Inclusion Criteria:  Healthy adults and age 20 years and above, subdivided into three groups, Early-life (younger than 45 years, midlife (45--65 years), and later-life (older than 65 years), respectively. Subject has provided written and dated informed consent to participate in the study. The subject is willing and able to comply with the study.  Exclusion Criteria:  The subject is participating in another clinical trial thirty days prior to enroll-ment. Subject has diabetes, obesity, hypertension, cardiovascular disease, liver or kid-ney disease, current infections, and smoking were exclusion criteria. Subject has any medical condition or uses any medication, nutritional product, amino acids supplement or program which might interfere with the conduct of the study or place the subject at risk. Subjects lost to follow-up, non-compliance, concomitant medication.