A Study to Evaluate the Efficacy and Safety of Lactococcus Lactis KD10 Powder for Improving Autism Spectrum Symptoms in Children With Autism Spectrum Symptoms.

Inclusion Criteria: 1. Children aged 3 years or older and 7 years and 7 months or younger 2. Those diagnosed with autism spectrum disorder through a standardized diagnostic tool according to the diagnostic criteria for autism spectrum disorder in the DSM-5 (Diagnostic and Statistical Manual of Mental disorder-5) at the time of screening \[Diagnostic tool: Korean version of Autism Diagnostic Observation Schedule version 2 (K-ADOS-2), Korean version of Autism Diagnostic Interview-Revised (K-ADI-R)\] (However, if diagnosed with autism spectrum disorder through a diagnostic evaluation within 6 months of screening, only the K-ADOS-2 test will be re-evaluated.) 3. Those judged by the investigator on the day of screening to be able to consume the food for this human test (control food) without chewing it, with water or the provided puree 4. Those subjects or/and their legal representatives who voluntarily agreed to participate in this human test and signed a written consent form and a consent form for research on human-derived materials 5. A person who can provide reliable information on the condition of the test subject during the human test period, attend all planned visits to the institution, supervise the intake of food for human test, and have the participation of a parent or the same legal representative who can fully understand and speak Korean, and conduct a questionnaire evaluation of the subject. Exclusion Criteria: \[Screening Visit (Visit 1)\] 1. Those with the following medical history, concomitant diseases, or surgical history at the time of screening ① Severe psychosis that may affect this test other than autism spectrum disorder ② History of organic brain disease, neurological disorder, uncontrolled epilepsy, or seizures. However, simple febrile seizures can be included at the investigator's discretion ③ Genetic diseases (Rett syndrome, Down syndrome, Fragile X syndrome, etc.) However, participation is allowed at the investigator's discretion only if it is confirmed to be a genetic disease that does not affect the results of this test ④ Gastrointestinal diseases and surgical history that may affect the intestinal absorption of food for human testing (simple appendectomy, hernia surgery are allowed) ⑤ Those with sensory abnormalities such as congenital hearing loss 2. Those with uncontrolled medical conditions (including arrhythmia, cancer, severe heart/kidney disease) during the screening period 3. Those who exhibit serious self-harming or other-harming behaviors that require medical treatment at the investigator's discretion during the screening period 4. Those who have been confirmed to have taken the following drugs within 2 weeks prior to screening or are expected to take the following drugs during the human application test period. However, for drugs with a sufficient washout period exceeding 2 weeks, a washout period of at least 5 times the maximum half-life must be confirmed before the screening time. ① Antipsychotic drugs (antipsychotic, psychostimulant, antidepressant, anxiolytic, mood stabilizer, and neuroleptic agents). If there is no change in the type or dosage of the drug within 3 months of screening due to long-term use, participation is possible at the investigator's discretion ② Selective Serotonin Reuptake Inhibitor (SSRI) 5. Those with the following test results confirmed during screening ① Moderate or higher renal impairment (eGFR \<60mL/min/1.73m2) ② Moderate or higher hepatic impairment(AST or ALT \>3 x ULN) 6. Those who cannot receive intravenous injection for blood collection 7. Those who have difficulty consuming human application test food or are sensitive or allergic to human test food 8. Those who participated in other clinical trials or human trials within 4 weeks prior to screening and were administered or consumed clinical trial drugs or human test food or were applied with clinical trial medical devices 9. Those who are judged unsuitable for participation in human trials by the investigator \[baseline visit (Visit 2)\] 1. Those with unsuitable items when reconfirming the selection/exclusion criteria at the time of randomization 2. Those judged unsuitable for participation in this human study by the investigator other than the above