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Aspartame: Why This Toxic Sweetener is FAR Worse than High Fructose Corn Syrup…

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It’s been nearly 20 years since the artificial sweetener aspartame gained FDA approval, but the debate about its safety, or lack thereof, has continued on unabated. Today, aspartame can be found in more than 6,000 products, including food products not specifically aimed at diabetics or dieters.

Might you be overdosing on this neurotoxic sweetener?

Dr. Mercola's Comments:

The first video above -- which contains highlights of Cori Brackett’s documentary film Sweet Misery -- is an excellent summary of the problems with aspartame. You can also obtain the entire DVD if you’re intrigued by these clips. I believe Sweet Misery is one of the best documentaries out there on this topic.

In this follow-up article, I will discuss recent findings that link aspartame to increased risk of premature birth; it’s potential carcinogenic effects; and the ironic ‘side effect’ of it promoting rather than combating weight gain – which of course is one of its primary objectives as a sugar substitute.

If you missed the first half of this discussion, you can read it here.

As I mentioned in that article, the lack of toxicity data should not be construed as proof that aspartame is safe. On the contrary! Aspartame appears to have been approved WITHOUT such data, which makes the issue of its inherent safety for human consumption all the more questionable.

Today, the sheer prevalence of this chemical sweetener in our food supply has re-ignited the issue of aspartame’s safety, despite the fact that the FDA approved it nearly 20 years ago, and has continuously refuted new studies suggesting their original approval was ignorant at best.

It was a decision heavily influenced by political wrangling and alleged scientific fraud that has put people’s health at risk ever since.

In the Source links above, you will find a link to a page on my website dedicated to documenting studies pertaining to health problems associated with aspartame.

You will also find a link to a free sample chapter from my book Sweet Deception for more information about aspartame and the health concerns associated with its use.

Before I delve into the evidence stacked against aspartame as a dieter’s best friend, and recent research that strongly questions its safety for pregnant women, I’d like to quickly address the issue of individual susceptibility to harm.

Although there are tens of thousands of FDA adverse reaction reports and countless more personal accounts of harm, many staunch aspartame users claim they’ve been using it for years and, well… they’re not dead yet, so how bad can it be?

Some People are Naturally More Prone to Formaldehyde Poisoning

An interesting tidbit that can help explain why some people experience ill effects from aspartame quite rapidly, whereas others can ingest aspartame for some time without noticing any ill effects, is that you may have more or less of a particular enzyme that breaks down alcohols that could otherwise be toxic.

Woodrow C. Monte, PhD, a retired professor of food science, explains this in his 2009 article Methanol: A chemical Trojan Horse as the root of the Inscrutable U[i].

Aspartame contains about 10 percent methanol by weight, also known as wood alcohol, which is broken down into formaldehyde, and then formic acid, in your body.

The only human enzyme capable of metabolizing methanol to formaldehyde is an enzyme called Class I alcohol dehydrogenase (ADH I).

Formaldehyde, in turn, damages your body by “attacking proteins and embalming them” – a simple layman’s description of what happens, courtesy of

According to, “small amounts of methanol can cause blindness, as the sensitive proteins in the retina are attacked…” And visual disturbance, including retinal detachment, is one of the reported side effects of aspartame consumption.

Now, Dr. Monte offers a clue as to why methanol may harm some more than others:

“Variability in sensitivity to exogenous methanol consumption may be accounted for in part by the presence of aldehyde dehydrogenase sufficient to reduce the toxic effect of formaldehyde production in tissue through its conversion to the much less toxic formic acid.”

In a nutshell, this is one of the ways in which your individual constitution may render you more or less vulnerable to the detrimental effects of aspartame.

That said, I am convinced that most of those who claim to be able to consume aspartame on a regular basis without ill effect, are still likely accruing damage in their bodies that will ultimately affect their long-term health.

It’s worth keeping in mind that most toxins that are harmful to your health are not going to harm you instantly. The reality is that few health hazards do. As with many other toxins and harmful chemicals, aspartame may be acutely toxic to some, while others can consume it without experiencing any immediate side effects.

However, there’s no guarantee it won’t lead to health problems later on, and it’s certainly not evidence of aspartame’s safety for the population at large – especially when you take into account the tens of thousands of people who HAVE experienced both acute and long-term side effects.

Please remember that just like other artificial sweeteners, there are no long-term safety studies in humans that support its use as they were never required by the FDA.

In addition, as I’ll discuss below, if you consume aspartame while pregnant, you may unwittingly expose your unborn child to completely unnecessary health risks, even if you feel that aspartame is not affecting you in a negative way.

Why Aspartame is NOT a Dieters Best Friend

Low-calorie artificial sweeteners were originally marketed primarily to diabetics and dieters, but now you find them in a variety of processed foodstuffs and snacks that are not specifically aimed at this target market.

But do these zero- or low-calorie products really help you lose weight and/or keep it off?

Well, the research and the epidemiologic data suggest the opposite is true, and that artificial sweeteners such as aspartame tend to lead to weight gain. As I’ve often said, there’s more to weight gain or weigh loss than mere calorie intake.

One reason for aspartame’s potential to cause weight gain is because phenylalanine and aspartic acid – the two amino acids that make up 90 percent of aspartame -- are known to rapidly stimulate the release of insulin and leptin; two hormones that are intricately involved with satiety and fat storage. Insulin and leptin are also the primary hormones that regulate your metabolism.

So although you’re not ingesting calories in the form of sugar, aspartame can still raise your insulin and leptin levels.

Elevated insulin and leptin levels, in turn, are two of the driving forces behind obesity, diabetes, and a number of our current chronic disease epidemics.

Over time, if your body is exposed to too much leptin, it will become resistant to it, just as your body can become resistant to insulin, and once that happens, your body can no longer “hear” the hormonal messages instructing your body to stop eating, burn fat, and maintain good sensitivity to sweet tastes in your taste buds.

What happens then?

You remain hungry; you crave sweets, and your body stores more fat.

Leptin-resistance also causes an increase in visceral fat, sending you on a vicious cycle of hunger, fat storage and an increased risk of heart disease, diabetes, metabolic syndrome and more.

Artificial Sweeteners Actually INCREASE Weight Gain

Most people use artificial sweeteners to lose weight. The amazing irony is that nearly all the studies that have carefully analyzed their effectiveness show that those who use artificial sweeteners actually gain more weight than those that drink regular sodas.

Common sense would also strongly suggest that they don’t work, because while their use has exploded in the last three decades, that increase closely parallels the obesity epidemic which continues to worsen, not improve, despite the use of these artificial sweeteners.

This connection between sweet taste alone and increased hunger can be found in the medical literature going back at least two decades. These two studies, for example, dating back to the late 80’s and early 90’s, both showed this link between artificial sweeteners and increased hunger:

  • Physiology & Behavior, 1988[ii] – In this study, they determined that intense (no- or low-calorie) sweeteners can produce significant changes in appetite. Of the three sweeteners tested, aspartame produced the most pronounced effects.
  • Physiology & Behavior 1990[iii] – Here, they again evaluated whether or not the mere taste of “sweet” increases hunger, by having human subjects chew gum for 15 minutes containing various levels of aspartame (0.05%, 0.3%, 0.5%, or 1.0%).

    Interestingly, although those who chewed artificially sweetened gum reported increased hunger compared to the control group who were given nothing or unsweetened gum base to chew, the increase did not directly correlate with the aspartame concentration in the gum.

    Women experienced the greatest increase in hunger after chewing gum containing 0.3 percent aspartame (the second lowest concentration amount), while men were the hungriest after chewing on gum containing 0.5 percent aspartame. The authors stated: “The highest aspartame concentrations had a time-dependent, biphasic effect on appetite, producing a transient decrease followed by a sustained increase in hunger ratings. Thus, the concentration of the sweetener, the sex of the subject, and the time after chewing, were all important determinants of whether "sweetness" increased hunger.

While no explanations for these findings were given at that time, researchers are now starting to be able to further explain why and how this happens.

As I explained above, phenylalanine and aspartic acid can stimulate the release of insulin and leptin, which are both involved in the mechanism of satiety.

Additionally, large doses of phenylalanine can lower important neurotransmitters like sero­tonin[iv], which also influences satiety. Decreased serotonin levels reduce feelings of satiety, which can then lead to over-eating or binge eating.

In a study of high-intensity artificial sweeteners performed on college students, there was no evidence that artificial sweetener use was associated with a decrease in their overall sugar intake either.

These results indicate that eating arti­ficial sweeteners simply perpetuates a craving for sweets, and overall sugar consumption is not reduced—leading to further problems controlling your weight.[v]

In 2005, data gathered from the 25-year long San Antonio Heart Study also showed that drinking diet soft drinks increased the likelihood of serious weight gain – far more so than regular soda.[vi]

According to Sharon Fowler, M.P.H:

“On average, for each diet soft drink our participants drank per day, they were 65 percent more likely to become overweight during the next seven to eight years, and 41 percent more likely to become obese.”

This finding supports a 2004 study at Purdue University, which found that rats fed artificially sweetened liquids ate more high-calorie food than rats fed high-caloric sweetened liquids.[vii]

The researchers believe the experience of drinking artificially sweetened liquids disrupted the animals' natural ability to compensate for the calories in the food.

A more recent review, published in June 2010 in the Yale Journal of Biology and Medicine, delves into the neurobiology of sugar cravings and summarizes the epidemiological and experimental evidence concerning the effect of artificial sweeteners on weight.[viii]

The author states:

“Several large scale prospective cohort studies found positive correlation between artificial sweetener use and weight gain.

… Preload experiments generally have found that sweet taste, whether delivered by sugar or artificial sweeteners, enhanced human appetite. Aspartame-sweetened water, but not aspartame capsule, increased subjective appetite rating in normal weight adult males…

Unlike glucose or sucrose, which decreased the energy intake at the test meal, artificial sweetener preloads either had no effect or increased subsequent energy intake. Those findings suggest that the calorie contained in natural sweeteners may trigger a response to keep the overall energy consumption constant.

... Increasing evidence suggests that artificial sweeteners do not activate the food reward pathways in the same fashion as natural sweeteners… Natural and artificial sweeteners also activate the gustatory branch differently.

… Lastly, artificial sweeteners, precisely because they are sweet, encourage sugar craving and sugar dependence.

… Unsweetening the world’s diet may be the key to reversing the obesity epidemic.”

That last statement is probably the most accurate conclusion there is. Americans in particular are addicted to the flavor sweet, which appears to trigger a complex set of biological systems, pathways, and mechanisms that in the end leads to excess weight gain whether that flavor comes loaded with calories or not.

In the end, the research tells us that artificial sweeteners are nothing more than a pipe dream when it comes to being a dieter’s aid, because contrary to what the marketing campaigns claim, low- or no-calorie artificial sweeteners are more likely to help you pack on the pounds than shed them.

Aspartame and Premature Birth

One of the most recent studies published on the health effects of aspartame could be likened to the Ajinomoto Titanic hitting the iceberg…

A Danish study published in June, which included more than 59,000 Danish women, found that daily intake of artificially sweetened soft drinks may increase the risk of preterm delivery by as much as 78 percent.[ix]

According to a recent article in the British MailOnline, some British public health experts are now advising pregnant women to avoid aspartame-containing foods and beverages to protect their unborn child, as preterm delivery exposes the baby to a number of health risks -- and staggering health care costs.

In the US, neonatal intensive care for an infant born prematurely, meaning before the 37th week of pregnancy, can cost anywhere from $20,000 to $100,000.

The researchers found that pregnant women who drank an average of just one diet soda per day increased their risk of going into labor before the 37th week by 38 percent.

Four or more diet sodas a day increased the risk of premature birth by 78 percent.

Meanwhile, no link was found between sugar-sweetened beverages and preterm delivery.

As usual, the researchers call for more studies to confirm these results, and I for one hope those studies are done so that, eventually, we may see a reversal in the recommendations by our health organizations, especially where expectant mothers are concerned.

Does Aspartame Cause Cancer?

The FDA, the media, and nearly all medical “experts” will tell you that it doesn’t, citing evidence such as the 2006 U.S. National Cancer Institute “study,” which involved more than 560,000 people between the ages of 50 to 69.[x]

What they fail to tell you is that this was NOT a controlled study.

In fact, it shouldn’t even be called a study, because actual studies are controlled.

It was a SURVEY, based on food and beverage consumption surveys filled out between 1995 and ’96.

Based on these self-reported rough estimates of what the participants ate and drank, the researchers calculated the amount of aspartame participants had consumed, and compared it with subsequent cancer rates in the five years following.

However, aside from being a mere survey, which in no way can determine cause, there are two glaring factors that make it very difficult to give it any credence whatsoever:

  1. In 1995 there were far fewer food products and beverages that contained aspartame, so consumption was likely FAR lower back then compared to today, and
  2. How many people – especially back then – actually read labels to determine whether or not something contained aspartame? After all, the old food surveys the researchers used were NOT specifically collected to ascertain aspartame consumption.

Some people sneer at animal studies, but there are reasons for using animals in lieu of humans in controlled studies. First of all, in many cases using humans would simply be unethical, but the human lifespan is also so long that a controlled study would be extremely impractical.

This is a major reason for using rats, as their lifespan is far shorter.

Many researchers will euthanize the animals after a set time, but others, such as Dr. Soffritti with The Cesare Maltoni Cancer Research Center of the European Ramazzini Foundation has performed two controlled aspartame safety study on rats, so far, in which the rats are observed over the course of their natural lifetime.

What did he find?

The first study found that after being fed the human equivalent of four to five bottles of diet soda a day, the rats developed high rates of lymphomas, leukemias and other cancers.

At the highest dose level, 25 percent of the female rats developed lymphomas-leukemias compared with just 8.7 percent of the controls.

His findings, which raised a firestorm of controversy and denial across the world, were published in the Environmental Health Perspectives in 2006.[xi]

The researchers determined that the carcinogenic effect of aspartame was as low as 400 parts per million (ppm), concluding that:

“The results of this mega-experiment indicate that APM [aspartame] is a multipotential carcinogenic agent, even at a daily dose of 20 mg/kg body weight, much less than the current acceptable daily intake.

On the basis of these results, a reevaluation of the present guidelines on the use and consumption of APM is urgent and cannot be delayed.”

A very important fact to consider here is that the Ramanizzi Foundation is an independent, non-profit institution that has been dedicated to cancer prevention for more than 35 years.

Not surprisingly, the results drew massive criticism from the industry. But the Ramanizzi Foundation refused to back down. reported the Foundation's rebuttal[xii]:

“… Prior long-term carcinogenesis studies on aspartame (4 total) were conducted over 20 years ago by the producers of the artificial sweetener using a small number of animals per sex per group. The results of these studies provided the basis for the current opinion regarding the non-carcinogenicity of aspartame.

In responding to the AFC panel comments, Soffritti noted that “what the panel considers shortcomings of the study are instead distinctive and positive characteristics of our research protocol, research which has provided the scientific basis for changes in international regulations numerous times over the last 30 years.”

For instance, the European Ramazzini Foundation conducts what are known as lifespan mega-experiments, meaning that large groups of rodents are allowed to live out their natural lifespan and are examined for histopathological changes upon spontaneous death. This model is in contrast with most laboratories where rodents are sacrificed at 110 weeks of age (representing about 2/3 of the lifespan).

The Ramazzini study design closely mirrors the human condition in which persons may be exposed to agents in the industrial and general environments from embryonic life until natural death.Since 80% of cancer is diagnosed in humans over the age of 55, it is of paramount importance to observe how an agent affects laboratory animals in the last third of their lives”, notes Soffritti.”

But the story doesn’t end there.

Two years later, in 2007, the Ramanizzi Foundation published a follow-up study -- again flagging the link between cancer and aspartame.

This time, their research highlighted the troubling discovery that when the exposure begins in the womb, aspartame’s carcinogenic effect is further increased.[xiii]

But the evidence still didn’t gain any traction. reported that FDA spokesman Michael Herndon told Reuters: "At this time, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food."[xiv]

Stonewalling at its finest…

This is why you must become an informed consumer. The FDA simply refuses to address and properly investigate this potential health threat for you.

Have You Experienced a Bad Aspartame Reaction? Report it!

Did you know that only a fraction of all adverse reactions are ever reported? When it comes to side effects from drugs and vaccines, a mere 1 to 4 percent of all adverse events are reported, which leads me to think that adverse reactions from other FDA-regulated products, such as aspartame, is likely even lower.

This is a problem that only you as the consumer can have an impact upon.

In order to truly alert the FDA to a problem with a product they’ve approved, they must be notified – by as many people who experience a problem as possible. So I urge you, if you experience side effects from aspartame, report it to the FDA.

Please go to the FDA Consumer Complaint Coordinator page, find the phone number listed for your state, and report your adverse reaction.

There’s no telling just how many reports they might need before considering taking another look at the safety of aspartame or reconsidering their stance on the findings from more recent studies, but the only way to press them is by reporting any and all adverse effects.