What Happens to Your Body When You Add Seed Oils to Your Diet
Medically reviewed by Allison Herries, RDN
The seed oil controversy may be due to a high omega-6 content. While omega-6 fatty acids benefit heart health, concerns exist about their role in inflammation.
1. They Can Boost Heart Health
Replacing saturated fats with polyunsaturated fats (PUFAS) like linoleic acid in seed oils lowers LDL (“bad”) cholesterol. This may reduce heart disease risk factors such as total cholesterol and triglycerides.
2. They Have Anti-Inflammatory Effects
Mono- and polyunsaturated fats in seed oils may reduce inflammation. Research suggests that incorporating omega-6 linoleic acid into the diet may not increase inflammation.
3. They May Support Weight Management
Studies suggest that omega-3s helped regulate fat storage and metabolism, while omega-6s aided fat breakdown. Studies also linked canola and sesame oil to weight loss. However, further research is needed.
4. They May Help Manage Blood Sugar
Polyphenols in seed oils may improve the metabolism of sugars from food and insulin sensitivity. Flaxseed oil may help reduce inflammation and support diabetes management, while sesame oil may reduce A1c and fasting blood sugar.
5. They Have Antioxidant Effects
Seed oils are rich in tocopherols (vitamin E-like compounds), which have antioxidant effects that may reduce oxidative stress. Polyphenols and phytosterols in seed oil may also help fight free radicals and protect cells from damage.
6. They Help Skin Health
Seed oils’ polyphenol and fatty acid composition may support skin health when applied topically (on the skin). Applying seed oils topically strengthened fatty acids naturally present in the skin, helped moisturize the skin, and reduced cell damage.
7. They Help Boost Brain Function
Fatty acids are essential for cognitive function. Some seed oils contain a small amount of omega-3s. Arachidonic acid from omega-6 fatty acids supports brain development and cognitive function.
8. They May Support Immune Function
Omega-6 fatty acids influence immune function involved in inflammatory responses, strengthening immune cell membranes. Other compounds in seed oils, like phytosterols, boost immune function.
Are Seed Oils Bad for You?
No, seed oils are not inherently bad for you unless you are allergic to them. Consider the following:
- Genetically modified organism (GMO) concerns: Many seed oils come from GMO crops (e.g., corn, canola, soy). They’re FDA-approved and may reduce pesticide use. However, concerns include potential biodiversity loss, gene transfer to other plants, and reliance on herbicides.
- Fatty acid balance: Seed oils contain mono- and polyunsaturated fats with anti-inflammatory and heart-healthy properties. Omega-6 and omega-3 fats compete for the same enzyme. An imbalance of the two may impact inflammation, though research is mixed.
- Omega-6 debate: Omega-6s, like linoleic acid in some seed oils, can convert into arachidonic acid and pro- or anti-inflammatory molecules. Critics link omega-6s to inflammation, but research is mixed.
- Omega-3 intake: Increase your omega-3s (e.g., fatty fish) rather than cutting omega-6s. Aim for two servings weekly of fatty fish.
- Cooking use: Seed oils have high smoke points, but repeated reuse for frying may create harmful compounds.
Who Should Avoid Seed Oils?
- Allergy warning: Avoid seed oils if you’re allergic (e.g., peanut, sesame, soy, sunflower).
- People with fat malabsorption issues: Gallbladder disease, pancreatic insufficiency, or specific liver disorders may require limiting dietary fats, including seed oils.
- People avoiding processed foods: Heated seed oils in processed foods may form compounds linked to heart disease. Limiting fried foods may be more beneficial than cutting out seed oils entirely.
- People with inflammatory conditions: Seed oils may not increase inflammation. However, people with inflammation or autoimmune conditions should boost omega-3s and cut ultraprocessed foods.
Follow the advice of your board-certified healthcare provider if they recommend avoiding specific oils.
What Are Seed Oils?
Seed oils are oils derived from the seeds of plants, such as vegetables, herbs, and fruits.
The “Hateful Eight”
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Corn
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Cottonseed
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Rice bran
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Soybean
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Sunflower
Other “Seed Oils”
Nutritional Profile of Seed Oils
- Fat content: Seed oils are nearly 100% fat. Unlike butter and tropical oils, seed oils have a low saturated fat content and are packed with unsaturated fats.
- Fatty acids: Seed oils contain a mix of mono- and polyunsaturated fats, and are especially rich in omega-6 linoleic acid.
- Fat-soluble vitamins: Seed oils contain vitamins E and K.
- Plant compounds: Include polyphenols and phytosterols, which benefit health and cholesterol.
- Refining impact: Refining reduces vitamin E, polyphenols, and phytosterols.
| Seed Oil Fat Profile | |||||
|---|---|---|---|---|---|
| Saturated fat | Monounsaturated fat | Polyunsaturated fat (total) | Omega-6 | Omega-3 | |
| Canola oil | 7% | 66% | 27% | 19% | 8% |
| Safflower oil | 8% | 77% | 15% | 14.5% | Less than 1% |
| Grapeseed oil | 9% | 16% | 70% | 69% | Less than 1% |
| Flaxseed oil | 9% | 18% | 68% | 14% | 53% |
| Sunflower oil | 9.5% | 68% | 22% | 22% | Less than 1% |
| Sesame oil | 14% | 40% | 42% | 42% | Less than 1% |
| Soybean oil | 16% | 23% | 61% | 54% | 7% |
| Peanut oil | 17% | 61% | 21% | 21% | Less than 1% |
| Rice bran oil | 20% | 39% | 35% | 35% | Less than 1% |
| Corn oil | 21% | 29% | 56% | 56% | Less than 1% |
Tips for Choosing Healthy Seed Oils
Consider the following factors when choosing the right seed oil:
- Read your label: No strict rules exist. Choose based on use. Cold-pressed or extra virgin oils suit salads and garnishes and retain more nutrients. GMO seed oils can’t be organic. Some oils, like pumpkin or walnut, may be organic.
- Storage: Store oils in opaque containers in a cool, dark place. Use within four months to avoid oxidation and spoilage.
- Shelf-life: Most oils last a few months. Buy smaller bottles if you don’t use oil quickly. Avoid oils that smell off. Avoid reusing or reheating cooking oils to prevent harmful compounds.
- Taste and flavor: Canola, grapeseed, corn, soybean, safflower, and sunflower oils are ideal for sautéing or baking. Sesame oil adds a nutty taste; flaxseed oil is bitter and may pair well with sweeter ingredients in dressings.
- Health goals: Seed oils may support heart health better than tropical oils or butter. Replacing saturated fat with PUFAs lowers heart disease risk by 25%. For more omega-3s, choose flaxseed or canola oil.
- Nutrition goals: Fat should comprise 20 to 35% of your daily calories (about five tablespoons of oil). Be mindful of how much you use.
- Smoke point: Seed oils have high smoke points, which vary by oil type and processing. They’re suitable for cooking methods that require higher temperatures.
- How you cook: Use refined oils (soybean, safflower, corn) for high-heat cooking (up to 450 degrees F). Use unrefined oils (flaxseed, almond) for lower heat (300–350 degrees F) or no-heat uses (salad dressings, garnishes).
Key Takeaways
- Cooking with seed oils at home poses little health risk.
- Seed oils may reduce inflammation and lower heart disease risk.
- Cut back on fried or ultraprocessed foods, which may be more harmful.
Read the original article on Verywell Health
