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NCT Number: NCT07563985

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.

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Key information

Conditions

Satiety Postprandial Glycemia

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Alanya Alaaddin Keykubat University

Alanya, Antalya, 07400, Turkey (Türkiye)

Location status: Recruiting

Location contact

Alanya Alaaddin Keykubat University

CONTACT

[email protected]

+90 242 510 60 60 ext. +90 242

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Control (Water + White Bread)

Dietary Supplement

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).

Lemon Juice 50 g

Dietary Supplement

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.

Lemon Juice 100 g

Dietary Supplement

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.

Apple Cider Vinegar 10 g

Dietary Supplement

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.

Apple Cider Vinegar 20 g

Dietary Supplement

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.

Primary outcomes

  1. Postprandial Blood Glucose (mg/dL)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day (with 1-week washout between interventions)

    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.

  2. Incremental Area Under the Curve (iAUC)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    Incremental area under the curve (iAUC) for postprandial blood glucose will be calculated based on capillary glucose measurements over 180 minutes.

  3. Total Area Under the Curve (AUC)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    Total area under the curve (AUC) for postprandial blood glucose will be calculated using capillary glucose measurements over 180 minutes.

  4. Peak Blood Glucose Level (mg/dL)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    Peak postprandial blood glucose level will be determined from capillary glucose measurements over the 180-minute period.

Secondary outcomes

  1. Subjective Appetite Score (VAS, mm)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    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.

  2. Time to Peak Glucose (minutes)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    Time to reach peak postprandial blood glucose will be calculated from capillary glucose measurements.

  3. Rate of Glucose Increase (mg/dL/min)

    Time frame: Baseline (0 min) to 180 minutes postprandial on each test day

    Rate of increase in postprandial blood glucose will be calculated based on capillary glucose measurements.

Study contacts

Contact information is provided by the study sponsor or research team.

Ezgi Toptaş Bıyıklı, Assistant Professor

CONTACT

[email protected]

90 505 751 96 21

Sponsors and collaborators

Lead sponsor

Alanya Alaaddin Keykubat University

Other

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
May 4, 2026
Registry last updated
May 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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