23 March 2005 - written by Bupa's Health information team
A study has shown that a chemical in baked and fried food does not increase the risk of breast cancer in women.1
The chemical, acrylamide, is found in fried foods, crisps, coffee, chips and biscuits.1,2 Laboratory studies have shown that high doses of acrylamide cause cancer in animals. Scientists feared that eating foods containing the substance may put people at risk too.2
Earlier studies in people have already shown that acrylamide does not cause bladder, bowel or kidney cancer either.2,3,4
These findings suggest that the potential cancer risk from eating acrylamide-containing foods is very small.
Acrylamide is a chemical used in a number of industrial processes including making cosmetics and glues, and removing particles from drinking water.5
However, acrylamide is also found in some cooked foods.
High levels of acrylamide are found in starchy foods (foods containing complex carbohydrates, such as potatoes and cereals) that have been fried, oven-baked or microwaved, including:1,2,9,12
Acrylamide is also found in coffee, formed when the coffee beans are roasted.1 Lower levels of acrylamide are found in protein-rich foods such as cooked beef and chicken.9,12 Very little or no acrylamide is found in uncooked or boiled foods.9,12
Acrylamide forms when starchy foods are cooked at temperatures of more than 100°C.
Certain foods contain a substance called asparagine. When this is heated to more than 100°C it reacts with the sugars in starchy food to produce acrylamide.11
Yes. Any cooking method that uses temperatures over 100°C can produce acrylamide in starchy foods. This includes:9
The higher the temperature the starchy food is heated to, the more acrylamide is formed.9
Boiled foods do not contain acrylamide because they are not cooked at temperatures above 100°C.9,12
The researchers looked at the diets of more than 43,000 Swedish women, including 667 women with breast cancer.1
In 1991 the women filled in questionnaires about how often they ate different foods. The researchers used their answers to work out how much acrylamide the women were eating each day.
The women were split into five groups according to how much acrylamide they ate. Group one ate the least, group five ate the most.
The researchers also followed the women's health until the end of 2002.1 This allowed the researchers to compare the women's daily acrylamide intake with the development of breast cancer.1
Women in group one ate about 12 micrograms a day and women in group five ate about 44 micrograms a day.1
The average daily acrylamide intake was 25.9 micrograms.1 This is roughly 1,000 to 100,000 times lower than the levels that cause cancer in animals.1
The foods that contributed the most to the women's daily intake of acrylamide were:1
The study found that the women who ate more foods containing acrylamide (groups two to five) had the same risk of developing breast cancer as those who ate the smallest amounts of these foods (group one).1
According to this study, eating acrylamide-rich foods does not increase the risk of developing breast cancer.1
Earlier research has found that found that eating acrylamide does not increase the risk of developing kidney, bladder or large bowel cancers. Scientists had previously thought that these were the cancers most likely to be caused by acrylamide.2,3,4
Rats and mice given high doses of acrylamide develop cancers in their breasts, lungs, thyroid glands, adrenal glands, testes and central nervous system.5,6
Because of these findings, acrylamide was classified as "probably carcinogenic (cancer-inducing) to humans" by the World Health Organisation's International Agency for Research on Cancer.5
However, it has never been shown that acrylamide actually causes cancer in humans.5,6
Acrylamide can affect the nervous system if high doses are eaten or inhaled, or people are exposed to it long-term - for example people working in an industry using the chemical.5,6 It can cause fits or hallucinations, or altered behaviour.6
Each year, 41,000 women are diagnosed with breast cancer in the UK.7 It accounts for one in three cases of cancer, making it the most common cancer in women.7 One in nine women will develop the disease at some time in her life.8
The risk of developing breast cancer is very small in young women and increases as women get older. More than half of breast cancers occur in women over the age of 65.8.
No. Breast cancer can occur in men, but it is more than 100 times less common than in women (there are roughly 300 new cases a year).7
For more information on breast cancer, please see Bupa's factsheet.
Breast cancer
The best way to reduce your risk of cancer is by eating a balanced diet that is low in fat and red meat, and rich in fruit, vegetables and fibre.2
All websites accessed on 18 March 2005