetic Association  (ADA), the American Heart Association (AHA), and numerous other agencies, have called to reduce intake of added sugars.

The average American consumes 78 pounds of added sugars per year.

These days, there are many kinds of sugars, and it is important to know the difference between them-- especially because the nutrient label does not distinguish between added sugar and natural sugar (read more: Marion Nestle's Food Politics blog post). 

Here is a simple breakdown of common sugars:

The simple, basic sugars:

• Glucose: All carbohydrates (not just sugars) are ultimately broken down in our bodies to form glucose, a monosaccharide. Glucose is what supplies the energy to our body for all of its metabolic and life-sustaining functions. This is what is measured in the blood (as blood sugar). These blood levels are tightly regulated in the body through the hormones insulin and glucagon-- because even small changes can have effects on brain function, appetite, and energy.  If glucose is added to foods, it appears on the label as dextrose, corn sugar, or glucose-- all identical molecules. Glucose itself is mildly sweet (think molasses!). 

Added sugars in soda!

• Fructose: this is typically known as fruit sugar. Fructose is twice as sweet as glucose, thus giving fresh fruit a unique, sweet taste. Though a part of a healthy diet when coming from fruit, fructose intake is concerning because consumption has increased dramatically over the recent years. This is likely a result of the food industry adding corn syrup, high fructose corn syrup, and fructose (itself) to foods. (The more fructose in the product-- the sweeter and more shelf-stable it is…) This is worrisome not just because of the increased calorie intake that results from consuming foods with added sugar, but because fructose is metabolized very differently in the body when compared to glucose. Unlike glucose which is processed in every cell of the body, fructose is processed only in the liver (like alcohol...), and does not have the same regulatory mechanisms that is seen with glucose. Though still up for debate about how much of a role it plays, some argue that large intakes of fructose from added sugars are really dangerous to overall health (i.e. increases in bad cholesterol, changes in hormone/appetite regulation, changes in normal fat/carbohydrate metabolism/increased fat storage, increases in the risk for non-alcoholic fatty liver disease and diabetes-like problems, etc.…)! WHOA… scary! But… small amounts of fructose (like those levels found in whole fruits) have been associated with lower glycemic indexes and decreases in blood sugar levels… phew!

• Sucrose: this is typically known as table sugar-- what you buy as "sugar" in the store. Sucrose is called a disaccharide-- a molecule that has one glucose molecule and one fructose molecule combined in a 50/50 ratio. Therefore, it is sweeter than glucose itself, but less sweet than fructose alone. Most commercial sucrose comes from sugar cane or sugar beets. Sucrose can be refined and look white (highly refined), brown (often less refined), granulated, or powdered (aka confectioner's sugar). A byproduct of the refining process is molasses, which gives brown sugars their unique flavor, moistness, and brown color. Natural brown sugars or raw sugars are simply those that have larger sugar molecules and are less refined-- they can have "flavors" depending on the amount of minerals and molasses they contain (demerara, dark muscovado and turbinado are all different types of brown sugar). Refined sugars are ideal for baking-- especially for things like cakes, smooth icings, etc., but refining removes nutrients from the sugar molecule (think something like sanding down the sugar crystal to look pretty but taking away the rough edges that contain the nutrients). Therefore, the less refined may have a slight advantage of also providing small amounts of minerals like calcium, potassium, magnesium and iron. However, all types of sucrose break down the same in the body… to glucose (remember from above!).

• Lactose: this is typically known as milk sugar-- and interestingly is the only sugar of animal source! This is a molecule of glucose and a molecule of galactose combined. As we age, the enzyme (lactase) needed to break the sugar bond becomes less functional, and we lose the ability to digest lactose as easily. Symptoms of lactose intolerance are gastrointestinal distress, pain, and gas. A lactose-free milk product contains enzymes that have already broken down the lactose into its two molecules-- easing digestion. This is also why it tastes sweeter (the single molecules taste sweeter on the tongue)

Malt affects beer color and flavor

• Maltose: this is typically known as malt sugar. It is two glucose molecules combined and is primary sugar found where wheat germinates. It has a unique, characteristic flavor often in milk shakes and candies but is used most often to make beer.

The other sugars you can find: 

• Corn syrup (or high fructose corn syrup): This is a cheap and abundant form of sugar, made from breaking down corn into a glucose-rich syrup. It can be chemically converted to contain more fructose to make it sweeter. This is typically added to many foods including beverages (sodas!!), but also crackers, bread, and peanut butter.

• Honey: Honey can come in many forms and flavors depending upon the type of flower (clover, wildflower, blueberry, etc.) that the bee population visited. Honey is naturally high in sugars-- typically containing fructose, glucose, sucrose, and maltose. Because it is a less refined sweetener, it is filled with antioxidants and other healthy nutrients. In fact-- there are over 180 substances found in honey! 

• Agave syrup: this sweetener harvested from the same plant as tequila and has a more mellow flavor than other sugars. Due to the high fructose content, it tends to be sweeter than both sucrose and honey, and it is considered a high-fructose sweetener (giving it the same problems that fructose has but also contributing to its low glycemic index).

Also called "polyols"

• Sugar alcohols (sorbitol, xylitol, erythritol, etc.): These sugars do provide calories but less than their “regular” sugar counterparts because the sugar alcohol molecules are not fully absorbed in the body. They are found naturally in fruits and vegetables, but they are often added sources of sugar in low-calorie foods like sugar-free gum. Because they cannot be absorbed well, ingestion of large amounts of this sugar may cause gas, abdominal discomfort, and diarrhea.

• Artificial sweeteners (also called nonnutritive sweeteners): These sugars include Sweet-n-Low, Splenda, and Equal and may be added to foods to sweeten them without adding a significant amount of calories. Though these have been approved for safety by the FDA and deemed acceptable as part of a healthy diet by the Academy of Nutrition and Dietetics, artificial sweeteners contain chemicals that are relatively untested in long-term studies. Additionally, some studies indicate that ingestion of non-caloric sweeteners may increase your appetite, causing you to want to eat additional other calorically rich foods-- though reviews of research found this relationship to be less clear.. The ADA and AHA cautiously endorse the use of nonnutritive sweeteners to replace the use of added sugars in the diet; however, it is acknowledged that more research needs to be done to make any real conclusions.

Take home message:

Sugar, no matter if naturally present or added, breaks down the same way in the body and results in glucose formation-- the body’s initial source of energy. Also regardless of the source-- sugars all break down and provide the same 4 calories per gram. However, when sugar is naturally present, the consumption provides nutrients and other healthy components like protein, healthy fats, vitamins, minerals, fiber, etc that are found in food. In comparison, added sugars provide little other nutrients-- just calories. Either way, high intakes of sugar increases the risk for weight gain, dental caries, and other chronic diseases-- so be careful. Monitoring what you eat and read food labels-- remember that sugars can appear in different forms (corn syrup, dextrose, high fructose corn syrup, etc)-- so don't be fooled!

Remember that extra calories from sugar require additional physical activity!