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It's a dieter's and diabetic's dream come true: artificially sweetened products one can consume all day without worrying
about the sugar or calories. As a clinical nutritionist I was skeptical and decided to examine this phenomenon more closely.
First of all, when you ask most consumers of diet soda to tell you what type of sweetener is added, they will give one
of the commercial names of the sweetener aspartame. But if you probe further and ask what is in aspartame, they will likely
shrug their shoulders. Most people are not aware of aspartame's composition because there is no requirement to list its individual
ingredients on food labels.
Aspartame was originally discovered by accident in 1965 by a chemist working for a pharmaceutical
company. He was actually testing an ulcer drug when he spilled some chemicals on his hand. Later when he licked his finger
to turn a page, he was amazed to discovered an intensely sweet taste. Today, aspartame is widely available and can be found
in almost 9,000 food products.
Although Aspartame is calorie-free, consuming it may not come without a price. Because
is is 200 to 400 times sweeter than sugar, the brain is fooled into believing an abnormally high amount of glucose has entered
the bloodstream. In response, the pancreas is stimulated to secrete insulin to lower serum glucose levels. This may in fact
cause blood sugar levels to fall below normal leading to a serious condition known as hypoglycemia. The brain's preferred
source of energy is derived from glucose and when blood sugar levels fall too low, the brain panics and sends out food craving
messages. This may cause the individual to actually eat more food (usually the wrong foods such as high sugar/high fat). This
may sabotage any weight loss intentions.
Aspartame's three ingredients can be found in any nutrition or biochemistry
textbook. It is 40% aspartic acid, (an amino acid) and 50% phenylalanine, (another amino acid). Both of these amino acids
are bound to a molecule of methanol (wood alcohol), which comprises the remaining 10% of this all-natural, artificial sweetener.
Since it contains two amino acids, it is not considered a carbohydrate.
Lets explore the ingredients separately, starting
with aspartic acid. This amino acid in free form (unbound) can pass the blood brain barrier and accumulate in the brain. Once
there, it has the potential to act as an excitotoxin and it can excite or over stimulate neurons.
Excess levels of
phenylalanine in the blood can interfere with the absorption into the brain of another amino acid, tryptophan. This in turn
can result in lower levels of the neurotransmitter serotonin since tryptophan is necessary its production. Decreased serotonin
in the brain may be associated with depression. In addition, since serotonin is a precursor to the hormone melatonin, sleep
disorders may also result.
One serious caution for the use of aspartame may involve individuals with the genetic disorder
known as phenylketonuria (PKU). In this instance, the enzyme required to metabolize phenylalanine is defective and compounds
known as phenylketones are produced. This substance accumulates in the blood and may cause brain damage in these individuals.
Once aspartame enters the small intestine, methanol is released and absorbed into the body. Methanol is then metabolized
to formaldehyde (embalming fluid) and to formic acid (normally found in the sting of red ants). Due to its low excretion rate,
the EPA considers methanol a cumulative poison. It is recommended that its consumption of methanol be limited to 7.8 mg per
day. One serving (8 ounces) of a diet beverage contains 14 mg. Symptoms of methanol toxicity include vision problems, headaches,
dizziness, nausea, gastrointestinal disorders, weakness, behavioral changes and memory loss.
Aspartame has been widely
tested on rodents, with no reported deaths attributed to aspartame consumption. However, one possible confounding variable
in these safety studies is the fact that rodents possess different enzyme systems than humans and are better able to metabolize
aspartame. Therefore, it can be concluded that it is perfectly safe to give aspartame to your pet rat.
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