Aspartame: health article by Pat Thomas

This article first appeared in the September 2005 issue of The Ecologist, Volume 35, No.7. This is Part II of the series; this partexamines the chemical contents of aspartame.

Aspartame Toxic Contents

Aspartame is made up of three chemicals: the amino acids aspartic acid and phenylalanine, and methanol. The chemical bond that holds these constituents together is fairly weak.

As a result, aspartame readily breaks down into its component parts in a variety of circumstances: in liquids, during prolonged storage, when exposed to heat in excess of 86° Fahrenheit (30° centigrade), and when ingested. These constituents further break down into other toxic by-products, namely formaldehyde, formic acid and aspartylphenylalanine diketopiperazine (DKP).

Manufacturers argue that the instability of aspartame is irrelevant since its constituents are all found naturally in food. This is only partially true and ignores the fact that in food amino acids like aspartic acid and phenylalanine are bound to proteins, which means that during digestion and metabolism they are released slowly into the body.

In aspartame, these amino acids are in an unbound or 'free' form that releases greater amounts of these chemicals into the system much more quickly. Similarly, the methanol present in natural foods like fruits, for example, is bound to pectin and also has a co-factor, ethanol, to mediate some of its effects. No such chemical 'back-stops' exist in aspartame.

According to neuroscientist Russell Blaylock, the effect of aspartame's breakdown components on brain function is central to its known adverse effects.

Like monosodium glutamate (MSG) and L-cysteine, an amino acid found in hydrolysed vegetable protein, aspartame is what is known as an 'excitotoxin' -- a chemical transmitter that allows brain cells to communicate.

Blaylock has written a book about them, "Excitotoxins: The Taste That Kills," and says: "Even a minute over-concentration of these chemicals causes the brain cells to become so over-excited that they very quickly burn themselves out and die."

While aspartame manufacturers say aspartame cannot penetrate the blood-brain barrier -- the tightly-walled membrane that keeps toxins from reaching the brain --Blaylock counters that a number of factors make the blood-brain barrier more porous, including exposure to pesticides, hypoglycaemia, all immune diseases (such as lupus and diabetes), Alzheimer's and Parkinson's, strokes (including silent strokes) and a whole range of medical drugs.

Under these conditions, ingesting aspartame-laced foods may cause a spike in the level of excitotoxins that directly reach thebrain, thus increasing the likelihood of adverse effects.

Each of aspartame's main constituents is a known neurotoxin capable of producing a unique array of adverse effects.


The essential amino acid phenylalanine comprises 50 percent of aspartame. In people with the genetic disorder phenylketonuria (PKU) the liver cannot metabolise phenylalanine, causing it to build up in the blood and tissues.

Chronically high levels of phenylalanine and some of its breakdown products can cause significant neurological problems, which is why foods and beverages containing aspartame must carry a warning for PKU sufferers.

But according to Dr. HJ Roberts, sensitivity to aspartame is not limited to PKU sufferers. PKU carriers -- people who inherited the gene for the disorder but do not themselves have the condition (around 2 percent of the general population) -- are also more prone to adverse effects. In Roberts' data there is also a high incidence of aspartame reactions among the close relatives of patients who cannot tolerate aspartame.

Furthermore, there is evidence that ingesting aspartame, especially along with carbohydrates, can lead to excess levels of phenylalanine in the brain even among those not affected by PKU.

Athough phenylalanine is sometimes used as a treatment for depression, excessive amounts in the brain can cause levels of the mood regulator serotonin to decrease, making depression more serious or likely.

Build-up of phenylalanine in the brain can also worsen schizophrenia or make individuals more susceptible to seizures. Moreover, a decrease in serotonin levels can result in carbohydrate craving. This could explain aspartame's lack of effectiveness as a diet aid.


DKP is a breakdown product of phenylalanine that forms when aspartame-containing liquids are stored for prolonged periods. In animal experiments it has produced brain tumors, uterine polyps and changes in blood cholesterol.

Before the FDA approved aspartame, the amount of DKP in our diets was essentially zero. So no claim of DKP's safety can be accepted as genuine until good-quality long-term studies have been performed. No such studies have been done.

Aspartic Acid

Aspartic acid (also known as aspartate) is a non-essential amino acid that comprises 40 percent of aspartame. In the brain, it functions as a neurotransmitter -- facilitating the transfer of information from one nerve cell (neuron) to another.

Both human and animal experiments have demonstrated a significant spike in blood-plasma levels of aspartate after the administration of aspartame in liquids. Too much aspartate in the brain produces free radicals, unstable molecules that damage and kill brain cells.

Humans are five times more sensitive to the effects of aspartic acid (as well as glutamic acid, found in MSG) than rodents, and 20 times more sensitive than monkeys, because we concentrate these excitatory amino acids in our blood at much higher levels and for a longer period of time.

Aspartic acid has a cumulative harmful effect on the endocrine and reproductive systems. Several animal experiments have shown that excitotoxins can penetrate the placental barrier and reach the fetus.

In addition, as levels of aspartic acid rise in the body so do levels of the key neurotransmitter norepinephrine (also known as noradrenaline), a 'stress hormone' that affects parts of the human brain where attention and impulsivity are controlled. Excessive norepinephrine is associated with symptoms such as anxiety, agitation and mania.


Methanol (wood alcohol) comprises 10 percent of aspartame. It is a deadly poison that is liberated from aspartame at temperatures in excess of 86° Fahrenheit (30° centigrade) -- for instance, during storage or inside the human body.

The U.S. Environmental Protection Agency considers methanol a 'cumulative poison due to the low rate of excretion once it is absorbed,' meaning that even small amounts in aspartame-containing foods can build up over time in the body.

The most well known problems from methanol poisoning are vision disorders, including misty or blurry vision, retinal damage and blindness.

Other symptoms include headaches, tinnitus, dizziness, nausea, gastrointestinal disturbances, weakness, vertigo, chills, memory lapses, numbness and shooting pains in the extremities behavioral disturbances and neuritis.

The EPA tightly controls methanol exposure, allowing only very minute levels to be present in foods or in environmental exposures. But Blaylock says: 'The level allowed in NutraSweet is seven times the amount that the EPA will allow anyone else to use.'


The methanol absorbed from aspartame is converted to formaldehyde in the liver. Formaldehyde is a neurotoxin and known carcinogen. It causes retinal damage and birth defects, interferes with DNA replication, and has been shown to cause squamous-cell carcinoma, a form of skin cancer, in animals. Several human studies have found that chronic, low-level formaldehyde exposure has been linked with a variety of symptoms, including headaches, fatigue, chest tightness, dizziness, nausea, poor concentration and seizures.

Formic acid

Formic acid is a cumulative poison produced by the breakdown of formaldehyde. It concentrates in the brain, kidneys, spinal fluid and other organs, and is highly toxic to cells. Formic acid can lead to accumulation of excessive acid in the body fluids -- a condition known as acidosis. The small amounts of formic acid derived from the methanol absorbed from aspartame may or may not be dangerous; there are no human or mammalian studies to enlighten us.

Part III of this series will discuss some of the problems with the aspartame safety studies and approval process.

Ecologist Online August 30, 2005

Dr. Mercola's Comment:Many health disasters, which are highlighted by horrific personal accounts found on Web sites against aspartame, can be attributed to its use. Just a few of the disasters that result from aspartame use include:

Cancer Hair loss Depression Dementia Behavioral disturbances

But that's not nearly all. Aspartame alone accounts foras much as 80 percent of the adverse reactions to food additives reported to the FDA. Many of these reactions are very serious, including seizures and death.

A few of the 90 different documented symptoms listed in a 1994 Department of Health and Human Services report as being caused by aspartame include:

Headaches and migraines, dizziness, seizures, nausea, numbness, muscle spasms, weight gain, rashes, depression, fatigue, irritability, tachycardia, insomnia, vision problems, hearing loss, heart palpitations, breathing difficulties, anxiety attacks, slurred speech, loss of taste, tinnitus, vertigo, memory loss and joint pain.

And, according to researchers and physicians studying the adverse effects of aspartame, the following chronic illnesses can be triggered or worsened by ingesting aspartame: Brain tumors, multiple sclerosis, epilepsy, chronic fatigue syndrome, Parkinson's disease, alzheimer's, mental retardation, lymphoma, birth defects, fibromyalgia and diabetes.

Is this really something you want to be eating?

More than 5,000 products contain aspartame. It's in your best interests, as well as your family's, for you to read the labels of any processed food you're concerned about.

If you want the full story on aspartame, you'll want to consider viewing Sweet Misery, a 90-minute documentary that perfectly summarizes its history.

About the author: This article is reprinted from, the world's #1 most visited and trusted natural/alternative health website. For a limited time only, you can take the FREE "Metabolic Type Test" to help you learn the right foods for your particular body type so you can achieve optimal fitness & health. Just go to right now to take this quick test!

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