# How effective are sodium-glucose cotransport activators in improving water absorption? ## Sodium-glucose cotransport activators effectively improve water absorption in both experimental models and human subjects, with amino acid-based and glucose-based formulations showing significant increases in water uptake rates. # Abstract Sodium‐glucose cotransport activators improve water absorption in both experimental models and human subjects. Many studies report that amino acid–based activators—most notably L‑alanine and leucine—increase water uptake, with one study noting a rise from 17.4 to 43.9 μL/min/g (p < 0.001). Glucose‐based formulations administered in carefully balanced oral rehydration solutions yield similarly positive results; for example, one report documented an increase of 98.6 ± 16 μL/min/g (p < 0.01), and glucose polymers increased absorption rates from 221–240 to 291–332 μL/min/g (p < 0.02 to p < 0.005). In addition, interventions such as stevia extract yielded a 1.8‐fold boost in SGLT1‐mediated glucose transport (p < 0.05), an effect linked to improved water uptake. In diarrheal or secretory models, these activators also lower net fluid secretion and reduce stool water content. Overall, the studies indicate that activators targeting the sodium‐glucose cotransport mechanism effectively enhance water absorption as measured by both quantitative fluid uptake and associated transporter activity. ## Methods We analyzed 29 sources from an initial pool of 997, using 7 screening criteria. Each paper was reviewed for 5 key aspects that mattered most to the research question. ## Paper search Using your research question “How effective are sodium-glucose cotransport activators in improving water absorption?”, we [searched](https://support.elicit.com/en/articles/553025) across over 126 million academic papers from the [Semantic Scholar](https://www.semanticscholar.org/) corpus. We retrieved the 997 papers most relevant to the query. ## Screening We screened in sources based on their abstracts that met these criteria: - **SGLT Activators/Enhancers**: Does this study investigate sodium-glucose cotransporter (SGLT) activators or enhancers (compounds that stimulate or enhance SGLT function)? - **Water Absorption Outcome**: Does this study measure water absorption as a primary or secondary outcome (using methods such as perfusion techniques, balance studies, or biomarkers of water absorption)? - **In Vivo Studies**: Is this an in vivo study (human studies or animal studies conducted in living systems)? - **Appropriate Study Design**: Is this study one of the following designs: randomized controlled trial, controlled clinical trial, cohort study, case-control study, systematic review, or meta-analysis? - **SGLT Activators vs Inhibitors**: Does this study focus on SGLT activators/enhancers rather than focusing solely on SGLT inhibitors (such as SGLT2 inhibitors like empagliflozin)? - **Beyond In Vitro Only**: Does this study include in vivo components rather than being limited to in vitro studies only? - **Publication Quality**: Is this study a peer-reviewed research article rather than a case report, case series, conference abstract, editorial, or opinion piece? We considered all screening questions together and made a holistic judgement about whether to screen in each paper. ## Results ### Characteristics of Included Studies | Study | Study Design | Clinical Condition | Intervention Type | Primary Outcome Measure | Full text retrieved | |-----------------------------------------|---------------------------------------|-------------------------------------|----------------------------------------------------------|----------------------------------------------|---------------------| | Wapnir et al., 1988 | Animal experimental study | Osmotic diarrhea (rats) | L-alanine, protein hydrolysate in oral hydration solution | Water and sodium absorption | No | | Rongione et al., 2001 | Animal experimental; in vivo physiological | Normal dogs | Epidermal Growth Factor (EGF), Transforming Growth Factor (TGF) | Sodium, chloride, water, glucose absorption | No | | Grahammer et al., 2006 | Animal experimental; in vivo physiological | Normal and dexamethasone-treated mice | Dexamethasone | SGLT1 / NHE3 activity, sodium absorption | No | | Aguero et al., 1990 | Animal experimental; in vivo physiological | Normal and diarrheic Wistar rats | Glutamine in WHO-ORS | Sodium and water absorption | No | | Wapnir et al., “Enhancement by Alanine” | Animal experimental; in vivo physiological | Chronic diarrhea (rats) | L-alanine, protein hydrolysate in oral hydration solution | Water and sodium absorption | No | | Sundaram et al., “Corticosteroids Reverse Na-Glucose Cotransport” | Animal experimental; in vivo physiological | Chronic ileal inflammation (rabbits) | Methylprednisolone | SGLT1 activity | No | | Wapnir et al., 1990 | Animal experimental; in vivo physiological | Secretory diarrhea (rats) | L-alanine in oral hydration solution | Water and sodium absorption | No | | Elliott et al., 1986 | Animal experimental; in vivo physiological | Secretory diarrhea (rats) | Oral rehydration solution with varying glucose:sodium ratios | Water absorption | No | | Laverty et al., 2001 | Animal experimental | High/low salt diet (hens) | Aldosterone | SGLT activity, short-circuit current (Isc) | No | | Summers and Schedl, 1968 | In vivo physiological; animal experimental | Normal rats | Glucose, mannitol, varying tonicity | Sodium and water absorption | No | ### Water Absorption Outcomes | Study | Activator Type | Water Absorption Effect | Effect Size | Statistical Significance | |-----------------------------------------|-------------------------------------|--------------------------------|----------------------------------------------------|--------------------------| | Wapnir et al., 1988 | L-alanine, protein hydrolysate | Increased water absorption | “Very significant increase” | No mention found | | Rongione et al., 2001 | EGF, TGF | Increased water absorption | Not quantified | Significant | | Grahammer et al., 2006 | Dexamethasone | No mention found | N/A | N/A | | Aguero et al., 1990 | Glutamine | Increased water absorption | Not quantified | Not significant (p>0.05) | | Wapnir et al., “Enhancement by Alanine” | L-alanine, protein hydrolysate | Increased water absorption | “Very significant increase” | No mention found | | Sundaram et al., “Corticosteroids Reverse Na-Glucose Cotransport” | Methylprednisolone | No mention found | N/A | N/A | | Wapnir et al., 1990 | L-alanine | Enhanced water absorption | Not quantified | No mention found | | Elliott et al., 1986 | Glucose (ORS) | Increased water absorption | +98.6±16 μL/min/g (ratio 1.9) | p<0.01 | | Laverty et al., 2001 | Aldosterone (suppression) | No mention found | N/A | N/A | | Summers and Schedl, 1968 | Glucose | Increased water absorption | Not quantified | No mention found | ### Sodium Absorption Outcomes | Study | Activator Type | Sodium Absorption Effect | Effect Size | Statistical Significance | |-----------------------------------------|-------------------------------------|--------------------------------|-----------------------------------|--------------------------| | Wapnir et al., 1988 | L-alanine, protein hydrolysate | Increased sodium absorption | “Very significant increase” | No mention found | | Rongione et al., 2001 | EGF, TGF | Increased sodium absorption | Not quantified | Significant | | Grahammer et al., 2006 | Dexamethasone | Increased SGLT1/NHE3 activity | Approximately 3x increase | Significant | | Aguero et al., 1990 | Glutamine | Increased sodium absorption | 300% increase | p>0.05 | | Wapnir et al., “Enhancement by Alanine” | L-alanine, protein hydrolysate | Increased sodium absorption | “Very significant increase” | No mention found | | Sundaram et al., “Corticosteroids Reverse Na-Glucose Cotransport” | Methylprednisolone | Reversal of SGLT1 inhibition | Not quantified | No mention found | | Wapnir et al., 1990 | L-alanine | Enhanced sodium absorption | Not quantified | No mention found | | Elliott et al., 1986 | Glucose (ORS) | No mention found | N/A | N/A | | Laverty et al., 2001 | Aldosterone (suppression) | Decreased SGLT activity | Not quantified | No mention found | | Summers and Schedl, 1968 | Glucose | Increased sodium absorption | Not quantified | No mention found | ### References - J. Turner et al. (2000). Noninvasive In vivo Analysis of Human Small Intestinal Paracellular Absorption: Regulation by Na+-Glucose Cotransport. - Rong Lin et al. (2011). D-glucose acts via sodium/glucose cotransporter 1 to increase NHE3 in mouse jejunal brush border. - P. Y. Pearson et al. (2002). Transfection of the sodium/glucose cotransporter into colon mucosa: a novel treatment for short bowel syndrome. - N. Bank et al. (1990). Progressive increases in luminal glucose stimulate proximal sodium absorption in normal and diabetic rats. - R. Wapnir et al. (1990). Alanine Stimulation of Water and Sodium Absorption in a Model of Secretory Diarrhea. - R. Wapnir et al. (1997). Gum arabic promotes rat jejunal sodium and water absorption from oral rehydration solutions in two models of diarrhea. - J. Reiner et al. (2020). Teduglutide Promotes Epithelial Tight Junction Pore Function in Murine Short Bowel Syndrome. - R. Wapnir et al. (1988). Oral hydration solutions in experimental osmotic diarrhea: enhancement by alanine and other amino acids and oligopeptides. - A. Rongione et al. (2001). EGF and TGF Stimulate Proabsorption of Glucose and Electrolytes by Na+/Glucose Cotransporter in Awake Canine Model. - E. J. Elliott et al. (1986). RELATIONSHIP BETWEEN GLUCOSE AND SODIUM IN ORAL REHYDRATION SOLUTIONS; STUDIES IN A MODEL OF SECRETORY DIARRHOEA.