Ajinomoto produces half the world’s aspartame, the 200x-sweeter-than-sucrose synthetic molecule used in Diet Coke. Many consumers assume the additive is harmful, a prior rooted in its lab-made origins and lack of familiar food sourcing. The FDA classifies aspartame as one of the most exhaustively studied substances in the human food supply, with approval dating to 1981.

Aspartame breaks down entirely in the gut into three components: 50% phenylalanine, 40% aspartic acid, and 10% methanol. A single can of Diet Coke contains 184 mg of aspartame, yielding 92 mg of phenylalanine, the same essential amino acid found in eggs, milk, and tofu. Most people consume far more phenylalanine from regular food daily.

The 18.4 mg of methanol in a can of Diet Coke is a fraction of the 130–1030 mg most people consume daily from fruit, vegetables, and wine. Methanol metabolizes to formaldehyde, but the compound has a 1-minute blood half-life. Only people with phenylketonuria, a rare genetic disorder, need to strictly limit phenylalanine from all sources.

Aspartame was first synthesized in 1965 and gained FDA approval in 1981. The European Food Safety Authority and FDA both affirm its safety for the general population based on decades of research. While no additive is 100% risk-free, the metabolic breakdown into common dietary components undermines most fears about synthetic harm.