With Halloween around the corner, and with it tons of sugary treats, we decided to do a deep dive on sugar. What’s the link between sugar and chronic disease? Is there such a thing as healthy sugar? How much sugar is too much? We laid it all out for you, so you have all the treats and none of the tricks this Halloween season.
In recent years, sugar has become pretty vilified — much like fat was during the 90’s — but does it deserve the bad rap? Unfortunately for cookie lovers everywhere, yes. High blood sugar and insulin resistance, both of which are caused by overconsumption of sugar, are at the root of many chronic health problems, from heart disease to cancer, diabetes, obesity, autoimmune conditions, and more. Luckily, by being aware of your sugar intake, and learning to separate more natural forms of sugars that aren’t as unhealthy from very unhealthy sugar, you can still eat sugar without it harming your long-term health.
The Link Between Sugar and Inflammation
So when you eat sugar, how exactly is it harming your body? One of the main pathways is through inflammation. In one study of 29 healthy people, researchers found that consuming just 40 grams of added sugar (the amount in an average can of non-diet soda) per day led to an increase in inflammatory markers, insulin resistance, and LDL cholesterol, as well as weight gain. When you consider that the average American man consumes 96 grams of added sugar a day, and the overall average is 94 grams, this is some pretty un-sweet news.
Unfortunately, cutting out sweets won’t solve the problem, because added sugars aren’t the only culprit when it comes to inflammation. Refined carbohydrates (like white bread, pasta, cereal) — which get broken down as sugar — have also been linked to increased inflammation in humans. If you want to know why all this is important, remember that inflammation is associated with tons of diseases, including coronary heart disease, diabetes, and stroke.
Here’s the science of the sugar/chronic inflammation relationship: when you eat too much sugar, your blood sugar is constantly spiking. This causes three things to happen: 1) your body produces pro-inflammatory molecules called cytokines; 2) high blood sugar levels trigger the production of molecules called advanced glycation end products (AGEs), which are destructive and trigger inflammation; and 3) your cells become insulin-resistant, meaning they won’t accept insulin or sugar, and so it gets stored as stomach fat, which — you guessed it — creates its own pro-inflammatory chemicals.
Does Sugar Cause Cancer?
One of the scariest things you might have heard about sugar is that it feeds cancer cells. We hate to spook you, but unfortunately the evidence suggests this one is true. According to a meta-analysis of 268 articles and 13 studies, tumors are dependent on glucose uptake, meaning they need simple sugars — like those from processed carbs and sweets — to survive and grow. When patients switched to a high-fat, low-carb (and therefore low-sugar) diet, such as the ketogenic diet, the growth of malignant cells was inhibited, and survival time increased. This was true for various types of cancer, including pancreatic, prostate, gastric, colon, brain, neuroblastoma and lung cancers.
Additionally, excess sugar consumption increases the risk of obesity and diabetes, both of which raise the risk of cancer.
Is “Healthy Sugar” A Thing?
With all the different types of sugar out there, it can be easy to get confused. Does your body process sugar from an apple the same way it processes sugar from a candy bar? Is “raw” sugar healthier than refined sugar? Is honey a healthy sugar? The answer is a bit complicated, but it all comes down to understanding three main forms of sugar:
Glucose: This is a simple sugar, aka a monosaccharide, and is the basic carbohydrate-based energy source. It’s quickly absorbed and so it raises blood sugar levels quickly and releases insulin. Glucose isn’t super sweet, and can be found in carbohydrates like bread and pasta, as well as fruits and vegetables.
Fructose: Often thought of as “fruit sugar,” fructose is another monosaccharide, though it is first processed by the liver, so it doesn’t affect insulin levels immediately and has the least impact on your blood sugar level. Fructose is super sweet, and is often added to processed foods in the form of high fructose corn syrup; it can also be found in honey, molasses, fruits, juices, and other sweets.
Sucrose: This is what we think of as table sugar. It is a disaccharide (meaning it’s formed from two monosaccharides), made of half fructose and half glucose.
So which of these three forms is the least healthy and which the most healthy sugar? Again, it’s not cut and dried, and each form has its downsides and upsides.
Glucose, on one hand, is readily available to your muscles and brain, giving you immediate energy, which is a good thing. Glucose also stays in the bloodstream for some period of time, keeping the glucose levels high, which is good for the brain. On the other hand, glucose causes the release of insulin and a spike in blood sugar, which poses its own health problems.
Fructose doesn’t cause that blood sugar spike, and is less likely to cause cavities, but it might be the most dangerous of all when consumed in excess. Because it needs to pass through your liver first, too much fructose can overload the organ, turning the fructose into cholesterol and triglycerides and leading to obesity, high cholesterol, and fatty liver disease. And you may be more likely to eat too much fructose, since it doesn’t suppress ghrelin (the “hunger hormone”) the same way that glucose does, and so you’ll keep feeling hungry and keep eating.
Sucrose has its dangers, too. Because only half of it (the glucose half) gets supplied as immediate energy, you brain wants you to eat twice as much to get the same amount of energy. Hence, sugar addiction. Plus, when glucose and fructose are eaten together, it can cause