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Aspartame does not cause physical or mental health problems

Does the artificial sweetener aspartame harm “almost every organ in the body”? 

A meme widely shared on Facebook in South Africa claims it does. “Aspartame is a chemical made up of aspartic acid and phenylalanine. It breaks down into formaldehyde, eventually into wood alcohol. It produces all sorts of problems, mental problems, and it impacts on literally every organ in the body. They know this, there are extensive animal studies that show this, and it never should’ve been put into our food.”

The text is attributed to Dr Stanley Monteith, a US doctor who hosted the syndicated Christian show Radio Liberty. He died in 2014.

In 1999 Monteith produced an audio book called Aspartame and MSG: The Taste That Kills, in which he “interviewed four experts” on aspartame. But Africa Check could find no evidence that the quote in the meme originated with Monteith.

What is aspartame?

A factsheet on aspartame by the Nutrition Information Centre at the at South Africa’s University of Stellenbosch says it is “one of the most widely used artificial sweeteners and can be found in products like diet cooldrinks and other diet products”. 

“The main purpose of artificial sweeteners, like aspartame, is to provide sweetness to foods and beverages without adding to their energy content or increasing blood glucose concentration.”

Aspartame’s components can be found naturally in common foods, it says. When it’s digested, the body transforms it into two amino acids, phenylalanine and aspartic acid, and methanol – “approximately 50% phenylalanine, 40% aspartic acid and 10% methanol”.

‘Quickly eliminated from body’

These amino acids are used by the body to “build proteins, promote growth and maintain bodily functions”. When aspartame is digested, “the body handles these amino acids in the same way as those in foods that we eat every day”.

But what about methanol?

“A very small amount of methanol (10% by weight) is formed when aspartame is digested,” the factsheet says

“It is less than the amounts found in many fruits and vegetables. The body converts the methanol to formaldehyde, which is instantly converted to formic acid. Formic acid is then quickly eliminated by the body in the form of carbon dioxide and water.”

Aspartame ‘exhaustively studied’

South Africa’s independent Food Advisory Consumer Service (FACS) says misinformation about aspartame is common.

The human body uses the components of aspartame “in exactly the same way regardless of whether they come from aspartame or from foods”, FACS says. “These components are provided in much higher quantities by common food products consumed daily, than by aspartame.”

It adds that more than “200 controlled medical studies” have “established the safety of aspartame, for the general public, diabetics, pregnant and nursing women, and children”. 

Sufferers of phenylketonuria, a rare hereditary disease, are the only ones affected by aspartame because they “do not have the enzymes needed for the breakdown of phenylalanine”.

“Although methanol, a substance that can cause blindness, is produced when aspartame is being digested, the amount is miniscule,” says FACS. A person would have to drink between 675 and 1,690 cans of an aspartame-sweetened soft drink at one sitting to reach dangerous levels. 

“Claims that aspartame is associated with numerous ailments are not supported by the facts,” FACS says. Myths about aspartame continue to circulate online “despite the evidence produced by three decades of scientific and medical research”. 

The US Food and Drug Administration also gives detailed information about “high-intensity sweeteners” like aspartame on its website. Aspartame is “one of the most exhaustively studied substances in the human food supply” and “safe for the general population”. – Taryn Willows


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