Key Findings
This study reviewed the effect flaxseed may have in breast cancer, using sources from PubMed, and websites of institutions like Cancer Research UK and the WHO. Some studies revealed that the ingestion of omega-3 fatty acids is associated with the reduction of breast cancer. Animal studies showed that ALA can decrease the growth, size, and cell proliferation and can increase the death of breast tumor cells. The majority of experimental studies conducted showed that flaxseed increases or maintains tamoxifen’s efficacy on the decrease of tumor growth on cell proliferation and on the increase of apoptosis. It is however necessary to conduct more clinical trials to confirm the association and respective efficacy of flaxseed with tamoxifen. In several experimental studies, diets including 5 or 10% of flaxseed (approximately 25–30 g of flaxseed daily, in humans) inhibited the growth of the ER+ in human breast cancer cells injected in mice. The same happened with the growth of the ER−. Flaxseed also reduced the metastasis of ER− breast tumor. During clinical trials, researchers have concluded that flaxseed has the potential to reduce the growth of tumors in patients with breast cancer, mainly postmenopausal women, and decrease the risk of this type of cancer. Although many of the studies reported in this paper concluded that flaxseed intake may be related to the decreased risk of breast cancer and also to the reduction of the tumor’s growth and size, some studies including premenopausal and postmenopausal women did not show the same results. However, more studies are still necessary, especially clinical trials, to verify the benefits of flaxseed on the treatment of breast cancer.
ABSTRACT
Breast cancer is one of the most common cancers and the second most responsible for cancer mortality worldwide. In 2014, in Portugal approximately 27,200 people died of cancer, of which 1,791 were women with breast cancer. Flaxseed has been one of the most studied foods, regarding possible relations to breast cancer, though mainly in experimental studies in animals, yet in few clinical trials. It is rich in omega-3 fatty acids, α-linolenic acid, lignan, and fibers. One of the main components of flaxseed is the lignans, of which 95% are made of the predominant secoisolariciresinol diglucoside (SDG). SDG is converted into enterolactone and enterodiol, both with antiestrogen activity and structurally similar to estrogen; they can bind to cell receptors, decreasing cell growth. Some studies have shown that the intake of omega-3 fatty acids is related to the reduction of breast cancer risk. In animal studies, α-linolenic acids have been shown to be able to suppress growth, size, and proliferation of cancer cells and also to promote breast cancer cell death. Other animal studies found that the intake of flaxseed combined with tamoxifen can reduce tumor size to a greater extent than taking tamoxifen alone. Additionally, some clinical trials showed that flaxseed can have an important role in decreasing breast cancer risk, mainly in postmenopausal women. Further studies are needed, specifically clinical trials that may demonstrate the potential benefits of flaxseed in breast cancer.
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