What is sugar?
When someone says sugar they might be talking about different things:
- Table sugar, the sugar we put in food.
- Sugars as a class of substances: the generalized name for sweet, short-chain, soluble carbohydrates, many of which are used in food.
- Blood sugar, as in blood sugar level. This is a misnomer because there is no sugar in our blood. We would probably die if there were. They are referring to the blood glucose level.
These are very different things. Confusion between them is dangerous. The most relevant for modern nutrition is the first one, table sugar or sucrose. It is one of several dangerous modern foodstuffs. On the surface, it seems like a very complicated ingredient. After all, it has more than 56 names on food labels:
Agave Nectar • Blackstrap Molasses • Cane Sugar • Confectioner's Sugar • Date Sugar • Golden Syrup • Icing Sugar • Muscovado • Refiner's Syrup • Sugar • Barbados Sugar • Brown Sugar • Caramel • Demerara Sugar • Diatase • Grape Sugar • Invert Sugar • Organic Raw Sugar • Rice Syrup • Treacle • Barley Malt • Buttered Syrup • Carob Syrup • Corn Syrup Solids • Dextran • Ethyl Maltol • Fruit Juice • Glucose Solids • High-fructose Corn Syrup • Lactose • Maple Syrup • Panocha • Sorghum Syrup • Turbinado Sugar • Beet Sugar • Cane Juice Crystals • Castor Sugar • Crystalline Fructose • Dextrose • Evaporated Cane Juice • Fruit Juice Concentrate • Golden Sugar • Honey • Malt Syrup • Molasses • Raw Sugar • Sucrose • Yellow Sugar • Powdered Sugar
Reading all these names for sugar does not answer the question what it is. If anything, it makes the issue even more confusing.
So what is sugar? Table sugar is a substance constructed of one molecule of glucose and one molecule of fructose.
Sucrose composition: one molecule of glucose linked by an oxygen atom with one molecule of fructose
Glucose and fructose
Glucose and fructose seem similar on a superficial level. Yet they are different in essence and function.
Glucose is the energy fuel for all life. When you eat glucose, the bloodstream distributes it throughout the body. All the cells in your body use it and produce energy. As does every cell in any other animal. Most of the digestion of carbohydrates can be reduced to transforming them into glucose so the body can use it.
Fructose is different. It cannot be transformed into energy like glucose. In fact, none of the cells in the human body can metabolize it, so it is sent to the liver. The liver is crucial in digestion. One of its tasks is to neutralize toxic substances. In fact if you ingest poison, the body will send it to the liver to try to render it harmless. Fructose also winds up in the liver.
Why do our cells process fructose differently than glucose?
It all starts with our late, late ancestors. Our current human body is the result of adaptation throughout hundreds of thousands of years of human history. Glucose use starts however even before the first humans. Animal cells have mitochondria. Mitochondria are called the 'powerhouses' of the cells because they produce energy for the cells. However, mitochondria themselves have strange origins. Mitochondria were bacteria which developed a symbiotic relationship with animal cells some millions of years ago. Their part in the relationship is to burn glucose with oxygen to produce energy for the cell. They evolved to burn glucose because it is widespread. Human cell, like all other animal cells, have the same basic metabolism of obtaining energy from glucose and oxygen.
Fructose is now common in our diets and environment. However, it is not common in nature. It exists in small amounts in fruits. And consumption of this fructose is limited: you can eat only a limited amount of fruit because of the high quantity of fiber. Plus, our ancestors only had temporary access to limited amounts of fruit. Fructose also exists in honey. This has an effective natural deterrent, illustrated here.
Because of this scarcity of fructose, humans never evolved an effective metabolic process for it. Sugar has been available in diet in reality for roughly 200 years. Much too little to produce physiological adaptations. Thus fructose is delegated to the liver. This is fine for the body in small quantities. Because we have evolved for fructose scarcity. In larger amounts, fructose has harmful effects because we have not had time adapt to it.
What are the effects of fructose on the human body?
1 Confuses the body’s self-regulation mechanism
2 Poisons the liver
3 Damages the whole body
4 Befogs the digestive system
5 Rots teeth
1 Fructose confuses body’s self-regulation
Fructose reduces insulin sensitivity. This creates a feedback loop that promotes more eating and less satiety. in time insulin insensitivity develops which generates continuously high blood glucose levels. These lead to diabetes, obesity, metabolic syndrome, heart disease, digestive issues. These kill you slowly and painfully.
Why would the body react like this to fructose? It might be an evolutionary advantage. Our ancestors found fructose rarely. When they did, it was to their advantage to eat as much as possible. This built up stores of energy for times of hunger.
Bonus: the high blood glucose in time damages eyesight. Ever wonder why so many people wear glasses? Primitive man lived just fine without prescription glasses.
2 Fructose poisons the liver
The liver metabolizes fructose into glycogen. However, it cannot store glycogen. It sends it to muscles and organs. The amount sent depends on the depletion: if you have just done something physically exhausting, then more is sent. If you were sitting on the couch all day, then very little is sent. That is why fructose, and sugar, are so powerful when you are tired from sports: they quickly replenish lost energy. But only a very small amount of fructose can be used for energy even in the most grueling conditions.
What happens to the rest of fructose? The liver cannot keep it. It processes it further into fat. Some of this fat is packaged as triglycerides and sent through the blood to fat cells. The rest of it is stored as fat in the liver. This is one of only two ways in which you get fat in your liver. The other one is alcoholism. Fat from fructose in the liver leads to non-alcoholic fatty liver disease. 31% of American adults and 13% of kids suffer from non-alcoholic fatty liver disease.(Source: 1, 2, 3 ). This has doubled in the past 20 years. Fatty liver disease kills you.
Fructose is one cause for fat in the liver. The other one is alcoholism.
3. Fructose damages the whole body
One of the roles of the liver in the body is to protect it from poisons by processing them. Sometimes this leads to waste products. These are also poisonous.
In the process of making fat out of fructose, the liver excretes large amounts of specific waste products. These are free radicals. They are poisonous and damage cells they meet. The body has special scrubber cells in the bloodstream to neutralize the free radicals. But these scrubbers are in limited numbers. Large quantities of free radicals overwhelm the scrubber system and damage the body. Average modern sugar consumption generates such large quantities of free radicals. Interestingly enough, another modern foodstuff, vegetable oil, also creates free radicals. Free radical damage is linked with autoimmune diseases, cancers, and numerous other chronic diseases. These either kill or leave you debilitated.
Bonus: fructose synthesis also produces high amounts of uric acid. This is thought to be one of the causes of gout and kidney stones.
4. Fructose confuses the digestive system
Bloating, gas, indigestion, burning sensation, reflux, diarrhea, constipation, IBS, Crohn’s disease, ulcer. Modern life is ripe with digestive problems.
Evidence shows sugar as a cause of such digestive issues. In the digestive tract (mainly the colon) there are bacteria. Some of these bacteria help us, some harm us and some seem to have no effect. All of them together form your microbiome. Modern science shows we are a complex organism, integrated with our microbiome, rather than living in symbiosis. This make it more important to health than any single organ.
Fructose travels through the digestive system to the liver. On the way it encounters bacteria. Some of this bacteria can eat the fructose. When they eat it, they make gas (hydrogen or methane). This gas bloats and exerts unnatural pressure through the whole digestive process. The fructose can also help such bacteria multiply (which leads to more gas). And the proliferation of fructose eating bacteria unbalances the microbiome equilibrium. This leads to bloating, diarrhea, flatulence, but even gastric reflux, ulcers, irritable bowel and a host of other digestion affections.
Recent research shows there are also immediate unpleasant effects. Around three-quarters of people suffer from fructose intolerance: they get digestive problems immediately after consuming fructose. Like with gluten sensitivity, this does not mean the rest are immune, just that it might take longer to feel effects.
Why would fructose befog digestion? Because fructose is something our ancestors consumed rarely and in minuscule amounts (compared to the modern diet). Thus our bodies have not adapted to it. Bacteria are much more nimble, they adapt in a fraction of the time that we can. They strive at our expense because of this adaptation.
5. Fructose rots teeth
Fossil analysis shows cavities were practically non-existent for primitive man. The colonial British Empire was the first society to introduce widespread consumption of sugar. As a consequence, the British are known for their rotten teeth.
Queen Elizabeth the 1st was the first British monarch with easy access to large quantities of sugar. And she took to eating it in quantities as big as her empire.
At court, sugar produced elaborate dishes. Chefs made sweets, made from sugar paste (a mix of egg, sugar, and gelatin), look like savory foods such as bacon, walnuts, and eggs. ‘Leach’ (or leech) was another popular dish. Leach was just milk, sugar and rosewater. However, possibly two of the most popular of these treats were marchpane and gingerbread. March-pane, like modern marzipan, was made of almond and sugar paste and could be molded into a variety of shapes and elaborately decorated. Gingerbread, on the other hand, might seem less elaborate but it required ginger, another exotic ingredient, alongside a good amount of sugar.
What was the effect of all this sugar? A German traveler, Paul Hentzner, paints a descriptive picture:"[Elizabeth I is] in the sixty-fifth year of her age… her face oblong, fair, but wrinkled; eyes small, yet black and pleasant; nose a little hooked; lips narrow and her teeth black (a fault the English seem to suffer from because of their great use of sugar); she wore false hair and that red …"
Why does sugar create cavities? Cavity formation starts with plaque. Plaque forms on the teeth. It contains protein, carbohydrates, and bacteria. The bacteria eat the carbohydrates. Specific bacteria, such as Streptococcus mutans, secrete acid when they eat certain carbohydrates. This acid eats away at the tooth walls and slowly creates the cavity. The favorite food of such bacteria is dextran. Dextran results in the mouth from sugar decomposition (source).
Bonus: sugar makes food stick to teeth so it produces even more plaque.
Key take-away
Sugar, through fructose, makes us sick and eventually kills us. The amount of sugar 'normal' in our modern diet is more than sufficient to do this.
How much sugar is then safe to eat?
Official institutions’ estimates vary significantly. But the truth is: nobody really knows.
We can get an indication by looking at primitive humans. How much sugar did they consume? Negligible amounts because it all came from fruits and honey. Fruits have incredible amounts of fiber relative to the fructose contained. In nature, honey is rare and defended by bees.
How much does the modern man consume? On average, an American consumes 19.5 teaspoons (82 grams) every day. That translates into about 30 kg of added sugar consumed each year, per person.
How much are you eating? It should be zero. We have not evolved to handle anything primitive humans were not eating. Especially not anything like fructose, which is an addictive poison.