Effect of ingestion of Vitamin D3 on Upper respiratory tract infection of healthy Japanese adult

INTERVENTION: Ingestion of 10 micro grams of Vitamin D3 per day for 112 days Ingestion of placebo without vitamin D3 for 112 days CONDITION: Healthy subject PRIMARY OUTCOME: Incidence proportion of upper respiratory tract infection during the test period SECONDARY OUTCOME: Longest duration, most severe physical and mental severity of upper respiratory tract infection during the study period; Incidence proportion longest duration, most severe physical and mental severity of upper respiratory tract infection of every 4 weeks of study period INCLUSION CRITERIA: 1.45 to 74 years of age of healthy Japanese subjects 2.BMI between 18.5 to 24.9 kg/m2 3.Defined serum 25‐OHD level: less‐than‐or‐equal‐to 30 ng/mL (= 75 nmol/L) 4. Subjects willing and able to give written informed consent and to understand, to participate and to comply with the study requirements