The study notes a potential risk between unhealthy low-fat diets and postmenopausal breast cancer


A recent study published in the journal feed Examining the association between low-fat diets (LFDs) and breast cancer risk.

Breast cancer is one of the most common types of breast cancer Cancers are common among females, and account for one in four new cancer cases. Several factors can affect the risk of breast cancer, and some of them are modifiable, such as diet. Besides genetic predisposition, hormonal and lifestyle factors are associated with the risk of developing breast cancer. Dietary factors are responsible for 20%-60% of cancers globally and one-third of cancer deaths in Western countries.

The Women’s Health Initiative trial examined the effect of low-fat dietary patterns with higher intakes of fruits, grains, and vegetables. The incidence of breast cancer after more than eight years of follow-up was 9% lower among the intervention arm. Besides, another study found that a dietary pattern with high-fat choices was associated with breast cancer. Furthermore, recent studies have emphasized the distinction between healthy and less healthy LFDs.

Applied Nutrition Inquiry: Associations between low general fat, healthy and unhealthy dietary patterns and risk of breast cancer in a Mediterranean cohort: the SUN project.  Image credit: Nadia Loboda/Shutterstock

Applied Nutrition Examination: Associations between generally low-fat, healthy and unhealthy dietary patterns and breast cancer risk in a Mediterranean cohort: the SUN project. Image credit: Nadia Loboda/Shutterstock

about studying

The current study investigated the relationship between different LFD patterns and breast cancer risk in a Mediterranean cohort. The group was established in 1999, and participants completed follow-up questionnaires at baseline and every two years after enrolment. The researchers included females who enrolled before March 2017 and completed a food frequency questionnaire (FFQ) before December 2019.

Subjects with a history of breast cancer, menopause before 35 years, and unreasonable total energy intake were excluded. Diet was examined at baseline and 10 years later using the validated FFQ. Participants were stratified by percentage of energy from proteins, carbohydrates, and fats. For proteins and carbohydrates, the researchers assigned 10 and 0 points to participants in the highest and lowest categories (of stickiness). The reverse fat scoring method is adopted.

Accordingly, the team estimated the total LFD, healthy LFD, and unhealthy LFD scores. The LFD health score was based on the percentage of energy from saturated fats, vegetable protein, and high-quality carbohydrates. The unhealthy LFD score was based on the percentage of energy from animal protein, unsaturated fats, and low-quality carbohydrates. In addition, adherence to LFDs was stratified by menopausal status. The primary outcome of the study was breast cancer.

Cox proportional hazard regression was used to estimate hazard ratios and 95% confidence intervals for the overall risk of breast cancer. In addition, pre- and post-menopausal breast cancer risks were assessed. The models were classified according to age and enrollment period. Adjusted multivariate models were used after controlling for confounders. Repeated measures were adjusted to use data from FFQs after 10 years of follow-up.

the findings

The study included 10,930 females with an average age of 35.2. The total LFD score was 0–12 and 19–30 points for the lowest and highest tertiles, respectively. The healthy LFD score was 0–11 and 20–30 points for the lowest and highest tertiles, respectively. The unhealthy LFD score was 0-13 points for the lowest tertile and 18-30 points for the highest tertile.

Participants with higher overall or healthy baseline LFD scores were older, more likely to have been former smokers or never smokers, consumed less alcohol, were more likely to menstruate at an earlier age, and were more physically active. Furthermore, among these participants, there was a higher incidence of hormone replacement therapy use.

By contrast, females with higher unhealthy LFD scores were older, had less energy from high-quality carbohydrates, lower amounts of fat, lower amounts of alcohol, and had a higher body mass index (BMI). Participants were followed for an average of 12.1 years. Researchers identified 150 cases of breast cancer from 1999 to 2000. Overall, healthy and unhealthy LFD scores were not associated with overall breast cancer risk.

Results were similar for repeated measurements after 10 years of follow-up. When stratified by menopausal status, LFD scores were not associated with risk of premenopausal breast cancer. However, moderate adherence to an unhealthy LFD was significantly associated with postmenopausal breast cancer risk, which was nonsignificant with repeated measurements.


In summary, the study found no association between LFD patterns and breast cancer risk. Notably, moderate adherence to unhealthy LFD medication was significantly associated with the risk of postmenopausal breast cancer. However, this should be interpreted with caution given the low number of postmenopausal breast cancer cases and lack of significance with repeated measurements. Future studies should explore the relationship between LFD scores and breast cancer subtypes with larger samples and longer follow-up times.

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