Is Rapeseed Oil Bad for You? The Omega-6 Truth

In the UK, rapeseed oil has been successfully rebranded as a health food. Cold-pressed in small batches on British farms, sold in distinctive artisan bottles, positioned as "the British olive oil" — rapeseed oil occupies a uniquely favourable position in UK food culture.

In North America, the same oil exists under the less romantic name "canola oil" — derived from "Canadian oil, low acid" — and is associated more with industrial food production than with artisan food credentials.

So which story is accurate? And what does the omega-6 content of rapeseed oil actually mean for your ratio?

What Is Rapeseed Oil?

Rapeseed oil is extracted from the seeds of Brassica napus, a bright yellow flowering plant in the cabbage family (rapeseed is closely related to kale, broccoli, and Brussels sprouts). The plant is widely cultivated across the UK, Canada, and central Europe.

The canola variety was developed in Canada in the early 1970s specifically to reduce the erucic acid content of natural rapeseed (high erucic acid rapeseed was linked to heart damage in animal studies at high doses). "Canola" — a portmanteau of Canadian and "ola" (oil, low acid) — is essentially a trademarked crop variety of rapeseed.

In the UK, "rapeseed oil" and "canola oil" are the same species with the same fatty acid profile. The difference is primarily in how the oil is produced and marketed.

The Omega-6 Content of Rapeseed Oil

This is where the picture gets more interesting than a simple "good" or "bad" verdict.

According to USDA FoodData Central, rapeseed/canola oil contains:

• Omega-6 (linoleic acid): ~2.9g per tablespoon
• Omega-3 (ALA): ~1.3g per tablespoon
• Oleic acid (monounsaturated): ~8.7g per tablespoon

Compare this to the other common oils:

| Oil | Omega-6/tbsp | Omega-3/tbsp | |-----|-------------|-------------| | Sunflower | 8.9g | trace | | Soybean (vegetable) | 7.0g | 0.9g | | Rapeseed/canola | 2.9g | 1.3g | | Olive oil (EVOO) | 0.8g | 0.1g | | Avocado oil | 1.2g | 0.1g |

Rapeseed oil's omega-6 content is significantly lower than sunflower or vegetable oil. It also contains meaningful amounts of omega-3 ALA, giving it a raw omega-6:omega-3 ratio of approximately 2:1 — which looks excellent on paper.

Why the Raw Ratio Is Misleading

Here is the critical caveat that proponents of rapeseed oil often overlook: the omega-3 in rapeseed oil is ALA (alpha-linolenic acid), not EPA or DHA.

ALA is a plant-form omega-3. The body can convert ALA to EPA and then to DHA, but this conversion is inefficient:

• Conversion of ALA to EPA: approximately 5–10% in healthy adults
• Conversion of ALA to DHA: approximately 0.5–5%

These numbers come from metabolic studies including Burdge and Calder (2005), who found that the conversion efficiency is even lower in men than women, and is suppressed by high dietary omega-6 intake.

This means that 1.3g of ALA in rapeseed oil might effectively contribute only 0.06–0.13g of EPA/DHA equivalent after conversion — far less than the 1.4g you would get from a 100g serving of salmon.

When you adjust for conversion efficiency, the effective omega-6:omega-3 ratio of rapeseed oil in terms of biologically active omega-3 is much worse than the raw numbers suggest.

Cold-Pressed British Rapeseed vs Refined Canola

Not all rapeseed oil is the same, and this distinction genuinely matters.

Cold-Pressed Rapeseed Oil (UK Artisan Products)

Produced by mechanically pressing rapeseed at ambient temperature (typically below 40–50°C). This minimal processing retains:

• Vitamin E (tocopherols) — natural antioxidant that also protects the oil from oxidation
• Polyphenols — modest amounts, less than EVOO but present
• Natural flavour compounds — the distinctive nutty, slightly grassy flavour of good cold-pressed rapeseed oil
• Phytosterols — compounds that can modestly reduce LDL cholesterol

Cold-pressed British rapeseed oil, from reputable producers, is genuinely a decent cooking oil. It is not equivalent to EVOO in polyphenol content, but it is meaningfully better than refined canola.

Refined Canola Oil (Supermarket Value Brands)

The "vegetable oil" sold in budget supermarket own-brands in the UK is often primarily or entirely refined rapeseed/canola oil. Produced through solvent extraction, bleaching, and steam deodorisation at temperatures up to 270°C, this product:

• Retains none of the polyphenols or vitamin E of cold-pressed oil
• Has a bland, neutral flavour
• May contain residual trans fats from high-temperature processing (regulations have reduced but not eliminated this)
• Is indistinguishable from budget "vegetable oil" in nutritional terms

The name "cold-pressed rapeseed oil" on the label is a meaningful quality indicator. "Vegetable oil" or "rapeseed oil" without the cold-pressed qualifier is likely refined.

How Rapeseed Oil Affects Your Ratio

Let's model this concretely. Assume someone uses 1.5 tablespoons of cooking oil daily:

| Oil | Daily omega-6 from oil | Daily omega-3 from oil (effective) | |-----|----------------------|------------------------------------| | Sunflower | 13.4g | ~0g | | Soybean (vegetable) | 10.5g | ~0.1g | | Rapeseed/canola | 4.4g | ~0.1g (after conversion) | | Extra virgin olive oil | 1.2g | ~0g |

Even at its best, rapeseed oil adds 4.4g of omega-6 daily from oil alone. Olive oil adds 1.2g. That 3g+ daily difference accumulates to significant ratio impact over time.

The Bottom Line on Rapeseed Oil

Rapeseed oil is not "bad" in the sense of being acutely harmful. As cooking oils go, it is significantly better than sunflower, corn, or soybean oil — particularly in the cold-pressed form. If cost is a significant constraint and olive oil feels inaccessible, cold-pressed British rapeseed is a reasonable choice.

However, it is demonstrably inferior to extra virgin olive oil for inflammation management:

• Higher omega-6 content (~3.6× more per tablespoon)
• The omega-3 content provides limited effective EPA/DHA due to poor ALA conversion
• Fewer polyphenols than quality EVOO
• The health halo around UK cold-pressed rapeseed, while partially deserved, has led to overconsumption compared to what the science supports

If you are trying to optimise your omega-6:omega-3 ratio, extra virgin olive oil is the better choice for everyday cooking. Rapeseed oil is acceptable, particularly in cold-pressed form — but it should not be treated as equivalent to olive oil.