Acrylamide in food could increase the risk of developing breast cancer, according to new, EU-funded research published in the International Journal of Cancer.

Acrylamide is a small molecule found in certain processed foods. 'Animal tests have shown acrylamide to be a carcinogen, but until recently no studies have demonstrated a link between acrylamide in foods and cancer in humans,' said Henrik Frandsen of the National Food Institute at the Technical University of Denmark. 'Ours is the first epidemiological study using biological markers for measuring acrylamide exposure, and the first to report a positive association between acrylamide and breast cancer.'

Previous studies have used food frequency questionnaires to assess acrylamide intake levels. To get a more accurate picture of the study participants' acrylamide intake, the Danish researchers measured the levels of acrylamide bound to haemoglobin in the red blood cells.

In total they analysed the acrylamide levels of 374 postmenopausal women who developed breast cancer and 374 healthy women. After adjusting for smoking behaviour, the findings revealed a positive association between a higher acrylamide-haemoglobin level and the development of breast cancer. The association was stronger for oestrogen receptor positive breast cancer.

The researchers underline the fact that their study does not prove a direct link between acrylamide in food and cancer. 'It is, for example, uncertain whether the observed effect on breast cancer is instead related to other chemical compounds formed along with acrylamide during the heating of foods. Another uncertainty is whether some of the acrylamide originates from sources other than foods,' explained lead author Pelle Thonning Olesen of the National Food Institute, Technical University of Denmark.

'Further research into the potential adverse effects of acrylamide is imperative before any definite conclusions can be drawn on the significance of the substance for cancer in general,' added Anne Tjønneland, chief physician at the Danish Cancer Society. 'At the same time, it emphasises the importance of continuing the research and initiatives aimed to reduce acrylamide levels in the human diet.'

Acrylamide has been used for a long time in the manufacture of plastics, glues, paper and cosmetics, and in the construction of dams and tunnels. However, it was not until 2002 that Swedish researchers discovered high levels of the chemical in processed foods such as crisps and chips. Similar discoveries in other cooked and processed foods in other countries followed, prompting alarm among food safety experts.

Research has since shown that acrylamide is formed during the heating of carbohydrate-rich foods, for example by toasting bread, roasting coffee or frying potatoes. Acrylamide is produced when the amino acid asparagine reacts at high temperatures with certain sugars such as glucose or fructose in what is known as the Maillard reaction.

However, it is precisely this reaction which gives fried foods their distinctive taste and texture and brown colouring. The challenge for researchers therefore is to find ways of processing and heating foods which will preserve the taste and colour imparted to foods by the Maillard reaction while reducing acrylamide levels.

EU support for the Danish study came from the HEATOX project, which was set up to answer key questions about acrylamide, including how it is formed and its effect in the body. In addition to epidemiological studies, the project partners have investigated the Maillard reaction in detail, and developed recommendations on how to reduce its creation during cooking. They have also investigated other, similar molecules.

'[Acrylamide] is the tip of the iceberg,' explained HEATOX Project Coordinator Professor Kerstin Skog of Lund University, who was not involved in the Danish study. 'There are 40 to 50 other compounds which could be formed in this way.' The project partners have created a database of these as a starting point for further studies.

Professor Skog also offered some tips on how to reduce acrylamide levels when cooking food in the home. 'The most important point is that it is important not to overfry,' she told CORDIS News. 'Most acrylamide formation happens during the last few minutes of cooking.'

In other words, burnt, blackened toast is off. Instead home-chefs should aim for a golden yellow colour. So has working on acrylamide affected how Professor Skog prepares food herself? 'To some extent,' she replies. 'I check potatoes are not too brown. But I still drink a lot of coffee.'

Further information

Source: Community R&D Information Service (CORDIS)