Is the sugar substitute stevia bad for our health? Written by Erika Watts on December 10, 2020 â Fact checked by Anna Guildford, Ph.D. New research into the plant-based sweetener stevia indicates that the sugar substitute may have negative implications for gut health. Alina Rosanova/Getty Images. People use sugar substitutes as a way to reduce their sugar intake. Excess sugar consumption can cause weight gain, lead to diabetes, and contribute to inflammation in the body. For this reason, researchers have worked to find the perfect replacement that tastes like real sugar and is safe to consume. Scientists have considered stevia a safe sugar alternative for years, but a new study raises the question of whether it can be harmful to gut health.