Flaxseed

Flaxseed has been used as a traditional food and remedy in Mediterranean cultures for thousands of years. Flaxseed and flaxseed oil - made from crushed flaxseed - is now popular in the UK.

Why do people take flaxseed?

Flaxseed and flaxseed oil contain alpha-linolenic acid (ALA), an omega-3 fatty acid that partly and inefficiently is converted into DHA and EPA - more active omega-3s - in the body. 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 studies suggest ground flaxseed may also ease constipation.

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 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.

What are the risks of taking flaxseed?

Side effects. Generally-speaking flaxseed and flaxseed oil seem to be safe. Flaxseed - but not flaxseed oil - contains soluble fibre. It might cause diarrhoea, cramping, wind and bloating. Large amounts of flaxseed, especially when not taken with enough water, can cause constipation and even bowel obstruction. 

Interactions. If you take any medicines or other supplements regularly, talk to your doctor before you start using flaxseed. Flaxseed may block the normal absorption of medicines. Always take medicines at least one hour before or two hours after using flaxseed. Flaxseed and flaxseed oil may also interact with drugs like blood thinners, non-steroidal anti-inflammatory drug (NSAID) painkillers, hormone treatments and medicines for blood pressure, cholesterol and diabetes. Use caution when taking flaxseed or flaxseed oil with supplements like St. John's wort and valerian. 

Risks. Never eat raw or unripe flaxseed - it could be poisonous. People who have diabetes, bipolar disorder, high triglycerides, bleeding disorders or prostate cancer should seek medical advice before using flaxseed or flaxseed oil. Anyone with digestive problems (like Crohn's disease, IBS or colitis) and women with hormone-sensitive diseases (like endometriosis, PCOS, breast cancer and uterine cancer) should not use flaxseed.

Given the lack of evidence about its safety, flaxseed and flaxseed oil is not recommended for children or for women who are pregnant or breastfeeding.