The role of sugar in nutrition and health

Published 3:32 pm Tuesday, February 7, 2023

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Last week, we learned about the composition of sugar. This week, let’s explore some of sugar’s role as it pertains to nutrition. Some believe sugar to be a necessary nutrient that provides bursts of energy, while others are convinced that sugar is the dietary villain. 


First, to some degree, every living thing on earth uses sugars for energy, including us. Both humans and animals are hard-wired to crave sugar. In nature, this is used as an indication of which foods are safe to eat, as poisonous foodstuffs tend to be bitter. 

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The body uses sugars and starches from carbohydrates to supply glucose to the brain and provide energy to the cells. So, just what happens when we eat sugar? When sugar is digested, enzymes in the small intestine break it down into glucose, which is then introduced into the bloodstream. As blood sugar levels rise, the pancreas produces insulin, a hormone that prompts cells to absorb blood sugar for energy or storage. However, excessive intake of sugar leads to increased fat storage in the body, type 2 diabetes, a fatty liver, cardiovascular disease, and even stroke. 


Now, does sugar consumption cause type 2 diabetes? Maybe not directly, but excess sugar can cause weight gain, and that could lead to type 2 diabetes and an array of other health disorder clusters known as metabolic syndrome. 


Glucose is the main source of fuel for the brain, too. Nerve cells and chemical messengers require it to process information. Also, too many carbohydrates or excessive amounts of simple sugars actually impair brain function. High blood sugar harms blood vessels throughout the body, including the brain and heart. One study demonstrated that increased sugar consumption decreases blood vessel function and lessens blood flow in only 14 days.  


Did you know that all sugars are carbohydrates, but all carbohydrates are not sugars? That’s right, some carbohydrates called “storage carbohydrates” provide energy. In plants, these are in the form of alpha D glucose units. That’s just a fancy phrase for starch. Plant starch consists of glucose polymers. Glycogen is the storage form of carbohydrates in animals. Structural carbohydrates don’t provide energy, but rather provide mechanical stability to cells, organs, and organisms. 


In plants, these are in the form of cellulose, long-chained molecules used to build biomass components, including cell walls, stalks and stems. Cellulose is the most abundant carbohydrate in the plant kingdom. Structural carbohydrates used by animals are in the form of glycosaminoglycans and chitin. Glycosaminoglycans are large polymers used as the body’s shock absorbers and are found throughout the body in skin, joints, blood plasma and the mucous membrane of various organs. Chitin is commonly found in lower organisms such as fungi, crustaceans and insects, and adds strength to their exoskeletons (an external skeleton that supports and protects an animal’s body). A mushroom’s cell walls contain chitin, which accounts for its unusual texture, and since chitin is remarkably heat-stable, it is practically impossible to overcook mushrooms. 


Sugar is a constituent of all plants, and some produce more than you’d think. For instance, lemons actually contain more sugar than strawberries. Lemons contain 70% sugar, while strawberries contain only 40% sugar. The acidity of lemons, which gives them their tangy taste masks their sweet flavor. Other fruits and vegetables that are relatively high in sugars include sweet potatoes, apples, beets, bananas, onions, cherries, green peas, grapes, sweet corn, mangoes, carrots, oranges, tomatoes and pears.  


While it’s true all plants contain sugars, it is only found in high enough concentrations to make sugar crystals from two plants, sugarcane and sugar beet. Unlike most other producing countries, the United States has large, and well-developed sugarcane and sugar beet industries. Sugarcane accounts for around 45% of the total sugar produced domestically, while sugar beets are responsible for around 55% of production. More on sugars next week. 


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David  Crocker is a nutritionist and master personal trainer. Questions? Email David at com or text 864-494-6215.