Sunday, July 7, 2013

Aspartame, a Cancer Protective Brain Toxin? Is There a Hormetic Threshold for the Consumption of the Dreaded Artificial Sweetener? Plus: What Do We Know, Anyway?

The beauty ideals have changed over the years. Coke, however, is still there. But are we going to say the same about the aspartame in diet coke 50 years from today? I don't think so - regardless of what the science says...
Artificial sweeteners are one of the "hot topics" here at the SuppVersity and I am already looking forward to the upheaval today's post on aspartame is probably going to cause - and that despite the fact that the bottom line is probably going to satisfy both the critics and "not so critics" (I actually don't know any real aspartame enthusiasts ;-) among the SuppVersity readers...

But let's not fast forward too much and rather take a peak at the review Karol Rycerz & Jadwiga E. Jaworska-Adamu from  University of Life Sciences in Lublin (Poland) recently published in a special issue of Folia Neuropatholgica (Rycerz. 2013).

Actually their paper starts out like one of the countless "aspartame is the devil" articles you would expect to see when you type the words "aspartame" and "cancer" into a search engine. Yet despite the fact that they refer to aspartame as a "widespread sweetener used in many food products" that is considered "a highly hazardous compound" (Rycerz. 2013), the abstract to their review also mentions that
 "[...] the action of astrocytes during aspartame poisoning may be advantageous for neuro-protection." (Rycers. 2013)
This statement is not just surprising it does also conflict with the authors' self-declared aim to "demonstrate the direct and indirect role of astrocytes participating in the harmful effects of aspartame metabolites on neurons" (Rycerz. 2013) and reminds you of the literal fish out of water.

The authors leave no doubt: They think aspartame is dangerous

The results of a study from the University of Western Sidney  to suggest that you could keep your insulin levels at bay, if you mixed your sugary intra-workout supplement with aspartame-laden diet coke instead of water (learn more)
You may remember from an older episode of the Science Round Up on the Super Human Radio Network that a more recent rodent study by Iyyaswamy & Rathinasamy suggested that we may have overlooked the negative effects of aspartame on the human brain in previous rodent trials due to differences in the way the methanol which comprises 10% of the breakdown products of aspartame, is metabolized in the human vs. the rodent body (Iyyaswamy. 2012). The Indians tried to mimic the slow(er) turnover rates by the provision of methotrexate and observed a significant increase in oxidative stress in the brain at much lower doses of aspartame than they have been used in any of the previous rodent studies, the majority of which support the notion that aspartame is totally benign unless it is consumed in amounts as high as you would find in a whole truckload of diet coke.

Despite the fact that we are thus still not 100% sure how dangerous aspartame actually is, it is probably not as benign as the pre-2012 data may have suggested. Against that background Rycerz' and Jaworska's elaborations shouldn't be discarded as totally irrelevant. It does after all appear logical that ...
  • ... the reduced levels of dopamine and serotonin in response to the aspartame induced presence of excess amounts of phenylalanine that blocks the transport of important neurotransmitter precursors (tryptophan, l-tyrosine & co) to the brain, as well as the
  • ... the neuronal hyper-excitability that's caused by the high aspartic acid concentrations in the presence of other excitatory amino acids like glutamates
may be detrimental to the brain, even in the absence of the previously mentioned brain toxic effects of methanol, which may "cause CNS depression, vision disorders and other symptoms leading ultimately to meta-bolic acidosis and coma" (Rycers. 2013).

Hyperexcitatory, toxic, dangerous and protective?

   Figure 1: Graphical illustration of the break down and down stream effects on GABA, dopamine, serotoine & co that are induced by high amounts of aspartame in the brain - keep in mind that "high" is more than the occasional glass of diet coke (Rycers. 2013)
In view of all these horror stories and accumulating evidence that dike-topiperazine (DKP) a metabolie of aspartame that is formed during prolonged storage of artificially sweetened foods ant is accordinly particularly high in (diet) energy drinks and cola (Roj. 2009) promotes the formation of brain tumors (Roberts. 1991; note: the incidence for lymphomas due to DKP consumption is much higher than that for brain cancer), it is hard to believe that "[...] the action of astrocytes during aspartame poisoning may be advantageous for neuro-protection." (Rycers. 2013)

While it is a matter of fact that the activation of the glia by the presence of smaller amounts of glutamate, aspartate and other excitatory neurotransmitters in response to aspartame consumption may exert hormetic effects by inducing corresponding autoregulatory effects that re-establish normal neurotransmitter levels and reduce the potential (over-)expression of the cancer promoting pro-inflam-matory cytokines IL-1, IL-6, TNF-α, PGE2. This is up to now nothing but a hypothesis.
Questionable "brain health effects": While you may remember that Carl and I talked about the beneficial effects / necessity of inflammation, when it comes to getting rid of  degenerate cells in several of the recent episodes of the Science Round Up (read up on hormesis, as well), I highly doubt that you will be able to hit that "sweet spot" of maximal hormesis, where a minimal amount of aspartame toxicity is going to give you an increase in your brains endogenous defense system that would not just negate the potential downsides, but exert the "neuroprotective"effects Rycers et al. imply in the abstract of their review.

Suggested Read: "Coke vs. Diet Coke vs. Milk - The Unhealthy Beverage Shoot-Out: Milk Reduces, Coke Increases Visceral Fat. Dreaded Diet Coke on Par With Plain Water" (read more)
That being said, it is not exactly likely that the occasional cup of diet coke or the consumption of a pre-workout, protein or other supplement with minor amounts of aspartame in it, will reach your brain in those amounts that would be necessary to elicit either beneficial or negative effects on your neurons.

For the true aspartame junkies, on the other hand, the sheer amount of other potentially health threatening agents, like citric acid, phosphor, carmine coloring and co may eventually be so high that they become a much greater thread to your health than the comparatively minor amounts of aspartame in the chemical cocktails that are marketed as healthy alternatives to regular sodas.

  • Iyyaswamy A, Rathinasamy S. Effect of chronic exposure to aspartame on oxidative stress in the brain of albino rats. J Biosci. 2012 Sep;37(4):679-88.
  • Roberts HJ. Does Aspartame Cause Human Brain Cancer? J Adv Med 1991; 4: 231-241.
  • Rój A, Stasiuk E. Oznaczenia  jakościowe w zakresie zawartości aspartamu i jego metabolitów w napojach gazowanych bezalko -holowych z zastosowaniem techniki HPLC. Bromat Chem Toksykol 2009; 3: 543-547.
  • Rycerz K, Jaworska-Adamu JE. Effects of aspartame metabolites on astrocytes and neurons. Folia Neuropathol. 2013;51(1):10-7.