Inclusion and exclusion criteria
| Inclusion criteria | Exclusion criteria |
| 18–59 years old adults | Individuals on immunosuppressant (ie, steroids) |
| Moderate stress (scoring Perceived Stress Scale 10 within 14–26) | Usage of immune-modifying medications or dietary supplements affecting the immune system (at least 2 weeks of washing period for inclusion) |
| Scored Patient Health Questionnaire 9 less than or equal to 9 | Any autoimmune or health concerns |
| Individuals with symptoms of common colds for the past 6 months assess using Jackson Cold Scale | Uncontrolled comorbidities including diabetes, hypertension, cardiovascular disease, chronic kidney disease, chronic liver disease, active malignancy, endocrine disorder and cancer |
| Willing to comply with protocol requirements | Uncontrolled chronic respiratory illness including allergic rhinitis or asthma, presence of nasal ulcers/polyps |
| Body temperature >38°C at study commencement (fever) | |
| Pregnant or lactating female | |
| On specific dietary requirements (diabetic diet/low salt diet/etc) | |
| On prebiotics or probiotics supplementation (at least 2 weeks of washing period for inclusion) | |
| On antibiotics washing period within 2 weeks for inclusion | |
| Individuals with disabilities (long-term physical, mental, intellectual and sensory impairment) | |
| Individuals without symptoms of common colds for the past 6 months | |
| Allergy to yeast, oat, wheat, barley | |
| Influenza vaccination for the past 1 year | |
| Pneumococcal Polysaccharide Vaccine-23/PSV23 (Pneumovax-23) in the last 5 years and those who had received Pneumococcal Conjugate Vaccine/PCV 13 (Prevenar 13) | |
| Participate in another research study |