Seed oils — like canola, sunflower, sesame, or flaxseed oil — have become a kitchen staple for their “heart-healthy” reputation. But while they can bring amazing benefits, using them the wrong way might do more harm than good. Here’s what nutrition experts say about how to make seed oils truly work for your health.

Why seed oils are more than just cooking fat

Seed oils are rich in unsaturated fats, particularly polyunsaturated fatty acids (PUFAs), which help reduce LDL (bad) cholesterol and support heart health.

According to Amy Brownstein, MS, RDN, “The unsaturated fats in seed oils not only improve cardiovascular function but also help control weight, reduce inflammation, and enhance brain activity.”

These oils also provide antioxidants like polyphenols and tocopherols (vitamin E), which fight free radicals and protect your cells from oxidative stress — one of the root causes of aging and chronic disease.

Some oils, such as flaxseed and canola, also contain omega-3 fatty acids. These balance out omega-6s in the diet, helping regulate inflammation and strengthen your immune system.

The hidden risks of seed oils

Despite their benefits, seed oils have stirred controversy. When overheated or reused, they can form toxic oxidation compounds that damage heart and liver health.

Many commercial oils — such as soybean, corn, or canola — are made from genetically modified (GMO) crops. While the FDA has deemed them safe, concerns remain about biodiversity and overuse of herbicides.

Another issue is the imbalance of omega-6 and omega-3. Most modern diets are overloaded with omega-6, which can promote chronic inflammation if omega-3 intake is too low.
Nutrition expert Allison Herries, RDN, advises:

“Instead of cutting out omega-6, balance your diet by adding more omega-3-rich foods like salmon, mackerel, chia seeds, or flaxseed oil.”

Who should be cautious when using seed oils

People with nut or seed allergies (like sesame, sunflower, or peanut) should limit seed oil intake to avoid allergic reactions.
Those with fat absorption disorders or liver issues should also consult a doctor before using them regularly.

On the other hand, individuals with diabetes can benefit from flaxseed or sesame oil, which may help improve insulin sensitivity and stabilize blood sugar levels.

How to choose and use seed oils safely

1. Pick cold-pressed or unrefined oils.
These retain the natural nutrients, antioxidants, and flavor of the seeds.

2. Store them correctly.
Keep your oil in a dark bottle, in a cool, dry place, and use it within 3–4 months after opening. Exposure to heat and sunlight accelerates oxidation.

3. Never reuse oil for frying.
Reheating creates harmful free radicals that can negatively affect heart health.

4. Match the oil to your cooking style.

• Canola, sunflower, or corn oil: great for stir-frying and roasting.

• Sesame oil: perfect for flavor and aroma in Asian dishes.

• Flaxseed oil: ideal for cold salads, smoothies, or drizzling after cooking (not for frying).

5. Control your daily intake.
Healthy fats should account for 20–35% of total daily calories, about five tablespoons of oil per day.

The takeaway

Seed oils can be your heart’s best friend — but only when used the right way. Variety, moderation, and mindful cooking are the keys. Rotate your oils, avoid overheating, and balance omega-3 and omega-6 to keep your heart, brain, and cells functioning at their best.