It’s common knowledge that a diet high in added sugars is not good for you. These diets are linked to an increased risk of diabetes, heart disease, stroke, obesity, dementia, and dental caries, amongst others. For years many people have turned to sugar substitutes to reduce their sugar intake, which is even more applicable as we move into the season for sweets (did someone say apple cider donuts and PSL?). Whether these substitutes are healthy has been a widely debated and researched topic. In this blog, we’ll review what sugar really is, the reason behind the controversy, and the latest research.
Sugar on its own is not inherently evil, as it's often made out to be. When most people hear the word sugar, they probably think of cakes, candy, and cookies. In truth, there are many types of sugars, based on their chemical structure. “Simple” sugars are made up of a single sugar molecule. The main ones are glucose, fructose, and galactose. These molecules can be combined in different ways to make up the three main types of sugars we hear about when we discuss nutrition: lactose (glucose + galactose), sucrose (glucose + fructose), and maltose (two glucose molecules). Lactose is primarily found in dairy. Maltose is found in grains, peaches, pears, sweet potatoes, molasses, beer, and some syrups. Sucrose is the type of sugar you hear of most frequently. Sucrose is found in table sugar, desserts, commercial cereals, pancakes, candies, fruit juice drinks, etc. A lot of foods containing sugar are essential parts of a healthy diet.
Sugars, particularly glucose, are a vital source of fuel for the human body. While it is not the only source, the body also uses amino acids and free fatty acids, the brain in particular primarily uses glucose to function. Where sugar becomes unhealthy is when it's consumed in excess in foods that are not sources of other vital nutrients. For example, fruit contains sugar but it is naturally occurring sugar. When we eat fruit we also get multiple vitamins and fiber as well as necessary fuel our body needs. The fiber in foods like fruits, vegetables, and whole grains also slows metabolism enough that we get a slow and steady source of energy and stay full for longer. While a donut here and there might be good for the soul we don’t get the benefits of additional nutrients, just the empty calories. As these sources of sugar often don’t have fiber, the energy we get is a quick burst and often leaves us crashing as soon as the food is done being metabolized. This “roller coaster effect” on blood glucose levels can be harmful, especially to those with diabetes. Scroll to the end for more information on diabetes.
This is where the sugar substitutes come in. The three big categories of substitutes are artificial sweeteners/non-nutritive sweeteners, sugar alcohols, and novel sweeteners. Artificial sweeteners are regulated by the FDA and include aspartame and sucralose. They are made from chemicals in a lab and are 200-700 times sweeter than table sugar. Sugar alcohols, like Xylitol and Sorbitol, are required to be listed on food labels and are present in many processed foods. They are man-made but are often derived from sugar itself and are not as sweet as artificial sweeteners. Sugar alcohols have been linked to more gastrointestinal symptoms, such as bloating. Novel sweeteners are plant-derived and include monk fruit and Stevia. They are lower in calories and sugar and do not result in a blood glucose increase.
It is important to be mindful of the nutrition label even if a product is labeled as low-sugar or sugar-free. These products can sometimes have a higher fat content to make it more palatable. Sugar substitutes are also often used alongside sugar to reduce overall added sugar content and may still be high sources of added sugar. The American Heart Association recommends no more than 100 calories or 6 tsp of sugar per day for women. For men, it's no more than 150 calories per day or about 9 teaspoons.
The seemingly obvious benefits of sugar substitutes are that they are often fewer calories, do not increase blood sugar levels, and do not increase the risk of cavities or tooth decay. In general, most sugar substitutes have been deemed safe in moderation by the FDA, although research is still ongoing regarding long-term effects. The World Health Organization (WHO) released a position statement in 2023 that recommended against using sugar substitutes as a means for weight control or loss. However, this has been widely criticized for flaws in the research model. Many researchers support the use of sugar substitutes as an adjunct to weight loss methods.
Other research has challenged the notion that sugar substitutes do not increase blood sugar levels. A study conducted by the Weizmann Institute of Science in Israel and the Microbiome & Cancer Division, DKFZ, Heidelberg, Germany, investigated the impact of these substitutes on the gut microbiome. The study divided participants into six groups and had five of the groups consume five packs of a specific sweetener per day for two weeks, with the sixth group being a control group. They found that the groups that had consumed saccharin, sucralose, stevia, and aspartame, had significant changes in the gut microbiome whereas the group consuming sugar did not have this change. Additionally, they found that the substitutes saccharin and sucralose were associated with an increase in blood sugar levels that was greater than that of the sugar group. This is concerning as changes in the gut microbiome have been linked to conditions such as depression, asthma, allergies, certain cancers, cardiovascular disease, inflammatory bowel disease, diabetes, and obesity. Further research is necessary regarding this connection.
Another common argument against using sugar substitutes is that it could increase the consumption of unhealthy foods. Sugar activates the reward center of the brain leading us to want more, so you actually can become addicted to chocolate. As if that wasn’t enough to have us craving something sweet, the human brain is hardwired to crave sugar dating back to the days of hunting and gathering as the body needs sugar to create energy and thus to survive. Sugar substitutes only partially activate this reward center as they contain fewer calories, so they still feed the cycle of craving but often leave us unsatisfied, leading us to consume more food in the end. Another theory is that the human brain will start to associate sweet tastes with lower-calorie foods and drinks, leading to a subconscious increase in the consumption of empty calories and eventually weight gain. Similarly, from a psychological standpoint, it can be easy to reason with yourself that a second slice of cake is fine because you had diet Coke instead of regular Coke. Although more controversial, research is also ongoing regarding how these sugar substitutes could affect taste buds. These substitutes are hundreds of times sweeter than regular sugar. The concern is that frequent consumption of sugar substitutes, especially artificial sweeteners, could increase our threshold for what is considered sweet and make foods such as fruit much less desirable.
There are multiple arguments on both sides and much more research is needed to determine the long-term effects regarding sugar substitutes, especially in children. The overarching consensus at this time appears to be that most substitutes are okay in moderation but the better solution would be to avoid added sugars where possible.
The following is for our gym pals with diabetes or those who are at risk of diabetes (as well as anyone simply curious), feel free to skip this if it doesn’t apply to you!
In a person without diabetes, when sugar is eaten the pancreas will release insulin to remove the sugar from the bloodstream and pack it away into various types of cells to be converted into energy or stored for later use. Think of insulin as a key, it's needed to “open the door” of a cell to pack glucose in and remove it from the bloodstream. When the body has enough fuel for energy the rest is packed away as fat cells. In a person with type 1 diabetes, the pancreas cannot produce insulin at all and they are thus insulin dependent. In someone with type 2 diabetes, the problem is something called insulin resistance, which occurs when cells have been exposed to high sugar levels for a prolonged time. In this case, the pancreas is releasing insulin but the cells are not responding to it. The cells are tired of having so much glucose all the time so they have gone on strike and changed most of the locks on the “doors”, so insulin no longer can remove glucose from the blood efficiently. Now the pancreas does not give up easily and will continue to release more and more insulin, in hopes that the cells will eventually respond. Over time this can damage the pancreatic cells that produce insulin, which is when someone might become dependent on giving themselves insulin. In the early stages, insulin resistance can be reversed with diet and exercise. Other treatment options might include drugs that improve insulin resistance.
Uncontrolled diabetes can lead to multiple other diseases or conditions. Risk is increased with the large fluctuations in blood sugar that occur when we eat simple carbohydrates. The following are some of the more common conditions associated with diabetes and how they can occur:
- Obesity: Remember that fuel that cannot be used at that time is stored in fat cells for later use. This also applies to fuel sources that are derived from amino acids, so if you eat more protein than your body needs this is what happens to those amino acids. In the case of our person with insulin resistance, the body assumes that because the cells are not taking this glucose it must be excess and is therefore stored in fat cells.
- Heart disease and stroke: Excess sugar in the bloodstream decreases the elasticity of vessels which causes them to narrow and prevents proper blood flow leading to high blood pressure, which increases the risk of heart attack and stroke.
- Peripheral arterial disease (PAD): High levels of insulin in the bloodstream (remember the pancreas doesn’t give up!) can cause inflammation in the arteries making them thicker and stiffer. Over time this can lead to heart attack, stroke, erectile dysfunction, and chronic nonhealing wounds.
- Chronic kidney disease (CKD): The kidneys are responsible for filtering our blood and removing waste. Over time. high glucose levels in the bloodstream can damage the kidneys leading to scarring.
- Diabetic Neuropathy: Similar to other diseases, high glucose levels in the bloodstream for a prolonged time can damage nerves leading to muscle weakness, loss of sensation, and balance issues.
- Vision Changes: The damage to blood vessels from high blood sugar levels also affects the blood vessels in the eye which can lead to loss of vision (diabetic retinopathy). It can also cause abnormal vessels to grow in the front of the eye, blocking the flow of fluid out of the eye and increasing the pressure inside the eye, which can lead to glaucoma.
- Dementia: damage to blood vessels from chronically elevated blood sugar levels can lead to brain cell death. Another theory is that insulin resistance in the vessels in the brain can lead to the formation of amyloid plaques and neurofibrillary tangles incriminated in Alzheimer's Disease.
About the Author
I am a Licensed Registered Dietitian with experience in critical care, cardiology, weight loss, allergy services, and food service. I graduated from Penn State University with a BS in nutrition and finished my RD training at University of Maryland. I am currently in PA school and am looking forward to combining my love of nutrition with medicine. After moving to Baltimore in 2019, I did a trial class at PUSH511 Fitness as I was looking for accountability and to meet new people. When I walked into the gym for the first time, everyone was congregated on one side cheering on a member who was struggling with ring muscle-ups at the end of the workout. It was such an uplifting moment to witness. I left the gym that day in dire need of ginger ale, but also very excited about this amazing and supportive community I had stumbled upon. I am grateful for this opportunity to give back and share my love of nutrition!
Sources
https://www.medicalnewstoday.com/articles/317483#cardiovascular-system
https://www.medicalnewstoday.com/articles/325018#link-with-diabetes
https://www.medicalnewstoday.com/articles/327512
https://www.utmb.edu/mdnews/podcast/episode/our-microbiome-on-artificial-sweeteners
https://academic.oup.com/ibdjournal/article-abstract/29/11/1751/6995355
https://health.clevelandclinic.org/whats-worse-sugar-or-artificial-sweetener
https://www.cmaj.ca/content/189/28/E929
https://www.nature.com/articles/s41430-023-01314-7
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10911947/
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1411560/full
https://www.cmaj.ca/content/189/28/E929
