Salt Intake, Hydration Status and Gastrointestinal Discomfort During 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.

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.

Eligibility Criteria:
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