Can Flaxseed Help Prevent Breast Cancer?

Flaxseed is high in lignans, a compound found naturally in a variety of food sources, including seeds (1).

Lignans are considered phytoestrogens, meaning that they mimic the effects of estrogen in the body but are substantially weaker (1).

Phytoestrogens may be particularly beneficial for the prevention of breast cancer, as some studies show that they could help block estrogen synthesis and metabolism to slow cancer cell growth (2, 3).

According to one study in over 400 people, increased consumption of lignans was associated with a lower risk of breast cancer (4).

Another 2012 study had similar findings, reporting that women who consumed the highest amount of lignans had 40–50% lower odds of breast cancer compared with those who consumed the lowest amount (5).

However, whether or not the lignan content of flaxseed could aid in cancer prevention remains controversial, as other studies have turned up mixed results (1, 6, 7).

Therefore, more studies are needed to understand the effects of lignan-rich foods, such as flaxseed, on cancer development.

However, for those diagnosed with estrogen receptor positive breast cancer, some oncologists recommend against consuming phytoestrogen-containing foods like flaxseed. There is some evidence that these compounds may interact with anti-cancer drugs (8, 9).

It’s best to talk with a healthcare professional before consuming flaxseed if you have a breast cancer diagnosis.

summary

Flaxseed is rich in lignans, a type of phytoestrogen that mimics the effects of estrogen in the body. Some studies have found that increased intake of lignans could be beneficial for the prevention of breast cancer, but more research is needed.

Flaxseed and flaxseed oil are rich in omega-3 fatty acids, a type of healthy fat that has been associated with a long list of benefits (10, 11).

Though omega-3 fatty acids may be most well-known for their effects on heart health, some research suggests that they could help protect against other conditions like cancer as well (12).

In fact, one review noted that omega-3 fatty acids could improve the effectiveness of some chemotherapy drugs and may help kill off breast cancer cells by blocking a specific pathway involved in cell growth (13).

However, omega-3 supplements may interact with some types of chemotherapy agents and other medications that people with cancer often take, such as blood thinners and glucocorticoids, so be sure to talk with a medical professional before consuming (14).

Interestingly, one review also reported that increased intake of omega-3 fatty acids from foods or supplements could be associated with a 31–50% lower risk of breast cancer in older women, plus a reduced risk of recurrence (15).

However, many of these studies focused on the effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are the two active forms of omega-3 fatty acids (16).

Flaxseed contains alpha-linolenic acid (ALA), a type of omega-3 fatty acid found in plant foods that the body converts into DHA and EPA in only limited amounts (16).

For this reason, more research is needed to understand how the omega-3 fatty acids found in flaxseed and flaxseed oil specifically could affect breast cancer.

summary

Flaxseed is high in omega-3 fatty acids, which may help block cancer cell growth. Some studies show that increased intake of omega-3 fatty acids may be linked to a lower risk of breast cancer development and recurrence, but more research is needed.

Flaxseed is loaded with fiber, packing around 2.5 grams into a single tablespoon (9 grams) (17).

Some research suggests that adding more fiber to your diet could protect against a range of conditions, including breast cancer (18).

According to one large review of 20 studies, higher total fiber intake was associated with an 8% lower risk of developing breast cancer in both premenopausal and postmenopausal women (19).

Another review of 24 studies showed that each 10-gram increase in daily fiber intake was associated with a 4% lower risk of breast cancer (20).

What’s more, an analysis of seven studies reported that higher fiber intake may significantly improve survival in people with breast cancer (21).

However, keep in mind that flaxseed oil does not contain fiber, so it may not offer the same fiber-related benefits as ground or whole forms of flaxseed (22).

summary

Whole and ground flaxseed are rich in fiber, which may be associated with a lower risk of developing breast cancer, as well as improved outcomes for people with breast cancer.

Like other nuts and seeds, flaxseed is a great source of antioxidants, including specific compounds like secoisolariciresinol diglucoside, p-coumaric acid, and ferulic acid (23).

Antioxidants can help neutralize harmful free radicals, reduce inflammation, and protect against oxidative damage to your cells (24).

Research also shows that antioxidants can protect against chronic disease and cancer (25).

Interestingly, one review reported that antioxidants could play a key role in the prevention of breast cancer and may even improve the effectiveness of certain therapies used to treat breast cancer (26).

On the other hand, another review concluded that antioxidant supplements had no effect on breast cancer prevention, though it’s unclear whether these results also apply to antioxidants obtained from food sources (27).

Thus, we need more high quality studies to understand how the antioxidants found in flaxseed specifically may affect breast cancer.

summary

Flaxseed is high in antioxidants, which may protect against chronic conditions like cancer. Some studies suggest that antioxidants could aid in the prevention of breast cancer, but additional research is needed.

Multiple older studies have found that flaxseed consumption could be associated with a reduced risk of breast cancer (28, 29, 30).

That association could be due to a combination of factors, including flaxseed’s fiber, lignan, antioxidant, or omega-3 fatty acid content.

However, though many of the individual components of flaxseed could be beneficial, consuming it shouldn’t be considered a quick fix to prevent breast cancer.

A variety of factors can contribute to breast cancer development, including your age, genetics, medical history, lifestyle, and overall diet (31).

For best results, flaxseed and flaxseed oil should be incorporated into a healthy, well-rounded diet and paired with a variety of other nutrient-dense foods.

summary

Though flaxseed may be associated with a lower risk of breast cancer, many factors can contribute to cancer development. As such, you should follow a balanced diet and combine flaxseed with other nutrient-dense foods to support overall health.

Some older studies have found that regular consumption of flaxseed could be linked to a lower risk of breast cancer (28, 29, 30).

Additionally, flaxseed contains several nutrients and compounds that could be beneficial for the prevention of breast cancer, including fiber, lignans, antioxidants, and omega-3 fatty acids (30).

While more thorough research is needed on how flaxseed intake may affect the risk of breast cancer long-term, pairing flaxseed with a balanced diet and healthy lifestyle is a great way to support overall health and add more nutrients to your diet.