Effect of Co-consuming Different Dietary Protein Sources With Salad on the Bioavailability of Carotenoids

The goal of this clinical trial is to learn if different protein types will affect carotenoid responses in humans when co-consumed with salad. The main questions it aims to answer are:

• What are the effect of dietary protein co-consumption with salad on postprandial carotenoid levels in Singapore adults?
• Do different whole-food protein sources enhance the bioavailability of carotenoids in Singapore adults?

Participants will:

Consume salad with a form of protein (chicken, tuna, egg, soybean) Have their postprandial plasma carotenoid and triglyceride outcomes evaluated

Study Overview

• Status: Not yet recruiting
• Conditions: Postprandial Carotenoid Response
• Intervention / Treatment: Other: Salad only; Other: Salad + Chicken; Other: Salad + Tuna; Other: Salad + Egg; Other: Salad + Soybean

Detailed Description

This study will be a single-blind, randomized, crossover acute trial, and all participants will complete an approximately 3-month study period. A total of 19 participants will be recruited and go through all 5 arms (4 intervention and 1 control), with the order randomized. The study will comprise 1 screening visit and 5 test visits, with another 5 compliance visits.

• Study Type: Interventional
• Enrollment (Estimated): 19
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Wei Xi Khu, B.Sc.; Phone Number: +65 9359 8952; Email: E0773498@u.nus.edu

Study Locations

• Singapore
  • Singapore, Singapore, 117542
    • NUS, Department of Food Science and Technology, 1 Science Drive 3, Block S13, #03-07, Singapore, 117542
    • Principal Investigator: Jung Eun Kim, Ph.D., R.D.
    • Contact: Wei Xi Khu, B.Sc.; Phone Number: +65 93598952; Email: E0773498@u.nus.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. English-literate and able to give informed consent
2. Singaporean Adults aged 21 to 45 (inclusive)
3. Body mass index of 18.5 to 23.0 kg/m2 (inclusive)
4. At least 50 kg
5. Healthy (based on screening results)

Exclusion Criteria:

1. Currently participating in another clinical study that involves altering regular diet and/or involves consuming a dietary supplement or investigated food product as an intervention
2. High blood pressure (≥ 140/90 mmHg)
3. Underlying health conditions that may affect metabolic functions
4. Consuming carotenoid supplements regularly (i.e., more than three times a week) for the past 3 months, and not willing to discontinue consumption 3 months before and during the study duration
5. Weight change > 3 kg in the past 3 months
6. Exercising vigorously over the past 3 months (i.e., engaging in high-intensity exercises for more than 3 hours a week, where high-intensity exercises leave one out of breath and unable to talk or sing during the workout)
7. Current smokers or have quit smoking for less than 5 years
8. Drinking > 2 alcoholic drinks per day (i.e., one drink is defined as either 150 ml of wine, 340 ml of beer/cider or 45 ml of distilled spirit)
9. If drinking ≤ 2 alcoholic drinks per day, not willing to stop consumption of alcoholic beverages two days before and on the day of the test visits
10. Not willing to stop consumption of caffeinated beverages 10 to 12 hours before and on the day of the test visits
11. Currently on a specialised diet (e.g., vegetarian, vegan, weight loss diet)
12. Had serious food allergies in the past, or having intolerance, sensitivities or allergies to any of the following: soy/soy-derived products, eggs, fish and crustaceans, starch/starch-derived products (e.g., rice, corn, wheat, potato), gluten
13. Disease or impairment of the liver
14. Currently diagnosed with diabetes, gastrointestinal issues (e.g., lactose intolerance, irritable bowel syndrome), gout and/or G6PD deficiency
15. Taking antibiotics 2 weeks prior to study participation
16. Taking anti-hypertensive or cholesterol-lowering drugs for less than 3 years unless medically declared by an official doctor to be in stable condition
17. Poor peripheral venous access based on past experiences with blood drawing
18. Individuals with pacemaker or related electrical medical devices
19. Pregnant, lactating, or planning pregnancy in the next 6 months
20. Have donated blood (whole blood or apheresis) or participated in any other clinical study or trial requiring blood draws within the last 3 months
21. Clinical anemia (hemoglobin <12.0 g/dL in women and <13.0 g/dL in men)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Salad only; Salad only (no protein)	Other: Salad only; Control group, consumption of only salad
Experimental: Salad + Chicken; Salad with chicken	Other: Salad + Chicken; Consumption of salad with chicken
Experimental: Salad + Tuna; Salad with tuna	Other: Salad + Tuna; Consumption of salad with tuna
Experimental: Salad + Egg; Salad with egg	Other: Salad + Egg; Consumption of salad with egg
Experimental: Salad + Soybean; Salad with soybeans	Other: Salad + Soybean; Consumption of salad with soybean

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Concentration of plasma carotenoids	Concentration of plasma carotenoids hourly	From start of salad consumption to the end of acute period (8 hours)
Concentration of blood triglycerides	Postprandial triglyceride response	From start of salad consumption to the end of acute period (8 hours)

Collaborators and Investigators

• Sponsor: National University of Singapore
• Investigators: Principal Investigator: Jung Eun Kim, Ph.D., R.D., National University of Singapore, Department of Food Science and Technology

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): February 1, 2027

Study Registration Dates

• First Submitted: August 26, 2026
• First Submitted That Met QC Criteria: August 26, 2026
• First Posted (Actual): August 31, 2026

Study Record Updates

• Last Update Posted (Actual): September 2, 2026
• Last Update Submitted That Met QC Criteria: August 30, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Plasma carotenoid; Protein Type
• Additional Relevant MeSH Terms: Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Eggs; Salads
• Other Study ID Numbers: S37; NUS-IRB-2026-590 (Other Identifier: National University of Singapore Institutional Review Board (NUS IRB))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Electronic copies of the data with identifiable participant information will be kept on NUS OneDrive with access limited only to Dr Kim Jung Eun and her research staff. All data will be de-identified prior to statistical analyses.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No