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Food Focus November 2007

Sweet nothings

Media reports about possible reactions to large doses of the sweetener aspartame from chewing gum, and studies suggesting a link with cancer fly in the face of dozens of those that have been evaluated by leading food safety agencies around the world. Food Focus finds out why

Detractors label it a toxic sludge and claim it damages the brain, causing – among other things – headaches, mental confusion, seizures and faulty balance. Symptoms created by its reported use range from abdominal pain through to heart palpitations, loss of vision, cancer – even death.

Since NZFSA moved to allay consumer fears over the continued use of aspartame as a low-calorie alternative to sugar, members of staff have found themselves the subject of vicious attacks on internet blog sites whose anonymous authors accuse them of “poisoning Aotearoans”.

If the tide of opposition to be found after just a couple of Google clicks is anything to go by, aspartame poses the biggest threat to human health since the plague.

Yet none of this seems to concern NZFSA’s principal toxicologist John Reeve who happily pops several tabs of the stuff into his daily tea, coffee and drinking chocolate – and has been doing so “for years”.

“I’ve read hundreds of studies on aspartame and I’m happy to continue using it as an alternative to sugar. I like the taste,” he says.

Unfortunately it appears not everybody is able to so easily get to grips with the weight of scientific evidence underpinning the safety of aspartame. Death threats and derision are among the arsenal of those campaigning to have it removed from the food supply.

New Zealanders – and consumers all around the world – are constantly exposed to a steady diet of pseudo-scientific ‘facts’ about the food we eat. This can make it difficult for those among us who don’t have a degree in toxicology, and yet display a preference for facts over fiction, to decide what we should – and shouldn’t – worry about.

Assessing the integrity and credibility of such diverse information against a background of bellowing headlines that urge us to steer clear of everything from apricots to amaranth is enough to cause headaches, crankiness, tiredness, muscle spasms – not to mention bitten fingernails and an overwhelming sense of confusion. Sound familiar?

As well, the old adage ‘everything in moderation’ needs to be considered here. Eating too much of any one thing is not good for you – even those things we consume every day, such as coffee, carrots and cake.

Competing sciences

Distinguishing between good science and junk science can seem like a science in itself. One definition of junk science is ‘faulty scientific data and analysis used to advance special and often hidden agendas’.

Good science follows the scientific method: observe, develop hypothesis, repeat testing and refinement until the final hypothesis fits the phenomenon. It involves peer review and robust systems of analysis and interpretation. The work can take decades, is slow – and rarely makes the headlines.

Junk science is just the opposite: the studies are poorly conducted; the results can be inconsistent; the research is not always accepted by peers – and the results are often sensational.

So how do NZFSA scientists know who – or what – to believe? In the case of aspartame, argues John, the case is clear-cut.

Aspartame, he says, is probably one of the most studied products on sale today. “And there is an extensive body of evidence that proves it offers consumers a safe, low-calorie option in their diets and is the preferred choice for many diabetics.”

Acceptable daily intakes

The skeptics among you may be forgiven, at this point, for thinking all that smoke must be evidence of a small fire burning somewhere. But, says John, such attention proves the opposite: the weight of evidence in support of aspartame means that regulatory bodies around the world continue to advocate its use and see no reason to alter its Acceptable Daily Intake (ADI) which is set at 40 milligrams per kilogram of body weight (40mg/kg bw) – one of the highest among food additives. This ADI also takes into account the body’s ability to process the relatively small amounts of methanol resulting from digesting aspartame – another issue often raised by aspartame critics. (An ADI is the amount of an additive that can be taken in daily over a lifetime without damaging people’s health. It is expressed in relation to bodyweight (bw) to allow for different body size, such as for children of different ages.)

“All the carcinogenicity studies carried out on aspartame to agreed OECD protocols show it to be safe,” says John. “None make any connection whatsoever between aspartame and cancer.”

And therein lies the rub. The fundamental flaw of both aspartame studies by the Ramazzini Foundation of Oncology and Environmental Sciences, produced in 2004 and more recently in June of this year to a flurry of media coverage, is that they do not follow the OECD protocols.

These protocols set out the parameters for such experiments which involve lifetime-feeding studies on animals (mainly rats), and are based on the premise that the longer the trial, the more likely it is that carcinogenic effects will be picked up.

Ageing pathology

However, though the length of the study is important when trying to identify a problem, running the experiment over too long a period will see the results become ‘uninterpretable’. And the reason is ageing pathology. In other words, the natural process of DNA breakdown that leads, inevitably, to death in all of us.

John explains: “Ageing pathology is the natural onset of old age. Mistakes occur in the DNA reproduction process, genetic variations begin to appear in animals – just as they do in humans.

“Because ageing pathology cannot be ignored, carcinogenicity experiments become carefully constructed juggling acts. To maintain statistical integrity, they must involve a set number of animals split into several dose groups ranging from a top dose group (which receives a maximum tolerated dose known to show a measurable health effect) through to groups fed incrementally decreasing amounts of the additive, down to the control group, which is fed a diet that does not include any additive. Normally there are at least five such groups.

“More importantly, the experiment must run for long enough to ensure any effects are picked up. [In the case of rats OECD protocols suggest two years which represents 90% of the animal’s average lifespan.] They should then stop either when the two years are up or, beyond that, once the surviving rats drop to 30% of their original number in any dose group. After that, ageing pathology begins to take hold and its effects overwhelm the results.”

Cancer rates

Both Ramazzini studies, says John, claim their carcinogenicity experiments resulted in massive increases in tumours among rats fed levels of aspartame similar to those considered normal in terms of human consumption and certainly at the ADI-agreed level.

The tests, they claimed, were carried out according to internationally recognised good laboratory practises. “But”, counters John, “the experiments ran until the rats all died naturally and any effect of aspartame (if present) was overwhelmed by ageing pathology. They could have been fed anything – the end results would have been the same.”

As well, the results showed very little difference in the cancer rates between those fed 400mg/kg of aspartame and the control group (around 45%). In fact all the rats – including those fed 2000mg/kg of aspartame – had cancer rates that make it statistically impossible, using sound scientific methodology, to claim an identifiable link between aspartame and cancer.

“When experiments such as these make claims which fly in the face of so many others carried out according to OECD protocols, NZFSA scientists are compelled to take a second look and consider what makes those studies so different. It often doesn’t take long for us to be able to work out the answer.”

Unsafe formaldehyde levels

“Furthermore, claims saying that aspartame leads to unsafe levels of formaldehyde in people are just ridiculous.”

The metabolism of aspartame in the human body is well known. Says John: “In the gastrointestinal tract, aspartame is hydrolysed to one of its component materials, methanol, as well as the two amino acids, phenylalanine and aspartic acid. This methanol is taken up by the cells of the body and metabolised first to formaldhyde and then to formate. The key information that is missing from highly misleading claims such as this, is that the levels of ingestion are very small.”

In fact, there are other foods that supply as much and even more methanol, such as citrus fruits and juices, and tomatoes or tomato juice. Thus, in the final analysis this methanol is the same as from other food sources and in the quantities consumed from aspartame, it is readily and naturally metabolised via the one-carbon biochemical cycle to entirely innocuous and natural body components.

NZFSA believes aspartame has a useful role in managing sugar and energy intakes without any adverse effects in most people. However, if you’d generally prefer to avoid it, make sure you study your food labels.

When it’s added to food, aspartame must be declared as ‘sweetener (aspartame)’ or by its code number: 951.

What they said about aspartame

European Food Safety Authority (EFSA)

The Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food has assessed the Ramazzini Foundation’s new carcinogenicity study. The Panel considers the study has flaws which bring into question the validity of the findings … the slight increase in incidence of tumours in rats fed aspartame is considered to be an incidental finding … and can therefore be dismissed. In summary, the Panel concludes, on the basis of all the evidence currently available from the ERF study, other recent studies and previous evaluations, that there is no reason to revise the previously established ADI for aspartame of 40mg/kg bw.

Food Standards Australia New Zealand (FSANZ)

The decision by the European Food Safety Authority not to alter the ADI for aspartame endorses FSANZ’s 2003 conclusion that aspartame, used in the approved manner, is safe for human consumption. It is identified either by name or by the number [951] on food labels if it is present in food. Consumers can use this information to assist decision-making.

US Food and Drug Administration (FDA)

FDA has completed its review concerning the long-term carcinogenicity study of aspartame … conducted by the European Ramazzini Foundation (ERF). FDA reviewed the study data made available to them and finds that it does not support ERF’s conclusion that aspartame is a carcinogen. Additionally, these data do not provide evidence to alter FDA’s conclusion that the use of aspartame is safe.