Immune-Mitochondrial Correction in Military Recruits

The goal of this clinical trial is to learn if a new immune-mitochondrial correction strategy works better than standard vitamins to prevent infections in young male military recruits during their first 6 months of service. The main questions it aims to answer are: 1. Does the new strategy lower the number of recruits who get infections (like colds, flu, or pneumonia) over 6 months? 2. Does the new strategy improve how well the immune cells work, specifically their mitochondria (the power source inside cells)? Researchers will compare: * Control group (100 participants): Standard multivitamin taken once a day for 30 days * Experimental group (100 participants): New strategy (sodium nucleinate, magnesium, vitamin B6, and vitamin D 5000 IU) taken as 3 tablets once a day for 30 days to see if the new strategy lowers infection rates more than standard vitamins. Who can take part: Healthy male military recruits aged 18-27 years who are starting their initial training at the Military Clinical Hospital in Almaty, Kazakhstan. What participants will do: Participants will be placed into one of the two groups by chance (like flipping a coin). They will: * Take study pills once a day for 30 days * Have blood draws 3 times over 6 months (baseline, 1 month, and 6 months) * Have daily health checks by medical staff * Complete quality of life questionnaires What we will measure: * Number of participants who get infections during 6 months * How well the mitochondria in immune cells work (from blood samples) * Immune system status * Stress and adaptation levels * Vitamin D and other blood markers Risks and benefits: The risks are very low. Participants may have mild discomfort or a small bruise from blood draws. All study pills are approved and registered in Kazakhstan. There is no direct benefit to participants, but they will receive extra medical monitoring. The indirect benefit is helping develop a better prevention program to protect future recruits. Where the study is taking place: Military Clinical Hospital of the Ministry of Defense of the Republic of Kazakhstan, Almaty, Kazakhstan. Study duration: January 2027 to December 2028.

Inclusion Criteria: * Male military recruits aged 18-27 years * Starting initial military training at the Military Clinical Hospital of the Ministry of Defense of the Republic of Kazakhstan (Almaty) * Signed informed consent * No acute infectious diseases at enrollment * Willingness to comply with the study protocol for 6 months * Absence of any exclusion criteria Exclusion Criteria: * Chronic immunodeficiency states (HIV infection, congenital immunodeficiencies, current immunosuppressive therapy) * Severe chronic diseases in decompensation stage (diabetes mellitus, renal failure, hepatic failure, heart failure) * Allergy or hypersensitivity to any components of the study interventions (multivitamin, sodium nucleinate, magnesium, vitamin B6, vitamin D) * Use of vitamin-mineral complexes or immunomodulators within the last 3 months prior to enrollment * Hypercalcemia (serum calcium \>2.6 mmol/L) or history of urolithiasis * Hypermagnesemia (serum magnesium \>1.1 mmol/L) * Sarcoidosis or other granulomatous diseases * Refusal or inability to provide informed consent