Salt and obesity
Thirst, which causes intake of water or other beverages, is an unavoidable physiological response to eating foods with a high salt content. A study carried out by Dr. Heikki Karppanen of the University of Helsinki and Dr. Eero Mervaala of the University of Kuopio reports that the increases in salt intake observed in the United States (USA) are strongly associated with increases in obesity there. Consequently the authors conclude that a reduction in salt intake could be a powerful means against obesity (1).
The authors note that until 1983 the use of salt showed a continuous decreasing trend in the United States . The prevalence of obesity was relatively low at this time and had remained essentially unchanged from early 1960s to early 1980s. Sales of salt in the USA were reported to have increased more than 50% between the mid-1980s to the late 1990s. The authors state that the progressive increase in the average intake of salt explains the parallel increase in the intake of beverages which, in turn, has contributed to a marked increase in the intake of calories during the same period in the USA .
Between 1977 and 2001, energy intake from sweetened beverages increased on the average by 135% in the United States . During the same period, the energy intake from milk declined by 38%. The overall effect on energy intake was a 278 kcal increase per person a day. The American Heart Association has estimated that, to burn off this extra energy intake of 278 kcal a day and avoid the development or worsening of obesity, each American should now walk or vacuum 1 hour 10 minutes more every day than in 1977. Unfortunately, this increase in energy expenditure does not appear to have taken place. During 1999 to 2002, the prevalence of obesity was 120% higher among men and 99% higher among women as compared with the 1976 to 1980 figures. Consequently the authors suggest that a comprehensive reduction in salt intake, which would reduce the intake of high-energy beverages, would be a potentially powerful means in the so far failed attempts to combat obesity in industrialized societies.
The authors conclude that the increased intake of salt, through its effect on thirst, has lead to an increased intake of high-energy beverages, which has in turn remarkably contributed to the increase of obesity in the United States .
A 25% decrease in the sales of carbonated soft drinks would mean an approximate $16 billion loss in the sales of carbonated beverages a year in the United States alone. Therefore the possibility exists that economic factors may play a role in the heavy fight of some beverage, food, and salt companies against initiatives and activities for a reduction in salt intake at a population level. The authors conclude that there now is conclusive population-wide evidence, which indicates powerful beneficial health effects of comprehensive salt reduction. Decrease of obesity is now added to the previous list of recognised benefits.
References
1. Sodium intake and hypertension. Progress in Cardiovascular Diseases. Vol. 49, No 2 (September/October), 2006:59-75