Effect of Lemon Juice and Apple Cider Vinegar on Postprandial Blood Glucose and Satiety in Healthy Individuals

The Effect of Lemon Juice and Apple Cider Vinegar on Postprandial Blood Glucose and Satiety in Healthy Individuals

This clinical study aims to examine how acidic drinks (lemon juice and apple cider vinegar) affect blood sugar when consumed with a starchy food. The study focuses on healthy individuals and aims to understand whether these drinks can slow the rise in blood sugar after meals and affect feelings of fullness.

The main questions this study aims to answer are:

Do lemon juice or apple cider vinegar lower the rise in blood sugar after a meal? Do these drinks increase feelings of fullness? Do different amounts change their effects?

Researchers will compare lemon juice and apple cider vinegar to see which one is more effective.

Participants will:

Consume white bread in the morning on an empty stomach with one of the following drinks:

Water only Water with lemon juice (50 g or 100 g) Water with apple cider vinegar (10 g or 20 g) Have a one-week break between each test. Have their blood sugar measured at regular intervals for 3 hours after eating. Report their level of fullness using a simple scale.

This study explores whether simple and practical dietary choices can help manage blood sugar levels. The findings may support new, easy-to-apply nutrition strategies for managing diabetes and weight.

Study Overview

• Status: Recruiting
• Conditions: Satiety; Postprandial Glycemia
• Intervention / Treatment: Dietary supplement: Control (Water + White Bread); Dietary supplement: Lemon Juice 50 g; Dietary supplement: Lemon Juice 100 g; Dietary supplement: Apple Cider Vinegar 10 g; Dietary supplement: Apple Cider Vinegar 20 g

Detailed Description

Glycemic response plays an important role in the prevention and management of metabolic conditions such as diabetes and obesity. Different foods can cause rapid or slow increases in blood sugar levels. One factor that may influence this response is the acidity of foods. Acidic components may slow starch digestion and delay the rise in blood glucose by affecting digestive enzymes and gastric emptying. However, there are limited studies examining how the acidity of meals influences glycemic response in practical, real-life conditions.

This study is designed to investigate the effects of consuming acidic beverages, specifically lemon juice and apple cider vinegar, together with a starch-rich food. The study will compare their effects on post-meal blood glucose levels and feelings of fullness in healthy individuals. Different amounts of these acidic components will also be evaluated to understand dose-related effects.

Participants will consume standardized meals under controlled conditions, and their blood glucose response and satiety levels will be monitored over time. The study follows a comparative approach to assess the relative effectiveness of each intervention.

The findings of this study may help identify simple and practical dietary strategies to support better blood sugar control. As lemon juice and vinegar are widely available and easy to include in daily meals, the results may offer accessible approaches for improving dietary habits and supporting metabolic health.

• Study Type: Interventional
• Enrollment (Estimated): 15
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Ezgi Toptaş Bıyıklı, Assistant Professor; Phone Number: 90 505 751 96 21; Email: ezgi.biyikli@alanya.edu.tr

Study Locations

• Turkey (Türkiye)
  • Antalya
    • Alanya, Antalya, Turkey (Türkiye), 07400
      • Recruiting
      • Alanya Alaaddin Keykubat University
      • Contact: Alanya Alaaddin Keykubat University; Phone Number: +90 242 +90 242 510 60 60; Email: alku@alanya.edu.tr

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Healthy male and female volunteers aged 18-35 years
• Body Mass Index (BMI) between 18.5 and 25.0 kg/m²
• Willingness to provide written informed consent
• Ability to comply with study procedures and fasting requirements
• No history of chronic metabolic, gastrointestinal, or endocrine diseases

Exclusion Criteria:

• Presence of any chronic disease (e.g., diabetes mellitus, cardiovascular disease, gastrointestinal disorders)
• Food allergies or intolerances to study foods (white bread, lemon juice, apple cider vinegar)
• BMI <18.5 or >25.0 kg/m²
• Regular participation in high-intensity physical activity (≥5 days/week)
• Current or recent (past 3 months) smoking or smoking cessation
• Use of any medication or supplements affecting glucose metabolism
• History of eating disorders
• Pregnancy, lactation, or menopause
• Female participants currently in menstruation period (testing will be postponed during menstruation days)
• Alcohol consumption within 24 hours prior to testing days
• Caffeine intake or major dietary changes on the day before testing

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Control (Water + White Bread); Participants consume white bread together with plain water only. This arm serves as the control condition to evaluate postprandial blood glucose response without any acidic additive.	Dietary supplement: Control (Water + White Bread); Participants will consume 100 g of white bread together with plain water (no acidic additive). This condition serves as the control arm for assessing baseline postprandial glycemic response and satiety. Capillary blood glucose will be measured at baseline and at multiple time points up to 180 minutes following consumption. Satiety and appetite sensations will be assessed using a 100-mm visual analog scale (VAS).
Experimental: Lemon Juice 50 g; Participants consume white bread together with water containing 50 g lemon juice. This arm evaluates the effect of low-dose lemon juice on postprandial blood glucose response and satiety.	Dietary supplement: Lemon Juice 50 g; Participants will consume 100 g of white bread together with 50 g of lemon juice diluted in water. This intervention is designed to evaluate the effect of a low-dose acidic beverage (citric acid source) on postprandial blood glucose response and satiety. Capillary blood glucose levels will be measured at predefined time points up to 180 minutes, and subjective appetite sensations will be assessed using a 100-mm VAS.
Experimental: Lemon Juice 100 g; Participants consume white bread together with water containing 100 g lemon juice. This arm evaluates the dose-dependent effect of lemon juice on postprandial blood glucose response and satiety.	Dietary supplement: Lemon Juice 100 g; Participants will consume 100 g of white bread together with 100 g of lemon juice diluted in water. This condition evaluates the dose-dependent effect of citric acid intake on postprandial glycemic response, glucose peak, and satiety. Serial capillary blood glucose measurements and VAS-based appetite assessments will be conducted over a 180-minute postprandial period.
Experimental: Apple Cider Vinegar 10 g; Participants consume white bread together with water containing 10 g apple cider vinegar. This arm evaluates the effect of low-dose apple cider vinegar on postprandial blood glucose response and satiety.	Dietary supplement: Apple Cider Vinegar 10 g; Participants will consume 100 g of white bread together with 10 g of apple cider vinegar diluted in water. This intervention aims to assess the effect of a low-dose acetic acid source on postprandial glucose regulation and satiety. Capillary blood glucose will be measured at multiple time points for 180 minutes, and subjective appetite ratings will be recorded using a visual analog scale.
Experimental: Apple Cider Vinegar 20 g; Participants consume white bread together with water containing 20 g apple cider vinegar. This arm evaluates the effect of higher-dose apple cider vinegar on postprandial blood glucose response and satiety.	Dietary supplement: Apple Cider Vinegar 20 g; Participants will consume 100 g of white bread together with 20 g of apple cider vinegar diluted in water. This intervention evaluates the potential dose-response effect of acetic acid on postprandial glycemic control, including glucose peak, incremental glucose response, and satiety perception over a 180-minute period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postprandial Blood Glucose (mg/dL)	Capillary blood glucose levels will be measured at baseline (0 min) and at 15, 30, 45, 60, 90, 120, 150, and 180 minutes after consumption of test meals. Measurements will be performed in duplicate and mean values will be used.	Baseline (0 min) to 180 minutes postprandial on each test day (with 1-week washout between interventions)
Incremental Area Under the Curve (iAUC)	Incremental area under the curve (iAUC) for postprandial blood glucose will be calculated based on capillary glucose measurements over 180 minutes.	Baseline (0 min) to 180 minutes postprandial on each test day
Total Area Under the Curve (AUC)	Total area under the curve (AUC) for postprandial blood glucose will be calculated using capillary glucose measurements over 180 minutes.	Baseline (0 min) to 180 minutes postprandial on each test day
Peak Blood Glucose Level (mg/dL)	Peak postprandial blood glucose level will be determined from capillary glucose measurements over the 180-minute period.	Baseline (0 min) to 180 minutes postprandial on each test day

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Subjective Appetite Score (VAS, mm)	Subjective appetite sensations (hunger, satiety, fullness, prospective food consumption, and desire for sweet foods) will be assessed using a 100-mm Visual Analog Scale (VAS) at baseline and at 15, 30, 45, 60, 90, 120, 150, and 180 minutes postprandially.	Baseline (0 min) to 180 minutes postprandial on each test day
Time to Peak Glucose (minutes)	Time to reach peak postprandial blood glucose will be calculated from capillary glucose measurements.	Baseline (0 min) to 180 minutes postprandial on each test day
Rate of Glucose Increase (mg/dL/min)	Rate of increase in postprandial blood glucose will be calculated based on capillary glucose measurements.	Baseline (0 min) to 180 minutes postprandial on each test day

Collaborators and Investigators

• Sponsor: Alanya Alaaddin Keykubat University

Publications and helpful links

General Publications

• Freitas D, Le Feunteun S. Inhibitory effect of black tea, lemon juice, and other beverages on salivary and pancreatic amylases: What impact on bread starch digestion? A dynamic in vitro study. Food Chem. 2019 Nov 1;297:124885. doi: 10.1016/j.foodchem.2019.05.159. Epub 2019 May 24.
• Ostman E, Granfeldt Y, Persson L, Bjorck I. Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects. Eur J Clin Nutr. 2005 Sep;59(9):983-8. doi: 10.1038/sj.ejcn.1602197.
• Gheflati A, Bashiri R, Ghadiri-Anari A, Reza JZ, Kord MT, Nadjarzadeh A. The effect of apple vinegar consumption on glycemic indices, blood pressure, oxidative stress, and homocysteine in patients with type 2 diabetes and dyslipidemia: A randomized controlled clinical trial. Clin Nutr ESPEN. 2019 Oct;33:132-138. doi: 10.1016/j.clnesp.2019.06.006. Epub 2019 Jul 9.
• Freitas D, Boue F, Benallaoua M, Airinei G, Benamouzig R, Le Feunteun S. Lemon juice, but not tea, reduces the glycemic response to bread in healthy volunteers: a randomized crossover trial. Eur J Nutr. 2021 Feb;60(1):113-122. doi: 10.1007/s00394-020-02228-x. Epub 2020 Mar 23.

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: April 21, 2026
• First Submitted That Met QC Criteria: April 26, 2026
• First Posted (Actual): May 4, 2026

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 26, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Satiety; Glycemic Response; Postprandial Glucose; Apple Cider Vinegar; Lemon Juice; Starch Hydrolysis
• Additional Relevant MeSH Terms: Inorganic Chemicals; Anions; Ions; Electrolytes; Hydroxides; Alkalies; Oxides; Oxygen Compounds; Water
• Other Study ID Numbers: 10354421-2025/09-10

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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