You have probably heard a thing or two about sweeteners—both good and bad. Nonnutritive sweeteners, also called sugar substitutes, were invented as a way to reduce the amount of sugar in foods and are now commonplace among many supplements, including protein powders to pre-workouts to nutrition bars. Wondering if you should steer clear or continue as is with your sweetener habit? Find out the good and bad, and some common sweeteners you can find in supplements and food.
Sweeteners provide a sweet taste without the added calories from sugar. Most are zero or very low in calories. Sweeteners can be added to both hot and cold beverages, as a replacement to sugar, and can be used for baking. Since sweeteners are much sweeter than sugar, you only require a small amount to substitute for similar sweetness. In general, most are not completely absorbed by the digestive system, so they do not increase blood glucose levels substantially or cause a glycemic response.
The one major problem that has arisen with sweeteners is their effect on the digestive system. Some sweeteners, particularly sugar alcohols, ferment in the intestines causing bloating and gastrointestinal distress, including a laxative effect when consumed in large quantities. There have also been some reports that certain sweeteners can cause problems with glucose metabolism and may cause insulin secretion, but results are currently mixed. They may also increase cravings for sweets if consumed too frequently.
The FDA has established ADI, or Acceptable Daily Intakes, for each artificial sweetener. An ADI is the amount of artificial sweetener a person can safely consume on average, every day over a lifetime without incurring any health risks. This includes a 100-fold safety factor, which means the ADI is only 1/100th of the actual amount that is considered safe for daily consumption. Lastly, although sweeteners have been accused of causing everything from obesity to cancer, there are no published, peer-reviewed, controlled scientific studies to support these claims. According to the National Cancer Institute, there is no scientific evidence that any artificial sweetener approved for use cause cancer in humans.
Five Common Sweeteners
Acesulfame K is 200 times sweeter than sugar, as sweet as aspartame and 1/3 as sweet as sucralose. Acesulfame K is often blended with other sweeteners such as sucralose or aspartame. Blended together, they can provide a taste that is more sugar-like. Ace K is stable under heat, allowing it to be used in baking or in products with long shelf life. It can be found in protein powders, ready-to-drink supplements and protein bars. The ADI is 15 mg/kg body weight per day. People who are on a potassium-restricted diet or have sulfa-antibiotic based allergies should discuss the use of Ace-K with their doctor before using.
Aspartame, also known as NutraSweetTM, EqualTM, and Sugar TwinTM, ~200 times sweeter than sugar and provides 4 calories per gram, because it is metabolized as a protein. Aspartame is made up of two amino acids – aspartic acid and phenylalanine. It is therefore digested and metabolized the same way as any other protein foods and is not stable under elevated temperatures or high pH. Therefore, it is not used in products with a long shelf life or that require baking. The ADI is 50 mg/kg body weight per day. People diagnosed with phenylketonuria (PKU), a rare hereditary disease, need to limit phenylalanine intake and therefore should not use aspartame.
Stevia and Rebiana
Stevia is a species of herbs and shrubs from the sunflower family. Stevia contains steviol glycoside, which is 300 times sweeter than sugar. Rebiana is the purified extract responsible for imparting stevia’s sweet taste. It has been found to have negligible effects on blood glucose levels, because it is not absorbed into the blood and, therefore, can leave the body unchanged. It may also enhance glucose tolerance. Since Rebiana is isolated from a natural source, it is often found in natural protein powders and protein bars instead of artificial sweeteners. Although crude Stevia extracts are not approved by the FDA, refined Stevia providing refined Rebiana do have GRAS status. In it’s branded form, look for Truvia or PureVia, which provide refined rebiana as well as Erythritol, a sugar alcohol, mixed in to reduce the liquorice aftertaste. The ADI for Stevia is 4 mg/kg body weight per day.
Sucralose, available as a tabletop sweetener and as an ingredient in food processing, is marketed as SplendaTM. Sucralose is a white crystalline powder made from sugar itself. Sucralose is 400 to 800 times sweeter than table sugar. Because it is stable even when subjected to extreme heat or cold, sucralose can be used in a variety of cold and hot drinks, pastries and baked goods and frozen and canned fruits and vegetables. Although its chemical structure is very close to that of sucrose or table sugar, sucralose does not provide calories. The ADI for Sucralose is 5 mg/kg.
Luo Han Guo
Also called Monk Fruit Extract, the sweetness comes from a combination of mogrosides. It is 150 to 300 times sweeter than sugar and provides zero calories per gram. It is also heat stable, so it can be used in baking. Luo han guo does not induce a glycemic response, so it doesn’t elevate blood sugar levels. It can be found by its brand name Nectresse. Although it does have GRAS status, the ADI is not yet determined.
Sugar Alcohols are manufactured from sugars and starches and provide a bit of calories unlike the other sweeteners discussed here, delivering 2.6 calories per gram. Although lower in calories, eating too many of them can cause serious gastrointestinal distress, including bloating. They are not completely absorbed by the body and therefore do not impact blood sugar levels the way normal carbohydrates do and, therefore, do not induce the same type of insulin response that comes from sugar.
Common Sugar Alcohols are sucrose, maltitol, xylitol, isomalt, sorbitol, lactitol, mannitol and erythritol. Sugar alcohols can be found in low sugar processed foods such as protein bars and are commonly found in gum and other sugar-free candies. Since they still provide some carbohydrates, eating too many of them will not only upset your stomach but also increase blood sugar levels. Be sure to consume in moderation. There is no ADI for sugar alcohols, but remember not only do they count toward your total daily calorie intake, they also can cause stomach distress.
What I Recommend To Clients
Having read all of this information on sweeteners, you may still feel unsure if and how much you should consume. I believe a few servings of sweeteners per day is completely acceptable and will not limit your fitness progress or negatively impact your health—unless you have pre-existing health concerns like I discussed above. However, I admit that each person’s personal tolerance and feelings about using artificial ingredients is different.
When I begin working with training/nutrition clients, I recommend that they limit their artificial sweeteners to a few packets a day (example: 1 packet for coffee and 1 for oatmeal) in addition to their protein powders and other necessary supplements. Overtime, I recommend that clients try to make the switch to Stevia, a natural sugar-free sweetener, for their coffee, tea, etc., but still limit the amount they consume daily. I
Prior to competition or photo shoots, I have my clients drop all sweeteners for about a week heading into the show to limit any potential water retention and bloating.
Artificial Sweeteners and Cancer. http://www.cancer.gov/cancertopics/factsheet/Risk/artificial-sweeteners
Renwick AG, Molinary SV. Sweet-taste receptors, low-energy sweeteners, glucose absorption and insulin release. Br J Nutr. 2010. 104(10): 1415-20.