This research project aims to provide the scientific findings about the beneficial effects of okara (soybean pulp) consumption on gut and glycaemic health in middle-aged and older individuals in Singapore. In addition, it aims to examine the health promoting impact of bio-transformed okara in this population. We hypothesise that consuming a habitual diet with an okara (untreated or bio-transformed) incorporated food product will improve the gut microbiome composition and will increase the production of short chain fatty acids when compared to a same diet with no okara. Okara-based food product can also improve the glycaemic response in individuals compared to a product without okara in meal tolerance test (acute).

For this double-blind, randomized, crossover experiment, the participants will complete a 16-week study period. Following a 1-wk pre-intervention baseline period, each participant will be randomly assigned to consume their habitual diet that either contains or do not contain okara food product (untreated and bio-transformed okara) for 3 weeks. The food product will be equivalent to a consumption of 20 g of okara (dried) per day. Following a 3-week dietary 'washout' period, the participants will be assigned to consume the other diets for another 3 weeks. This process will be repeated until each participant have completed all three interventions. Fecal and fasting-state blood samples will be obtained at study weeks 1, 4, 7, 10, 13, and 16, which correspond to before and end of the three 3-week intervention periods.

Additionally, during Weeks 1, 7 and 13, fasted participants will also be required to undergo a meal tolerance test. A cannula will first be inserted into the participant's forearm for blood sampling by a trained phlebotomist. One of three meals prepared by designated study personnel will then be randomly assigned during each visit, namely, control biscuit, untreated okara biscuit and bio-transformed okara biscuit. During each test, the participants will eat the prepared meal within 10 minutes and have blood samples drawn by intravenous cannulation at time = 0, 15, 30, 45, 60, 90, 120, 180 and 240 min, with time 0 being the time the participants first start eating the biscuits. The blood samples will analyzed for the postprandial blood glucose, insulin responses and lipid levels.

Inclusion Criteria:

1. Ability to give an informed consent
2. Age 50 to 75 years
3. Willing to follow the study procedures

Exclusion Criteria:

All subjects meeting any of the exclusion criteria at baseline will be excluded from participation

1. Significant change in weight (≥ 3 kg body weight) during the past 3 months
2. Allergy to soy-based products
3. Acute illness at the study baseline
4. Exercising vigorously over the past 3 months
5. Following any restricted diet (e.g. vegetarian)
6. Smoking
7. Have a daily intake of more than 2 alcoholic drinks per day
8. Prescribed and taking antihypertensive/cholesterol-lowering/ type-2 diabetic medication which started less than 5 years prior to the intervention participation
9. Taking dietary supplements which may impact the outcome of interests (e.g. vitamin supplements, probiotic supplement etc.)
10. Pregnant, lactating, or planning pregnancy in the next 6 months
11. Insufficient venous access to allow the blood collection
12. Very high intake of fibre/ vegetables on a daily basis

Electronic data with any identifiable participant information will be de-identified prior to statistical analysis.

Primary investigator of the study will be blinded in this intervention trial through blinding of the intervention allocation to subjects.