Hydrogenated vegetable fat and breast cancer in European women
What it found
In 318,607 European women followed for about 8 years, those who ate the most industrial trans fatty acids had a slightly higher rate of breast cancer than those who ate the least.
The link was also seen for trans fats from dairy and meat.
What they found
Studies in people
Industrial trans fats
Women who ate the most industrial trans fatty acids had a 14% higher rate of breast cancer than those who ate the least. The link was seen from intakes of 0.54 g per day upwards.
Elaidic acid
Elaidic acid, the main industrial trans fat, showed the same pattern: women in the top fifth had a 14% higher rate of breast cancer than those in the bottom fifth.
Ruminant trans fats
Trans fats from dairy and meat were also linked to a higher rate of breast cancer, with a 9% higher rate in the top fifth compared with the bottom fifth.
Individual ruminant fats
Two related ruminant trans fats, conjugated linoleic acid and palmitelaidic acid, were each linked to a higher rate of breast cancer. Vaccenic acid was not linked.
Subgroups
The links were similar when the women were grouped by menopause status, body mass index, or tumour subtype.
What the authors conclude
“These results support the hypothesis that higher dietary intakes of ITFAs, in particular elaidic acid, are associated with elevated breast cancer risk.”
Also in their conclusions
- They say their results support the idea that eating more industrial trans fats, especially elaidic acid, may raise breast cancer risk.
- They note that because conjugated linoleic acid and palmitelaidic acid were so closely linked in the diet, they could not tell which one was driving the association.
- They call for further studies to find the biological pathways behind these links, and say that if the results are confirmed, current limits for industrial trans fats in food may need to be revised.
How it was done
Trans fatty acids have been suggested to affect breast cancer risk, but few large studies had looked at this, especially by tumour subtype, menopause status and body size.
They followed 318,607 women in 9 European countries for a median of 8.1 years, measuring their usual diet at the start with questionnaires. During follow-up, 13,241 breast cancer cases were diagnosed.
What it can’t tell you
- This study followed women over time and measured diet once at the start, so it can show a link but not prove that trans fats cause breast cancer.
- Diet was self-reported, which can lead to measurement error and may underestimate the true links.
Who paid
- Funding
- Funded by World Health Organization; Medical Research Council; Cancer Research UK (from the PubMed record).
- Conflicts
- The authors declare that they have no competing interests.
- Authors work at
- International Agency for Research on Cancer, France; University of Tromsø, Norway; Navarra Public Health Institute, Spain
The paper
- Title
- Dietary intake of trans fatty acids and breast cancer risk in 9 European countries
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Matta M, Huybrechts I, Biessy C, et al (2021). Dietary intake of trans fatty acids and breast cancer risk in 9 European countries. BMC medicine. doi:10.1186/s12916-021-01952-3Free full textPubMed 33781249DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error