The effects of artificial and natural sweeteners on various physiological systems

Abstract

This study aimed to investigate the effects of commercially available natural (sugar cane molasses, white sugar and brown sugar) and artificial (Canderel™, Equal™, Natreen™, Sweetex™, Splenda™ and Swheet™) sweeteners on various physiological systems. The artificial sweeteners tested in this study may be categorised into their respective groups based on their primary ingredient. The brands Canderel™ and Equal™ contain aspartame, Natreen™ and Sweetex™ consist of saccharin and Splenda™ and Swheet™ are composed of sucralose. The inclusion of artificial or natural sweeteners in the human diet has been continually debated and their implication in the development of certain diseases has raised concern regarding their safe use. Therefore, it is necessary that these food products be subjected to a battery of tests to determine adverse effects on human health. Firstly, we investigated the effect of the popular sweetener, sugar cane molasses on the immune system. Whole blood cultures were used to assess the impact of molasses on cytokines regulating specific immune pathways. Lactate dehydrogenase activity was used to determine potential cytotoxicity of sugar cane molasses. Results showed that exposure of molasses to whole blood cultures caused no cell death. However, molasses stimulated interleukin-6 and interleukin-10 secretion, indicating effects on inflammation and humoral immunity respectively. The enhanced humoral response produced by molasses may be associated with increased antibody production that acts in defense against extracellular pathogens. Conversely, high IL-6 levels may be associated with the development of hypersensitivity reactions. Based on this outcome, we aimed to further investigate the comparative effect of molasses to other natural and artificial sweeteners using a similar model system. Results of this study showed that all artificial sweeteners had an inhibitory effect on the inflammatory response, while molasses stimulated the inflammatory process in vitro. The artificial, sucralose-containing sweeteners inhibited IL-10 under stimulatory conditions. Thus, exposure to sucralose induces a reduced humoral response that may be associated with adverse effects on the immune system. Secondly, we investigated the effects of sugar cane molasses on the male reproductive system. The effect of molasses on steroidogenesis was monitored using testicular cell cultures. Testes cultures were either stimulated or not stimulated with luteinizing hormone and exposed to molasses samples. The endpoints namely, lactate dehydrogenase activity, testosterone and estradiol synthesis were measured. Results show that molasses causes no cell death and has no impact on estradiol synthesis. However, molasses does exhibit a stimulatory effect on testosterone biosynthesis in vitro. Based on this outcome, we further investigated the comparative effect of molasses to various natural and artificial sweeteners. Results of these experiments indicate that in comparison to all tested sweeteners, molasses significantly enhanced testosterone secretion under stimulatory conditions. Perhaps the supplementation of molasses in diets of males suffering with low testosterone levels may be of beneficial use. The third objective of this study was to investigate the effects of natural and artificial sweeteners on the female reproductive system. Injury to the female reproductive tract was evaluated using frog, ovarian cell cultures. The biomarkers, testosterone and estradiol synthesis were measured to determine the impact of sweeteners on ovarian steroidogenesis. Cultured, oocyte fragments (Xenopus laevis) were exposed to either natural or artificial sweeteners under stimulated or unstimulated conditions. Results showed that the artificial sweetener, Natreen™ elevated testosterone levels while the natural sweetener, molasses enhanced estradiol levels. These results were supported by a correlating decrease on the E2/T ratio by Natreen™ and an increase in the E2/T ratio by molasses. Exposure to the aspartame and sucralose branded sweeteners reduced estradiol synthesis and this was confirmed by the decrease observed in the E2/T ratio. These results suggest that certain sweeteners have potential androgenic, estrogenic or anti-estrogenic characteristics that may beassociated with either harmful or beneficial effects on the female reproductive system. Sugar cane molasses demonstrated a significant effect on all investigated physiological systems in vitro. In order to validate these results, our final objective was to determine the impact of molasses on physiological systems using in vivo and in vitro methods. For this study, Balb/C, male mice were given an oral dosage of molasses for the exposure period of two months. Animals were allocated into either a molasses-treated or a control group. Parameters such as body weight, physiological changes and molasses intake were measured. Collected blood samples were assayed for potential toxicity using plasma biomarkers and liver enzyme activity. The effect of molasses on the immune system was investigated by monitoring antibody titre levels in immunised treated and untreated animals. Testes harvested from treated and untreated groups were cultured and assayed for testosterone synthesis. This was used to determine the impact of molasses on the process of testicular steroidogenesis. Results showed that molasses-treated groups consumed a significant amount of fluid and displayed symptoms of loose faeces. No significant change on body weight was observed in both treated and untreated groups. Plasma biomarkers and liver enzymes remained unaffected in molasses-exposed animals. However, a decrease in levels of IgG anti-antigen in treated groups indicated that molasses suppresses the humoral immune response. This may be associated with an increased risk to infection with extracellular pathogens. Molasses-treated animals significantly elevated levels of testosterone production in vitro. This result was consistent with previous findings and supports the use of molasses as a supplement to augment testosterone synthesis.