Watching what you eat usually involves counting calories - this week though, the colour of your food has become a hot topic.

Warnings about the health risks of eating browned potatoes and burnt toast hit the media and filled social media, yet none of the articles answered the key questions "how much is too much?" or "what are the proven risks?".

The stories were based on a United Kingdom Food Standards Agency (FSA) campaign launched this week, called Go for Gold.

The campaign hopes to reduce the amount of starchy food people eat with a darker brown colour.


This follows a new warning about the health consequences of the chemical acrylamide.

Acrylamide - a chemical produced during the Maillard reaction when food browns - is created when sugars and amino acids react during cooking.

High levels of acrylamide have been found in starchy foods that are roasted, fried or grilled at temperatures over 120C and are common in burnt toast, French fries and potato chips.

Acrylamide has been shown to convert to glycidamide in the body - a compound which can bind to DNA and cause mutations.

It has been shown to cause cancers in mice and, as a result, the International Agency for Research on Cancer has labelled acrylamide a "probable carcinogen".

But can we relate animal studies to human ones?

Although evidence from animal studies shows acrylamide in food could be linked to cancer, this link is not clear or consistent in humans.

Research on adults has tried to estimate how much acrylamide is consumed by analysing reports of daily diets or by directly measuring the levels of acrylamide in the blood over time.

Some studies showed an increased risk of cancer with increased acrylamide consumption, while others showed no additional risk.

The difficulty in human studies is that other lifestyle factors - smoking, drinking alcohol and obesity - as well as differing genetics can carry much more defined cancer risks.

Lab mice don't get to make these lifestyle choices, which is why it's much easier to study animals than humans.

There is no reason to think that at a biological level acrylamide couldn't damage human DNA too; the question is, if it does - how much is too much?

The Go for Gold campaign provides no estimate of the current harm caused, nor the benefit from any reduction.

A quick calculation from the research so far suggests that those adults labelled as the highest consumers of acrylamide would still need to consume over 150 times more to achieve the levels that resulted in increased tumour risk in mice.

That's a lot of fries.

This does not mean there is no risk, but it doesn't mean that burnt toast conclusively causes cancer in the average person's diet.

Instead of sensationalist headlines vilifying certain foods, perhaps more helpful articles suggesting how to reduce acrylamide intake as part of a balanced diet could be more helpful.

Suggestions such as blanching potatoes to remove some of the sugar before frying, or not putting raw potatoes in the fridge, where an enzyme called invertase breaks down the sugar into glucose and fructose.

Both of these suggestions result in lower levels of acrylamide after cooking, as do simple changes such as boiling potatoes and toasting your bread to a lighter colour.

As scientists carry out more experiments to try and determine how acrylamide consumption may affect health, the good news is that food scientists are already producing potato varieties which naturally produce less asparagine, an amino acid that seems to be important for making acrylamide, so there is hope for us chip lovers yet!

Dr Michelle Dickinson

, also known as Nanogirl, is an Auckland University nanotechnologist who is passionate about getting Kiwis hooked on science. Tweet her your science questions