Aspartame is metabolized into phenylalanine, aspartic acid, and methanol, which are compounds naturally present in common protein-rich and plant-based foods and are not bioaccumulative in humans.

Study: Comparative metabolism of aspartame in experimental animals and humans.

The study found that when your body breaks down aspartame, it turns into the same tiny parts found in eggs, meat, and fruits—and your body knows how to handle them without storing them up.

Study: Aspartame Metabolism in Normal Adults, Phenylketonuric Heterozygotes, and Diabetic Subjects

This study checked what happens when people eat aspartame and found that it breaks down into three substances that our bodies already handle from food—and they don’t build up in us. So yes, it supports the claim.