What Are Seed Oils And Why Are They Used Everywhere? · Vitality & Wellness

Foundations · Seed Oils Explained

What Are Seed Oils
And Why Are They Used Everywhere?

From the supermarket shelf to restaurant kitchens, seed oils have quietly become one of the most prevalent ingredients in the modern food supply. But what exactly are they — and how did they get there?

Stephanie Johnson Vitality & Wellness Anti-Inflammatory Series 10 min read

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Introduction

The Oils You Use Every Day — But Rarely Think About

Open almost any packaged food in your kitchen right now and there is a good chance you will find at least one seed oil listed in the ingredients. Biscuits, bread, salad dressing, plant-based spreads, crisps, ready meals, stir-fry sauces — seed oils appear in all of them, often without much fanfare.

Yet despite their quiet dominance in our food supply, most people know remarkably little about what seed oils actually are, where they come from, or why the food industry relies on them so heavily. And in an era when these oils have become the subject of heated online debate, understanding the basics is more useful than ever.

This article explains what seed oils are, how the three most widely used varieties — soybean, sunflower, and canola — are produced and used, and why they became so prevalent in modern food manufacturing in the first place.

What Exactly Is a Seed Oil?

A seed oil is any edible oil extracted from the seed — rather than the fruit or flesh — of a plant. The seed contains the plant’s stored energy in the form of fats, which can be pressed or chemically extracted to produce a liquid oil.

The term “seed oil” is often used interchangeably with “vegetable oil,” though technically not all vegetable oils come from seeds. Avocado oil is extracted from the fruit pulp. Olive oil comes from the olive fruit. True seed oils include soybean, sunflower, canola (rapeseed), corn, safflower, grapeseed, and cottonseed oil — the varieties most commonly found in food manufacturing.

Seed oils are not a modern invention. Humans have pressed oils from seeds for thousands of years. What changed in the twentieth century was the scale — and the technology used to extract them.

Modern industrial extraction involves mechanical pressing followed by chemical solvent extraction (typically using hexane), refining, bleaching, and deodorising. This process produces a stable, consistent, neutral-flavoured oil at high volume and low cost — qualities that make seed oils ideal for food manufacturing.

85%

Of global edible oil production from seed & vegetable oils

~40g

Average daily vegetable oil consumption per person in Western diets

3×

Increase in global seed oil production since 1990

Soybean, Sunflower & Canola — What Sets Them Apart?

While dozens of seed oils exist, three dominate global production and are the most likely to appear in the foods you buy. Each has a distinct origin, fatty acid profile, and set of uses.

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Soybean Oil

The World’s Most Produced Oil

Extracted from soybeans, this is the single most produced edible oil globally. It has a mild flavour and high smoke point, making it suitable for frying, baking, and as a base for margarines and dressings. It is high in omega-6 linoleic acid and contains some omega-3 alpha-linolenic acid.

Main fat: Omega-6 (linoleic acid ~51%)

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Sunflower Oil

Bright, Neutral & Versatile

Pressed from sunflower seeds, this oil is prized for its light colour, neutral taste, and high smoke point. It is one of the most popular cooking oils in Europe and widely used in snack food production. High-oleic varieties have become more common as manufacturers seek greater heat stability.

Main fat: Omega-6 (linoleic acid ~65%)

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Canola Oil

The Low-Erucic Acid Rapeseed

Canola is a variety of rapeseed bred specifically to be low in erucic acid. The resulting oil is mild, light, and relatively high in heart-healthy monounsaturated fats. It also contains a meaningful amount of omega-3 ALA, making it nutritionally distinctive among common seed oils.

Main fat: Monounsaturated (oleic acid ~62%)

Why Did Seed Oils Become So Ubiquitous?

The dominance of seed oils in the modern food supply is not accidental. Soybean, sunflower, and rapeseed crops can be grown at enormous scale in temperate climates, yielding large quantities of oil per hectare at very low cost. Refined seed oils are also near-flavourless and remarkably stable at room temperature — with shelf lives often exceeding twelve months — making them ideal for packaged food production and distribution.

From the 1960s onward, public health guidance began steering consumers away from saturated fats. Seed oils, being predominantly unsaturated, were positioned as the healthier alternative, and the food industry reformulated products accordingly. Beyond cost and health messaging, seed oils perform specific technical functions in food: emulsifying dressings, giving baked goods their tender crumb, and providing the fry-stability needed in snack food production.

The story of seed oils is inseparable from the story of twentieth-century food manufacturing — a system built around efficiency, shelf stability, and scalability. Understanding that context matters when evaluating any claims made about these oils and health.

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Are Seed Oils Inflammatory? What the Research Actually Says

The Seed Oil Debate · Vitality & Wellness

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Key Takeaways

What to Remember from This Article

Seed oils are edible oils extracted from plant seeds. The most widely used are soybean, sunflower, and canola (rapeseed).
They dominate the food supply for practical reasons: low cost, neutral flavour, long shelf life, and technical versatility in food manufacturing.
Their fatty acid profiles differ meaningfully. Canola is notably higher in monounsaturated fat and omega-3 ALA compared to soybean or sunflower oil.
Seed oils are not the same as ultra-processed foods. Their presence in unhealthy foods is a product of food system economics — it does not tell us whether the oils themselves are harmful.
The debate around seed oils and inflammation is covered in depth in our companion article and podcast episode.

FAQ

Frequently Asked Questions

Essentially, yes. Canola is a specific variety of rapeseed that was bred in Canada in the 1970s to have very low levels of erucic acid, which had raised health concerns in earlier rapeseed varieties. In North America, the oil is sold as “canola oil.” In the UK and Europe, it is more often labelled “rapeseed oil.” The nutritional profiles are very similar.

The terms are often used interchangeably, but they are not identical. “Vegetable oil” is a broader category that includes oils from fruits (olive, avocado) and nuts, as well as seeds. Products labelled simply “vegetable oil” in the supermarket typically contain one or more seed oils — most commonly soybean or sunflower — blended together.

Three reasons dominate: cost, stability, and flavour neutrality. Seed oils are among the cheapest fats available at scale. They are stable at room temperature for long periods, which suits the shelf-life demands of packaged goods. And their refining removes most flavour compounds, so they don’t compete with the taste the manufacturer intends the product to have.

All three are predominantly unsaturated fats, which is generally considered beneficial compared to saturated fats. Canola oil stands out nutritionally for its higher monounsaturated fat content (similar to olive oil) and the presence of omega-3 ALA. Sunflower oil is higher in omega-6 linoleic acid. In practice, the healthfulness of any oil depends on the overall dietary context — no single ingredient determines health outcomes.

This is the central question in the current seed oil debate, and the research does not support the claim that they do. Multiple controlled trials and large observational studies have found no significant increase in inflammatory markers from linoleic acid — the main omega-6 fat in seed oils. For a full breakdown of the evidence, read our companion article or listen to The Seed Oil Debate podcast episode.

Sources

References

Petersen KS, Maki KC, Calder PC et al. (2024). Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. British Journal of Nutrition, 132(8):1039–1050.
Fornari Laurindo L et al. (2025). Evaluating the effects of seed oils on lipid profile, inflammatory and oxidative markers, and glycemic control. Frontiers in Nutrition, 12:1502815.
World Cancer Research Fund. (2025). Are seed oils good or bad for our health? WCRF.org.
Gardner C. (2025). Five things to know about seed oils and your health. Stanford Medicine News & Insights.
Rett BS & Whelan J. (2011). Increasing dietary linoleic acid does not increase tissue arachidonic acid content in adults consuming Western-type diets. Nutrition & Metabolism. PMC6179509.
U.S. Department of Agriculture & Department of Health and Human Services. (2020). Dietary Guidelines for Americans 2020–2025. 9th Edition.

What are seed oils ?