Many of us are trying to reduce consumption of sugar. In an effort to do so, we turn to lower or zero-calorie sweeteners. One of the most controversial sugar alternatives is aspartame. But is it really dangerous?

Aspartame, generally sold under the brand Equal, is composed of two molecules: aspartic acid and phenylalanine. These are amino acids, which are the building blocks of protein, and are found naturally in protein foods. Upon digestion, aspartame breaks down and is absorbed into the blood steam as these amino acids.

The FDA has done numerous evaluations and studies of the effects of aspartame, and has never found a reason to remove it from the food supply. Questions about artificial sweeteners and an association with cancer arose when early studies showed a link between aspartame and cancers in laboratory animals. However, subsequent studies have not displayed clear evidence of cancer in humans as a result of consuming aspartame. Some believe that aspartame, like MSG, may be an "excitotoxin," which is a compound that over stimulates nerve cells. But this needs to be studied further.

One undisputed problem of consuming aspartame affects some people with a genetic disorder called phenylketonuria. This is the inborn inability of some people to metabolize one of the molecules in aspartame, phenylalanine. Some people with liver disease or those who have a high level of phenylalanine in their blood may also need to avoid aspartame. High phenylalanine levels can result in brain damage; therefore products with aspartame display a warning regarding their phenylalanine content.

The Acceptable Daily Intake (ADI) is an estimate of the amount of a product that the average person can safely consume on a daily basis. The FDA has set the ADI for aspartame at 50 mg/kg of body weight per day. In order to reach the ADI for aspartame, it would take an adult to drink 20 12-oz soft drinks per day, or consume 97 packets of Equal.

It's unknown what the long-term affects of aspartame and zero-calorie sweeteners are, but aspartame has been widely studied and is generally recognized as safe. It is a processed food, however, and its consumption should be minimized as much as possible. It may be a good tool for those trying to lose weight, who can use it as a stepping stone from sugary products to less sweet, more natural foods.