In August last year, PepsiCo removed aspartame from Diet Pepsi, replacing it with sucralose, an artificial sweetener usually known by the brand name Splenda. The decision was prompted by campaigns over concerns that the artificial sweetener is linked to increased risk for cancer.

The decision was also an attempt to boost sales, as industry executives blame the declining sales of the company's diet sodas on consumers' concern about the ingredient.

Less than a year following the reformulation, however, Diet Pepsi with aspartame is set to return to U.S. shelves after PepsiCo suffered plummeting sales after its move to remove the artificial sweetener from its beverage.

The company said that it will offer "Diet Pepsi Classic Sweetener Blend" made with aspartame beginning September in 20-ounce bottles, 2-liter bottles and 12-ounce cans.

The decision to bring back the controversial ingredient is aimed at appeasing consumers who do not like how the reformulated drink made with the artificial sweetener sucralose tastes like.

Replacing aspartame in Diet Pepsi is largely driven by the idea that the sweetener caused declining sales. Replacing it with another sweetener appeared to be a good idea to boost sales, but the company's move seems to have backfired.

In the first quarter of the year, the sales volume for Diet Pepsi dropped 10.6 percent, figures from industry tracker Beverage Digest show. Diet Coke, which continued using aspartame, on the other hand, saw a more moderate 5.7 percent decline in sales.

Aspartame has been linked to cancer in lab mice, but it is green-lighted for use with the Food and Drug Administration (FDA) citing more than 100 studies that support its safety.

"Considering results from the large number of studies on aspartame's safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food," the FDA has said.

Newly published studies, however, have raised concern on the health impact of using artificial sweeteners, particularly aspartame.

A study by researchers from York University published earlier this year found that obese people who consume artificial sweeteners such as saccharin and aspartame have worse glucose management compared to their counterparts who do not take sugar substitutes, raising risks for type 2 diabetes.