With continued efforts to find solutions to rising rates of obesity and diabetes, there is increased interest in the potential health benefits of the use of low- and no-calorie sweeteners (LNCSs). Concerns about safety often deter the use of LNCSs as a tool in helping control caloric intake, even though the safety of LNCS use has been affirmed by regulatory agencies worldwide. In many cases, an understanding of the biological fate of the different LNSCs can help health professionals to address safety concerns. The objectives of this review are to compare the similarities and differences in the chemistry, regulatory status, and biological fate (including absorption, distribution, metabolism, and excretion) of the commonly used LNCSs: acesulfame potassium, aspartame, saccharin, stevia leaf extract (steviol glycoside), and sucralose. Understanding the biological fate of the different LNCSs is helpful in evaluating whether reports of biological effects in animal studies or in humans are indicative of possible safety concerns. Illustrations of the usefulness of this information to address questions about LNCSs include discussion of systemic exposure to LNCSs, the use of sweetener combinations, and the potential for effects of LNCSs on the gut microflora.
This review provides in depth information on the absorption, distribution, metabolism and excretion of the five commonly used LCS: Ace-K, aspartame, saccharin, sucralose and steviol glycosides, as well as an overview of the scientific literature showing that there is a lack of evidence for effects of low calorie sweeteners on gut microbiome. It is important that nutritionists and other health professions are familiar with LCS biological fate so that they can be authoritative sources of scientifically sound information for their patients and the public.
The different compounds are very diverse in their structure, metabolism and biological fate following consumption of foods and beverages sweetened with LCS. This is critically important to understand, as there are many examples in the scientific literature in which biological or dietary effects observed in studies with one LCS are incorrectly extrapolated to all LCSs without supporting scientific evidence.
The LCS can be divided into 2 main groups on the basis of their metabolism. Saccharin, Ace-K, and sucralose belong to the first group, which consists of LCS that undergo virtually no metabolism following either minimal absorption (sucralose) or extensive absorption (Ace-K and saccharin). Aspartame and steviol glycosides comprise the second group of compounds, which are first digested/metabolized in the intestinal tract before absorption, after which only their digestion breakdown products are absorbed systemically and metabolized. In all cases, elimination is rapid, with no bioaccumulation of either LCSs or their metabolites in the body.
Blends of intense sweeteners are becoming more popular in food and beverage formulations because mixtures provide synergistic enhancement of sweetness intensity and improved sweetness quality beyond those afforded by individual sweeteners. In addition, the use of sweetener blends results in lower amounts of each individual LCS being used, further lowering exposure to each compound. Consistently, no evidence for mixtures to represent a safety concern has been found.