ANSWER
Regulations on Isomalt
There is no specific regulation that stipulates Isomalt limitations in consumption (Food Regulations 1985, 2017; Specific Requirements for Health Claims, 2017).
Human Studies on Isomalt Tolerance Level
A study showed an improvement of the glycaemia control after an intake of 24g Isomalt daily over a period of 12 weeks (Mitchell, 2006).
There was another human study which was demonstrated by receiving 30g of Isomalt daily for two 4-week test period. It was concluded the daily consumption of 30 g Isomalt was well tolerated and that consumption of Isomalt does not impair metabolic function but could be useful in improving bowel functions (Gostner et al., 2005).
However, the laxative effects in man were noted at intake of 20 to 30g Isomalt/day. The fact that high doses of Isomalt exert a laxative effect in man, which is a common feature of polyols, should be taken into account when considering appropriate levels of polyols use, alone and in combination (JECFA, n.d.).
In conclusion, Isomalt may not be consumed by adults in quantities larger than about 50 g per day as flatulence and diarrhea may occur. For children, 25 g per day may represent a practical upper limit (Makinen, 2016).
References
Ministry of Health Malaysia. (2017). Food Regulations 1985.
Specific Requirements for Health Claims, 21 CFR 101.80 (2017).
Makinen, K. K. (2016). Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals. International Journal of Dentistry, 2016, 1-16. https://doi.org/10.1155/2016/5967907
Mitchell, H. (2006). Sweeteners and sugar alternatives in food technology. Oxford, UK: Blackwell Publishing Ltd.
Gostner, A., Schaffer, V., Theis, S., Menzel, T., Luhrs, H., Melcher, R., Schauber, J., Kudlich, T., Dusel, G., Dorbath, D., Kozianowski, G. & Scheppach, W. (2005). Effects of isomalt consumption on gastrointestinal and metabolic parameters in healthy volunteers. British Journal of Nutrition, 94(4), 575-581. https://doi.org/10.1079/BJN20051510
Joint Expert Committee on Food Additives (JECFA). (n.d.). International Programme on Chemical Safety (IPCS): Isomalt (WHO Food Additives Series 20).