Linseed oil vs flaxseed oil: same seed, different bottles
Linseed oil vs flaxseed oil: both come from the same seed, but not every bottle belongs in the kitchen. Here is the naming, the boiled linseed oil warning, and how to buy and store the food kind.
Linseed oil vs flaxseed oil is a question of grade, not plant: both are pressed from the same seed of flax (Linum usitatissimum). "Flaxseed oil" usually means food-grade, cold pressed oil sold for eating, while "linseed oil" often means oil for wood and paint. Boiled linseed oil contains chemical drying agents and must never be eaten.
The confusion is understandable. In the UK and much of Europe, the oil on a supermarket shelf is often called linseed oil, and in eastern Germany and Silesia, Leinöl with quark and potatoes has been a classic for generations. In India it is alsi ka tel, from alsi, the Hindi name for the seed. Meanwhile, hardware shops sell bottles called linseed oil that are not food at all. So the name tells you little; the label tells you everything.
At a glance
- Same plant, same seed: Linum usitatissimum, the plant that also gives us linen.
- The difference is grade: food oil is pressed, handled and labelled as food.
- Boiled linseed oil is linseed oil with metal-based drying agents, and often solvents, added so it dries fast. Never eat it.
- Flaxseed oil is about half alpha-linolenic acid (ALA), an omega-3 fat: about 7 g in a tablespoon.
- Keep food-grade oil cool and dark, use it raw, and never heat it.
Is linseed oil the same as flaxseed oil?
Botanically, yes. Both are pressed from the seeds of the flax plant. The names come from different traditions:
- Flax is the plant and its fibre, the source of linen.
- Linseed is the older English name for the seed, still common in the UK, Europe and Indian English, for food and industry alike.
- Flaxseed is the usual name in North America, especially for food and supplements.
In Indian languages the seed is alsi in Hindi, tishi in Bengali and javas in Marathi. Whatever the name, it is the same seed. What changes from bottle to bottle is how the oil was made, handled and finished.
What is boiled linseed oil?
A wood and paint product. Raw linseed oil hardens slowly in air, over days, as its omega-3 fats link together. To speed this up, makers once heated the oil. Today, most "boiled" linseed oil gets its speed from metal-based drying agents (often cobalt or manganese compounds) rather than from long boiling, and many brands add solvents too, so it dries in hours.
Those additives make it useful for furniture, floors and tool handles, and unsafe to eat. It belongs in the shed, well away from the kitchen.
Can you eat linseed oil from a hardware store?
No. Even "raw" linseed oil from a hardware or paint shop is not made, handled or labelled as food. It is meant for industry, packed in containers not meant for food, and its safety data sheet carries fire warnings rather than nutrition facts. Some brands are pure oil; others are not. Since you cannot tell from the shelf, the rule is simple: if it is sold for wood or paint, it is not for eating.
Is food-grade linseed oil safe to eat?
Yes. Food-grade linseed oil and food-grade flaxseed oil are the same thing. In a British or German supermarket, linseed oil in the food aisle is simply flaxseed oil by its European name, and it is safe to eat in normal amounts, raw.
| Product | Made for | Safe to eat? | Where you see it |
|---|---|---|---|
| Food-grade flaxseed oil (cold pressed) | Eating, raw | Yes | Food shops, often in dark bottles |
| Food-grade linseed oil | Eating, raw | Yes, same as above | UK and European supermarkets |
| Raw linseed oil (hardware) | Wood, paint, putty | No | Hardware and paint shops |
| Boiled linseed oil | Faster-drying wood finish | No, never | Hardware and paint shops |
| Flax seeds, whole or ground | Eating | Yes | Food shops, sold as alsi in India |
Flaxseed oil's main draw is its omega-3. The US National Institutes of Health lists about 7.3 g of alpha-linolenic acid (ALA) in a tablespoon, while the adequate intake for adults is 1.1 g a day for women and 1.6 g for men, so a teaspoon covers the day for most people. Our guide to omega-3 and omega-6 in plain language explains what ALA is, and four real ways to use flaxseed oil shows how to eat it.
Why is flaxseed oil sold in dark bottles?
Because light, heat and air spoil it quickly. The same omega-3 fat that makes linseed oil harden on wood reacts readily with oxygen, and light and heat speed that up. Fresh flaxseed oil smells mild, nutty and a little grassy; oxidised oil smells of paint or fish and tastes harsh and bitter.
So buy it in a dark bottle, keep it closed, cool and out of the light, and use it within its best-before date. Many people keep an open bottle in the fridge; a little cloudiness in the cold is normal for unrefined oil. Our guides on how to store cold pressed oil and on whether cold pressed oil goes bad too fast cover the details.
Linseed oil vs flaxseed oil: how to tell food grade from industrial
- Check where it is sold: the food aisle or a food shop, not the paint or hardware section.
- Read the label. Look for food wording, a nutrition panel, a best-before date and a food licence number, such as an FSSAI number in India.
- Read the ingredients. A single ingredient, flaxseed or linseed oil, with no driers, solvents or "petroleum distillates".
- Look at the packaging. Food oil comes in food packaging, usually a dark bottle; wood oil comes in tins or workshop containers with hazard symbols.
- Smell it. Mild, nutty and fresh is right. A paint-like or solvent smell means it is not for the kitchen.
Safety: oily rags, children and medicines
- Oily rags can catch fire. Cloths and paper soaked in linseed or flaxseed oil can heat up as the oil hardens and ignite on their own. The US National Park Service has described a linseed oil rag that set a workbench alight, and the safety data sheet for raw linseed oil warns of the same. Lay used rags flat outdoors to dry, or seal them in a metal tin filled with water.
- Keep wood oils away from children. If anyone swallows boiled linseed oil or a solvent-based finish, call a doctor or poison centre straight away.
- Medicines and pregnancy. If you take blood-thinning medicines, are pregnant or have a health condition, ask your doctor before taking flaxseed oil in large amounts, as you would with any supplement.
- Never heat flaxseed oil for cooking. It breaks down quickly with heat, so use it raw over food.
Our flaxseed oil
Our Truly Cold Pressed flaxseed oil is made and sold as food: pressed slowly in a wooden ghaani from flax seeds, unrefined, single ingredient and free of preservatives. It is best used within about 4 to 6 months, raw, and stored away from light and heat.
The bottom line
Linseed oil and flaxseed oil are the same oil from the same seed. What separates the bottle for your dahi from the tin for your teak chair is grade, not name. Buy food-grade oil for the kitchen, keep boiled linseed oil in the shed, and read the label every time.
Frequently asked questions
Is linseed oil good for wooden furniture?
Yes, it is one of the oldest wood finishes. Raw linseed oil soaks in and hardens slowly, giving a warm, low sheen, while boiled linseed oil dries faster. Apply thin coats, wipe off the excess and let each coat dry fully. Dispose of the rags safely, because oily rags can catch fire on their own.
Is flaxseed oil the same as eating flax seeds?
Not quite. The oil gives you the omega-3 fat, ALA, in concentrated form. Whole or ground seeds give you less ALA per spoon, but they also bring fibre and other plant compounds that mostly stay behind in the seed when it is pressed. Many people use both: seeds in roti or laddoo, oil drizzled raw.
Can I cook with linseed oil?
No. Food-grade linseed or flaxseed oil should be eaten raw: drizzled over dal, dahi, salads or chutney after cooking. Heat breaks down its omega-3 fat quickly and creates off-flavours. Industrial linseed oil should never be used near food at all, heated or not.
Why does my flaxseed oil taste bitter?
Fresh flaxseed oil can have a faint grassy bitterness, which is normal. Strong bitterness, a paint-like or fishy smell, or a sharp aftertaste means the oil has oxidised, which happens with time, light, heat or air. Store it closed, cool and dark, and finish it within its best-before date.
Does linseed oil go off?
Yes. Food-grade linseed or flaxseed oil oxidises faster than most oils because of its omega-3 fat, which is why it comes in dark bottles with a short shelf life. Wood-finishing linseed oil also thickens and skins over in an open tin, but that is a different product altogether.
