AKK Study in Improving Obesity and Metabolic Status in Children and Adolescents

This intervention trial intends to use pasteurized AKK bacteria, with each dose containing the equivalent of 30 billion inactivated bacterial cells. AKK bacteria are a research hotspot in the field of intestinal microecology. The pasteurized AKK bacteria (belonging to prebiotics) have been proven to have good safety and metabolic improvement effects in adults. Compared to live bacterial preparations, the inactivated form has higher stability, a longer shelf life, and better safety.

AKK group (n=50): The subjects take one AKK probiotic capsule orally before each breakfast and dinner every day, and the intervention lasted for 12 weeks.

During the study period, both groups of participants will receive unified and standardized health education, which includes the principles of balanced diet provided by registered dietitians and the suggestions for physical activities provided by exercise rehabilitation specialists.

Placebo group (n=50): The subjects took one placebo capsule (containing inert ingredients such as maltodextrin) identical in appearance and taste to the AKK probiotic capsules before each breakfast and dinner every day for 12 consecutive weeks. After the study ended, the subjects in the placebo group could receive the same dose and specification of AKK probiotic capsules.

Basic intervention: During the study period, both groups of subjects would receive unified and standardized health education, including the principles of balanced diet provided by registered dietitians and the physical activity suggestions provided by exercise rehabilitation specialists.

The Z-score for children (Z-score) is a statistical indicator that measures the deviation of children's growth indicators such as height (in meters), weight (in kilograms), and BMI (in kg/m^2) from the reference population of the same age and gender. It is used to assess nutritional status and growth development levels.

The nutritional status can be judged by evaluating the height-for-age z-score (HAZ), weight-for-age Z-score (WAZ), and weight-for-height z-score (WHZ) of children and BMI-for-age Z-score (BMIZ).

The Z-score formula is: Z = (Measured value - Average value of the reference population) / Standard deviation of the reference population.

Standard： ±2 : Normal range (95% healthy children)

• -2 ≤ Z < -1: Less than Normal
• Z < -2： Growth retardation, low weight or emaciation (<-3 is severe)
• +1 ≤ Z ≤ +2： Overweight
• +2 ≤ Z ≤ +3： Obesity
• Z > +3： Severe obesity

The dietary intake of the research subjects was understood through 24-hour recall and food frequency questionnaires (for the past month). The dietary and nutrient intake of the research subjects was evaluated through food diversity scores and the intake of energy and nutrients(converts the weekly intake volume (ml/g) into "servings per week").

A designed dietary frequency questionnaire was used to evaluate the regular and environmental dietary behaviors of adolescents in the past three months. The questionnaire is based on common dimensions of dietary behavior and mainly covers five core behavioral categories: having breakfast, having a late-night snack, having meals at school, eating alone, and using food delivery platforms. The frequency options for each category are "Never", "once a month or less", "2 to 3 times a month", "once a week", "2 to 3 times a week", "4 to 5 times a week", "once a day", "twice a day", and "three or more times a day".

The Pittsburgh Sleep Quality Index (PSQI) in Chinese was used to assess the subjective sleep quality of participants aged 13 to 18 years. This scale consists of 19 self-rated items and 5 other-rated items, and the scoring can yield 7 scoring items including sleep latency, sleep disorders, sleep quality, sleep duration, hypnotic drugs, sleep efficiency and daytime function.

Each component score of the PSQI ranges from 0 to 3, with 3 indicating the greatest dysfunction or disturbance. The seven component scores are then summed to obtain a global PSQI score, which ranges from 0 to 21. Higher scores indicate poorer sleep quality, with a score greater than 5 suggesting significant sleep difficulties.

The evaluation of different dimensions of the scale will be separately described.

For children aged 7 to 12 years, the sleep questionnaire items were designed based on the CSHQ (Children's Sleep Habits Questionnaire). It consists of 48 items (33 scoring items), and can assess specific sleep problems in eight aspects: poor sleep habits, sleep anxiety, irregular sleep duration, sleep breathing disorders, abnormal sleep patterns, daytime sleepiness, night awakenings, and prolonged sleep latency.

CSHQ requires parents to recall their child's sleep patterns over the past 4 weeks, and to select the sleep condition that best represents the typical week for a 3-point Likert scale rating of "often" (5-7 times per week), "sometimes" (2-4 times per week), and "rarely" (0-1 time per week).

Gastrointestinal symptoms will be evaluated using the Gastrointestinal Symptom Rating Scale (GSRS).

The GSRS is a specific scale consisting of 15 items , with each item scored from 1 (no symptoms at all) to 7 (extremely severe symptoms). The GSRS was used to assess the occurrence of gastrointestinal symptoms in the subjects over the past week, covering five types of digestive tract symptoms: reflux syndrome, abdominal pain syndrome, dyspepsia, diarrhea syndrome, and constipation syndrome. The total score is the sum of all items, with a higher score indicating a more severe condition.

The Bristol Stool Classification Scale (BSFS) was used to evaluate the type of stool. The BSFS is a widely used scale for assessing intestinal motility and can be used to understand the type of stool of the subjects over the past week. This scale presents the transformation from hard stool to watery stool through pictures of types one to seven.

The seven types of stool are:

Type 1: Separate hard lumps, like nuts (difficult to pass) Type 2: Sausage-shaped, but lumpy Type 3: Like a sausage but with cracks on its surface Type 4: Like a sausage or snake, smooth and soft (average stool) Type 5: Soft blobs with clear cut edges Type 6: Fluffy pieces with ragged edges, a mushy stool (diarrhea) Type 7: Watery, no solid pieces, entirely liquid (diarrhea)