Will flaxseeds improve your health? Here's what the evidence says

Flaxseeds are small but mighty.

Packed with fibre, plant-based omega-3s and antioxidant-rich lignans, they may help support heart health, lower cholesterol and ease constipation.

Dietitian Bini Suresh breaks down the evidence, how much you actually need and whether ground flaxseed is a better choice than whole.

Suresh explains that flaxseeds come with three particularly useful nutritional components:

Most people (90% of us, in fact) don't eat enough fibre. So for that alone, flaxseed could be a worthwhile addition to our diets.

"Clinical evidence for flaxseed is stronger than it is for many fashionable 'superfoods', although the effects are still generally modest," says Suresh.

"Research has found that flaxseed consumption may help reduce total and LDL ('bad') cholesterol in some people, particularly when whole or ground flaxseed is used rather than flaxseed oil."

Some studies also suggest regular flaxseed consumption could contribute to slight reductions in blood pressure, particularly among people with elevated cardiovascular risk.

But, says Suresh, "it should complement, not replace, prescribed treatment or an overall heart-healthy diet."

Suresh says it could have some legitimate impact here.

The fibre in flaxseeds "may help to soften and bulk stools," although you need to tread carefully when boosting your fibre intake quickly, she warns.

"Make sure you increase your fluid intake too, else that sudden influx of extra fibre could have the opposite effect."

It's true: taking on too much fibre without drinking extra fluids could actually help cause constipation, as well as bloating and gas.

"Most people see a useful impact from one to two tablespoons daily, with sufficient fluid," says Suresh. "This is a practical amount for most adults."

But be wary of going from zero to hero, as drastically upping your fibre intake all of a sudden can come with digestive issues.

"Start with around one teaspoon to one tablespoon and increase gradually.

"Larger amounts are not automatically better and more than the recommended amount is likely to cause gastrointestinal symptoms.

"Although they don't have to be soaked before eating, soaking can soften them and may make them easier to tolerate."

To get the most nutritional benefit, ground or milled flaxseed is generally the better option.

"The outer shell of the whole seed is relatively resistant to digestion, so fewer of the internal fats and lignans may be absorbed.

"A human study comparing flaxseed forms found that milled flaxseed and flaxseed oil increased blood levels of ALA, whereas whole flaxseed did not. (Though flaxseed oil does not provide fibre)."

You can grind them yourself at home using a seed, spice or coffee grinder.

Don't grind too much at once, though, because this exposes them more to oxygen, which can cause the fats to become rancid.

Suresh recommends:

Ground flaxseed has a mild, nutty flavour and can easily be added to your usual meals.

"A practical approach is to use one tablespoon in breakfast and, once you're used to it, another tablespoon later in the day," says Suresh.

Allergies to flaxseed are possible but rare.

If you get symptoms like bloating, wind, cramps or diarrhoea, you may have had too much too soon, or haven't been drinking enough fluids.

In addition, Suresh says you should avoid having flaxseed at the same time as medication – its fibre may affect the absorption of some medicines.

Seek medical advice before adding it to your diet if you have an existing bowel narrowing, bowel obstruction, severe gastrointestinal symptoms or swallowing difficulties.

Suresh is also quick to point out that fibre-based supplements can contain much higher doses than when you have it in food and come with their own set of risks.

This is especially true of people who are taking anticoagulants, are pregnant, breastfeeding, taking diabetes or blood-pressure medication, or undergoing treatment for a hormone-sensitive condition.

If you fall into these categories, speak to a health professional before taking a supplement, says Suresh.

It's true that it does come with small quantities of cyanogenic glycosides, says Suresh.

"This can sound alarming, but it usually only becomes a concern when excessive intake happens. A normal daily amount (1–2 tablespoons) of commercially produced flaxseed is perfectly safe."

There's guidance about how much cyanogenic glycosides people can have and flaxseed in moderate food portions rather than in very large medicinal doses is not dangerous.

While flaxseed is a good source of fibre (something most of us aren't getting enough of), and it could potentially help lower your cholesterol and blood pressure, Suresh points out it's not a "miracle food, detox ingredient or substitute for an otherwise healthy diet."

In other words, flaxseed can be a useful addition but it isn't a substitute for a balanced and healthy overall diet.

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