Sweetener Review

This document compares 3 widely used, commercially manufactured, low calorie, non-nutritive sweeteners, namely, monk fruit, erythritol and stevia. These sweeteners are often blended in food products but can be used independently.

Monk fruit

Monk fruit is a small, green melon-shaped fruit also known as Buddha fruit which is native to Southeast Asia. It has historically been dried and utilised in Traditional Chinese Medicine to make medicinal teas. Monk fruit juice is manufactured from the fruit’s extract removing the seeds and skin of the fruit and crushing it to collect the juice which is then dried and commercially available in powder, liquid or granular form where it is commonly used as a sweetener substitute. Monk fruit has no calories, carbohydrates or fat. Monk fruit sweetener does not contain fructose or glucose. Its sweetness derives from antioxidant mogrosides which are thought to have low glycaemic properties (Zhou et al., 2009).  Mogrosides are also thought to be anti-inflammatory and may potentially help reduce oxidative stress (Xu et al., 2013). The processing of monk fruit however can impact its nutritional profile and there is some evidence that monk fruit may stimulate insulin secretion when mixed with other sweeteners such as dextrose. However, monk fruit is collectively linked to many health benefits and is considered safe for consumption by diabetics and those wanting to restrict dietary sugar. Monk fruit extract is estimated to be 150-250 times sweeter than white, refined table sugar and it is often mixed with inulin or erythritol to reduce the intensity of its sweetness. It is considered as generally recognised as safe by regulatory authorities such as the Food and Drug Administration (FDA). There is a risk of allergies to monk fruit although this is considered rare. It is a member of the Curcurbitaceae family (known as the gourd family) which also includes melons, squash, pumpkins and cucumbers and should be avoided by individuals have known allergies to this group of fruits. Experimental studies in animals have reported that mice fed monk fruit extract experienced lower oxidative stress and blood sugar levels (Qi et al., 2008; Xiangyang et al., 2006; Xu et al., 2013). Although, more studies in humans are required to confirms these effects.

Erythritol

Erythritol is a non-caloric and non-glycemic sugar alcohol which belongs to a class of compounds called polyols (Regnat et al., 2018). It can be found naturally in foods such as mushrooms and fruits and is commercially available in the form of powder and categorized as a “zero-calorie” sugar substitute. Erythritol is widely used in a range of baked food products, beverages and snacks as a low-calorie sweetener. Erythritol does not dissolve in food products in the same way as white as refined sugar and is prone to crystalising for example in ice-cream. It is 60-80% as sweet as sugar and contains approximately 0.2 calories per gram. The human body does not have the digestive enzymes to fully metabolise erythritol and therefore most of it is absorbed by the bloodstream and excreted via urine unmodified (Regnat et al., 2018). Around 10% of erythritol travels undigested to the colon and appears to be resistant to fermentation by colon-based bacteria (Arrigoni et al., 2005). Over consumption of erythritol may lead to digestive issues such as bloating, nausea and gas. It may also produce laxative effects. Multiple experimental animal studies have examined the effects of erythritol in relation to toxicity and side effects. Overall, it is considered safe for human consumption although there are continued research efforts exploring the role of the metabolization of erythritol and its metabolites, especially erythronate (Bordier et al., 2022). It is currently used in over 60 countries within the food, pharmaceutical and cosmetic industries. Research has found that erythritol does not appear to increase (spike) blood sugar or insulin levels, and therefore is widely thought to be suitable for use in individuals who are overweight, have diabetes or are at risk of diseases related to metabolic syndrome (Wen et al., 2018). A small recent study linked erythritol use to adverse cardiac events and in particular, thrombosis (Witkowski et al., 2023). However, the reliability of this study is currently under question, namely because it only involved 8 participants who were asked to drink a large amount of the sweetener (30 grams) in water in less than 2 minutes. All the participants although considered to be healthy volunteers had previously presented with symptoms associated to heart disease and previous consumption of erythritol was not recorded. Although artificial sweeteners are generally considered safe by regulatory agencies such as the US Food and Drug Administration (FDA) and European Union, the authors of this study have called for further long-term investigations to assess the safety and health effects (and potential cardiovascular risks) of erythritol and other artificial sweeteners (Witkowski et al., 2023).

Stevia

Stevia is a natural, non-nutritive sweetener meaning it has virtually no calories which has been manufactured from the leaves of a plant native to South America called Stevia rebaudiana. In its natural form, stevia contains a small number of vitamins and minerals, but these are often removed during processing. Stevia is estimated to be between 50 and 400 times as sweet as refined table sugar (Ashwell, 2015). Stevia production undergoes a series of filtration processes to extract high-purity steviol glycosides (> 95%) from the dry stevia leaves. Stevia is added to soft drinks, ice cream, dairy products, canned fruit and jams, cakes, and desserts. In terms of metabolism, research studies have demonstrated that high-purity stevia leaf extract does not accumulate in the form of calories and passes through the body unmetabolized (Gardana et al., 2003). Stevia is a popular choice of sweetener in low carbohydrate and ketogenic diets. Although, it has a slightly bitter aftertaste which may alter the flavor of a product hence is often used in combination with other sweeteners such as erythritol and monk fruit.

Stevia is a suitable sugar replacement for individuals with diabetes because it does not increase blood sugar levels. A recent study recruited a small number of people with type 2 diabetes and gave them a cup (237 mL) of sweetened tea for 8 weeks containing stevia and evaluated their blood sugar levels. The results reported no effects on insulin, fasting blood sugar or long-term regulation of blood sugar (Ajami et al., 2020).  Additional research also assessed the use of stevia in patients with type 2 diabetes and concluded that its use significantly lowered fasting and post-prandial (i.e., relating to the period immediately after a meal) blood glucose levels as well as reducing very-low-density lipoprotein (VLDL) cholesterol and serum triglycerides (Ritu & Nandini, 2016). The authors of this study concluded that stevia may be safely used as an anti-diabetic, sweetener substitute and may also help in patients to lower risk of cardiovascular related diseases (Ritu & Nandini, 2016). A meta-analysis employing the stringent Cochrane review criteria reported that stevia use revealed an overall statistically significant reduction in blood pressure compared to placebo warranting further research investigating the effects of stevia in human health (Bundgaard Anker et al., 2019).

The Food and Drug Administration (FDA) have deemed purified steviol glycosides when extracted from the stevia plant to be generally recognised as safe (GRAS). There have been some concerns that high doses may cause digestive issues and, recent research efforts have focused on the potential effects of non-nutritive sweeteners on gut health.

References

Ajami, M., Seyfi, M., Abdollah Pouri Hosseini, F., Naseri, P., Velayati, A., Mahmoudnia, F., Zahedirad, M., & Hajifaraji, M. (2020). Effects of stevia on glycemic and lipid profile of type 2 diabetic patients: A randomized controlled trial. Avicenna J Phytomed, 10(2), 118-127.

Arrigoni, E., Brouns, F., & Amadò, R. (2005). Human gut microbiota does not ferment erythritol. Br J Nutr, 94(5), 643-646. https://doi.org/10.1079/bjn20051546

Ashwell, M. (2015). Stevia, Nature’s Zero-Calorie Sustainable Sweetener: A New Player in the Fight Against Obesity. Nutr Today, 50(3), 129-134. https://doi.org/10.1097/nt.0000000000000094

Bordier, V., Teysseire, F., Senner, F., Schlotterbeck, G., Drewe, J., Beglinger, C., Wölnerhanssen, B. K., & Meyer-Gerspach, A. C. (2022). Absorption and Metabolism of the Natural Sweeteners Erythritol and Xylitol in Humans: A Dose-Ranging Study. Int J Mol Sci, 23(17). https://doi.org/10.3390/ijms23179867

Bundgaard Anker, C. C., Rafiq, S., & Jeppesen, P. B. (2019). Effect of Steviol Glycosides on Human Health with Emphasis on Type 2 Diabetic Biomarkers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients, 11(9). https://doi.org/10.3390/nu11091965

Gardana, C., Simonetti, P., Canzi, E., Zanchi, R., & Pietta, P. (2003). Metabolism of stevioside and rebaudioside A from Stevia rebaudiana extracts by human microflora. J Agric Food Chem, 51(22), 6618-6622. https://doi.org/10.1021/jf0303619

Qi, X. Y., Chen, W. J., Zhang, L. Q., & Xie, B. J. (2008). Mogrosides extract from Siraitia grosvenori scavenges free radicals in vitro and lowers oxidative stress, serum glucose, and lipid levels in alloxan-induced diabetic mice. Nutr Res, 28(4), 278-284. https://doi.org/10.1016/j.nutres.2008.02.008

Regnat, K., Mach, R. L., & Mach-Aigner, A. R. (2018). Erythritol as sweetener-wherefrom and whereto? Appl Microbiol Biotechnol, 102(2), 587-595. https://doi.org/10.1007/s00253-017-8654-1

Ritu, M., & Nandini, J. (2016). Nutritional composition of Stevia rebaudiana, a sweet herb, and its hypoglycaemic and hypolipidaemic effect on patients with non-insulin dependent diabetes mellitus. J Sci Food Agric, 96(12), 4231-4234. https://doi.org/10.1002/jsfa.7627

Wen, H., Tang, B., Stewart, A. J., Tao, Y., Shao, Y., Cui, Y., Yue, H., Pei, J., Liu, Z., Mei, L., Yu, R., & Jiang, L. (2018). Erythritol Attenuates Postprandial Blood Glucose by Inhibiting α-Glucosidase. J Agric Food Chem, 66(6), 1401-1407. https://doi.org/10.1021/acs.jafc.7b05033

Witkowski, M., Nemet, I., Alamri, H., Wilcox, J., Gupta, N., Nimer, N., Haghikia, A., Li, X. S., Wu, Y., Saha, P. P., Demuth, I., König, M., Steinhagen-Thiessen, E., Cajka, T., Fiehn, O., Landmesser, U., Tang, W. H. W., & Hazen, S. L. (2023). The artificial sweetener erythritol and cardiovascular event risk. Nature Medicine. https://doi.org/10.1038/s41591-023-02223-9

Xiangyang, Q., Weijun, C., Liegang, L., Ping, Y., & Bijun, X. (2006). Effect of a Siraitia grosvenori extract containing mogrosides on the cellular immune system of type 1 diabetes mellitus mice. Mol Nutr Food Res, 50(8), 732-738. https://doi.org/10.1002/mnfr.200500252

Xu, Q., Chen, S. Y., Deng, L. D., Feng, L. P., Huang, L. Z., & Yu, R. R. (2013). Antioxidant effect of mogrosides against oxidative stress induced by palmitic acid in mouse insulinoma NIT-1 cells. Braz J Med Biol Res, 46(11), 949-955. https://doi.org/10.1590/1414-431×20133163

Zhou, Y., Zheng, Y., Ebersole, J., & Huang, C. F. (2009). Insulin secretion stimulating effects of mogroside V and fruit extract of luo han kuo (Siraitia grosvenori Swingle) fruit extract. Yao Xue Xue Bao, 44(11), 1252-1257.