Flax oil and flaxseed oil are the same product. Both names refer to the oil extracted from the seeds of the flax plant, and you’ll see them used interchangeably on supplement bottles, grocery shelves, and in recipes. The only terminology distinction worth knowing is between food-grade flaxseed oil and industrial linseed oil, which comes from the same plant but is processed very differently and is not safe to consume.
Why the Names Vary
Flax, flaxseed, and linseed all refer to the same plant. “Flax oil” is simply a shortened version of “flaxseed oil,” the way “olive oil” doesn’t need to be called “olive fruit oil.” Some brands use one label, some use the other, and neither signals a difference in quality or processing. If you’re shopping for a dietary supplement or cooking oil, treat these terms as identical.
The Real Distinction: Food-Grade vs. Industrial
Where terminology actually matters is the difference between food-grade flaxseed oil and industrial linseed oil. Though they start from the same seed, they end up as very different products.
Food-grade flaxseed oil is cold-pressed, meaning the seeds are mechanically squeezed at temperatures below about 49°C (120°F). This gentle process preserves the oil’s delicate omega-3 fats and leaves no chemical residues behind. The trade-off is that cold pressing only recovers about 30 to 35 percent of the oil from the seeds.
Industrial linseed oil, the kind sold at hardware stores for wood finishing, goes through a much harsher extraction. After an initial pressing, manufacturers use hexane (a petroleum-based solvent) at temperatures of 60 to 90°C or higher to pull out nearly all the remaining oil. This recovers 98 to 99 percent of available oil but leaves chemical residues of 5 to 25 parts per million. “Boiled” linseed oil is even worse: it contains added heavy metal compounds like cobalt or manganese that speed drying time for wood treatment. These additives pose serious toxicity risks, including nervous system damage. Never consume hardware store linseed oil or use it on surfaces that contact food.
What’s in Flaxseed Oil
Flaxseed oil is one of the richest plant sources of alpha-linolenic acid (ALA), an omega-3 fatty acid. ALA makes up 39 to 60 percent of the oil’s total fat content, which is why flaxseed oil has become popular as a vegetarian omega-3 supplement.
Your body can convert ALA into the longer-chain omega-3s found in fish oil, but the conversion rate is limited. In healthy young men, roughly 8 percent of ALA converts to EPA and 0 to 4 percent converts to DHA. Women convert it more efficiently: about 21 percent to EPA and 9 percent to DHA, likely due to the influence of estrogen on the conversion pathway. This means flaxseed oil provides meaningful omega-3 benefits, but it’s not a one-to-one replacement for fish oil if you’re specifically trying to raise your EPA and DHA levels.
How to Use and Store It
Flaxseed oil has a very low smoke point of about 107°C (225°F), so it’s not suitable for cooking. Heat damages the omega-3 fats and creates off-flavors. Instead, use it in salad dressings, drizzle it over soups or cooked vegetables after they’ve come off the heat, blend it into smoothies, or stir it into dips.
Because of its high polyunsaturated fat content, flaxseed oil goes rancid faster than most cooking oils. An unopened bottle stored in a cool, dark place can last up to two years, but once you break the seal, plan to use it within one to two months. Keep it refrigerated after opening. If it smells sharp, bitter, or like paint, it’s oxidized and should be discarded.
Typical Dosages
Most supplements and studies use 1 to 2 grams of flaxseed oil daily, a dose that has been used safely for up to six months. Higher amounts, up to 24 grams per day, have been used safely in shorter studies lasting about seven weeks. A standard tablespoon of flaxseed oil contains roughly 7 grams of ALA, so even a small daily drizzle delivers a substantial omega-3 dose. If you take flaxseed oil in capsule form, check the label for ALA content per capsule, since concentrations vary between brands.