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While a 2018 review concluded that small doses of fructose may improve glycemic control over time,[3] there is still concern that a diet high in fructose leads to worsening hypertriglyceridemia and obesity, and it may contribute to the development of type 2 diabetes. In contrast to glucose, which can be used easily by all cells of the body, fructose must be metabolized by the liver. In large quantities, fructose may be toxic to the liver, contributing to fatty liver, insulin resistance, and uric acid production, the latter of which has been linked to high blood pressure, kidney stones, and gout. Fructose also stimulates insulin secretion less than glucose-containing carbohydrates. Insulin is necessary for leptin release; leptin is a hormone that inhibits appetite. Lower insulin and leptin levels after fructose ingestion inhibit appetite less than consumption of other carbohydrates and may lead to increased energy intake and more obesity.[2]

These concerns were widely popularized by Dr. Robert Lustig in his book Fat Chance[4] and the online lecture, Sugar: The Bitter Truth, a video produced by the University of Californias Osher Integrative Medical Center. In light of this growing body of evidence, it seems prudent to counsel patients to use high fructose-containing sweeteners modestly even though they have a low GI and to encourage patients to eat whole fruits with fiber instead of fruit juice, because the fiber slows absorption.

Artificial sweeteners add sweetness with minimal calories in two ways. First, they are hundreds to thousands of times sweeter than sugar, so only a small amount is needed to have sweetness equal to that of sugar. Second, because the body doesnt fully absorb them, it also doesnt fully absorb the few calories they do contain, so they have a GI of 0 or 1. A 2018 review and meta-analysis of nonnutritive sweeteners concluded that their consumption was not found to elevate blood glucose levels, though more studies are necessary to determine the effects of chronic artificial sweetener consumption.[5]

Despite tremendous interest in artificial sweeteners as a potential tool to prevent obesity and minimize hyperglycemia in diabetics, there is little evidence available to support their having health benefits. While some studies show decreased caloric intake and modest short-term weight loss with artificial sweeteners, there is no substantive evidence to support clinically meaningful long-term benefits for diabetic patients.[1]

The safety of artificial sweeteners has been controversial for some time. Many users report digestive issues, migraine headaches, and skin rashes. Most studies on artificial sweetenersthose attesting to its safety and those warning of dangershave been done in animals. There is no high-level human data proving artificial sweeteners are harmful, nor is there human data proving safety. The precautionary principle would advise against use of artificial sweeteners until more safety data is available.

Sugar alcohols can also be used as sweetener additives and provide less calories per gram than other sweeteners. Erythritol, xylitol, and other sugar alcohols have been used for decades to sweeten chewing gum, candy, fruit spreads, toothpaste, cough syrup, and other products. However, because sugar alcohols are not absorbed, they can cause gastrointestinal symptoms in some individuals due to incomplete absorption in the small intestine.

The plant species Stevia rebaudiana has gained attention as a natural sugar substitute. The stevia plant has a long history of use as a sweetener in South America. It has zero calories, its GI is 0, and it is 200-300 times sweeter than sugar. Stevia appears to be safe, though extensive research is lacking and some believe this product was approved by the FDA prematurely.

• Discuss sweeteners and glycemic index when counseling patients on nutrition and glycemic control
• Recommend small amounts of low GI sweeteners, keeping in mind that the safety of artificial sweeteners, sugar alcohols, and Stevia has not been firmly established
• Counsel patients that fruit nutrients are best consumed as a whole fruit, not as fruit juice

Understanding Sweeteners was written by Jacqueline Redmer, MD, MPH and updated by Vincent Minichiello, MD (2014, updated 2020).