Regulated by the FDA as a food additive, sugar substitutes---also known as artificial sweeteners---provide many times the sweetness of table sugar. Because they are so intensely sweet, sugar substitutes enhance the sweetness of foods and beverages with few or no added calories, making them a popular diet food ingredient. Some sugar substitutes derive from natural products while others are synthetic, but whatever their source, they may cause unhealthy side effects when included as part of your diet.
Saccharin, the sweetening agent in Sweet'N Low, offers 300 times the sweetness of table sugar. Once linked with the development of bladder cancer in rats, saccharin is not a human carcinogen, explains the National Cancer Institute. However, if you are allergic to sulfa drugs, saccharin can cause itching and hives when ingested. If you are sensitive to sulfa drugs, choose an artificial sweetener other than saccharin to avoid an allergic reaction.
Aspartame consists of two amino acids, aspartic acid and phenylalanine, bonded together. Marketed as NutraSweet or Equal, aspartame is 180 times sweeter than table sugar. The amino acids contribute calories to your diet, but the amount of aspartame eaten is generally low enough that the calories are negligible. When ingested, aspartame breaks down into its component amino acids. The presence of phenylalanine in your diet is a health hazard if you have phenylketonuria, an inborn disease in which you are unable to properly metabolize phenylalanine. The Mayo Clinic recommends avoiding any foods or medications containing aspartame if you are phenylketonuric.
Currently banned in the U.S. but approved as a food additive in 50 other countries, including Canada, cyclamate is 30 times sweeter than table sugar. Health risks associated with cyclamate use include chromosome damage and bladder cancer. However, points out the American Council on Science and Health, no researchers have reproduced these results in subsequent studies on cyclamate ingestion. With the health effects of cyclamate in dispute, err on the side of caution and avoid cyclamate if you are concerned with its possible health risks.
Polyols are sugar alcohols such as xylitol, mannitol and sorbitol. They occur naturally in foods such as apples and berries, and are approximately as sweet as table sugar. Polyols do contribute calories when eaten but, because they are not completely absorbed and metabolized by your body, they don't add as many calories to your diet as regular sugar. Exercise caution when using polyols as a sugar substitute, however, because in high doses they may cause a laxative effect.