The objectives of this study are to examine the effects of ethnicity, gender, and proton pump inhibitor (PPI, omeprazole), on the human gut microbiome. The investigators hypothesize that PPI therapy might perturb microbial communities and alter the gut microbiome. Young, healthy subjects of Chinese, Malay and Indian ancestry, were enrolled. They were required to provide a baseline stool sample (Day 1) and were then given a course of omeprazole at therapeutic dose (20 mg daily) for a duration of 7 days. Stool samples were collected again on Day 7 and Day 14 (one week after stopping omeprazole). The DNA samples were subjected to 16S ribosomal ribonucleic acid (rRNA) sequencing.

Background and Aim: The objectives of this study are to examine the effects of ethnicity, gender, and proton pump inhibitor (PPI, omeprazole), on the human gut microbiome. PPIs are commonly used for the treatment of acid-related disorders. The investigators hypothesize that PPI therapy might perturb microbial communities and alter the gut microbiome.

Methods: Healthy subjects of Chinese (n=12), Malay (n=12) and Indian (n=10) ancestry, aged 21-37 years old, were enrolled. They were required to provide a baseline stool sample (Day 1) and were then given a course of omeprazole at therapeutic dose (20 mg daily) for a duration of 7 days. Stool samples were collected again on Day 7 and Day 14 (one week after stopping omeprazole). Microbial DNA was extracted from the stool samples. This was followed by PCR, library construction, 16S rRNA sequencing using Illumina MiSEQ, and statistical and bioinformatics analyses.

Inclusion Criteria:

1. Provision of signed written informed consent,
2. Aged between 21-35 years of age,
3. Chinese, Malay or Indian ancestry through three generations,
4. Clinical laboratory assessment results within normal limits, unless the deviation is considered not clinically significant by the investigator,
5. Subject is healthy with no clinically significant disease or condition as determined through their medical history, physical examination, and results from clinical laboratory tests that are performed within 2 weeks before the baseline visit at Day 1,
6. Ability to communicate with the investigator and to understand and comply with all requirements of study participation.
7. Female subjects must be in the first half of their menstrual cycle (i.e. 1 to 14 days after the end of the previous menstruation) at Research Study entry.

Exclusion Criteria:

1. Any acute illness within 2 weeks before Day 1, unless otherwise approved by the PI,
2. Presence of chronic illnesses e.g. diabetes, renal disease, gastrointestinal disease, etc., which, in the opinion of the investigator, could compromise the data of the study,
3. Subjects who declare themselves positive for HIV or viral hepatitis (Hepatitis A, B, C),
4. Treatment within the previous 3 months with antibiotics,
5. Treatment with any prescription or over-the-counter (OTC) medications, or herbal supplements within 4 weeks of Day 1 unless approved by the PI,
6. Consumption of probiotics or lactobacillus-containing products e.g. Yakult, Vitagen or Yogurt within 4 weeks of Day 1 unless approved by the PI,
7. Abnormal biochemistry indicators,
8. Poor peripheral venous access,
9. Involvement in the planning or conduct of this study,
10. Irregular bowel habits or complains of constipation problem.