📊 Full nutrition facts — per 100g
| Nutrient | Amount | % Daily value | Level |
|---|---|---|---|
| Calories | 534 kcal | 27% | |
| Carbohydrates | 28.9g | 10% | |
| Dietary fibre | 27.3g | 97% | |
| Sugars | 1.55g | — | |
| Glycaemic Index (GI) | 35 — Low | — | |
| Omega-3 ALA | 22.8g | — | |
| Protein | 18.3g | 37% | |
| Thiamine (B1) | 1.64mg | 109% | |
| Magnesium | 392mg | 98% | |
| Phosphorus | 642mg | 64% | |
| Lignans (SDG) | highest of all foods | — |
Based on Australian NRV. Source: FSANZ Australian Food Composition Database.
📈 Glycaemic index (GI)
💊 Key vitamins & minerals
✅ Health benefits
Flax seeds contain 22.8g of alpha-linolenic acid (ALA omega-3) per 100g — more than any other plant food. ALA reduces inflammation, lowers triglycerides and reduces cardiovascular disease risk. Ground flax (not whole) is required for ALA absorption — whole seeds pass undigested through the gut.
Flax seeds contain 75–800 times more lignans than any other plant food. Secoisolariciresinol diglucoside (SDG) is converted by gut bacteria to enterolignans with proven anti-proliferative effects on hormone-sensitive cancers (breast, prostate, colon). Multiple clinical trials show flax consumption reduces breast cancer tumour growth rates.
Flax seeds provide more dietary fibre per gram than virtually any common food — nearly the entire daily requirement per 100g. The mix of soluble (mucilage gel) and insoluble fibre provides both prebiotic feeding of gut bacteria and mechanical bulk for bowel regularity.
Flax seed mucilage (the gel formed when seeds are mixed with water) slows gastric emptying and glucose absorption significantly. Regular flax consumption is associated with improved glycaemic control in type 2 diabetes and significant reductions in systolic blood pressure.
⚠️ Who should limit or avoid
Flax seeds contain phytoestrogens (lignans and ALA) that may have hormonal effects at very high doses during pregnancy. Current evidence suggests moderate consumption (1–2 tbsp daily) is safe, but large supplemental doses are not recommended during pregnancy. Consult your obstetrician or midwife.
Flax omega-3s have mild blood-thinning effects. People on warfarin or antiplatelet medications should maintain consistent flax intake and inform their doctor. The blood pressure-lowering effect can be additive with antihypertensive medications.
True flax allergy exists and can cause respiratory symptoms (particularly in occupational exposure) and anaphylaxis. Cross-reactivity with sesame is reported.
🔬 Possible side effects
Suddenly adding large amounts of flax (over 30g) to a low-fibre diet will cause bloating and changes in bowel habits. Start with 1 teaspoon and build up to 1–2 tablespoons over 2 weeks. Always drink adequate water — flax fibre absorbs significantly more water than most fibres.
Whole flax seeds are essentially indigestible by the human gut. The omega-3 and lignans inside the hard seed coat are not accessed without grinding. Always use ground (milled) flax for nutritional benefit. Whole seeds only provide fibre (the seed coat).
🛒 How to buy flax seeds
The most important buying decision for flax seeds. Whole seeds pass undigested through the human gut — the omega-3, lignans and most nutrition are locked inside the hard seed coat. Buy pre-ground (milled flax) or grind whole seeds in a coffee grinder or food processor. Store ground flax in the fridge to prevent oxidation of the omega-3 oils.
Brown and golden (yellow) flax seeds have essentially identical nutritional profiles. Golden flax has a slightly milder flavour. Both provide the same omega-3, fibre and lignan content. Choose based on availability and price rather than colour.
Pre-ground flax can become rancid within weeks if improperly stored. Check the best-before date. Fresh ground flax has a mild nutty scent; rancid flax smells sharp or musty. If buying pre-ground, choose vacuum-sealed or nitrogen-flushed packages and refrigerate immediately after opening.
🧊 Storage tips & shelf life
Whole flax seeds store well in a sealed jar for 12 months. Ground flax is highly susceptible to oxidation — ONLY keep at room temperature for a few days maximum. Rancid ground flax produces harmful oxidation products.
Essential storage for ground flax. The cold and darkness protect the omega-3 ALA from oxidation. Keep in an opaque container — light accelerates oxidation. This is the standard recommended storage for ground flax by all nutritionists.
Best long-term storage for both whole and ground flax. Omega-3 oils are protected completely by freezing. Use directly from frozen — no thawing needed for adding to smoothies, porridge or baking.
📖 About flax seeds — complete guide
Flax seeds (also called linseeds in Australia — the same plant, Linum usitatissimum) have a dual agricultural history: cultivated simultaneously for fibre (linen fabric, rope, paper) and oil (linseed oil for paint, varnish, wood treatment) for over 8,000 years. The food use of flax seeds was relatively minor historically — it is only in the past two decades that flax has been recognised as one of the most nutritionally significant foods available, driven by three specific findings: their extraordinary omega-3 ALA content, their status as the world's richest lignan source, and their exceptional fibre profile.
The critical practical point with flax seeds is grinding. The seed coat of a whole flax seed is essentially impervious to human digestive enzymes — whole seeds pass through the gastrointestinal tract intact, delivering only the fibre from the outer coat while all omega-3 fatty acids, lignans and minerals remain locked inside and unavailable. Studies comparing whole versus ground flax supplementation consistently show ground flax produces dramatically superior outcomes for all measured endpoints including omega-3 status, LDL cholesterol reduction, lignan metabolite levels and blood sugar control. The simplest approach: grind 1–2 weeks' worth of whole seeds in a coffee grinder and store the result in the fridge.