> Human studies show that formic acid is excreted faster than it is formed after ingestion of aspartame. In some fruit juices, higher concentrations of methanol can be found than the amount produced from aspartame in beverages.
Also:
> Aspartame consists of two amino acids—aspartic acid and phenylalanine. When ingested, aspartame is broken down into these amino acids for use in protein synthesis and metabolism. In addition to aspartic acid and phenylalanine, aspartame digestion also yields a small amount of methanol, a compound that is naturally found in foods like fruits and vegetables and their juices. The amount of methanol resulting from consuming an aspartame-sweetened beverage is about five to six times less than that resulting from the same volume of tomato juice.[1]
[1] https://foodinsight.org/everything-you-need-to-know-about-as...