Physiological Effects of Stevia Consumption in Humans
Condition: Glucose Intolerance; Obesity
MeSH terms: Glucose Intolerance
Study type: Interventional

Summary: 
      This study will evaluate whether long-term consumption of the low calorie sweetener stevia
      affects glucose tolerance in healthy participants. With regard to this aim, we will recruit 2
      study groups, the stevia group where participants will be required to add stevia drops twice
      daily in their habitual drinks and the control group where participants will be asked not to
      change anything in their diet and lifestyle.
    

Detailed description: 
      Excess consumption of caloric sweeteners contributes to the alarming rates of overweight and
      obesity, whereas non-nutritive sweeteners (NNS) are non-caloric alternatives offering sensory
      and health benefits. NNS are widely used to moderate energy intake and postprandial
      glycaemia, but there is controversial evidence about their role and effects. Stevia, a
      natural NNS, has been suggested to assist with glucose regulation but data on glucose
      tolerance after daily consumption of stevia are lacking. The investigators plan to undertake
      a pilot randomized 2-parallel arm open-label 12-week trial, where participants will start
      consuming stevia with their habitual drinks. Thirty healthy volunteers (not habitual
      consumers of stevia or other NNS) will be recruited. The intervention group (n=15) will
      consume 5 drops of stevia with their habitual drinks twice daily whereas the control group
      (n=15) will not be required to change anything in their diet, but avoid consuming NNS or diet
      beverages for the study duration.

      Key measures in glucose homeostasis including glucose response to an oral glucose tolerance
      test will be performed before and after the intervention period. Serum and plasma samples
      will be stored for potential analysis of insulin and gut hormones levels.

      Participants will have to attend 3 study visits, visit week 0, visit week 6 and visit week
      12, but the primary outcome will be assessed in visit week 0 and visit week 12.

      Participants will be weighed; dietary intake, physical activity and appetite will be also
      assessed. Faecal samples will be collected and gut microbiome analysis may be performed. Gut
      microbiome has been considered to be a key linked topic, since it has been suggested that
      saccharin consumption may induce glucose intolerance in humans through alterations in gut
      microbiota in humans.

      The trial will assess whether regular use of stevia in realistic amounts has any effects on
      glucose homeostasis, and aims to elucidate our understanding of long-term physiological
      effects of NNS.
    

Intervention name(s): stevia
Intervention type(s): Dietary Supplement
Intervention description(s): This arm will be required to consume 5 stevia drops twice daily in habitual drinks
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: 2-group parallel 12-week intervention study with control group
Masking: None (Open Label)
Primary purpose: Basic Science