Alcohol ingestion and temperature regulation during cold exposure

Abstract

Outdoor or wilderness activities are sometimes combined with the ingestion of alcoholic beverages. Despite the feeling of warmth induced by alcohol ingestion, it is widely believed that alcohol actually causes a decrease in body core temperature and increases the risk of hypothermia during cold exposure. However, the literature on the effects of alcohol ingestion on thermoregulation is conflicting. This review summarizes the scientific findings concerning this topic and identifies a number of confounding factors that may explain the conflicting observations. These factors include quantity of alcohol ingested, severity of the cold stress, nutritional state of the individual, composition of the drink, body composition of the individual and alcohol tolerance of the individual. When these factors are considered, it appears that (1) alcohol acts as a poikilothermic agent, causing a reduction in body core temperature during cold exposure, with the magnitude of reduction related to blood alcohol concentration, (2) the severity of cold and the individual's body composition modify the thermoregulatory effects of alcohol, and (3) hypoglycemia greatly exacerbates the reduction in body temperature caused by alcohol ingestion. Furthermore, the primary mechanism by which alcohol ingestion exacerbates the fall in body core temperature during cold exposure appears to be via an impairment of shivering thermogenesis resulting from alcohol-induced hypoglycemia, rather than by increasing heat dissipation via vasodilation as commonly believed.