What does aspartame do to the body?

my dad, after drinking diet soda and other aspartame-laden products for the better part of 15–20 years or more, eventually developed stiffness in his joints so bad that he couldn’t stand up without extreme effort. It was diagnosed as aspartame toxicity, and he switched to diet sodas and products with Splenda instead, and it cleared up almost instantly. If he drinks aspartame diet sodas for a couple of days, it comes back with a vengeance.

I don’t know much about aspartame, but…

1) I read somewhere (I don’t know that this is true) that when heated over 98 F, it takes on the properties of fermeldahide (spelled right?) aka: embalming fluid. Think those cans of diet coke that have been sitting out in the sun. Now think of the diet coke entering your warm, 98.6 F body.

2) I quit drinking diet sodas because I always get a minor stomachache after drinking anything with aspartame, but it goes away after about 5–10 minutes. Nobody has really been able to explain why.

About 10% (by mass) of aspartame is broken down into methanol in the gut. This is then converted in to formaldehyde and then formic acid. This is nothing to worry about as both methanol and formaldehyde are natural by products of human metabolism and the body has processes to deal with them.

About 50% of aspartame by mass is broken down into phenylalanine an essential amino acid (ie one of the amino acids the body is unable to produce itself and therefore must get from the diet).

40% gets turned into aspartic acid (another amino acid). At very high concentrations aspartic acid can damge brain cells however aspartic acid does not usually cross the blood brain barrier. (Rodents are more susseptable then primates so using rodent models is useless in showing that aspartame is dangerous to humans).

Most studies have shown that it is safe however consuming huge amounts of it is not a good idea. With fast food chains and cinemas selling soft drinks by the gallon it is probably very easy to consume more of the stuff than you think. The bottom line is that you need eat a balanced diet and while the ocasional soda will be OK, like the ocasional glass of wine or bar of chocolate, it should not be a regular part of your diet.

I should also note that my dad is diabetic, so it’s much more likely that he’d consume more aspartame since he specifically can’t consume sugar.

I have a friend who had a diabetic father who was an aspartame user for years. She believes his dementia and cognitive disfunction was the result of aspartame use.

This site has quite a bit of data including these points:

Analysis Shows Nearly 100% of Independent Research Finds Problems With Aspartame

Aspartame Ingestion Causes Formaldehyde Accumulation in the Body

Aspartame and Brain Tumors (Swedish Study)

Aspartame Causes Memory Loss

Aspartame and Lymphomas / Leukemias / Kidney & Peripheral Nerve Cancer

Environmental Health Experts Call for Aspartame Review and Possible Ban

I’m not sure of the physiological effects, but I’ve read that it has psychological effects. Such as: making you crave more of it and/or inducing false hunger. The trade off seems to be less calories consumed in a beverage (for example) and more consumed in snacking and over-eating.

Scientific studies on humans have not made any conclusive identifications of what varying levels of aspartame in your body result in. Scientific studies with rats shows some interesting results, but it is important to note that rats are not humans. At this time I believe the results are inconclusive enough to make a generalization not wise.

Having had a look at the site @Marina sugested and then gone and read some of the evidence it cites (several of the links were dead so it was impossible so say if the evidence exists at all) I would like to point out a couple of things.

i. Aspartame Ingestion Causes Formaldehyde Accumulation in the Body

The study the site quotes for this (Life Sciences, Vol. 63, No. 5, pp. 337) is flawed. What they did was label aspatame with radioactive carbon and then watch to see what happened to the radioactive carbon. What they found was the radioactive carbon accumulated in the brain, liver and kidney(of rats). However they were not measuirng formaldehyde directly so you can’t say it accumulated as formaldehyde. The body is capable of metabolising formaldehyde so the carbon atoms are then used by the body in other compounds.

ii. Environmental Health Experts Call for Aspartame Review and Possible Ban

This is with regards to a letter sent to Science after a study (Soffritti M, Belpoggi F, Degli Esposti D, Lambertini L, Tibaldi E, Rigano A (March 2006). “First experimental demonstration of the multipotential carcinogenic effects of aspartame administered in the feed to Sprague-Dawley rats”. Environ. Health Perspect. 114 (3): 379–85) showed a link between leukaemias and lymphomas in male rats receiving aspartame. However when the EFSA and the FDA reviewed the research they found significant flaws in the methodology, for example the control group of rats were much healthier than experimantal group before they started the study(link to FDA statement)

Incidently in 2006, the US National Cancer Institute published a study of over half a million people aged 50 to 69 that found there was no statistically significant link between aspartame consumption and leukemias, lymphomas or brain tumors.

You guys are all making me feel so guilty. I’m an adict. I need the bubbles and the sweet. I don’t need sugar. I go crazy with Splenda. It’s way worse than caffine on me. Anyone know of any soft drinks that use stevia?

Even though results may be somewhat inconclusive, I think it’s safe to assume that the potential risks are small compared to other very common risks. Just to give you a general feeling: suppose we define the consumption of 600 mg aspartame (1 liter of diet soda) per day as risk factor 1. In comparison we might look at risk factors of

> 100,000 – for smoking 20 cigarettes a day
> 60,000 – for drinking more than 50 ml of alcohol every day
> 50,000 – for not exercising enough
> 40,000 – for eating too much high-glycemic food every day
> 35,000 – for working too much
> 30,000 – for living near a very busy street
> 25,000 – for not taking enough vacations
> 20,000 – for rarely eating fruit, vegetables and salads
> 15,000 – for eating meat every day
> 10,000 – for worrying too much
> 5,000 – for commuting 30 miles by car every day (risk of accidents)
> 1,000 – for swimming in a lake during a thunderstorm
> 100 – for pointing a gun the wrong way when pulling the trigger

Note: Those numbers are far from being precise. The order could also be quite different. Maybe someone knows a scientific study offering a more precise numbers about common health risk factors.

My point is: aspartame discussions seem to reappear all the time. We need to keep things in perspective. There seem to be thousands of people who worry about having diet coke, but they never use sidewalks preferring drive through services everywhere. They think walking is some kind of waste of time. But someone told them stories about aspartame. Give me a break.

@Judi – I also use sweeteners and I don’t feel guilty. I would feel guilty if I didn’t care about real risks, see above.

I can verify that aspartame and Diet Coke, in particular, can definitely cause health issues. I was getting terrible headaches that never seemed to go away. During that same period, I stopped drinking Diet Coke for roughly 6 weeks. For the entire 6 week period, I was headache free, though I didn’t correspond that fact with my cessation of Diet Coke in my diet.

One afternoon I had a Diet Coke to drink and my headache re-appeared almost immediately. Once I made that connection, I have not consciously chosen to drink any diet drinks. On the rare occasion I get a diet drink by mistake from a drive-thru or whatever my headache reappears immediately.

In my case, I do not have any doubts that Diet Coke and, more pointedly, aspartame play a major role in causing headaches.