The Great Sugar Debate – Glucose, Fructose, and Sucrose Demythed

“Sugars” have always been a topic of debate, and the discussion may be as old as allopathic medicine and pharmacopeia. And as popular as they are, they are just as reasonably notorious and still as important for the body. There is no sugar coating this fact.

What we refer to as “sugars” in the food, are all carbohydrates. That is, they are the molecules formed from Carbon, which we find everywhere from coal to animal tissues, and Hydrogen and Oxygen, which of course, are everywhere around us – in the very air we breathe and the water we drink.

Carbohydrates can be broadly classified as fibers, starches, and sugars. 

Fibers are found in most vegetables and fruits. They aid digestion, produce the least calories (2 calories per consumed gram), cleanse the digestive system, and ultimately helps in weight loss. But they are still classified as carbohydrates because they are composed of Carbon, Hydrogen, and Oxygen atoms, contain nothing else, provide a little bit of energy, and do not provide any nutritional value per se. Let’s call them the ‘good (or too good to be true) carbs’.

Starches are large chain-like molecules formed from small ‘sugar’ molecules, and hence are called polysaccharides (‘poly’ = many and ‘saccharum’ = sugar). They are in comparison difficult for the body to manage. Although starches from various sources have been in use since civilization, the studies and debates regarding their health effects never seem to arrive at a conclusion, leaving them in a grey area (the area which we still put to good use!). The health effects may depend on the nature of the starch source, the processes, the types of use, and mostly the quantity used. Starches produce 4 calories of energy per gram.

Nevertheless, they are used everywhere from the food industry (as food additives for volume, crunch, or mushiness, depending on the starch, processes, and expected result) to the textile industry (where they stiffen fabric) to mass manufacture of gum and other products. They are literally everywhere! 

Both fibers and starches are large chains of sugar molecules, and fiber molecules tend to be lengthier than starches. Both are insoluble in water (but starches are soluble in water at temperatures greater than 75⁰C), and hence do not taste sweet.

Now as for the sugars found in your diet, there are basicly 4 types – lactose, glucose, fructose, and sucrose. Lactose is the kind of sugar found naturally in all animals’ milk and hence in some dairy products. It is soluble in water and hence slightly sweet, but does not shoot your blood sugar levels up by itself. 

We will be dealing with the three prominent “vegan” sugars here, which are most notorious for causing diabetes and other ‘lifestyle’ diseases.

Glucose and Fructose:

Glucose and Fructose are both monosaccharides, meaning they are both elemental sugar molecules that can make up larger carbs. They are both soluble in water and hence taste instantly sweet. Fructose is not just sweeter but also creates cravings. 

“Where you goin’, sugar?”

80% of dietary glucose is absorbed by the (small) intestines and is used as the major source of energy. The brain, RBCs, muscles, and basically all tissues synthesize glucose for energy. The remaining 20% goes to the liver where it is stored as glycogen. The liver uses this reserve and breaks it up to form glucose for energy when the body is starving.

All of the dietary fructose goes to the liver through the bloodstream and 30% of it is converted to fats or bad cholesterol. The liver sometimes synthesizes it into glucose for energy and the process is called hepatic metabolism, but still can cause non-alcoholic fatty liver and metabolic syndrome. Furthermore, fructose is a huge burden on the body’s filtration system. 

We need to debunk a (major) myth now:

Glucose raises blood sugar levels almost instantly because it is absorbed by the small intestine’s lining. Fructose releases sugar slower and has a lesser impact on blood sugar. So fructose must be better than glucose, right? Wrong!

Glucose stimulates Leptin and Insulin responses in the body, and quickly makes the body feel full, and satiates hunger. But fructose inhibits insulin function, leaving the body wanting more.

So, it is safe to say that not all sugars that do not raise blood sugar levels are safe to indulge in. 

Sucrose = Glucose + Fructose

Sucrose is a disaccharide and is composed of a glucose molecule and a fructose molecule. The body starts breaking up sucrose right from the mouth where enzymes in the saliva split some of the molecules into monosaccharides. The enzymes in the small intestine do the rest of the splitting and the glucose is absorbed by the blood.  

What common foods contain these sugars? The answer will turn the tables!

No carb-containing food has just one of these sugars or carbs – they are all found in a ratio unique to the food item. But in general, Glucose is found in pasta, bread, rice, corn, oats, etc. – the classic 50% of the classic “diet” and in some vegetables and fruits. Fructose is a.k.a. “fruit sugar” is what makes fruits, some vegetables, honey, agave nectar, maple syrup, etc., sweet.

But it is worthy of note, that Sucrose is the chief product of photosynthesis and hence what elementary school teaches you when they say “…plants use water, sunlight and the nutrients from the soil to make food…”. It is most abundant in sugar cane and sugar beets. So, we found ways to mass-produce versatile, multi-purpose forms of sugar from them. 

Special Mention – Nutritional Information: 

This article aims at throwing some light on the dangerous carbs, and it would not do well to skip (the bamboozling) “No Added Sugar” claims. Let us not be misled. 

A food item that has a “No Added Sugar” label would have no artificial sugars (like aspartame, sucralose, and sugar alcohols) or sucrose as ingredients. But this does not rule out the presence of the ingredients that naturally contain sugars. This fact has failed to reach many diabetic patients all over the world despite the internet.

But of course, this also means that the product may contain harmless, naturally zero-caloric sweeteners like Stevia. 

The sweet Bottom Line:

What we can understand from this discussion is that no sugars cause obesity or diabetes directly, but sugars that inhibit insulin can. 

The long-term health effects of each sugar depend on the type of food providing it, the absorption process, and most importantly, the quantity. For example, fructose by itself is bad, but the fruit is good for you because of the fibers, vitamins, minerals, and the whole satiation that results. But the fruit juice may be a watered-down and sugared-up unhealthy option.

The sense that the health effects of sugars depend on the quantity of sugar intake rather than the type of sugar itself, is the whole point of discussing “sugars”.