Impact of Regular Consumption of Grapes on Eye Health in Singapore Older Adults

Aging epidemics in Singapore are rapidly increasing and Age-related macular degeneration (AMD) prevalence is significantly associated with older age. This study aims to understand the effect of consuming freeze-dried table grape powder on AMD in an older population.

Study Overview

• Status: Active, not recruiting
• Conditions: Age-related Macular Degeneration; Eye Health
• Intervention / Treatment: Dietary supplement: Freeze-dried table grape powder; Dietary supplement: Placebo of the table grape powder

Detailed Description

This will be carried out through a 16-week double-blind, randomized, placebo-controlled trial of parallel study design. Thirty-eight men and women (aged between 60 and 85 years old inclusive) will recruited and assigned to an intervention or placebo group. The intervention group will consume 46 g/day of a freeze-dried table grape and the control group will consume the same amount of a placebo, table grape placebo powder. Measurements of 1) macular pigment optical density (MPOD), a clinical marker for eye health, 2) carotenoids status, 3) markers of oxidative stress, 4) markers of endothelial function, 5) body size and blood pressure, and 6) dietary assessment will be assessed over the 16-week study. This study will consist of 1 screening visit and 5 study visits in 4-week intervals to the Food Science and Technology Department, Occupational Health Clinic and National University Heart Centre.

• Study Type: Interventional
• Enrollment (Actual): 34
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Weili Hu; Phone Number: 80393103; Email: weili.hu@u.nus.edu

Study Locations

• Singapore
  • Singapore, Singapore, 117546
    • National University of Singapore

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Male and female participants, aged between 60 and 85 years old inclusive
• Able to give informed consent in English

Exclusion Criteria:

• Smokers
• Allergy to grapes
• Known eye diseases (macular degeneration, cataracts, retinopathy or glaucoma), blindness in at least one eye or have had eye surgery
• Abnormal kidney and liver function
• Taking eye medication and/or dietary supplements for the eyes for the past 3 months
• Taking supplements containing carotenoids (e.g. Vitamin A, lutein, zeaxanthin) for the past 3 months
• Currently on type 2 diabetic medication.
• Currently on anti-hypertensive or cholesterol-lowering; unless this prescription has been ongoing for more than 3 years prior to study participation.
• Currently on a specialized diet (e.g. vegetarian, vegan, weight loss diet, low fat diet)
• Consumes more than 2 alcoholic drinks per day i.e. one drink is defined as either 150ml of wine, 340ml of beer/cider or 45ml of distilled spirit.
• Significant change in weight (≥ 3 kg body weight) in the past 3 months
• Significant exercise pattern over the past 3 months defined as high-intensity exercise of more than 3 hours per week
• Poor peripheral venous access based on past experiences with blood draw
• Participating in another clinical study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Freeze-dried table grape powder; The intervention group will consume 46 g/day of a freeze-dried table grape powder.	Dietary supplement: Freeze-dried table grape powder; Consumption of 46g/day freeze-dried table grape powder
Placebo Comparator: Placebo grape powder; The control group will consume the same amount of a placebo with a similar taste to the table grape powder.	Dietary supplement: Placebo of the table grape powder; Consumption of 46g/day placebo version of the freeze-dried table grape powder

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in macular pigment optical density	Macular pigment optical density will be measured using macular pigment scanner	Every four weeks (week 0, week 4, week 8, week 12, week 16)
Change in skin carotenoid status	Skin carotenoid status (a.u) measured using NuSkin II, resonance Raman spectroscopy	Every four weeks (week 0, week 4, week 8, week 12, week 16)
Change in blood carotenoid concentration	Blood carotenoid concentration to be quantified by HPLC	Every eight weeks (week 0, week 8, week 16)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in flow mediate dilation	Flow mediate dilation (%)	week 0 and week 16
Change in endothelial function	Endothelial functions are determined by the function of endothelial progenitor cells	week 0 and week 16
Change in the concentration if Endothelin-1 in plasma	Endothelin-1 concentration	week 0 and week 16
Change in the concentration if Nitric Oxide in plasma	Nitric Oxide concentration	week 0 and week 16
Change in body weight	Body weight (kg) measured using body scale	Every four weeks (week 0, week 4, week 8, week 12, week 16)
Change in BMI	Weight and height will be combined to report BMI in kg/m^2	Every four weeks (week 0, week 4, week 8, week 12, week 16)
Change in blood pressure	Systolic and diastolic blood pressure (mmHg) measured using sphygmomanometer	Every four weeks (week 0, week 4, week 8, week 12, week 16)
change in waist circumference	Waist circumference (cm) measured using measuring tape	Every four weeks (week 0, week 4, week 8, week 12, week 16)
Change in the concentration of malondialdehyde in plasma	Malondialdehyde concentration	Every eight weeks (week 0, week 8, week 16)
Change in the concentration of 8-iso-prostaglandin F2α in plasma	8-iso-prostaglandin F2α concentration	Every eight weeks (week 0, week 8, week 16)
Change in blood glucose concentration	Blood glucose concentration (mmol/l)	Every eight weeks (week 0, week 8, week 16)
Change in total cholesterol	Total cholesterol (mmol/l)	Every eight weeks (week 0, week 8, week 16)
Change in high-density lipoprotein cholesterol	High-density lipoprotein cholesterol (mmol/l)	Every eight weeks (week 0, week 8, week 16)
Change in low-density lipoprotein cholesterol	Low-density lipoprotein cholesterol (mmol/l)	Every eight weeks (week 0, week 8, week 16)
Change in total triglyceride	Total triglyceride (mmol/l)	Every eight weeks (week 0, week 8, week 16)

Collaborators and Investigators

• Sponsor: National University of Singapore
• Collaborators: National University Hospital, Singapore; Ministry of Education, Singapore
• Investigators: Principal Investigator: Jung Eun Kim, National University of Singapore

Publications and helpful links

General Publications

• Gehrs KM, Anderson DH, Johnson LV, Hageman GS. Age-related macular degeneration--emerging pathogenetic and therapeutic concepts. Ann Med. 2006;38(7):450-71. doi: 10.1080/07853890600946724.

Study record dates

Study Major Dates

• Study Start (Actual): January 28, 2022
• Primary Completion (Actual): August 31, 2022
• Study Completion (Estimated): October 1, 2024

Study Registration Dates

• First Submitted: August 30, 2021
• First Submitted That Met QC Criteria: September 23, 2021
• First Posted (Actual): October 1, 2021

Study Record Updates

• Last Update Posted (Estimated): November 9, 2023
• Last Update Submitted That Met QC Criteria: November 7, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Keywords: Age-related Macular Degeneration; carotenoids; Eye Health
• Additional Relevant MeSH Terms: Eye Diseases; Retinal Degeneration; Retinal Diseases; Macular Degeneration
• Other Study ID Numbers: S15

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 key data will be de-identified prior to statistical analysis

Drug and device information, study documents

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