Parental Intake of Non-Nutritive Sweeteners Shows Intergenerational Effects in Mouse Study

A study published in Frontiers in Nutrition investigated the effects of parental consumption of non-nutritive sweeteners (NNS) on offspring across multiple generations in mice. The research found that parental intake of stevia or sucralose was associated with intergenerational changes in offspring gut microbiota composition, short-chain fatty acid production, glycemic responses, and gene expression, despite the offspring receiving no direct exposure to the sweeteners.

The researchers concluded that parental NNS intake can induce intergenerational changes in offspring biology in this mouse model.

Study Design and Methodology

The research utilized a multi-generational mouse model with the following experimental design:

• Parental Generation (F0): Four-week-old male and female mice were divided into three groups for 16 weeks: a control group receiving water, a group receiving stevia-supplemented water, and a group receiving sucralose-supplemented water.
• Mating and Offspring: Mice from the same treatment group were mated. Their offspring constituted the first generation (F1). F1 mice from the same groups were subsequently mated to produce a second generation (F2).
• Offspring Protocol: Both F1 and F2 generations received only standard chow and water without any direct NNS exposure.
• Analysis: At 20 weeks of age, researchers collected fecal samples and hepatic and ileal tissues. They performed oral glucose tolerance tests and analyzed gut microbiota composition, short-chain fatty acid (SCFA) levels, and gene expression related to inflammation, metabolism, and gut barrier function.

Key Findings

Glucose tolerance tests revealed selective changes across generations:

• F0 Generation: Male mice in the stevia group showed lower glucose levels at 120 minutes compared to the sucralose and control groups. No differences were observed between the control and sucralose groups.
• F1 Generation: Male mice in the sucralose group had lower glucose levels than those in the stevia and control groups.
• F2 Generation: Females in the stevia group had higher fasting glycemia. Males in the sucralose group had lower glycemia than the stevia group but higher fasting glucose than controls.
• No inter-generational glycemic changes were observed in the control group.

• F0 Generation: Sucralose consumption was associated with elevated intestinal expression of the genes Tnf and Tlr4 (inflammation markers) and reduced hepatic expression of Srebp1 (a metabolism-related gene) compared to controls.
• F1 Generation: Intestinal Tnf and Tlr4 were overexpressed in both NNS groups relative to controls.
• F2 Generation: These gene expression changes normalized.
• Expression of the intestinal tight junction gene Tjp1 remained unaffected across all generations.

• Alpha Diversity: In F0 animals, the Shannon diversity index was higher in the stevia group than in the sucralose and control groups. In F1 mice, both NNS groups had higher Shannon indices than controls. In F2 animals, the sucralose group had more observed species and a higher Shannon index than the stevia and control groups.
• Beta Diversity: Significant differences in microbial community structure were observed across treatment groups in all generations.
• Transmission: NNS intake induced substantial changes in fecal microbiota composition in F0 and F1 animals, particularly in the sucralose group. These changes were transmitted to the F1 generation but were partially restored in the F2 generation.

Total SCFA levels were generally lower in NNS groups across generations, with specific patterns:

• F0 Generation: Both NNS groups showed lower fecal valerate and acetate levels than controls.
• F1 Generation: Acetate, butyrate, valerate, and propionate levels were significantly reduced in the sucralose group.
• F2 Generation: The sucralose group had lower propionate and acetate levels. The stevia group had lower valerate, butyrate, acetate, and propionate levels than controls.

Research Context and Implications

• Usage Context: Non-nutritive sweeteners, including aspartame, saccharin, acesulfame K, stevia, sucralose, and cyclamate, are widely used. A 2020 U.S. survey indicated over 140 million adults used NNS. The World Health Organization has suggested that long-term NNS use may be associated with a higher risk of cardiovascular disease and type 2 diabetes.

• Study Conclusions: The researchers reported that sucralose showed stronger and more persistent transgenerational effects than stevia, with stevia-related effects being more prominent in the F1 generation and attenuated in the F2 generation.

• Research Notes: The study authors stated these findings challenge assumptions that NNS are metabolically inert. They noted that the impact of parental sweetener intake on offspring had been an understudied area and called for further research to delineate the underlying mechanisms and determine the relevance of these findings to human health. The research was conducted in mice, and its direct applicability to humans requires further investigation.