Myth busting? High salt intake may not increase thirst

18-Nov-2014 - Last updated on 18-Nov-2014 at 08:57 GMT

Eating salty snacks has been suggested to increase thirst, and therefore drive excess calorie intake.

It is commonly believed that consumption of salty foods increases thirst, and could be a reason for increased consumption of sugary soft drinks and alcoholic beverages. But just how true is this notion?

New research investigating whether salt intake really does increase thirst has suggested that the routine intake of salt loads does not increase the frequency of drinking.

Led by Professor Micah Leshem from The University of Haifa, Israel, the research tested whether snacking on salty foods increases thirst and drinking in a group of 58 participants – finding that thirst and the rate of drinking over two hours was similar after consuming salty, sweet or unflavoured nuts.

“A commonly held belief is that salt intake arouses thirst to redress hydromineral balance. In so doing, dietary sodium may increase beverage drinking and its associated caloric content, and contribute to obesity during growth and adulthood,” noted Lesham.

“We can suggest that if the ingestion of a substantive load of salt in nuts does not increase thirst or drinking there is limited evidence for a robust thirst or drinking response to an acute sodium load roughly equivalent to the sodium intake of a meal or a salted snack, amounting to some 20% of daily dietary sodium intake,” he said.

Study details

The research, which was supported by the Salt Institute, examined whether voluntary, acute intake of a sodium load, as occurs in routine eating and snacking, increases thirst and drinking.

“We find that after ingesting 3.5 or 4.4g NaCl (men) and 1.9 or 3.7g (women) on nuts during 15 minutes, there is no increase in thirst or drinking of freely available water in the following 2h compared with eating similar amounts of sugared or unflavoured nuts,” he wrote.

The research found that both men and women participants respectively drank some 500 and 400 ml water during the two hour session, but Leshem conceded that a weakness in the study was that it did not have a control group to compare drinking in such circumstances without eating nuts.

Indeed he noted that the relationship between salt intake and thirst may be ‘tenuous’ in routine conditions, “but may emerge more robustly when thirst is more extreme and plasma osmolality increases above 2-3%.

As a result the Israeli researcher suggested that the findings ‘provide a mitigating perspective’ to the idea that eating salt invariably promotes thirst, “and suggest that bar-owners can reduce the sodium content of their titbits without compromising their drink sales or customer health."

Source: Appetite
Published online ahead of print, doi: 10.1016/j.appet.2014.11.014
“Does salt increase thirst”
Author: Micah Leshem