Why Alcohol, Sugar Lead to Thirst
Source: UT Southwestern Medical Center
Summary: Researchers identify a hormone that acts on the brain to increase the desire to drink water in response to specific nutrient stresses that can cause dehydration.
Why does drinking alcohol or consuming sugar make us thirsty? UT Southwestern researchers identify a hormone that acts on the brain to increase the desire to drink water in response to specific nutrient stresses that can cause dehydration. The researchers Mangelsdorf/Kliewer has long studied the liver hormone FGF21, or fibroblast growth factor 21. In earlier research, they found that FGF21 acts via the brain’s reward pathway in mice to suppress the desire for sugar and alcohol in favor of drinking water. Already known fact is that exposure to alcohol or sugar turns on production of FGF21 in the liver. What the researchers now show is that this hormone then travels in the blood to a specific part of the brain, the hypothalamus, to stimulate thirst, thereby preventing dehydration. Unexpectedly, FGF21 works through a new pathway that is independent of the classical renin-angiotensin-aldosterone thirst pathway in the kidneys. The study findings were published in the journal Cell Metabolism.
In mice, the study revealed, the hormone-regulated hydration (water drinking) in response to nutrient stress. In one experiment, the researchers found that normal mice and mice genetically unable to produce FGF21 drank similar amounts of water when given the typical chow diet. However, a high-fat/low-carbohydrate ketogenic diet stimulated water drinking in normal mice while mice genetically unable to produce FGF21 failed to increase water intake in response to that nutritional stress. Those findings confirmed the hormone’s role in the signaling pathway. A second important finding in this study is the very strong response to the hormone in humans.
Prof. Dr. Kliewer said, “To put this in context, we always look at food intake, and the metabolic field has spent comparatively little time studying water intake. This study suggests that we should think more about hydration and how it might contribute to metabolism.”
More Information: Parkyong Song et al, “The Hormone FGF21 Stimulates Water Drinking in Response to Ketogenic Diet and Alcohol”, Cell Metabolism (2018). https://doi.org/10.1016/j.cmet.2018.04.001