A 2013 study is often cited when the discussion turns to the cancer-fighting properties of citrus fruits, and their flavonoids, in particular. The study by researchers at the Jeju National University School of Medicine in Jeju, Korea was published in the journal Breast Cancer with the title Citrus Fruit Intake and Breast Cancer Risk: A Quantitative Systematic Review.
The landmark study took in the results of all epidemiological studies up to 2012 that directly evaluated the relationship between the amount of citrus fruit consumed and the risk of breast cancer.
In 2023, breast cancer is the most common type of cancer across the globe. It makes up about 12.5% of all the new cases of cancer diagnosed each year. Finding effective methods of prevention and reducing the risk are crucial to dropping a rate that has been increasing annually across the globe. Many of the other factors, such as menstrual history and lactation, can’t be modified – diet is one method that can.
In 2007, the World Cancer Research Fund report made the conclusion that consuming fruits in general was likely to provide protection against various types of cancer, including mouth, lungs, and stomach cancers.
First, the researchers sifted through hundreds of published articles to find five that fit their fairly strict criteria – five papers which reported on six clinical studies. Citrus intake, in all cases, was part of a broader study of dietary components. In other words, they weren’t looking for a specific link between citrus and breast cancer – but, that’s what they found.
- Pooled results from all the studies showed that the more citrus was eaten, the lower the risk of breast cancer;
- A high intake of citrus fruits was associated with a 10% reduced risk of breast cancer;
Since the review and analysis showed only a relationship, even if it was quantified to a certain extent, it does not show the cause or hint at the mechanism. Future studies are recommended to look into those issues – and in the decade since, many have focused on the role of citrus flavonoids and antioxidants.