"Does Aspartame Cause Cancer?"
The approval of aspartame has a controversial history.
The FDA Commissioner concluded that there was reasonable certainty
that human exposure to aspartame
would not pose a risk of brain damage
resulting in mental retardation, hormonal dysfunction, or both;
and will not cause brain tumors,
however, the FDA’s own Public Board of Inquiry
withdrew their approval over cancer concerns.
Furthermore, several FDA scientists advised
against the approval,
citing the Aspartame company’s own brain tumor tests.
The Commissioner approved aspartame anyway,
before he left the FDA and enjoyed a thousand dollar a day
consultancy position with the aspartame company’s PR firm.
Then the FDA actually prevented the National Toxicology Program (NTP)
from doing further cancer testing,
so we were left with people battling over different rodent studies,
some of which showed increased cancer risk
and some that didn’t.
Reminds me of the whole saccharin story,
where it caused bladder cancer in rats, but not in mice,
leaving us with unanswerable questions like,
"So, are we more like a rat or a mouse?"
We obviously had to put the aspartame question to the test in people,
but the longest human safety study lasted only 18 weeks.
We needed better human data.
Since the largest rat study highlighted lymphomas and leukemias,
the NIH-AARP study tracked blood cancer diagnoses…
and higher levels of aspartame intake
were not associated with the risk of cancer.
It’s a massive study, but was criticized
for only evaluating relatively short-term exposure—
people were only studied for 5 years.
Hey—better than 18 weeks.
But how about 18 years?
All eyes then turned to Harvard,
which started following the health and diets
of medical professionals since before aspartame even came on the market.
In the most comprehensive long-term population study
to evaluate the association
between aspartame intake and cancer risk in humans,
they did find an association between both diet soda
and total aspartame intake and the risks of non-Hodgkin’s lymphoma
and multiple myeloma in men
and leukemia in both men and women.
OK, but why more cancer in men than women?
A similar result was found for pancreatic cancer and diet soda.
Not soda in general,
in fact the only sugar tied to pancreatic cancer risk
was the milk sugar, lactose.
It was the diet soda.
So the male/female discrepancy
could have just been a statistical fluke,
but they decided to dig a little deeper.
Aspartame is broken down into methanol,
and the methanol is turned into formaldehyde,
a documented human carcinogen by this enzyme here,
alcohol dehydrogenase.
The same enzyme that detoxifies regular alcohol
is the same enzyme that converts methanol to formaldehyde.
Is it possible men just have higher levels
of this enzyme than women?
Yes. That’s why women get higher blood alcohol levels
drinking the same amount of alcohol.
If you look at liver samples from men and women,
there’s significantly greater enzyme activity in the men.
So maybe that explains the increased cancer risk in men—
the higher conversion rates from aspartame to formaldehyde.
But how do we test it though?
Ethanol—regular alcohol—
competes with methanol for this same enzyme’s attention.
In fact regular alcohol is actually used as an antidote
for methanol poisoning.
So men who don’t drink
may have higher formaldehyde conversion rates from aspartame
if this whole formaldehyde theory is correct.
And indeed, consistent with this line of reasoning,
it was the men that drank the least alcohol
that appeared to have the greatest cancer risk from aspartame.
A third cohort study has since been published
and found no increased lymphoma risk
associated with diet soda
during a ten year follow-up period.
So no risk detected in the 18 week study,
the 5 year study or the 10 year study,
only in the 18 year study.
What should we make of all this?
Some have called for a re-evaluation of the safety of aspartame.
The horse is kind of "out of the barn" at this point
with 34 million pounds of the stuff produced annually,
but that doesn’t mean we have to eat it,
especially, perhaps, pregnant women and children.