In this blog we will delve into the topic of sugar, addressing the conflicting messages surrounding its effects on health. From claims of it being a silent killer to its association with obesity, diabetes, and even cancer, the media bombards us with alarming headlines. At the same time, we hear about sugar being a crucial fuel for athletes. Is there any truth to these conflicting messages? We will begin by exploring the nature of sugar itself.
Understanding the Composition of Sugar
Sugar is categorized as a carbohydrate, with its name derived from "carbo" (carbon) and "hydrate" (water), indicating its composition of carbon, hydrogen, and oxygen molecules. The general formula for carbohydrates is CH2O, maintaining a molar ratio of 1:2:1 for carbon, hydrogen, and oxygen. Glucose, the most common carbohydrate in the body, has the molecular formula C6-H12-O6. It is produced through photosynthesis in plants, which serve as our primary source of carbohydrates. Although carbohydrates are prevalent in all living cells, glucose specifically serves as a beneficial fuel for muscles and is stored as glycogen—a starch comprising a chain of glucose molecules.
Varieties of Sugars in Our Diet
Glucose is a monosaccharide, a small molecule often referred to as grape sugar. By linking two glucose molecules, maltose, also known as malt sugar, is formed. Fructose, another monosaccharide, will be discussed further in subsequent blogs. When glucose and fructose combine, they create sucrose, the most commonly consumed sugar known as table sugar. Galactose, yet another monosaccharide, combines with glucose to form lactose, the sugar found in milk.
These mono- and disaccharides encompass the sugars present in our diet, each possessing varying levels of sweetness. Fructose emerges as the clear winner in terms of sweetness. As previously discussed in a separate blog, the sugars found in our diet include glucose, fructose, galactose, sucrose, lactose, and maltose.
Understanding Complex Carbohydrates
On the other end of the spectrum, we encounter complex carbohydrates. These carbohydrates consist of chains of glucose molecules, ranging from short chains of 6-20 glucose molecules known as maltodextrins (found in many sports nutrition products) to long chains known as starch. Generally, complex carbohydrates exhibit lower levels of sweetness compared to sugars.
Key Points about Sugar and Polysaccharides
Several crucial aspects must be understood regarding sugar and polysaccharides (multiple glucose units):
- Sugars tend to be sweet, while polysaccharides like maltodextrins or starches are less sweet.
- Fructose stands as the sweetest carbohydrate, approximately 1.5 times sweeter than sucrose, while galactose is half as sweet as sucrose. However, sweetness does not correlate with function.
- During the ripening process of foods, complex carbohydrates break down into sugars, resulting in a sweeter taste in fruits.
- An interesting experiment involving crackers demonstrates that amylase in saliva breaks down starch into sugar, gradually transforming a tasteless cracker into a sweet one when held in the mouth for an extended period.
- Not all sugars are metabolized at the same rate; some are fast, while others are slow. Maltodextrins and certain starches (such as amylopectin) behave similarly to glucose upon ingestion.
- The terms "complex" and "simple" carbohydrates are employed in various contexts, leading to significant confusion.
Common Misconceptions about Sugar
Misunderstandings and misconceptions surrounding sugar abound. One prevailing misconception is the classification of sugars as "fast" and starches as "slow." This notion is incorrect, as some sugars are fast, some are slow, and certain starches are just as fast as glucose. The distinction between fast and slow carbohydrates refers to the rate at which they are converted into glucose in the bloodstream. Maltodextrins and specific starches break down rapidly into glucose, resulting in similar blood glucose levels when measured.
To compound the confusion, the term "complex carbohydrate" is also used differently, denoting foods containing not only starches but also other nutrients and fiber. Examples include whole grains and brown rice, often referred to as complex carbohydrates. However, it may be more accurate to label these carbohydrates as "unrefined" rather than "complex." Unrefined carbohydrates play a vital role in a healthy diet, while sugars should be consumed in moderation. In certain situations, athletes may prefer refined carbohydrates over unrefined carbohydrates.
Conclusion
By understanding the composition of sugar, the various types of sugars in our diet, and the differences between simple and complex carbohydrates, we can unravel the misconceptions surrounding sugar. This knowledge forms the foundation for further exploration into the effects of sugar on our health, which we will delve into in future blogs.
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Scientific reference
- Jeukendrup AE and Gleeson M. Sport Nutrition 2018 Human Kinetics Champaign IL
