Sweetener in diet soda may cause weight gain
Researchers have suggested sweetener in diet soda can cause weight gain or obesity. Some research have even indicated that even acceptable daily intakes of aspartame as regulated by the United States Food and Drug Administration (FDA), might make you hungrier and further lead to weight gain.
Other studies have also shown that compared with sugar, sweeteners like the saccharin and aspartame causes weight gain instead of weight loss.
Reasons why this may happen are not yet entirely clear, but a team of researchers from the Massachusetts General Hospital have decided to investigate why aspartame does not promote weight loss.
Their research – published in the journal Applied Physiology, Nutrition and Metabolism. – suggests one of aspartame’s metabolites may play a role into this.
The researchers were led by Dr. Richard Hodin, from the Massachusetts General Hospital Department of Surgery.
Studying aspartame intake in mice
One of the breakdown products of the aspartame is phenylalanine, which is an inhibitor of a gut enzyme called the intestinal alkaline phosphatase (IAP) that has been shown to prevent metabolic syndrome in mice.
Metabolic syndrome is a generic name, which is given to a group symptoms that are associated with type 2 diabetes, cardiovascular disease, and obesity.
Dr. Hodin and team had conducted previous research where they fed IAP to mice that were on a high-fat diet. They found that the IAP can further prevent the onset of metabolic syndrome, as well as reduce the symptoms in animals that already had the condition.
Based on this known relationship between IAP, phenylalanine, and aspartame, researchers hypothesized that consuming aspartame may further promote metabolic syndrome because of its inhibition of phenylalanine.
For the study, researchers added that aspartame to diet and regular soda, before measuring IAP activity in mice.
The scientists used four groups of mice. Two groups were put on a normal diet, with one group receiving drinking water with aspartame and the other group just plain water. The other two groups were put on a high-fat diet, with one group getting plain water and the other getting water with aspartame.
The normal-diet group that have received aspartame consumed the equivalent of 3 ½ cans of diet soda every day. The group that was on a high-fat diet has received aspartame in doses that were equivalent to almost two cans of diet soda.
The mice were monitored for almost 18 weeks.
Aspartame blocks enzyme that would prevent obesity
Inside the human body, aspartame is further metabolized and broken down into phenylalanine, aspartic acid, and methanol. Phenylalanine and aspartic acid are amino acids that are naturally present in many protein-containing foods.
However, phenylalanine inhibits the production of IAP.
“We think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP,” Dr. Hodin says.