Last updated: October 2026
Flaxseed (also called linseed) is one of the richest plant sources of omega-3 ALA, fibre and lignans. A 10g spoonful of ground seed gives about 2.3g of ALA and 2.7g of fibre for 53 calories. Trials link it to modestly lower blood pressure and cholesterol and easier bowel movements. Eat it ground, with plenty of water.
Below: the nutrition in a spoonful, what the research shows for each claim, ground vs whole, the raw flaxseed and cyanide question, flaxseed oil, how much a day, flax vs chia and who should be careful.
Quick facts: Flaxseed and linseed are the same seed. 1 to 2 tablespoons of ground flaxseed a day is a sensible amount for adults, with about 150ml of extra fluid for each tablespoon.
Is flaxseed the same as linseed?
Yes. Flaxseed and linseed are two names for the seed of the flax plant, Linum usitatissimum. The NHS tends to say linseed, while most research says flaxseed. You’ll see brown and golden linseed in the shops, and an NHS dietetics leaflet says it doesn’t matter which you choose for constipation.
Flaxseed nutrition per spoonful
These figures are from the US Department of Agriculture’s FoodData Central database. 10g is about a heaped tablespoon of ground flaxseed or a level tablespoon of whole seeds.
| Nutrient | Per 10g | Per 20g (2 heaped tbsp) | 10g vs UK daily amount |
|---|---|---|---|
| Energy | 53 kcal | 107 kcal | n/a |
| ALA omega-3 | 2.3g | 4.6g | Above the 2g linked to the cholesterol claim |
| Fibre | 2.7g | 5.5g | 9% of 30g |
| Protein | 1.8g | 3.7g | 4% of the 50g label reference |
| Magnesium | 39mg | 78mg | 13% of 300mg (men), 15% of 270mg (women) |
| Fat (of which saturates) | 4.2g (0.4g) | 8.4g (0.7g) | n/a |
| Lignans | About 30mg | About 60mg | No UK figure |
Flaxseed is by far the richest food source of lignans (figure from the Linus Pauling Institute), plant compounds that gut bacteria turn into “enterolignans” with weak oestrogen-like activity.
Flaxseed is high in fibre and high in omega-3 by UK labelling rules, so this authorised GB health claim applies: ALA contributes to the maintenance of normal blood cholesterol levels. The beneficial effect is obtained with a daily intake of 2g of ALA, and 10g of flaxseed gives about 2.3g. There is no authorised claim for flaxseed itself: the rest of this guide is research. See also our omega 3 guide, high fibre foods and foods high in magnesium.
Flaxseed benefits: evidence by claim
Flaxseed has more trials behind it than most seeds. Here is an honest summary.
| Claim | What the research shows | Evidence |
|---|---|---|
| Blood pressure | Small average fall across 33 trials, larger with 30g a day for over 20 weeks | Moderate |
| Cholesterol | Small falls in total and LDL cholesterol, from the seed rather than the oil | Moderate |
| Constipation | Recommended by the NHS; a few small trials are positive | Low to moderate |
| Blood sugar | Small fall in fasting glucose with the whole seed, not the oil | Low to moderate |
| Weight | Under 1kg extra weight loss on average | Small effect |
| Hot flushes | The largest trials found no benefit over placebo | Not supported |
| Hair and skin | Popular online, but we found no good trials of eating flaxseed for hair growth | None |
Flaxseed, blood pressure and cholesterol
Blood pressure is the standout result. In the Canadian FLAX-PAD trial, 110 people with peripheral artery disease ate 30g of milled flaxseed or a placebo daily for 6 months. Blood pressure ended about 10/7 mmHg lower with flax, and systolic fell 15 mmHg in those who started high.
Reviews show a smaller average: a 2023 meta-analysis of 33 trials found blood pressure about 3/2.6 mmHg lower, with bigger effects at 30g a day or more, over 20 weeks and in people with high blood pressure. If you’re working on blood pressure, see also beetroot juice.
Cholesterol. A 2020 meta-analysis of 62 trials found flaxseed lowered total cholesterol by about 0.14 mmol/L and LDL by about 0.11 mmol/L, with no change in HDL. An earlier review found the effect came from the whole seed, not the oil, and was clearest in women after the menopause and people with high cholesterol.
Flaxseed for constipation and gut health
The NHS suggests adding wheat bran, oats or linseed to your diet for constipation, alongside plenty of fluids. For IBS bloating and wind, it suggests up to 1 tablespoon of linseeds (whole or ground) a day.
The trials are small but positive. In a Chinese study of 90 adults with chronic constipation, 50g of flaxseed flour a day for 4 weeks raised bowel movements from 2 to 7 a week, slightly better than the laxative lactulose. A 12-week trial in adults with type 2 diabetes found 20g a day in cookies eased constipation compared with placebo.
Build up slowly and drink more as you go (see how much water should I drink). NHS dietitians in Sussex say it can take up to six months to get the full benefit. For a wider plan, see gut health and magnesium for constipation.
Flaxseed, blood sugar and weight loss
Blood sugar. A 2018 meta-analysis of 25 trials found flaxseed slightly lowered fasting blood sugar, insulin and insulin resistance, but not HbA1c, the three-month marker. The effects only showed with the whole seed, not the oil. A 2023 review in type 2 diabetes did find a fall in HbA1c, mostly where diabetes was poorly controlled. Helpful, but not a replacement for treatment. See also sugar cravings.
Weight. Meta-analyses of 45 and 64 trials found flaxseed was linked to slightly more weight loss than control groups: about 0.6 to 1kg on average, and around 0.8 to 1.4cm off the waist. Effects were larger with 30g a day or more for 12 weeks or longer, and in people with a higher BMI. Easy to add to breakfast, but no fat burner. Ideas in breakfast for energy.
Flaxseed for women and menopause
Because its lignans have weak oestrogen-like activity, flaxseed is often recommended for hot flushes. The best trials don’t back this up. In a US trial of 188 women after the menopause, a daily flaxseed bar for 6 weeks cut hot flushes no more than a placebo bar. A Brazilian trial of 25g a day in bread for 12 weeks found the same: improvements in both groups, no difference between them.
Where flax may help women in midlife is the heart: the cholesterol-lowering effect was clearest in women after the menopause. For what does help with hot flushes, see hot flushes and best supplements for menopause, and for a wider routine, supplements for women over 40.
Ground vs whole flaxseed
For the nutrients, choose ground (also sold as milled) flaxseed. Whole seeds have a tough coat and can pass through undigested. In a Canadian study, milled flaxseed and flaxseed oil raised blood ALA levels within a month, but whole seeds did not. A Dutch study found the body absorbed only 28% as much lignan from whole seeds as from ground.
For constipation alone, whole seeds still add bulk, which is why the NHS says whole or ground both work for IBS. You can buy flaxseed ready-milled or grind whole seeds in a coffee or spice grinder. We’d keep milled flaxseed sealed in the fridge once opened, and throw it away if it smells bitter or like paint.
Is raw flaxseed safe? The cyanide question
Flaxseed contains cyanogenic glycosides, which release small amounts of cyanide when the seed is ground or chewed. In 2019 the European Food Safety Authority (EFSA) confirmed that its safe single-day limit for cyanide applies whatever the food, and found that average intakes from food stayed below it. Media stories that a teaspoon of ground linseed could harm young children were based on a deliberately worst-case calculation, and EFSA said they were taken out of context.
The clearest practical advice comes from Germany’s Federal Institute for Risk Assessment (BfR) in June 2026: no harmful effects are expected in adults eating up to 15 to 20g of raw ground linseed a day (about 2 to 3 level tablespoons), but young children shouldn’t eat raw ground linseed. Heat, as in baking or cooking, reduces the risk, and whole seeds release very little. Because linseed can also contain cadmium, the BfR advises adults to eat no more than 20g of linseed a day in total. We couldn’t find specific UK advice on raw linseed.
Flaxseed oil vs ground flaxseed
A tablespoon of flaxseed oil (about 14g) gives roughly 7.3g of ALA and 120 calories, but no fibre and almost no lignans, which stay in the seed rather than the oil. That matters: the cholesterol and blood sugar benefits in trials came from the whole seed, not the oil.
Neither form is a swap for the long-chain omega-3s EPA and DHA found in oily fish. In the Canadian study, flaxseed oil and milled seed raised blood ALA but neither changed blood EPA or DHA. Ground seed is the better all-rounder.
How much flaxseed should you eat a day?
There’s no official amount. 1 to 2 tablespoons (10 to 20g) of ground flaxseed a day is a sensible amount for most adults. Start with a teaspoon if you don’t eat much fibre and build up over a week or two. The University Hospitals Sussex NHS leaflet suggests a maximum of 2 tablespoons a day and around 150ml of fluid with each tablespoon. Many heart trials used about 30g a day, above the German 20g advice, so we’d stick to 1 to 2 tablespoons.
There’s no best time of day. Easy ways in: stirred into porridge or yoghurt, blended into a smoothie, sprinkled on soup or salad, or baked into bread and flapjacks. Mix it with pumpkin seeds for a seed topper.
Flaxseed vs chia seeds
Per 10g, from the same USDA database:
| Per 10g | Flaxseed (linseed) | Chia seeds |
|---|---|---|
| Calories | 53 kcal | 49 kcal |
| ALA omega-3 | 2.3g | 1.8g |
| Fibre | 2.7g | 3.4g |
| Calcium | 26mg | 63mg |
| Magnesium | 39mg | 34mg |
| Best eaten | Ground | Whole, soaked |
Flax has more omega-3, is the richest food source of lignans and has far more research, especially on blood pressure. Chia has more fibre and calcium and is easier to use whole. Both are good: use whichever you’ll eat, or mix them. More in our chia seeds guide.
Flaxseed side effects and who should be careful
- Wind, bloating and loose stools. Usually from adding lots of fibre fast. Build up slowly and drink more. See magnesium for bloating for other common causes.
- Swallowing problems or bowel conditions. Fibre that swells needs plenty of fluid. If you have trouble swallowing, a narrowed gut or a history of bowel blockage, or Crohn’s disease, check with your GP or specialist team first.
- Medicines. Flaxseed may lower blood pressure and blood sugar, and the US National Center for Complementary and Integrative Health says it might interact with blood thinners. If you take blood pressure, diabetes or blood-thinning medicines, talk to your GP or pharmacist before eating it daily.
- Hormone-sensitive conditions. Lignans have weak oestrogen-like effects. If you have or have had a hormone-sensitive cancer or condition, ask your specialist team before eating large amounts or taking flaxseed supplements.
- Pregnancy and breastfeeding. The NCCIH says some studies suggest flaxseed may be unsafe in pregnancy, though the evidence is not conclusive, and little is known about breastfeeding. Speak to your midwife or GP before eating it regularly or taking flaxseed supplements.
- Children. Germany’s BfR advises young children not to eat raw ground linseed.
Where our range fits
Food comes first, and flaxseed is a cheap, easy way to add omega-3 and fibre. If you’d like more magnesium than a spoonful gives, our Magnesium Glycinate Sleep Complex is a berry-flavoured evening drink with magnesium bisglycinate and citrate (148mg magnesium per serving), glycine and L-theanine. Magnesium contributes to a reduction of tiredness and fatigue. It’s vegan, made in the UK and for adults only. We don’t recommend our products during pregnancy or breastfeeding.
FAQs
Is flaxseed the same as linseed?
Yes. Flaxseed and linseed are two names for the same seed from the flax plant. The NHS usually says linseed, and brown or golden both work for constipation.
Is it OK to eat flaxseed every day?
Yes, for most adults 1 to 2 tablespoons a day is fine as part of a balanced diet, with plenty of water. Germany’s food risk agency suggests no more than 20g a day. Check with your GP or pharmacist first if you take blood pressure, diabetes or blood-thinning medicines.
Should I eat flaxseed ground or whole?
Ground, if you want the omega-3 and lignans. Whole seeds often pass through undigested: in one study they didn’t raise blood ALA, while milled seed did. Whole seeds still add bulk for constipation.
Is raw ground flaxseed safe?
For adults, yes in normal amounts. Germany’s food risk agency says up to 15 to 20g of raw ground linseed a day is not expected to cause harm in adults, but young children shouldn’t eat it raw. Baking reduces the cyanide risk.
Does flaxseed help with constipation?
It can. The NHS suggests adding linseed to your diet for constipation, and small trials found it increased bowel movements. Start small, build up gradually and drink around 150ml of extra fluid with each tablespoon.
Is flaxseed oil as good as ground flaxseed?
Not quite. The oil is richer in ALA omega-3 but has no fibre and almost no lignans, and the cholesterol and blood sugar benefits in trials came from the whole seed rather than the oil.
Does flaxseed help with hot flushes?
Probably not. The largest placebo-controlled trials found flaxseed reduced hot flushes no more than a placebo. It may still help heart health in midlife.
Sources
- US Department of Agriculture. FoodData Central (SR Legacy entries 169414 flaxseed, 170554 chia seeds, dried, 167702 flaxseed oil, cold pressed). Linus Pauling Institute. Lignans.
- NHS. Constipation, IBS: diet, lifestyle and medicines, How to get more fibre into your diet and Vitamins and minerals: others (magnesium). University Hospitals Sussex NHS Foundation Trust Dietetics. Constipation leaflet (2024).
- DHSC. Great Britain nutrition and health claims register.
- EFSA CONTAM Panel (2019). Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels. EFSA Journal. German Federal Institute for Risk Assessment (2026). Hydrocyanic acid and cadmium in linseeds. IFST. EFSA responds to media reports on cyanide in linseed.
- Rodriguez-Leyva D et al (2013). Potent antihypertensive action of dietary flaxseed in hypertensive patients. Hypertension. Li L et al (2023). Effect of flaxseed supplementation on blood pressure: a systematic review, and dose-response meta-analysis. Food and Function.
- Hadi A et al (2020). Effect of flaxseed supplementation on lipid profile: an updated systematic review and dose-response meta-analysis of sixty-two randomized controlled trials. Pan A et al (2009). Meta-analysis of the effects of flaxseed interventions on blood lipids.
- Mohammadi-Sartang M et al (2018). Flaxseed supplementation on glucose control and insulin sensitivity: a meta-analysis of 25 randomized, placebo-controlled trials. Xi H et al (2023). Flaxseed supplementation significantly reduces hemoglobin A1c in patients with type 2 diabetes mellitus. Mohammadi-Sartang M et al (2017). The effect of flaxseed supplementation on body weight and body composition: 45 randomized placebo-controlled trials. Musazadeh V et al (2024). The effects of flaxseed supplementation on anthropometric indices: an updated systematic review and meta-analysis.
- Sun J et al (2020). Effects of flaxseed supplementation on functional constipation and quality of life in a Chinese population. Soltanian N, Janghorbani M (2018). A randomized trial of the effects of flaxseed to manage constipation, weight, glycemia, and lipids in constipated patients with type 2 diabetes.
- Pruthi S et al (2012). A phase III, randomized, placebo-controlled, double-blind trial of flaxseed for the treatment of hot flashes. Simbalista RL et al (2010). Consumption of a flaxseed-rich food is not more effective than a placebo in alleviating the climacteric symptoms of postmenopausal women.
- Austria JA et al (2008). Bioavailability of alpha-linolenic acid in subjects after ingestion of three different forms of flaxseed. Kuijsten A et al (2005). The relative bioavailability of enterolignans in humans is enhanced by milling and crushing of flaxseed.
- National Center for Complementary and Integrative Health. Flaxseed and flaxseed oil.
This guide is general information, not medical advice. If you have swallowing problems, a bowel condition, high blood pressure, diabetes or a hormone-sensitive condition, are pregnant or breastfeeding, or take regular medicines, speak to your GP or pharmacist. Evopure makes the Magnesium Glycinate Sleep Complex. We don’t sell flaxseed.
