In this post I hope to give you a balanced, evidence based perspective on sugar. Is it really as bad as everyone says it is? Should you avoid it like the plague? In most cases where there is fear mongering, dogma, and hype around food, it is usually over exaggerated and the research on the topic is taken out of context. Taking the midline approach is usually the best option. Let me explain.
What is sugar?
Every cell in our body depends on sugar for energy. It is our brains primary energy source. Therefore, sugar is vital to our survival, hence it is no wonder we are genetically programmed to crave sweetness.
From an evolutionary perspective, this ensured our survival because before agriculture, our ancestors did not have much control over the sugars in their diet, which would have come from whatever plants were available in a given place and season. Therefore, when they got hold of foods that tasted sweet, they probably pigged out. Sweet food meant calorie density, low toxicity and because food was scarce at that time, it was important to load up on calories as much as possible when they could.
Sugar cultivation first started with sugar cane. Sugar was an expensive luxury until manufacturing became efficient enough to make “white gold” much more affordable.
Today, we add sugar in one form or another to the majority of processed foods we eat—everything from bread, cereals, crunchy snacks and desserts, to soft drinks, juices, salad dressings and sauces.
With our innate tendency to love sweet tasting foods (they ensured our survival as a species), and the availability of high calorie, sugar laden foods all around us, it can lead to overeating on these foods, which can be an issue, but as I will explain, it doesn’t make sugar intrinsically toxic.
Now before we start to dive into the crux of this post, it is important to sought out some terminology and technical information. In the Australian food industry, processed food, confectionary and soft drinks usually contain sucrose as a sweetener from sugar cane, which contains 50% fructose and 50% glucose. Sucrose is a glucose and fructose molecule bound together. Table sugar is sucrose.
Other processed foods use various other caloric sweeteners like dextrose, glucose syrup, high fructose corn syrup, honey, golden syrup, maltodextrose and trehalose. These sugars essentially contain varying ratios of fructose, glucose and sucrose, contained in various chemical structures.
Lastly, I would like to make a special mention about high fructose corn syrup (HFCS). HFCS was developed in the 1960s, where new technology allowed the U.S. corn industry to cheaply convert corn-derived glucose into fructose and produce high fructose corn syrup, which—despite its name—is almost equal parts free-floating fructose and glucose: 55 percent fructose, 42 percent glucose. Because fructose is about twice as sweet as glucose, an inexpensive syrup mixing the two was an appealing alternative to sucrose from sugarcane and beets. High fructose corn syrup is mainly used in the U.S food industry and has received a lot of hype as of late.
Virtually all plants have glucose, fructose and sucrose—not just one or another of these sugars. Although some fruits, such as apples and pears, have three times as much fructose as glucose (which is why they are sweeter), most of the fruits and veggies we eat are more balanced. Even foods like potato and sweet potato have mostly glucose in the form of starch but also contain small amounts of sucrose and fructose, just not as much, therefore they are not as sweet as fruit.
The difference between the sugars consumed in whole-foods like fruit and vegetables compared to processed food is that whole-food sugars exist within plant cell walls of fibre. Whereas Sugar-sweetened beverages and food do not contain fibre and other nutrients that are found in fruits and vegetables. The presence of fibre in fruits and vegetables slows the digestion of sugar into the blood. Enzymes in our digestive system must first break down the plant cell walls to reach the sugars (glucose and fructose) within, as opposed to processed foods and drinks, where the sugars are absorbed straight away, in high amounts.
Sugar and overeating?
Dr. Lustig’s famous presentation called “Sugar: The bitter truth”, did a very good job of creating fear mongering and food dogma surrounding sugar, specifically fructose, in both processed foods and natural sources.
In his presentation he outlines how fructose is an evil toxin that causes weight gain and metabolic issues. He outlined that fructose is easy to over consume because unlike glucose, fructose does not trigger the release of insulin, which is a hormone that removes glucose from the blood and is involved in satiety. But is this really true? Let’s take a look.
Insulin causes the release of leptin, which is a hormone that suppresses hunger. In rats, fructose also supposedly appears to raise ghrelin, which increases hunger, therefore this could lead to overeating of fructose and other calories as satiety signals are supposedly not working. However, these rats were fed isolated fructose.
Studies show that when humans are given fructose, glucose or sucrose, there is no difference to appetite hormones. Furthermore, fructose within our diet is never ingested without glucose. Foods/drinks that contain fructose, even processed ones, will also contain glucose.
Therefore, the claim that sugar (mainly fructose) in processed foods and plants can lead to overeating because it disrupts hormonal signals that are responsible for hunger and satiety, are not supported by research.
What is supported by research is that if refined sugar products are making up a lot of your caloric intake in your diet (especially sugar filled drinks), it is unlikely that you will be compensating for these additional calories in other parts of your diet, therefore leading to an overall increased caloric intake, which can cause weight gain and increased blood lipids. This is because these foods lack nutrient density and caloric density is not associated with satiety.
However, in the backdrop of a nutrient dense diet from mostly wholefoods, it is less likely that you will overeat on processed foods. Also, when people consume sugars in fruit, since whole fruit contains fiber and other nutrients, it’s difficult to eat a lot of fruit without simultaneously reducing the intake of other foods, therefore decreasing overall caloric intake.
The proposed mechanism of this may be due to the fact that sugar filled, processed foods are high in calories but low in nutrients, which means that we are less likely to feel satiated from these foods, even if we are consuming a lot of calories. Where is if we are consuming many of our calories from nutrient dense foods, we are more likely to feel full and therefore decrease our overall caloric intake, even if we are eating some amounts of refined sugar. This supports the notion that in the backdrop of a nutrient dense diet, a small amount of sugar from processed foods is unlikely to cause issues, because it doesn’t magically cause you to want to eat more. Nutrient density is associated with satiety.
Sugar and a fatty liver?
When we ingest sugar such as sucrose, the body breaks sucrose into its free parts, which are made up of glucose and fructose. The body only uses glucose in energy production; therefore the fructose must first go to the liver so it can be converted into glucose. It was then proposed that eating large amounts of fructose taxes the liver because it spends so much energy turning fructose into other molecules that it may not have much energy left for all its other functions. A consequence of this energy depletion is the production of uric acid, which research has linked to gout, kidney stones, high blood pressure and insulin resistance (feature of type 2 diabetes).
Furthermore, because the liver plays an important role in fat metabolism, if it is overworked in converting fructose to glucose, then fat metabolism is put on the back burner and fats can’t be transported out of the liver, leading to a fat accumulation in the liver (fatty liver disease). A fatty liver can also be caused by excess alcohol consumption and is implicated in heart disease and diabetes. It was also thought that fructose is the most efficient substrate for de novo lipogenesis (DNL), which is the process by which the liver converts carbohydrates to fat.
High fructose consumption was shown to cause a fatty liver in mice, however, the issue with these studies is that mice have a very different carbohydrate metabolism to humans. When mice are on a high fructose diet that doesn’t provide excess calories, it’s common to see 50 percent of the fructose turned into fat, even when they’re not overeating.
However, in humans, 50 percent ends up as glucose, 25 percent goes to lactate and greater than 15 percent goes to glycogen. The remainder is converted to energy and 2-3% is converted to fat via de novo lipogenesis.
The mice in these studies were also being fed isolated fructose in amounts that humans don’t even come close to consuming on a daily bases, even if a person has a diet high in processed food. This is why fructose in these mice were treated as a “toxin” by their bodies. Too much of anything can be a toxin, as the dose makes the poison.
Lastly, human studies have not found any positive associations between fructose consumption and a fatty liver, levels of triglycerides, cholesterol or uric acid, nor any significant link to waist circumference or body mass index (BMI).
Is sugar addictive?
Sugar is contained in highly palatable foods, but it is not addictive.
The human brain is hard-wired to be motivated by certain key goals that supported the survival and reproduction of our ancestors. One of these key goals is of course food intake.
When our brains accomplish a key goal that is hard wired in us because it is essential to our survival (e.g. food intake), a powerful brain chemical called dopamine is released. Dopamine is a “reward” chemical in the brain and after its release, it causes you to become more likely to execute specific behaviours that are essential to your survival, the next time you find yourself in a situation with sensory cues associated with carrying out that specific survival behaviour. These cues include sounds, smell, taste and location. This is a reason as to why you may crave certain foods just at the smell of them or if you are in a location where you usually consume a particular type of food.
Dopamine causes you to become more likely to execute specific behaviours that cause its release, when environmental cues are provided. In this case, it could be the sight and smell of certain foods.
The larger the surge of dopamine, the more motivated you will be the next time you encounter those cues. This is well illustrated by highly addictive drugs like crack cocaine and methamphetamine, which cause an immense release of dopamine that motivates drug-seeking behaviours. Addiction, at its core, is a very strong craving. The dopamine release in response to sugar is not even close to the magnitude of dopamine release in response to drugs, which is why it is wrong to proclaim that sugar is as addictive as drugs. Drug withdrawal is nothing like processed food/sugar withdrawal.
When we consume food, sensors in the mouth and small intestine detect the glucose, fructose, fatty acids, and amino acids in starch, sugar, fat, and protein and send a signal to the brain that releases dopamine. And the more concentrated those nutrients are in a food source, the greater the surge in dopamine.
From an evolutionary perspective, the release of dopamine is response to high calorie, highly palatable, sweet and fatty foods, makes sense. As mentioned above, when we were hunter gatherers, food was scarce and when we came across calorie dense foods like sugary fruits and honey, the dopamine surge was crucial to our survival as it made us splurge on these foods because we didn’t know where our next meal was going to come from. Now in the modern world, where high calorie food is so accessible, this evolutionary response leads to weight gain.
Highly processed, high calorie foods such as foods like chips, fries, bacon, cookies, cake, ice cream, and chocolate deliver exactly what our brains are instinctively looking for, concentrated starch, sugar, fat, salt, and protein, which is why we crave these foods when we see them, hear them, smell them and find ourselves in locations/situations where we are used to consuming them. This is not a coincidence that these foods are manufactured in this way. Food companies higher scientists to manufacture foods that stimulate reward centres in or brains.
Interestingly, chocolate is the most frequently craved food among women, and it’s also a common craving for men. From the brain’s perspective, this isn’t hard to understand. Chocolate is not only a highly concentrated source of fat and sugar, it also contains a chemical called theobromine. Like its cousin caffeine, theobromine is a mild stimulant that acts on the same brain pathway as dopamine.
As you can see, ultimately, our brain and its reward pathways are what drive weight gain. Everyone talks about insulin, leptin and other hormones, however the malfunctioning of these hormones are usually a downstream effect of consuming to many processed foods, which is driven by our brain.
Sugar and the immune system?
Refined sugar in processed food has also been implicated in reduced immune system efficiency. The studies that have shown this are done with immune cells in a petri dish and they demonstrated a reduced capacity to kill pathogens (e.g. viruses, bacteria) following sugar exposure (from sucrose, glucose and fructose) however, cells in a petri dish work very differently to cells in the body, therefore these studies are unreliable.
Sugar and cancer?
It is true that cancer cells use glucose in the blood to replicate. However, for as long as a person lives, they will have glucose in their blood stream to supply the brain, nervous system and other organs. Therefore, it is unavoidable to remove glucose from your blood completely, however the goal in cancer treatment would be to minimise huge amounts of glucose in your blood from eating excessive amounts of carbohydrates, beyond your energy needs.
Due to the fear mongering around processed and refined sugar, natural sweeteners like honey, stevia, maple syrup and coconut sugar have grown in popularity, especially with their use in “healthier” snack food options like chocolate and protein bars. The word “natural” has started to become synonymous with “harmless” or “healthy,” however just because something is natural, doesn’t mean it is harmless or healthy. Take snake venom for example, extremely natural yet extremely dangerous.
Natural sweeteners, similar to refined sugar, contain sucrose, glucose and fructose in varying amounts. However, unlike refined sugar, natural sweeteners, due the fact they are extracted from plants, often contain other compounds that may be good for our health, as well as slow the absorption of glucose into the blood stream. Putting it simply, you still get sugar content and calories with natural sweeteners (maybe not as much in some cases) but you also get some beneficial plant compounds as well, which is why some people pick these sweeteners over refined sugar. However, contrary to what people think, these sweeteners still contain the same molecules as refined sugar. Sugar is sugar.
Here are some common natural sweeteners that are used as alternatives to refined sugar, as well as the added health benefits they may confer.
Honey contains phytochemicals that have been shown in animal studies to confer potential health benefits. 3-5 teaspoons of honey has been shown to increase vitamin C and glutathione levels (anti-oxidants). It also may have anti-cancer, anti-oxidant, anti-inflammatory (in the gut), anti-viral and anti-bacterial properties. Lastly, in obese and diabetic individuals it has been shown to decrease LDL cholesterol, triglycerides, inflammatory markers (CRP), homocystiene and blood glucose, as well as increase HDL. Furthermore, these studies showed that honey had slightly less harmful effects on blood sugar levels and metabolism than regular sugar. This may be because the presence of certain plant compounds slow its absorption into the blood stream.
There is also molasses, which contains anti-oxidant phytonutrients, as well as relatively high amounts of potassium, calcium, B6, iron and magnesium. Molasses is a sweet, brown liquid with a thick, syrup-like consistency. It’s made from boiling down sugar cane or sugar beet juice.
Maple syrup is another commonly used natural sweetener, which is a thick, sugary liquid that’s made by cooking down the sap of maple trees. It contains a decent amount of minerals, including calcium, potassium, iron, zinc and manganese. It also contains at least 24 different types of antioxidants. A couple test-tube studies have indicated that maple syrup may even have anti-cancer benefits, but more research is needed to confirm this. While maple syrup contains some beneficial nutrients and antioxidants, it’s very high in sugar. It has a slightly lower glycemic index than regular sugar, so it may not raise blood sugar levels as quickly, but it will still raise them.
Another example is yacon syrup. It is extracted from the yacón plant, which is native to South America. Yacon syrup contains 40–50% fructooligosaccharides, which are a special type of sugar molecule that the human body cannot digest. Because these sugar molecules are not digested, yacon syrup contains one-third of the calories of regular sugar, or about 1.3 calories per gram. What’s more, studies show that fructooligosaccharides can decrease the hunger hormone ghrelin, which may reduce appetite and help you eat less. They also feed the friendly bacteria in your gut, which are incredibly important for your overall health. Yacon syrup is generally considered safe, but eating large amounts of it may lead to excess gas, diarrhea or general digestive discomfort. Another downside to yacon syrup is that you cannot cook or bake with it, as high temperatures break down the structure of the fructooligosaccharides. Instead, you can use yacon syrup to sweeten your coffee or tea, add it to salad dressings or stir it into oatmeal.
Moreover, coconut sugar is yet another commonly used natural sweetener in place of refined sugar. It is extracted from the sap of the coconut palm. It contains a few nutrients, including iron, zinc, calcium and potassium, as well as antioxidants. It also has a lower glycemic index than sugar, which may be partly due to its inulin content. Inulin is a type of fiber that has been shown to slow glucose absorption and feed the good bacteria in the gut. Nevertheless, coconut sugar is still pretty high in calories, containing the same number of calories per serving as regular sugar. Coconut sugar is very similar to regular table sugar in fact.
Agave nectar is produced by the agave plant. It consists of 85% fructose, which is much higher than regular sugar, hence its sweet taste.
Lastly, although the stevia plant does not contain any calories, it is commonly used as a natural sweetener, which can be traced back to glycoside (bound to sugar) compounds of steviol that contain the active rebaudioside A and stevinosides. Unlike artificial sweeteners, stevia confers pharmacological actions and may have anti-cancer, blood pressure lowering, satiety, anti-oxidant (in the liver, kidneys, pancreas, brain), anti-inflammatory, insulin sensitising, anti-bacterial and glucose lowering properties. It must be noted that high doses may cause infertility and potentially cancer based on animal studies, therefore it is probably best not to over consume stevia, with the upper limit sitting at 8mg/kg.
When can sugar be a real issue?
Refined sugar from processed foods becomes an issue when it starts to displace other more nutrient dense foods in the diet that are beneficial to health and it becomes the foundation of a persons diet. We need certain nutrients for our body to function and they do not come from processed foods. Therefore, if processed foods become a large part of a persons diet, it can lead to increased caloric intake and poor health due to nutrient deficiencies, high blood glucose levels, inflammation and weight gain. Just like refined sugar, eating processed foods with “natural sweeteners” from natural sources of sugar is still going to have similar poor health outcomes if these foods displace healthy, minimally processed, whole-foods.
Sugar can also be an issue when people have diabetes or insulin resistance, because these people’s bodies cannot effectively shuttle the sugar they ingest into their cells, therefore it lingers in the blood causing all sorts of issues that can lead to kidney damage, nerve damage, eye damage, increased infection risk, high blood pressure and cardiovascular disease risk.
Fructose may also be an issue in those who have gut issues like IBS (irritable bowel syndrome). People with digestive issues sometimes find it difficult to absorb fructose within fruits and vegetables that contain high amounts, relative glucose. This leads to fructose being excessively fermented in the gut casing uncomfortable gut symptoms.
In conclusion, excess sugar (refined or natural) can be harmful to health however there is actually no evidence that small amounts of refined (or natural) sugar in the context of a nutrient-dense, whole food diet (and active lifestyle) is harmful.
When people decide to “avoid” sugar, such as in Feb fast, or as part of a detox, they generally feel better because they end up making more conscious food decisions, eating less nutrient void foods and eating more nutrient dense foods. It’s not magic, it is the basic principles of eating well, which is trying to eat more whole-foods and less processed and refined foods.
Avoiding all refined sugar from the diet is rarely necessary as refined sugar is not harmful to health in moderate amounts, and most people would be better off avoiding the stress that comes from being unnecessarily fearful of any food that has even a trace amount of refined sugar in it. The stress that comes along with excessive food restrictions and the guilt when you stray from your food restrictive diet, can be much more harmful than having a bit of refined sugar here and there.
As long as the foundation of your diet looks something like this, and is made of mostly unprocessed, nutrient dense, whole-foods, then there is no problem with the occasional sugar treat, especially on special occasions. Sometimes the context in which we consume food is more important than the actual food we are consuming. Consuming processed food with good company in a joyful environment once in a while, is very different to consuming it alone at home after a stressful day at work, when you couldn’t be bothered cooking yourself a wholesome meal.