Two studies published in Chemical Senses and the Journal of Nutrition show that high salt intake may lead to overconsumption of fatty foods. For the first study, the team set out to investigate the effects of salt on the taste of fat and food preference. The researchers enrolled 49 healthy participants aged 18–54 and asked them to taste a variety of tomato soups that had four different fat concentrations (0%, 5%, 10%, and 20%) and five different salt concentrations (no added salt: 0.04%, 0.25%, 0.5%, 1%, and 2%).
After consuming the soups, participants were asked to rank the pleasantness and desire to eat each soup, as well as the perceived fattiness and saltiness of each soup. Fat taste sensitivity among participants was measured by their ability to taste oleic acid—a fatty acid in vegetable fats and oils—at various concentrations in long-life skimmed milk.
The researchers found that salt is a major player in the pleasantness of a food, with rating of food pleasantness varying greatly dependent on different salt contents. However, there was no difference in food pleasantness when it came to fat concentrations of 5%, 10%, or 15%, though a fat content of 20% was rated as least pleasant. They concluded that the strong effect of salt on pleasantness suggests that salt, rather than fat, play a major role in the attraction to savory fatty foods.
For the second study, the researchers wanted to examine the effect of salt on food intake. They enrolled 48 healthy adults aged 18–54, and, as in the first study, determined the participants’ fat taste sensitivity. Over a six-day period, participants were required to attend four lunchtime sessions. Lunches consisted of elbow macaroni and sauce, with the sauces containing varying concentrations of fat and salt. The researchers measured subjects’ food intake over the study period and participants were required to rate the pleasantness of each food.
The researchers found that participants consumed around 11% less food and energy when their lunches contained low salt and high fat. However, when given high-salt high-fat foods, those same subjects consumed significantly more food and energy. Those who were less sensitive to fat consumed the same amount in each salt condition.
Overall, the authors say their studies indicate that salt may interfere with the body’s biological processes that stop us from eating too much. “Our body has biological mechanisms to tell us when to stop eating, and fat activates those mechanisms in people who are sensitive to the taste of fat,” said study author Russell Keast. Deakin University in Australia. “However when salt is added to the food, those mechanisms are blunted and people end up eating more food.”
