People have used seed oils in cooking for decades to replace foods high in saturated fats like butter or lard. Seeds oils contain healthy fats known as polyunsaturated fatty acids, or PUFAs. Research shows that using seed oils instead of saturated fats can be beneficial for your heart. However, there’s some concern that seed oils may cause inflammation, possibly causing more harm than good.
Seed oils include corn, soybean, sunflower, and canola oil. They come from the seeds of these plants and are commonly used in cooking and processed foods. Seed oils are typically extracted using a refining process that can involve high heat and solvents. Solvents are substances, usually liquids, that break down other substances to form a solution.
Some solvents used to make seed oils can be harmful in large amounts. However, the amount found in seed oils is very little, especially when consumed in moderation.
Other common concerns about seed oils include:
- They often come from genetically modified (GMO) crops, fruits and vegetables that aren’t grown completely naturally, which some people prefer to avoid.
- Some oils have raised health concerns due to substances found in unrefined versions, specifically canola oil, which comes from the rapeseed plant. However, refined canola oil contains low amounts and is recognized as safe by the FDA.
- They may cause inflammation. However, current research and advice from health experts suggest that seed oils may provide more benefits than risks.
While more research is necessary due to conflicting evidence regarding seed oils and inflammation, seed oils aren’t inherently harmful when consumed in moderation.
Seed oils contain mostly healthy fats called PUFAs, which include omega-3 and omega-6 fatty acids. Both are important for your health and can only come from your diet. Omega-3s are found in foods like fish, flaxseeds, chia seeds, and walnuts, which help lower inflammation and protect your heart.
Seed oils have large amounts of omega-6 fats, especially linoleic acid (LA). LA can turn into arachidonic acid, a substance that may cause inflammation when there’s too much of it.
However, your body only turns about 2% of LA into arachidonic acid, which is a relatively small amount.
Some people worry that seed oils contain too many omega-6s and not enough omega-3s. However, research shows that moderate amounts of omega-6s, particularly LA, may help lower your risk of heart disease. Some small studies suggest that the omega-6s in seed oils may also help fight inflammation, rather than cause it. This may be especially true if you’re replacing saturated fats or sugary, processed carbohydrates. However, more research is necessary.
Seed oils may also be beneficial because it:
- May improve cholesterol levels: Cholesterol is a type of fat found in your blood. Some research suggests that flaxseed (a good source of omega-3s) and sunflower seed oils may lower LDL (bad) cholesterol, which can lead to heart disease and strokes, and raise HDL (good) cholesterol, which supports a healthy heart.
- May support glycemic (sugar) control: Flaxseed oil in particular may be able to help maintain blood sugar levels, both long-term and short-term, which can lower your risk of developing type 2 diabetes. However, more research is needed to confirm this.
- May help reduce blood pressure: Seed oils are low in saturated and trans fats, making them better for your heart. Replacing these types of fats, like butter or lard, with seed oils may help lower your blood pressure over time and support better blood flow.
- Could aid in weight management: Since seed oils are made from healthier fats, using them in place of unhealthy fats may help prevent or reduce fat, particularly belly fat or visceral fat, which is harmful to the heart. However, more research is needed.
Ultimately, the impact of seed oils on your health depends more on your overall diet than on any single ingredient. Diets that include 5-10% of calories from PUFAs—especially when replacing saturated, trans fats, and refined carbohydrates—are associated with better health outcomes.
When buying and using any oils, there are a few things you should keep in mind:
- Use oils in moderation: Whether you’re using olive oil, avocado oil, or seed oils, moderate consumption is best. Any of these oils can support heart health, especially when used in place of saturated fats and trans fats.
- Be mindful of heat temperatures: Different oils have different smoke points, which is the temperature an oil starts to burn and smoke. When oil starts smoking, it breaks down and releases harmful toxins. Seed oils generally withstand higher heat than olive oil.
- Avoid overcooking: Cooking oil over heat for long periods of time can also release harmful substances and lead to trans fats forming.
- Choose cooking methods wisely: To stay heart-healthy, bake, roast, or sauté rather than deep-frying, regardless of the oil used. This helps preserve the nutritional value of fats in the oils and reduces harmful substances from being made, especially when using high-heat methods such as deep-frying.
- Buy in smaller containers and store in a cool, dark place: If you don’t use oils frequently, they can go bad over time, which affects the taste and quality. Storing in a cool, dark place can prevent this from happening.
- Include a variety of fat sources: While oils provide beneficial polyunsaturated fats (PUFAs), it’s best not to rely on any single type of food. Consider including a variety of healthy fat sources such as walnuts, flaxseeds, chia, and fatty fish like salmon, for a balanced intake of essential fatty acids.
If you’re still concerned about seed oils and would prefer not to include them in your diet, make sure you’re still getting enough heart-healthy PUFAs through other foods. You can include foods like walnuts, chia seeds, salmon, tofu or edamame, and eggs. You can also switch out seed oils for avocado oil. Like olive oil, avocado oil is made from the flesh of the fruit, not the seed.
Consuming too much seed oils, particularly those rich in omega-6s, may cause inflammation. However, research is mixed. The omega-6 fatty acids found in seed oils have also shown anti-inflammatory and heart-healthy benefits. More large-scale studies are needed to determine their overall effects on health.
Still, replacing saturated fats, trans fats, and refined carbohydrates with PUFAs, which are found abundantly in seed oils, can be beneficial for your heart.
