Flaxseed is a popular traditional food and remedy, as flaxseed and flaxseed oil, or linseed oil, contain alpha-linolenic acid (ALA), an omega-3 fatty acid.
Omega-3 fats are important for maintaining the body's health. Oily fish are a common source of some types of omega-3, but for non-fish eaters, alpha linolenic acid from vegetable oils, including flaxseed, are an alternative.
However, chemical differences mean vegetable sources of omega-3 fatty acids may not be as heart-healthy as those from oily fish.
Why do people take flaxseed?
Linseed is an ingredient in traditional herbal remedies registered with the medicines regulator MHRA for the short term relief of constipation.
Some people believe flaxseed helps with heart health, supports a person's mood and emotional wellbeing and helps maintain the skin's barriers. However, the European food regulator EFSA has rejected health claims for these uses due to a lack of evidence.
There are no authorised health claims for flaxseed, but some research suggests it may have some possible health benefits.
Arthritis Research UK says evidence so far suggests that flaxseed oil isn’t effective for treating rheumatoid arthritis.
While flaxseed hasn't yet been shown to improve heart disease risk, there's some evidence that flaxseed and flaxseed oil may lower cholesterol levels. For instance, a 2008 study of 66 patients published in the British Journal of Nutrition, found lipid-lowering effects following a daily supplement of tablets containing flaxseed. However, the NHS says: "Evidence suggests that vegetarian sources of omega-3 fatty acids may not have the same benefits for reducing the risk of heart disease as those in oily fish."
Ground flaxseed - but not flaxseed oil - may also help with menopausal symptoms. Research has shown that 40 grams per day may be similar to hormone therapy for improving mild menopause symptoms, such as hot flushes and night sweats. However, another study found no benefits of flaxseed in relieving menopausal symptoms.
Some study results suggest flaxseed may improve kidney function in people with lupus, but more research is needed. If you have lupus - or any other medical condition - it's very important to talk to your doctor about any supplements you take.
Flaxseed is being studied for many other conditions, ranging from cancer to diabetes to osteoporosis. At this point, there is not enough evidence to support flaxseed for these conditions.
How much flaxseed should you take?
There is no set dose for flaxseed. Flaxseed must be ground prior to ingestion or it won’t be able to provide benefits for the health conditions described. Ask your doctor or a dietitian for advice.
Flaxseed can be mixed with liquid or food, such as muffins or bread. For better absorption, some people grind whole flaxseed before using it.
Can you get flaxseed naturally from foods?
While no other food sources contain flaxseed, flaxseed is itself sometimes added to foods. Ground flaxseed is sold as flour. Flaxseed oil is sometimes added to salad dressing.