This food and dietary supplement may reduce prostate cancer spread, improve survival in breast cancer, and lower the risk of several cancers.

Flaxseed at a glance

Flaxseed contains many components beneficial to health: lignan precursors, fiber, magnesium, thiamin, and the omega-3 fatty acid alpha-linolenic acid (ALA). The lignan precursor secoisolariciresinol diglycoside (SDG) is found in high concentrations in flaxseed but also in lesser amounts in several other plant foods. 

Flax lignans weakly alter the effects of your natural estrogen but do not have a consistent pro-estrogen effect, and they may even have an anti-estrogen effect. Flaxseed may reduce the spread of prostate cancer and improve survival in breast cancer. It may also lower risk of breast, colon, or lung cancers. 

Research sometimes shows different effects from whole flaxseed and flaxseed supplements. For example, whole (dietary) flax and supplements have different Impacts on blood sugar control and insulin sensitivity. As with many other supplements made from foods, the supplements may not have all the components of the whole food that combine to contribute to the benefits seen with whole flaxseed.

Bacteria in your colon metabolize the precursor into enterolactone and enterodiol. These substances are called “lignans” in some studies, but “lignan metabolites” in other studies. For simplicity, we’ll use the term “lignans” to refer to both precursors and metabolites in general. 

CancerChoices ratings for flaxseed

We rate flaxseed on seven attributes, with 0 the lowest rating and 5 the highest.

See how we evaluate and rate complementary therapies ›



Improving treatment outcomes

See More

Optimizing your body terrain

See More

Managing side effects and promoting wellness

See More

Reducing cancer risk

See More

Use by integrative oncology experts

See More


See More

Affordability and access

See More

Keep reading about flaxseed


Maria Williams

Research and Communications Consultant
View profile

Maria Williams is a research and communications consultant who brings over 15 years’ experience in research, consumer education, and science communication to CancerChoices. She has worked primarily in public health and environmental health.

Maria Williams Research and Communications Consultant

Nancy Hepp, MS

Lead Researcher and Program Manager
View profile

Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher, program manager, and writer for CancerChoices. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher and Program Manager


Laura Pole, RN, MSN, OCNS

Senior Clinical Consultant
View profile

Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, RN, MSN, OCNS Senior Clinical Consultant

Last update: January 6, 2023

Last full literature review: September 2021

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.