High-temperature processing of foods results in the formation of acrylamide, a substance which may increase the risk of breast cancer. This is the conclusion of research conducted by the National Food Institute, Technical University of Denmark and the Danish Cancer Society. The findings have just been published in the International Journal of Cancer.
Acrylamide is a chemical formed when frying, roasting, grilling or baking carbohydrate-rich foods at temperatures above 120°C. Acrylamide is thus found in a number of foods, such as bread, crisps, French fries and coffee. Tobacco smoking also generates substantial amounts of acrylamide.
"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. 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," says Henrik Frandsen, senior scientist at the National Food Institute, Technical University of Denmark.
Positive association
The study comprises 374 postmenopausal women who developed breast cancer and 374 healthy women as controls. All of them are included in the Danish Cancer Society's “Diet, Cancer and Health” cohort study which enrolled 29,875 women aged 50 to 64 years in the period 1993-1997.
All previous epidemiological studies have been based on food frequency questionnaires. The scientists behind this study have instead used biological markers to be able to more accurately determine the acrylamide levels ingested by the women participating in the study. The women's blood has been tested for the level of acrylamide bound to haemoglobin in red blood cells.
The findings show a positive association between an increased acrylamide-haemoglobin level and the development of breast cancer after adjustment for smoking behaviour. The risk of breast cancer doubles with a tenfold increase in the acrylamide-haemoglobin level. A tenfold increase in the acrylamide-haemoglobin level corresponds more or less to the difference measured between the women with the lowest and highest exposure. The study also shows a stronger association for estrogen receptor positive breast cancer.
Further research required
The findings strengthen the concern that acrylamide is carcinogenic in the quantities to which ordinary people are exposed through their diet. It should also be noted that a new Dutch study shows an association between acrylamide in foods and ovarian and endometrial cancer.
"It is, however, important to stress that neither study indicates an unambiguous association between acrylamide in foods 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," says Pelle Thonning Olesen, scientist at 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. At the same time, it emphasises the importance of continuing the research and initiatives aimed to reduce acrylamide levels in the human diet," adds Anne Tjønneland, chief physician at the Danish Cancer Society.
Read more
The paper in which the new research findings are described is published in the International Journal of Cancer: Acrylamide exposure and incidence of breast cancer among postmenopausal women in the Danish Diet, Cancer and Health study.
The research project was conducted by scientists from the National Food Institute, Technical University of Denmark in collaboration with the Institute of Cancer Epidemiology, the Danish Cancer Society as part of the HEATOX EU project. See www.heatox.org for information about how to manage the acrylamide risk.
The project was funded by the EU's Sixth Framework Programme and by a grant from the Nordic Council of Ministers and was completed with support from the National Food Institute, Technical University of Denmark and the Danish Cancer Society.
Contact
Scientist Pelle Thonning Olesen,
petol@food.dtu.dk, tel. +45 7234 7564
Head of department, chief physician Anne Tjønneland
annet@cancer.dk, tel. +45 3525 7607