It is safe to say that aspartame is not 100% natural. What happens inside the body in the presence of aspartame is questionable and of significant risk, especially over long term use.
"In food, phenylalanine and aspartic acid are bound to other amino acids in long, complex chains of proteins so that they are not absorbed in a way that could cause damage.
But in aspartame they are not, and enzymes in the gut can easily split them apart.
Once phenylalanine is released in its free form, it is metabolized into diketopiperazine, a carcinogen. Aspartic acid in its free form becomes an excitotoxin, a toxic molecule that stimulates nerve cells to the point of damage or death.
The third component of aspartame, methyl ester, is the most harmful. It is metabolised by the body into methanol, a well-known poison.
In the US, the Environmental Protection Agency defines safe consumption of methanol as no more than 7.8mg a day.
Anyone drinking three cans of a drink sweetened with aspartame a day is consuming about 56mg of methanol."
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