Wednesday, March 23, 2016
Too much salt can lead to weight gain
Excessive salt consumption is known to increase blood pressure, and elevate the risk of stroke and heart disease. Now, a team of researchers from Australia has identified another reason to avoid high salt intake. Their studies have shown that too much salt in the diet can lead to overconsumption of fatty foods, raising the risk of weight gain and obesity.
The researchers conducted two studies to examine how the amount of salt present in food can influence food preferences and quantity. The studies were published in the Journal of Nutrition and Chemical Senses. The researchers enrolled 49 healthy subjects aged 18-54 years for the first study. Participants were given tomato soups that had varying concentrations of fat (0%, 5%, 10%, and 20%) and salt (0.04% - no added salt - 0.25%, 0.5%, 1%, and 2%). They were asked to taste the soups and score the perceived fattiness and saltiness of each soup, as well as the pleasantness and desire to eat each soup. Fat taste sensitivity among participants was ascertained by their ability to taste oleic acid (a fatty acid) at various concentrations in long-life skimmed milk.
The study found that salt concentration of 0.25%-5% was preferred by participants. However, this was not the case with fat content; there was no difference in pleasantness between fat concentrations of 5%, 10%, or 15%. Interestingly, when soup without salt was served, participants who were sensitive to the taste of fat showed a preference for lower fat concentrations compared to those who were less sensitive to the taste of fat. These findings indicate that salt might have a "masking effect" on fat preferences.
For the second study, the researchers enrolled 48 healthy adults aged 18-54 years. The participants' fat taste sensitivity was ascertained by their ability to taste oleic acid. Participants were asked to attend four lunchtime sessions over a 6-day period during which they were given meals of elbow macaroni with sauce with varying amounts of salt and fat. The food intake of the participants was measured over the study period.
The study found that when the lunches contained low salt and high fat, the participants ate about 11% less food. In contrast, when high-salt, high-fat lunches were served, the same subjects ate significantly more food. Participants who were less sensitive to fat consumed the same amount of food, regardless of the salt content.
Explaining these findings, the study author Professor Russell Keast of Deakin University in Australia said, "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. However when salt is added to the food, those mechanisms are blunted and people end up eating more food. This can cause you to eat more fatty foods and over time, your body adapts or becomes less sensitive to fat, leading you to eat more to get the same feelings of fullness. Adding salt to high-fat foods has the potential to speed up this process. High-fat and high-salt foods override our body’s ability to recognise when we are full and cause us to eat more energy. If we eat too much energy, we get fat. This high fat and salt combination is a toxic mix for our health."
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