Dose-dependent increase and decrease in active glucose uptake in jejunal epithelium of broilers after acute exposure to ethanol

The Influence of Alcohol Consumption on Intestinal Nutrient Absorption: A Comprehensive Review

Chronic alcohol use has been attributed to the development of malnutrition. This is in part due to the inhibitory effect of ethanol on the absorption of vital nutrients, including glucose, amino acids, lipids, water, vitamins, and minerals within the small intestine. Recent advances in research, along with new cutting-edge technologies, have advanced our understanding of the mechanism of ethanol's effect on intestinal nutrient absorption at the brush border membrane (BBM) of the small intestine. However, further studies are needed to delineate how ethanol consumption could have an impact on altered nutrient absorption under various disease conditions. Current research has elucidated the relationship of alcohol consumption on glucose, glutamine, vitamins B1 (thiamine), B2 (riboflavin), B9 (folate), C (ascorbic acid), selenium, iron, and zinc absorption within the small intestine. We conducted systematic computerized searches in PubMed using the following keywords: (1) "Alcohol effects on nutrient transport"; (2) "Alcohol mediated malabsorption of nutrients"; (3) "Alcohol effects on small intestinal nutrient transport"; and (4) "Alcohol mediated malabsorption of nutrients in small intestine". We included the relevant studies in this review. The main objective of this review is to marshal and analyze previously published research articles and discuss, in-depth, the understanding of ethanol's effect in modulating absorption of vital macro and micronutrients in health and disease conditions. This could ultimately provide great insights in the development of new therapeutic strategies to combat malnutrition associated with alcohol consumption.

Combination of alcohol and glucose consumption as a risk to induce reactive hypoglycemia

Aims/Introduction

Alcohol consumption has been reported to cause hypoglycemia. However, the mechanism involved has not been unequivocally established. This study comprised healthy volunteers. We carried out a prospective trial to compare the effects of glucose and alcohol consumption, alone or in combination, on glucose and lipid metabolism.

Materials and Methods

A 75‐g oral glucose tolerance test (OGTT), a combined 75‐g glucose plus 20‐g alcohol tolerance test (OGATT) and a 20‐g alcohol tolerance test (OATT) were carried out in the participants. Plasma glucose, insulin, triglyceride and ethanol concentrations during each test were compared.

Results

We studied 10 participants. Their plasma glucose concentrations 15 and 30 min after the intake of 75 g of glucose were significantly higher during the OGATT than the OGTT. Hypoglycemia occurred in five participants after the OGATT, which was significantly more frequently than after the OGTT (P = 0.046). Hypoglycemia did not occur after the OATT, and the ethanol concentration was significantly lower after the OGATT than the OATT. The changes in triglyceride concentration from 30 min after the consumption of 75 g of glucose were significantly greater during the OGATT than the OGTT. The plasma insulin concentrations peaked after 60 min during both the OGTT and OGATT, and were significantly higher during the OGATT (P = 0.047). There were no differences between the two interventions in the Matsuda or disposition indexes.

Conclusions

Hypoglycemia occurred more frequently after the simultaneous consumption of alcohol plus glucose than after the consumption of glucose alone, suggesting that alcohol in the combination of glucose induces reactive hypoglycemia.

Moderate Alcohol Consumption Uniquely Regulates Sodium-Dependent Glucose Co-Transport in Rat Intestinal Epithelial Cells In Vitro and In Vivo

BACKGROUND

Chronic alcohol use often leads to malnutrition. However, how the intestinal absorption of nutrients such as glucose may be affected during moderate ethanol use has not been investigated. Glucose is absorbed via sodium (Na)-dependent glucose co-transport (SGLT1; SLC5A1) along the brush border membrane (BBM) of intestinal absorptive villus cells.

OBJECTIVE

The aim of this study was to investigate how moderate alcohol consumption affects the absorption of glucose via SGLT1.

METHODS

Intestinal epithelial cells (IEC-18; rat) were exposed to 8.64 mM ethanol over 1, 3, 6, and 12 h. Rats (16-wk-old, male, Sprague-Dawley) were administered 2 g/kg ethanol over 1, 3, and 6 h. Na-dependent 3H-O-methyl-d-glucose uptake was measured to assess SGLT1 activity. Na-K-ATPase activity was measured as a function of inorganic phosphate release. Protein expression was analyzed by Western blot analysis and immunohistochemical staining.

RESULTS

Ethanol significantly decreased Na-dependent glucose absorption in enterocytes in vitro (ethanol treatment: 48.4% of controls at 1 h; P < 0.01) and in vivo (ethanol treatment: 60.0% of controls at 1 h; P < 0.01). Na-K-ATPase activity was significantly inhibited in vitro (ethanol treatment: 36.9% of controls at 1 h; P < 0.01) and in vivo (ethanol treatment: 42.1% of controls at 1 h; P < 0.01). Kinetic studies showed that the mechanism of inhibition of Na-glucose co-transport was secondary to a decrease in the affinity (1/Km) of the co-transporter for glucose both in vitro and in vivo. Western blots and immunohistochemistry further demonstrated unaltered amounts of SGLT1 after ethanol treatment.

CONCLUSIONS

Moderate ethanol significantly decreases glucose absorption in IEC-18 cells and in villus cells of Sprague-Dawley rats. The inhibition of SGLT1 is secondary to an altered Na gradient at the cellular level and secondary to diminished affinity of the co-transporter for glucose at the protein level in the BBM. These observations may, at least in part, explain 1 possible mechanism of the onset of malnutrition associated with alcohol consumption.

Effects of antioxidant supplementation on duodenal Se-Met absorption in ethanol-exposed rat offspring in vivo

The nutritional deficiencies provoked by ethanol consumption, during gestation or lactation, can contribute to multiple birth defects in offspring. In order to improve our knowledge about selenium (Se) distribution in pups exposed to ethanol, the present study evaluated the effect of this drug on intestinal development and determined its action on duodenal absorption of selenomethionine (Se-Met). To determinate if supplementation could improve Se absorption and its serum values, we used two antioxidant supplemented regimens on dams, with selenium alone or selenium plus folic acid, and obtained six groups of pups: C (control), A (alcohol), CS (control + Se), AS (alcohol + Se), CFS (control + Se + folic acid) and AFS (alcohol + Se + folic acid). Duodenal Se-Met transport was performed using an in vivo perfusion method. Se levels were measured by graphite furnace atomic absorption spectrometry. The supplemented diets utilized had a positive influence on body growth, duodenal perimeter and Se content in ethanol-exposed pups. Ethanol exposure increased Se-Met duodenal absorption in all pups, supplemented or not, presenting the highest values of maximal velocity (V(max)) compared with their control counterparts. The affinity constant (K(m)) increased according to rank: A>AS>AFS groups. These results suggest that although antioxidant supplementation does not restore Se-Met absorption to normal values, it enhances the affinity of the transporters for the substrate and improves the damage caused by ethanol in the duodenal mucosa.