Aspartame: Don't Use It!

[April 28, 2008]

"Artificial Sweetener Raises Lifelong Concerns Long-term use of aspartame-sweetened sodas and candy may risk brain function/development and accelerate aging"
by Craig Weatherby

For 20 years and more, doubts about aspartame – sold as Equal or NutraSweet – have lingered despite repeated affirmations of its safety by U.S. and EU health authorities.

In 1995, FDA Epidemiology Branch Chief Thomas Wilcox reported that aspartame complaints represented 75 percent of all reports of adverse reactions to substances in the food supply from 1981 to 1995.

But last year, scientists published another review of the evidence pertaining to aspartame, and found no indications that the artificial sweetener harms brain function or promotes cancer.

Key Points

New review of cell-level evidence casts doubt on long-term safety of aspartame (Equal, NutraSweet). Artificial sweetener was approved without adequate research into chronic effects. Chemical’s troubling effects are not outweighed by any well-proven weight control benefits.

However, the review (Magnuson BA et al. 2007) was funded by a major producer of aspartame – Ajinomoto of Japan – and conducted by researchers-for-hire with glaring conflicts of interest.

The Ajinomoto-funded review was full of omissions that would mislead any expert reader who failed to read all of the studies cited, and failed to find the many damaging studies excluded from the analysis. (HM 2008)

This conflict of interest fits a disturbing pattern revealed by Professor Ralph G. Walton, Chairman of Psychiatry at Northeastern Ohio Universities College of Medicine.

Dr. Walton surveyed 166 studies of aspartame in peer reviewed medical literature. Of the total, 74 studies had aspartame-industry-related funding and 92 were independently funded. All of the industry funded research attested to aspartame's safety, whereas 92 percent of the independently funded research identified a problem of some kind. (Walton RG 2008)

New findings from South Africa suggest that scientists should definitely keep studying aspartame … and may prompt you to educate yourself on the subject.

Aspartame is most commonly used to sweeten uncooked consumables such as sugar-free sodas and chewing gums. (Because heat degrades its sweetening properties and taste, aspartame is rarely used in edibles that are normally cooked or baked.)

What is Aspartame?

In the body, this synthetic chemical compound breaks down into methanol (10 percent), aspartate (40 percent), and phenylalanine (50 percent).

Aspartate and phenylalanine alike act as neurotransmitters and as precursors to other neurotransmitters. Consumption of aspartame can cause big spikes in aspartate levels, which are known to damage brain cells.

Phenylalanine can cross the blood–brain barrier and cause large changes in the production of key neurotransmitters.

Methanol breaks down into formate, which is lethal to cells, is linked to a broad range of toxic effects, and also turns into toxic formaldehyde.

Previous studies have found that aspartame can induce neurological and behavioral disturbances in some people, with symptoms that include headaches, insomnia and seizures.

These effects appear related to changes in brain concentrations of amino acids, neurotransmitters, and hormones such as norepinephrine, epinephrine and dopamine.

And the new findings suggest that aspartame could be responsible for more subtle, long-term problems with brain function.

Safety Studies Seen as Misleading

The effects of aspartame have been studied extensively in humans, rats, mice and rabbits.

In safety studies, the aspartame doses given to animals were very high, and far in excess of anything humans would ever consume, which is standard and sensible in chemical safety tests.

Defenders of aspartame point to the results of animal studies, which often – but not always – show harm only at enormous doses.

That's true only with some substantial exceptions.

And as the South Africans noted, “… the animals tested for phenylalanine toxicity are approximately 60 times less sensitive than human beings. Humans are 10-20 times more sensitive to methanol poisoning … Test animals being used are 8-10 times less sensitive than humans to the effects of aspartic acid and glutamates.” (Humphries P et al. 2008)

Problem is, the ill effects of “normal” aspartame intake accumulate over time, they may only appear in the fairly intangible form of accelerated aging, and it’d be very hard to link the damage to the sweet synthetic.

The South African academics who authored the new review of cell-level aspartame studies made a cogent criticism of the animal and human (“macroscopic”) research upon which approval of aspartame is based (Humphries P et al. 2008):

“Most studies described in the literature have a macroscopic approach. If no adverse effects are visible after a single large administered dose of aspartame, it is believed that aspartame has no effect.”

“Thus [because of the very different responses of species and individuals to aspartame], results obtained from different studies vary from severe adverse effects to none observed.”

“Further studies are not carried out microscopically to demonstrate possible adverse effects on the cellular basis.”

In other words, the usual animal and human studies ("macroscopic" research) are probably in adequate to the task of identifying long-term problems with aspartame. Instead, we must pay attention to the red flags raised by cell studies ("microscopic" research).

Aspartame seems a dubious aid to weight and diabetes control given the adverse effects seen in some animal studies, the big differences between humans’ and animals’ reactions to aspartame, and what the new review reveals about cell-level effects.

Let's take a closer look at the disturbing new review of cell-level evidence concerning aspartame.

South African review cites aspartame’s adverse impacts on brain function

The South African team, led by researchers at the University of Pretoria, set out to examine the extant scientific evidence concerning direct and indirect effects of aspartame on brain cells and metabolism.

The results make sobering reading, to say the least.

They found that prior research documents a number of direct and indirect changes that occur in the brain as a result of high consumption levels of aspartame, leading to degeneration of brain cells and functions.

Based on the results of prior studies, the African team concluded that aspartame can disturb a series of key, interlocking factors in brain health (Humphries P et al. 2008):

  • Concentrations of key stress hormones, including norepinephrine, epinephrine (adrenalin), and dopamine.
  • Metabolism of amino acids.
  • Structure and metabolism of proteins.
  • Integrity of nucleic acids.
  • Brain cell function.

And they cited evidence showing these negative effects of aspartame (Humphries P et al. 2008):

  • Breakdown of aspartame in the body causes nerve cells to fire excessively.
  • Aspartame consumption impairs the energy systems for certain required enzyme reactions, which indirectly decreases the synthesis of key neurotransmitters or their functioning.
  • Aspartame’s effects damage the brain cells’ energy centers (mitochondria): an effect that could kill cells and reduce the efficiency of energy production.

Why Aspartame’s Methanol Content Matters

Aspartame’s effects on brain hormones, cells, and neurotransmitters are only the tip of the iceberg.

Methanol converts to toxic formate and formaldehyde in the body.

While common plant foods contain higher levels of methanol than a can of soda – a misleading fact cited by aspartame defenders – these foods, unlike aspartame, contain compounds that prevent methanol from converting into formate and formaldehyde.

It’s pretty chilling to read the South Africans’ dry summary of the impacts of ingesting the methanol as part of aspartame (Humphries P et al. 2008):

“… the wood alcohol in aspartame is converted into formaldehyde and then to formic acid, which in turn causes metabolic acidosis. The methanol toxicity is thought to mimic the symptoms of multiple sclerosis … symptoms of fibromyalgia, spasms, shooting pains, numbness in the legs, cramps, vertigo, dizziness, headaches, tinnitus, joint pain, depression, anxiety, slurred speech, blurred vision or memory loss have been attributed to aspartame.”

“The methanol in the body … can also give rise to formaldehyde, diketopiperazine (a carcinogen) and a number of other highly toxic derivatives … Methanol and formaldehyde are also known to be carcinogenic and mutagenic. The damaged DNA could cause the cell to function inadequately or have an unbalanced homoeostasis, thus initiating disease states.”

“… we propose that excessive aspartame ingestion might be involved in the pathogenesis [disease-promotion process] of certain mental disorders … and also in compromised learning and emotional functioning.”

Obviously, the vast majority of people who consume aspartame experience no obvious symptoms such as these.

Instead, the effects cited here could take years or decades to produce noticeable damage, which would be very hard to trace back to chronic aspartame consumption.

Aspartame’s Impact on Weight Control

The authors of the review point out that, ironically, consumption of aspartame results in a craving for carbohydrates that could eventually result in weight gain.

Studies on artificial sweeteners are mixed … most show weight benefit, but others don’t.

The conclusions of a conference held in Paris in 2006 noted the increasing evidence that even modest reductions in calorie consumption can reduce the risk factors associated with diabetes, cardiovascular disease, and more.

Some research suggests that choosing sodas and sweets with aspartame could cut in calorie intake enough to reduce heart and diabetes risks.

But as the South Africans say, the metabolic effects of aspartame could worsen blood sugar control over time.

Aspartame’s Impact on Child Brain Development

The African team added these disturbing predictions (Humphries P et al. 2008):

“In addition, prenatal consumption of aspartame [via the umbilical cord] might result in mental retardation, impaired vision, birth defects and is thought to play a role in the pathogenesis of Alzheimer's disease; furthermore, it is implicated in disruption of learning and emotional functioning …”

“… earlier research findings show that aspartame consumption might affect early brain development and neurotransmitter systems, which might result in specific emotional, behavioral and learning difficulties ...”

The researchers said more testing is required to further determine the health effects on aspartame and bring an end to the controversy.

No kidding!

When you add up the many alarming facts about aspartame revealed by their review, it seems odd that the FDA has not banned the sweetener until all of the many legitimate concerns have been settled by objective, scientifically sound studies.

Sadly, we wouldn’t advise holding your breath waiting for industry-influenced Federal agencies and elected representatives to protect public health at the expense of profits.

Instead, it will likely take citizen pressure to force new research.

Info Source: Vital Choice website:
Visit Vital Choice Wild and Organic Seafoods.


[No authors listed] Aspartame. Review of safety issues. Council on Scientific Affairs. JAMA. 1985 Jul 19;254(3):400-2.

Coulombe RA Jr, Sharma RP. Neurobiochemical alterations induced by the artificial sweetener aspartame (NutraSweet). Toxicol Appl Pharmacol. 1986 Mar 30;83(1):79-85. (HM). Aspartame and Manufacturer-Funded Scientific Reviews. Accessed online April 24, 2008 at

Humphries P, Pretorius E, Naudé H. Direct and indirect cellular effects of aspartame on the brain. Eur J Clin Nutr. 2008 Apr;62(4):451-62. Epub 2007 Aug 8.

Magnuson BA, Burdock GA, Doull J, Kroes RM, Marsh GM, Pariza MW, Spencer PS, Waddell WJ, Walker R, Williams GM. Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies. Crit Rev Toxicol. 2007;37(8):629-727. Review.

Oyama Y, Sakai H, Arata T, Okano Y, Akaike N, Sakai K, Noda K. Cytotoxic effects of methanol, formaldehyde, and formate on dissociated rat thymocytes: a possibility of aspartame toxicity. Cell Biol Toxicol. 2002;18(1):43-50.

Walton RG. Survey of Aspartame studies: correlation of outcome and funding sources. Accessed online April 24, 2008 at

Walton RG, Hudak R, Green-Waite RJ. Adverse reactions to aspartame: double-blind challenge in patients from a vulnerable population. Biol Psychiatry. 1993 Jul 1-15;34(1-2):13-7.

Walton RG. Seizure and mania after high intake of aspartame. Psychosomatics. 1986 Mar;27(3):218, 220.

Wurtman RJ. Neurochemical changes following high-dose aspartame with dietary carbohydrates. N Engl J Med. 1983 Aug 18;309(7):429-30.

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