Effects of Miracle Fruit Pill Application on Food Likings and Energy Intake in Diabetic or Prediabetic Patients

The high prevalence of diabetes and prediabetes has increased the demand for nonnutritive sweeteners in recent years. Miracle fruit has been considered a healthy alternative sweetener for diabetic patients due to its sweetness-enhancing effects and high antioxidant activity. The purposes of this study are to examine whether the miracle fruit pill application to mouth prior to food consumption could improve the likings of different types of sour food (green apple, goat cheese, lemonade, cucumber pickle, and plain fat-free yogurt) and meals (breakfast, lunch, and dinner), and reduce energy intakes at the meals. Fifty volunteers (25 men and 25 women) aged 45 to 75 years with diabetes or prediabetes participate in the study. In this study, two interventions (miracle fruit and placebo) are provided, and all participants receive both applications. Participants are randomly assigned to one of the two interventions in part 1 and the assignment is switched from one application to another in part 2. The study hypotheses of this study are that the miracle fruit intervention improves the likings for sour foods and meals more than the placebo does; The miracle fruit intervention also reduces energy intakes from the meals more than the placebo does. Participants are asked to participate in a total of 6 sessions (1 hour/session, 1 session/day, Part 1: session 1, 2, \& 3, Part 2: session 4, 5, \& 6). Each session consists of two 30-min assessments, which are liking tests and meal intake assessment. The potential participants who have known food allergies or food intolerances are screened through consented screening procedure. If unknown food allergies or intolerances unintentionally become present during the study, medical help will be sought immediately. Participants may enjoy food samples and meals provided in this study and benefit by learning more about their acceptances for miracle fruit pill as an alternative sweetener. The results of this research are expected to develop generalizable knowledge about the miracle fruit's potential to improve the food palatability for people with diabetes or prediabetes.

Due to the rise in rates of obesity and diabetes in recent years, the consumer demand for alternative sweetener is growing especially among people with diabetes or prediabetes. Given the need for alternative sweeteners, miracle fruit (Synsepalum dulcificum) may be a good candidate to fulfill the demand. Miracle fruit has been used as a sweet enhancer for thousands of years by the natives in Western Africa without any reports of adverse effects. The red, cranberry-sized miracle fruit is named for its unique ability to transform sour taste into sweet. In addition to the miracle fruit's taste modification function, miracle fruit has valuable antioxidant activities that can be applied for functional food and has also been studied to improve insulin resistance induced by fructose-rich chow in rats. With the potential health benefit of miracle fruit, miracle fruit has been considered as a healthy alternative sweetener that can meet diabetic patients' needs. However, for the practical applications of miracle fruit for diabetic diet, the acceptability of miracle fruit and its effect on energy intake need to be examined among diabetic patients. Fresh miracle fruits are highly perishable, and they cannot be cooked because the taste modifying effect found in the pulp of the miracle fruit is due to a protein, which is deactivated by heat. For these reasons, a freeze-dried pill form of miracle fruit needs to be applied on a tongue to coat taste buds before food is consumed. Therefore, in this study, the effects of oral application of miracle fruit pill are compared with placebo (sugar candy) on the likings of different sour food products (green apple, goat cheese, lemonade, cucumber pickle, and plain fat-free yogurt) and meals (breakfast, lunch, and dinner), and energy intakes from the meals in people with diabetes or prediabetes. A total of 50 patients aged 45 to 75 years who have been diagnosed with diabetes or prediabetes (25 men and 25 women) participate in this study. They should be nonsmokers; not have food allergies or food intolerances; not be diagnosed with taste disorders; not be pregnant; not breastfeed; and not use medications that could affect taste perception and food intake. This study is a randomized placebo-controlled crossover trial. As an intervention, a miracle fruit pill is orally administered prior to eating food samples. The same protocol is followed in the control group but with placebo (sugar candy). Participants are asked to participate in a total of six 1-hour sessions (1 session/day). Participants are randomly assigned to either of two applications (miracle fruit and placebo) in part 1 and one week after part 1 (1-week washout), their intervention assignment is switched from one application to another in part 2. Each part/intervention consists of 3 sessions and each session consists of two assessments (liking tests and meal intake assessment). In each part/intervention, each participant performs the liking tests for five sour foods in triplicate and consumes breakfast, lunch, and dinner meals once. The order of the experiments in each session is as follows: 1. preliking test; 2. miracle fruit pill/placebo administration; 3. postliking test; and 4. meal intake. At the liking tests, the pre- and postlikings of overall, flavor, texture, and aftertaste for all 5 sour food samples are assessed using a 9-point hedonic scale (1=dislike extremely, 9=like extremely). For the meal intake assessment, standardized breakfast, lunch, and dinner meals are provided to participants according to the experimental design. During the meal intake session, participants are allowed to consume any food, beverage, or condiments, including sweeteners that are provided at the session. All foods and beverages that are consumed by each participant at the meals are weighed, and the energy intakes from the meals are calculated using the food weight via online nutrient tracker.

Eligibility Criteria:
Inclusion Criteria:

* Having a score of 5 or higher on the 'Prediabetes Risk Test' provided by the American Diabetes Association and the Centers for Disease Control and Prevention
* Having been diagnosed with prediabetes or diabetes by doctor

Exclusion Criteria:

* Smoking
* Having food allergies or food intolerances
* Being diagnosed with taste disorders
* Being pregnant
* Breastfeeding
* Using medications that could affect taste perception and food intake