Salt Intake, Hydration Status and Gastrointestinal Discomfort During Fasting

The Effect of Low and High Salt Intake on Hydration Status and Gastrointestinal Discomfort During Seven Hours of Dry Fasting

This study is part of a hyperhydration project and it has been designed based on a scoping review (Hyperhydration in healthy adults: a scoping review on different methodologies and vehicles utilized) and a previous study (Dietary patterns and gastrointestinal discomfort during Ramadan in a UK Muslim population). The current study aims to examine the impact of different levels of salt intake (6 & 9 grams) with [15 milliliters per kilogram of bodyweight (ml/ kg/ bw)] of water intake during 7 hours of dry fasting compared to a control group (3g salt) under the state of water balance (euhydrated). A previous study and a review by the authors highlighted the potential negative impact of salt and fasting on gastrointestinal (GI) discomfort; hence, the potential negative side effects on gastrointestinal (GI) discomfort during the intervention period will be investigated. By studying a hyperhydration protocol, this research will help the population to reduce dehydration during dry fasting. By doing so, it may improve the quality of life during Ramadan fasting.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Other: Salt 3 g; Other: Salt 6 g; Other: Salt 9 g

Detailed Description

Dry fasting has been reported to cause changes in body weight, lipid profile, blood pressure, glucose level, metabolism, hormones homeostasis, and hydration status. A scoping review by the investigators highlighted that dehydration had been linked to changes in plasma volume and osmolality (concentration of all chemical particles), urine volume and osmolality, blood pressure, glucocorticoid hormones, body weight loss, negative impact on mood, irritability, short-term memory, and work productivity. It has been reported that prolonged dry fasting can contribute to a loss of up to 1.5 kg in body weight on the day after fasting. This weight loss is associated with loss of body water.

Hyperhydration (overhydration) has not yet been defined. However, any improvement in the fluid matrix in the plasma volume is considered hyperhydration. Simulating hyperhydration strategies, such as those used by athletes competing in long-distance events and in hot environments, has the potential to reduce the level of dehydration during dry fasting.

Sodium and water intake have essential roles in maintaining and improving the fluid matrix in plasma. By investigating the relationship between sodium and water intake on biomarkers such as urine sodium concentration, blood pressure, speed of urine production, urine colour, urine specific gravity, and net body fluid balance, it is possible to distinguish the impact of hyperhydration protocols on hydration levels.

The primary aim of this study is to examine the impact of salt intake (6 & 9 g/l) on the level of hydration by measuring urine sodium, urine potassium, urine production, and changes in body weight compared to the control group during 8 hours of dry fasting. The secondary outcome of this study will be the impact of the hyperhydration protocol on GI discomfort.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Oxford, United Kingdom, OX3 0BP
    • Oxford Brookes Centre for Nutrition and Health

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Aged 18 to 45
• BMI between 18.5 and 29.9
• No higher (140/90mmHg) or lower (80/60mmHg) blood pressure
• Non-pregnant or lactating
• No diabetes (type 1 & 2)
• No gastrointestinal disease such as inflammatory bowel disease (IBD) or Irritable bowel syndrome (IBS)
• No disease including the common cold and high cholesterol (total cholesterol above 5 mmol/l)
• No covid symptoms
• No allergy to the food in the meal list and tomatoes

Exclusion Criteria:

• Aged <18 or >45 years
• BMI between <18.5 or > 29.9
• Higher (>140/90mmHg) or lower (<80/60mmHg) blood pressure
• Pregnant or lactating
• Having diabetes (type 1 & 2)
• Having gastrointestinal disease such as inflammatory bowel disease (IBD) or Irritable bowel syndrome (IBS)
• Having disease including the common cold and high cholesterol (total cholesterol above 5 mmol/l)
• Having covid symptoms
• Having allergy to the food in the meal list and tomatoes

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: 3 g salt; Tomatoes with 3 g salt	Other: Salt 3 g; Placebo group taking a breakfast meal and 3g salt on tomatoes before fasting for 7 hours
Experimental: 6 g salt; Tomatoes with 6 g salt and 1 L of water	Other: Salt 6 g; Intervention group taking a breakfast meal and 6g salt on tomatoes plus 1 L water before fasting for 7 hours
Experimental: 9 g salt; Tomatoes with 9 g salt and 1 L of water	Other: Salt 9 g; Intervention group taking a breakfast meal and 9g salt on tomatoes plus 1 L water before fasting for 7 hours

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total urine production baseline	Volume of urine produced at baseline	0 hour
Total urine production 1 hour	Volume of urine produced at 1 hour after starting fasting	1 hour
Total urine production 2 hours	Volume of urine produced at at 2 hours after starting fasting	2 hours
Total urine production 3 hours	Volume of urine produced at at 3 hours after starting fasting	3 hours
Total urine production 4 hours	Volume of urine produced at at 4 hours after starting fasting	4 hours
Total urine production 5 hours	Volume of urine produced at at 5 hours after starting fasting	5 hours
Total urine production 6 hours	Volume of urine produced at at 6 hours after starting fasting	6 hours
Total urine production 7 hours	Volume of urine produced at at 7 hours after starting fasting	7 hours
Body weight baseline	Body weight at baseline before fasting	0 hours
Body weight 1 hour	Body weight at 1 hour after starting fasting	1 hour
Body weight 2 hours	Body weight at 2 hours after starting fasting	2 hours
Body weight 3 hours	Body weight at 3 hours after starting fasting	3 hours
Body weight 4 hours	Body weight at 4 hours after starting fasting	4 hours
Body weight 5 hours	Body weight at 5 hours after starting fasting	5 hours
Body weight 6 hours	Body weight at 6 hours after starting fasting	6 hours
Body weight 7 hours	Body weight at 7 hours after starting fasting	7 hours
Urinary sodium baseline	Urinary sodium at baseline before starting fasting	0 hours
Urinary sodium 1 hour	Urinary sodium at 1 hour after starting fasting	1 hour
Urinary sodium 2 hours	Urinary sodium at 2 hours after starting fasting	2 hours
Urinary sodium 3 hours	Urinary sodium at 3 hours after starting fasting	3 hours
Urinary sodium 4 hours	Urinary sodium at 4 hours after starting fasting	4 hours
Urinary sodium 5 hours	Urinary sodium at 5 hours after starting fasting	5 hours
Urinary sodium 6 hours	Urinary sodium at 6 hours after starting fasting	6 hours
Urinary sodium 7 hours	Urinary sodium at 7 hours after starting fasting	7 hours
Urinary potassium baseline	Urinary potassium at baseline before starting fasting	0 hours
Urinary potassium 1 hour	Urinary potassium at 1 hour after starting fasting	1 hour
Urinary potassium 2 hours	Urinary potassium at 2 hours after starting fasting	2 hours
Urinary potassium 3 hours	Urinary potassium at 3 hours after starting fasting	3 hours
Urinary potassium 4 hours	Urinary potassium at 4 hours after starting fasting	4 hours
Urinary potassium 5 hours	Urinary potassium at 5 hours after starting fasting	5 hours
Urinary potassium 6 hours	Urinary potassium at 6 hours after starting fasting	6 hours
Urinary potassium 7 hours	Urinary potassium at 7 hours after starting fasting	7 hours
Urine colour baseline	Urine colour at baseline before starting fasting	0 hours
Urine colour 1 hour	Urine colour at 1 hour after starting fasting	1 hour
Urine colour 2 hours	Urine colour at 2 hours after starting fasting	2 hours
Urine colour 3 hours	Urine colour at 3 hours after starting fasting	3 hours
Urine colour 4 hours	Urine colour at 4 hours after starting fasting	4 hours
Urine colour 5 hours	Urine colour at 5 hours after starting fasting	5 hours
Urine colour 6 hours	Urine colour at 6 hours after starting fasting	6 hours
Urine colour 7 hours	Urine colour at 7 hours after starting fasting	7 hours
Urine specific gravity baseline	Urine specific gravity at baseline before starting fasting	0 hours
Urine specific gravity 1 hour	Urine specific gravity at 1 hour after starting fasting	1 hour
Urine specific gravity 2 hours	Urine specific gravity at 2 hours after starting fasting	2 hours
Urine specific gravity 3 hours	Urine specific gravity at 3 hours after starting fasting	3 hours
Urine specific gravity 4 hours	Urine specific gravity at 4 hours after starting fasting	4 hours
Urine specific gravity 5 hours	Urine specific gravity at 5 hours after starting fasting	5 hours
Urine specific gravity 6 hours	Urine specific gravity at 6 hours after starting fasting	6 hours
Urine specific gravity 7 hours	Urine specific gravity at 7 hours after starting fasting	7 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gastrointestinal discomfort baseline	Gastrointestinal discomfort at baseline before starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	0 hours
Gastrointestinal discomfort 1 hour	Gastrointestinal discomfort at 1 hour after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	1 hour
Gastrointestinal discomfort 2 hours	Gastrointestinal discomfort at 2 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	2 hours
Gastrointestinal discomfort 3 hours	Gastrointestinal discomfort at 3 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	3 hours
Gastrointestinal discomfort 4 hours	Gastrointestinal discomfort at 4 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	4 hours
Gastrointestinal discomfort 5 hours	Gastrointestinal discomfort at 5 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	5 hours
Gastrointestinal discomfort 6 hours	Gastrointestinal discomfort at 6 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	6 hours
Gastrointestinal discomfort 7 hours	Gastrointestinal discomfort at 7 hours after starting fasting using a Gastrointestinal Symptoms Questionnaire to measure 1.Abdominal pain 2.Epigastric pain (pain or discomfort right below your ribs in the area of your upper abdomen) 3. Heartburn 4. Regurgitation 5. Abdominal rumbling 6. Bloating 7. Empty feeling 8. Nausea 9. Vomiting 10. Loss of appetite 11. Postprandial fullness (an unpleasant sensation like prolonged persistence of food in the stomach) 12. belching (otherwise known as burping or eructation) 13. Flatulence (buildup of gas in the digestive system that can lead to abdominal discomfort) on a 7 point scale labelled 0 for none, 1 for mild, 2 for moderate, 3 for quite a lot, 4 for severe, 5 for very severe, 6 for unbearable. Higher scores mean worst outcome.	7 hours
Blood Pressure baseline	Systolic and Diastolic Blood Pressure at baseline before starting fasting	0 hours
Blood Pressure 1 hour	Systolic and Diastolic Blood Pressure at 1 hour after starting fasting	1 hour
Blood Pressure 2 hours	Systolic and Diastolic Blood Pressure at 2 hours after starting fasting	2 hours
Blood Pressure 3 hours	Systolic and Diastolic Blood Pressure at 3 hours after starting fasting	3 hours
Blood Pressure 4 hours	Systolic and Diastolic Blood Pressure at 4 hours after starting fasting	4 hours
Blood Pressure 5 hours	Systolic and Diastolic Blood Pressure at 5 hours after starting fasting	5 hours
Blood Pressure 6 hours	Systolic and Diastolic Blood Pressure at 6 hours after starting fasting	6 hours
Blood Pressure 7 hours	Systolic and Diastolic Blood Pressure at 7 hours after starting fasting	7 hours
Perception of thirst at baseline	Perception of thirst at baseline before starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	0 hours
Perception of thirst at 1 hour	Perception of thirst at 1 hour after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	1 hour
Perception of thirst at 2 hours	Perception of thirst at 2 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	2 hours
Perception of thirst at 3 hours	Perception of thirst at 3 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	3 hours
Perception of thirst at 4 hours	Perception of thirst at 4 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	4 hours
Perception of thirst at 5 hours	Perception of thirst at 5 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	5 hours
Perception of thirst at 6 hours	Perception of thirst at 6 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	6 hours
Perception of thirst at 7 hours	Perception of thirst at 7 hours after starting fasting using a 7 point scale labelled as 1=not thirsty at all, 2=not thirsty, 3=not very thirsty, 4=neutral, 5=thirsty, 6=very thirsty and 7=very, very thirsty.	7 hours

Collaborators and Investigators

• Sponsor: Oxford Brookes University
• Investigators: Principal Investigator: Sangeetha Thondre, PhD, Oxford Brookes University

Publications and helpful links

General Publications

• Goulet EDB, De La Flore A, Savoie FA, Gosselin J. Salt + Glycerol-Induced Hyperhydration Enhances Fluid Retention More Than Salt- or Glycerol-Induced Hyperhydration. Int J Sport Nutr Exerc Metab. 2018 May 1;28(3):246-252. doi: 10.1123/ijsnem.2017-0310. Epub 2018 May 17.
• Zanetti D, Bergman H, Burgess S, Assimes TL, Bhalla V, Ingelsson E. Urinary Albumin, Sodium, and Potassium and Cardiovascular Outcomes in the UK Biobank: Observational and Mendelian Randomization Analyses. Hypertension. 2020 Mar;75(3):714-722. doi: 10.1161/HYPERTENSIONAHA.119.14028. Epub 2020 Feb 3.

Study record dates

Study Major Dates

• Study Start (Actual): February 14, 2023
• Primary Completion (Actual): May 31, 2023
• Study Completion (Actual): July 31, 2023

Study Registration Dates

• First Submitted: March 23, 2023
• First Submitted That Met QC Criteria: April 20, 2023
• First Posted (Actual): May 3, 2023

Study Record Updates

• Last Update Posted (Actual): September 6, 2023
• Last Update Submitted That Met QC Criteria: September 4, 2023
• Last Verified: September 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: UREC 221630

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