As trends come and go, certain foods are demonized. First it was fat, then sugar, cholesterol, carbohydrates, grains, nuts, wheat, corn, fruits, vegetables, and more. Now, seed oils are the new food enemy. Seed oils are in everything from salad dressings and fast food to processed foods, snacks, protein bars, and even baby formula. Critics blame seed oils for obesity, inflammation, and chronic disease. However, as always, there is more to the story. Even the term “seed oil” is misleading, as it fails to distinguish between oils that have been a healthy part of traditional diets for centuries and those found in ultra-processed foods.
What are Seed Oils?
Seed oils are extracted from seeds. But not all seed oils are the same. Seed oils can vary significantly in their health impact, depending on how they’re processed and their fatty acid profile. For example, sesame seeds and flaxseeds have been integral to traditional diets and are extracted through natural methods. Cold-pressed, unrefined seed oils retain beneficial nutrients and antioxidants. These oils are typically not exposed to high heat, chemicals, or bleaching. They are best suited for use in salad dressings, raw dips, and smoothies. Here are some healthier seed oils that are typically cold-pressed:
- Flaxseed oil
- Hemp oil
- Pumpkin seed oil
- Sesame seed oil
- Black cumin seed oil
However, other seed oils are highly processed. They are referred to as “industrial” seed oils, including canola, sunflower, safflower, cottonseed, grapeseed, soybean, and rice bran. These oils are mass-produced through high-heat extraction and chemical refining. During the process, solvents such as hexane are used to extract the maximum amount of oil. These oils are refined, bleached, and deodorized, which makes them taste neutral and shelf-stable, but devoid of beneficial nutrients. Industrial seed oils are in most ultra-processed and fast foods.
Seed Oils and Health
How did seed oils get a bad rap? One possibility is that seed oils are high in omega-6 fatty acids, especially linoleic acid (LA). The thought is that linoleic acid turns into a different fatty acid called arachidonic acid, which is a building block for compounds that cause inflammation. However, only a small percentage of LA is converted to arachidonic acid.1 It is misleading to say that omega-6 fats promote inflammation because they can also be made into many anti-inflammatory compounds. Linoleic acid (omega-6) is an essential fat that’s important for brain health, metabolism, and overall growth. What’s most important is the balance between omega-3 and omega-6 fatty acids. Human research evidence indicates that seed oils or LA-rich oils are generally safe, as they do not increase cardiometabolic risks or contribute to chronic diseases. This evidence does not support eliminating these oils from one´s diet.6
If you read the health headlines, you will see the following claims:
- Seed oils are toxic and cause inflammation
- Seed oils are responsible for rising obesity and chronic disease
- Seed oils are full of oxidized fats that harm cellular function
- Saturated fats like coconut oil, Ghee, and beef tallow are always healthier
But science and history tell a different story. Let’s examine each of these claims to put seed oils into perspective.
“Seed oils are toxic and cause inflammation” – The claim that all seed oils are toxic and inflammatory is a standard narrative in wellness and online nutrition circles. However, the evidence from peer-reviewed scientific research provides a clearer picture. A 2017 review and meta-analysis of 30 randomized controlled trials involving 1,377 participants found no connection between a diet high in linoleic acid and inflammatory markers.2
“Seed oils are responsible for rising obesity and chronic disease.” – The more likely culprit associated with obesity and poor health is a diet high in ultra-processed foods, many of which contain refined seed oils.3 These foods are also high in calories, added sugars, and low in nutrients and fiber.
“Seed oils are full of oxidized fats that harm cellular function.” – Industrial seed oils lose their stabilizing compounds during processing and are more vulnerable to oxidation. Oxidation produces compounds that can harm cells, induce inflammation, and contribute to the development of chronic diseases. This process occurs more rapidly in seed oils than in other fats and degrades more quickly when exposed to heat. Monounsaturated fats (olive oil) and saturated fats (butter and beef tallow) are more stable. Studies4 show that repeatedly heating vegetable oils, including seed oils, can generate oxidative byproducts linked to poor health outcomes. Concerns about oxidation are valid when it comes to cooking with seed oils, not dietary intake.5 Once again, it seems that the refined oils, used in processed foods and restaurant fryers, are a bigger factor than the seed oils themselves.
“Saturated fats like coconut oil, ghee, and beef tallow are always healthier.” – While saturated fats are more stable for cooking, not everyone should eat them freely. Individuals who carry the APOE4 gene variant, which plays a key role in the processing of fat and cholesterol, may be at an increased risk of developing heart disease. Although these fats can be healthy, they should be consumed in moderation.
Choosing Oils
Rather than completely eliminating seed oils, choose high-quality, stable fats for cooking at home and cold-pressed, minimally processed oils for salad dressings and smoothies. Cutting back on ultra-processed foods, which often include refined industrial seed oils, can also help improve health by reducing sugar, sodium, toxins, and refined grains. Here are some options for choosing oils:
For cooking:
- Avocado Oil (stable for high heat)
- Extra-Virgin Olive Oil (for drizzling or light cooking)
- Butter and Ghee (naturally stable for high-heat cooking)
- Coconut Oil (medium heat)
Best used cold:
- Flaxseed Oil (high omega-3, best for salad dressings)
- Walnut Oil (flavorful and nutrient-rich)
- Sesame Oil (aromatic and moderately heat stable)
- Extra-Virgin Olive Oil (for drizzling and dressings)
Refined industrial oils to reduce or eliminate:
(Some specialty versions of these oils are available in cold-pressed forms, but may sometimes be hard to find.)
- Canola
- Corn
- Cottonseed
- Grapeseed
- Rice Bran
- Safflower
- Soybean
- Sunflower
- “Vegetable” Oil
- “Partially hydrogenated” oils
Remember, whenever a food is demonized, the most critical question to ask is about the quality of that food and how (or if) it’s processed. With seed oils, cold-pressed, unrefined oils can be considered a friend, and refined, ultra-processed seed oils can be viewed as a foe. As with most foods, the key to better health is in reducing ultra-processed and fast foods and incorporating more whole foods in your diet.
REFERENCES
- Dennett MPH, RDN, C. Healthful Oils: Myths and Facts about Seed Oils, Todays Dietician, Vol. 25, No. 6, p 18. 2025
- Su H, Liu R, Chang M, Huang J, Wang X. Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food Funct. 2017 Sep 20;8(9):3091-3103.
- Elizabeth L, Machado P, Zinöcker M, Baker P, Lawrence M. Ultra-Processed Foods and Health Outcomes: A Narrative Review. Nutrients. 2020 Jun 30;12(7):1955.
- Soundararajan P, Parthasarathy S, Sakthivelu M, Karuppiah KM, Velusamy P, Gopinath SCB, Raman P. Effects of Consuming Repeatedly Heated Edible Oils on Cardiovascular Diseases: A Narrative Review. Curr Med Chem. 2024;31(40):6630-6648.
- Falade AO, Oboh G, Okoh AI. Potential Health Implications of the Consumption of Thermally-Oxidized Cooking Oils – a Review. Polish Journal of Food and Nutrition Sciences. 2017;67(2):95-105.
- Lee K, Kurniawan K. Are Seed Oils the Culprit in Cardiometabolic and Chronic Diseases? A Narrative Review. Nutr Rev. 2025 Jul 1;83(7):e2106-e2112. doi: 10.1093/nutrit/nuae205