When I talk about sugar in this article I am referring to added sugar or table sugar. The chemically correct name for it is “sucrose”.
Chemically, carbohydrates consist of a big variety of different “sugar” molecule combinations: single molecule sugars (glucose, fructose, galactose...) or paired molecule sugars called disaccharides (e.g. sucrose or lactose), and lastly polysaccharides (starches and fibers). Simply said, the longer the molecule chain the more complex the carb is. The shorter it is, the simpler it is. Hence the terms simple and complex carbs or sugars.
Digestion enzymes break down these molecule chains starting in our mouth and continuing in the small intestine. As mentioned above, table sugar is a disaccharide (the chain is only made from 2 molecules: glucose + fructose). Therefore, enzymes only need to break down one bond before molecules get absorbed into our blood. Whenever you eat complex carbs (whole grains, vegetables, fruits…) it takes much longer to break down the long sugar chains into single molecules and thus you will not feel that quick sugar rush in your blood.
The chemistry of carbohydrates and their bonds and varieties would largely extend the length of this article, that's why I will stick to so called “free sugars” added to foods.
Types of sugar
White sugar = sugar extracted from either sugar cane or sugar beets. Processed and refined, molasses is removed.
Brown sugar = white sugar (refined) with added molasses syrup.
Natural brown sugars (muscovado, raw sugar, whole cane sugar, piloncillo, panela etc.) keep their molasses which comes from cane juice, no molasses is added.
Corn syrup: syrup made from cornstarch (treated with acid, enzymes and high temperatures)
Dextrose: chemically identical to glucose, or blood sugar.
Invert sugar: chemically produced sugar (glucose+fructose) in liquid form, food additive to inhibit crystallization.
How does sugar get into my blood?
As mentioned above, sugar is a disaccharide. It consists of one molecule glucose paired with one molecule fructose. The break-down process of sugar into these two molecules starts already in our mouth, facilitated by the enzyme amylase. The absorption for the most part takes place in our small intestine. Glucose is immediately transported into our blood and there ready as a source of energy. Fructose, however, takes a little detour through the liver. Consequently, our blood sugar rises after a carbohydrate rich meal.
Blood glucose facilitates the production of insulin, which transports blood glucose to our muscle tissue and liver. Thanks to this genius mechanism, our brain and body functions are maintained and have energy supply even if we do not eat every 2 hours.
Globally, the use of added sugar has increased steadily over the last decades. Under names such as invert sugar, sucrose, corn syrup, high-fructose corn syrup (HFCS) sugar has been on the rise and due to its synonyms, it seems easily incomprehensibly and confusing for consumers
Consuming sugar in moderate amounts is not harmful for our body. Consumed in higher amounts but combined with increased physical activity is not harmful either. However, consumed in excess, sugar can cause overweight, obesity and certain chronic diseases.
Added sugars do not contain any essential nutrients. They simply provide energy without any other nutrients, hence the name “empty calories”.
Sugar is not good for your teeth. It’s true! Listen to your parents. It feeds the harmful bacteria in your mouth causing tooth decay. (1,2)
Excess consumption of fructose can cause liver damages (non-alcoholic fatty liver disease). High amounts are in high fructose corn syrups (HFCS) which is added to most processed foods (breakfast cereal, salad dressing, yogurt, candy, sodas, nutrition bars…) Even though fruits contain fructose too, it will never be as concentrated as in processed foods.
Too much sugar can cause insulin resistance and metabolic syndrome, especially diabetes type 2.
The World Health Organization (WHO) suggests to consume less than 10 percent of energy intake in form of sugar. (If your daily energy intake is 2000kcal, it would be recommended to consume 200kcal or less from sugar, which is a maximum of 50g sugar per day). The WHO and American Heart Association agree that 5 % or less provide additional benefits.(3)
Does it count if I eat fruit sugar? Its from fruits right...so must be healthy..
Fruit sugar is sugar too! Don't take an excuse that a handful of dates or a honey in your tea is less harmful than a spoon of sugar. They do contain more fiber, minerals and vitamins than table sugar but are still very caloric and sugar dense. Natural sugar sources are the better choice but should only to be used limited (same rules as table sugar).
Our body cannot distinguish whether sugar molecules like fructose and glucose originate from honey, table sugar, a banana, a grapefruit, a liquid sport energy gel, chocolate or grandma’s Christmas cookies. However, what benefits our body and health is what other nutrients come with the sugary source (vitamins, minerals, fiber, antioxidants, phytochemicals etc.). Consider you eat an apple, it gives you the same amount of fructose and glucose and the equal number of calories as a teaspoon of sugar in your tea. The major benefit from eating the apple is that it provides your body with fiber, essential vitamins and minerals, anti-oxidants, keeps you full, is delicious, aids digestion and much more.
The important factor you should always consider is the volume and concentration of the food. The amount of sugar in a raisin is the same as in its fresher form, the grape. The difference is the volume. We tend to eat much more of the concentrated product than of the fresh fruit, since the volume is much smaller. Moderation is key, also with “natural” sugars such as honey, maple syrup, dates etc. (4)
Does sugar turn into fat in our bodies?
In healthy individuals, the intake of carbohydrates spikes insulin, a hormone responsible for our glucose metabolism (transport sugar from the blood to the cells).
The preferred way by our system to win energy is to “burn” carbohydrates. There is another pathway in which fat is burnt to win energy, but it’s less sufficient for our metabolism. However, when blood sugar levels and sugar storages (liver, muscles) are low, the “fat-burning” mechanism is activated and our body needs to use fat as energy for our survival.
Whenever insulin levels are high it means there is sugar present and the body is switched into carbohydrate burning mode, meaning carbohydrates and glycogen (form of sugar stored in muscle) is burnt at a greater rate but also at the same time reduces the opportunity for fat to be lost. Our body always prefers sugar as fuel, prior to fat! So, in theory, fat will be used when blood sugar and thus insulin levels are low.
How can you achieve that? Low carb diets (not necessary recommended), increased physical activity (highly recommended), fasting periods (e.g. intermittent fasting; careful: not applicable for everyone). It is to be noted, that insulin is only one of many factors involved in our nutrient and body weight regulation metabolism. (4)
What are sweeteners?
Sweeteners, artificial sweeteners or non-nutritive sweeteners are sugar substitutes that provide no energy aka have zero calories. Currently, aspartame, saccharin, acesulfame K, stevia, and sucralose are the approved sweeteners. Artificial sweeteners are among the most controversial foods. They are categorized under the regulations of “food additives” and approved by the FDA, thus considered as safe. However, side effects may occur in some individuals. (4)
Aspartame (e.g. NutraSweet, Equal) is 200 times sweeter than sugar, but loses sweetness when heated. It is often associated with headaches. However, there is not sufficient evidence to make a final conclusion. The Acceptable Daily Intake (ADI) is 50 mg/kg body weightg (18 cans diet soda), in Europe it is 40mg/kg body weight.
Acesulfame-K (Sunnet, Sweet One) is structurally related to saccharin and 200 times sweeter than sucrose. It is stable for baking and heating. The ADI is 15mg/kg bodyweight which equals 30 cans diet soda.
Saccharin (Sweet’N Low) was initially removed from the market due to fear its carcinogenetic. It still is not recommended during pregnancy. It is 300 times sweeter than sucrose. The ADI for saccharin is 5 mg/kg body weight (10 packets of sweetener).
Sucralose (Splenda) is 600 times sweeter than sucrose and is heat tolerant. The ADI is 5 mg/kg body weight (6 cans diet soda).
Stevia is a natural sweetener extracted from the plant Stevia rebaudiana. It is 300 times sweeter than sugar and generally recognized as safe. The FAO/WHO Expert Committee on Food Additives (JECFA) considers stevia as neither genotoxic nor carcinogenic and established an ADI of 4 mg/kg bw/day
Will I lose weight when I eat sweeteners instead of sugar?
In theory, yes. The perception is that the consumption of these sweeteners will lead to 0 kcal intake and thus to weight loss. However, increased appetite after consumption is reported in many studies. (5)
On a neurological level, after sweetener consumption your brain goes “mmm sugar” but you do not provide any sugar/fuel for the brain. There is, hence a lack of complete satisfaction since the usual postingestive factor or reward response is missing. Consequently, a food seeking behaviour is activated which leads to cravings and may contribute to obesity. (6)
Artificial sweeteners encourage sugar cravings and the “sweet taste” favouring resulting on a dependence on sugar. Since artificial sweetener’s sweetness potential is much higher than that from sugar, our palate adapts and we get used to the taste and establish an new flavour preference. Therefore, natural sweet foods like fruits taste boring and not sweet enough. (7)
In addition, the balance of our gut bacteria might be disrupted by artificial sweeteners. The consequent is increased risk of diseases. There is not sufficient evidence present to this day in time, more research is needed. (4)
Do sweeteners have an effect on insulin pikes?
Is diet soda and artificial sweeteners bad for us?
Combined with a balanced and controlled diet, moderately consumption of diet soda is harmless. Studies show that people who are on an unhealthy diet already consume diet sodas, trying to save some calories. Current research considered diet soda sweeteners as safe per se. In my opinion, moderation is key.
Sugar alcohols have obviously, nothing to do with booze. They are some kind of hybrids of sugar + alcohol molecules (alcohol means there is a hydroxyl group attached to the carbon atom)
Natural sugar alcohols are found in fruits and vegetables. Industrially produced and used as food additives is the more common use. As derivate from sugars, sugar alcohols have a similar chemical structure but fewer calories (not like zero kcal sweeteners).
These products may claim to be “sugar-free” on their labels, but in this case, “sugar-free” does not mean free of calories.
Most common sugar alcohols are erythritol, glycerol, arabitol, xylitol, mannitol, sorbitol, galactitol, inositol, maltitol, isomalt and lactitol.
Their mouth taste is very similar to sugar. When consumed, parts of them are absorbed into the blood and spike blood sugar levels minimal, the unabsorbed parts are metabolized in the GI tract by gut bacteria and may result in abdominal discomfort like intestinal gas or diarrhea. That is why you can read on sugar alcohol containing products “Excess consumption may have a laxative effect”.
The good thing about sugar alcohols is that they do not contribute to dental cavities since mouth bacteria is unable to metabolize them as quickly as sugar. For this reason, chewing gums, mints or other sugar free candy is sweetened with sugar alcohols. (4)
At the end of the day, it’s important to experiment. For some people it works to eat a little bit more sugar in their diet, while others react very sensitive to spiked blood glucose and experience cravings, binge eating, diseases or rapid weight loss. I recommend to try to not consume any added sugar and stick to whole foods and naturally sweet products.
The same principle applies to sweeteners and sugar alcohols. If you can handle them without side effects, go ahead but keep in mind: moderation is key! I would personally try to eat as little of them as possible because it changes my palate preference and increases my sugar cravings.
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