Flaxseed antioxidants and anti-cancer effects in lab and human studies
What it found
Flaxseed contains omega-3 fatty acids, lignans and polyphenols that showed antioxidant and anti-cancer activity in lab and animal studies, but human results on inflammation were mixed.
The authors say more research is needed on safety and long-term effects.
What they found
Studies in people
Mixed human inflammation results
Some human studies found no significant effect of flaxseed on inflammatory markers. In overweight perimenopausal women, overweight prediabetic adults, and normal-weight people on a healthy diet, flaxseed or flaxseed oil did not significantly change inflammatory markers or lipid profiles.
Animal and lab studies
Anti-cancer activity in cells
Lab studies found that substances in flaxseed acted against breast cancer cells, cervical cancer cells, ovarian cancer, colon cancer, leukemia cells and melanoma cells. Flaxseed oil inhibited melanoma metastasis and reduced lung cancer growth in these studies, and did not inhibit the growth of non-cancerous cells.
Studies in people and animals
Antioxidant and anti-inflammatory effects
In overweight people with a BMI over 30, flaxseed consumption reduced levels of TNF-alpha, CRP and hs-CRP compared to placebo. In other population subgroups, no significant differences were seen. In rodents, an ALA-enriched diet reduced oxidative stress and inflammation during heart attack.
Lignans and hormone-related cancers
The lignans enterodiol and enterolactone are believed to be partly responsible for inhibiting the growth of human prostate cancer. Case-control studies have shown a link between higher urinary enterolactone levels and lower breast cancer risk.
Other findings
Active compounds in flaxseed
Flaxseed contains omega-3 fatty acids including alpha-linolenic acid (ALA), lignans such as secoisolariciresinol diglucoside (SDG), polyphenols, fibre, vitamins and minerals. ALA makes up about 55% of the total fatty acid content, and SDG makes up about 95% of the lignan content.
Harmful compounds in flaxseed
Flaxseed contains cyanogenic glycosides at around 100 to 300 mg hydrogen cyanide per kilogram of seeds, which can be broken down into toxic hydrogen cyanide in the body. It also contains phytic acid, which blocks absorption of minerals like calcium, iron, magnesium and zinc, and proteolytic enzyme inhibitors that can interfere with protein digestion.
What the authors conclude
“However, the anti-inflammatory effects of flaxseed have been reported inconsistently, and the lack of a strong anti-inflammatory response could limit its preventive impact on cancer development.”
Also in their conclusions
- They conclude that recent scientific research has increasingly confirmed flaxseed's anti-cancer properties, particularly its effectiveness in preventing hormone-related cancers such as breast and prostate cancer, and its ability to inhibit tumour growth.
- They note that the anti-inflammatory effects of flaxseed have been reported inconsistently, and that this lack of a strong anti-inflammatory response could limit its preventive impact on cancer development.
- They advise that further research is needed to refine consumption guidelines, ensuring maximum benefits while minimising risks associated with overconsumption or improper use.
How it was done
The authors wanted to summarise the scientific literature on flaxseed's antioxidant and anti-cancer properties, and to highlight gaps in knowledge about safety and long-term adverse effects.
They reviewed 117 scientific papers published between 1997 and 2024, found through PubMed/MEDLINE, ScienceDirect and Wiley Online Library, that documented the antioxidant and anti-cancer effects of flaxseed.
What it can’t tell you
- This is a review of many different studies, so it cannot show cause and effect for any single outcome.
- Many of the anti-cancer findings come from lab and animal studies, which cannot show what happens in people.
- The human studies on inflammation gave mixed results, so it is not clear who might benefit or at what dose.
Who paid
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Medical College of Rzeszów University, Poland
The paper
- Title
- Anti-Oxidant and Anti-Cancer Properties of Flaxseed
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Stepień AE, Trojniak J, Tabarkiewicz J (2025). Anti-Oxidant and Anti-Cancer Properties of Flaxseed. International journal of molecular sciences. doi:10.3390/ijms26031226Free full textPubMed 39940995DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error