Why You Shouldn't Cook in Olive Oil Only

A preventive cardiologist argues for reintroducing seed oils into your kitchen and addresses the two main concerns that keep them out- why you shouldn't be cooking in olive oil only.

Many health-conscious individuals have made a similar choice: using olive oil exclusively and eliminating seed oils, such as canola, soybean, sunflower, and corn, from their pantries. This decision often stems from information encountered online, which claims that seed oils are "inflammatory" and contain "too much omega-6," suggesting they should be avoided.

While I understand this instinct, as a cardiologist, I aim to present an evidence-based argument for the opposite perspective: if you're solely cooking with olive oil, you might be missing out on significant health benefits. Extra-virgin olive oil is excellent and deserves a permanent place in your kitchen, but it shouldn't be your only oil.

Two primary concerns lead people to stick with olive oil alone. Let’s examine both of these fears and discuss what you may be sacrificing by avoiding seed oils.

Fear 1: "Seed oils are inflammatory"

This is the main reason many people exclude seed oils from their diets. The theory posits that omega-6 fats found in seed oils elevate inflammatory markers and, ultimately, cardiovascular risk.

However, when measured, this theory does not hold up. Canola and sunflower oils are shown to reduce inflammation similarly to olive oil. Randomized controlled trials indicate that replacing saturated fats with polyunsaturated fats from seed oils results in no increase in the inflammatory markers we monitor—such as CRP, interleukins, and TNF-α.

Fear 2: "The omega-6 to omega-3 ratio is wrong"

This concern is more nuanced and warrants a thorough response. The argument suggests that humans evolved with a balanced ratio of omega-6 to omega-3 fats, approximately 1:1, while modern diets skew closer to 15:1, with seed oils being blamed for this imbalance and the resulting inflammation.

While this narrative is compelling, current cardiometabolic science suggests that the ratio itself is largely unimportant. What truly matters is the total intake of each fat, not their proportions. Here’s why the ratio concern is not as significant as it may seem:

• Raising omega-6 doesn't cause harm. A major 2020 review found that concerns about a high omega-6:omega-3 ratio lack substantial support. Feeding trials that significantly increased omega-6 (linoleic acid) while keeping omega-3 constant, thereby raising the ratio, showed no worsening of inflammation or oxidative stress, even with caloric excess.

  
  

• The mechanism is flawed. The alarming notion that linoleic acid easily converts to arachidonic acid (a precursor to inflammatory compounds) is inaccurate. Linoleic acid supplements do not significantly raise arachidonic acid levels in blood or tissue, and omega-6 fats are not inherently proinflammatory.

  
  

• Higher linoleic acid correlates with less disease. Evidence from diet and blood biomarkers consistently shows that increased linoleic acid is associated with a lower risk of cardiovascular disease, cardiovascular death, overall mortality, and type 2 diabetes. A Cochrane review found that substituting saturated fat with omega-6 reduced heart attack risk.

  
  

• Omega-6 does not negate omega-3. Large prospective studies have found no significant interaction between the two; the cardioprotective effects of omega-3 remain intact regardless of omega-6 intake levels.

  
  

Both sides of the debate agree on one point: even researchers who emphasize the ratio advocate for *increasing omega-3* intake rather than restricting seed oils. The evidence-based approach is to ensure adequate omega-3 consumption, not to fear omega-6. Conveniently, canola and soybean oils also provide plant-based omega-3 (ALA), which can actually enhance your omega-3 status.

One honest caveat: there is a weak, low-quality signal indicating that higher omega-6 intake might raise cardiovascular risk specifically in individuals with established heart disease. If this applies to you, it’s worth discussing with a healthcare professional rather than applying a blanket rule. However, for the larger population focused on *preventing* a first cardiovascular event, the omega-6 to omega-3 ratio is not a valid reason to avoid seed oils.

What cooking exclusively with olive oil actually costs you- why you shouldn't cook with olive oil only

With both fears addressed, let’s explore what seed oils offer that olive oil cannot:

• Stronger LDL lowering. This may surprise some. A meta-analysis of 42 trials revealed that canola oil outperformed olive oil in reducing total cholesterol, LDL-C, triglycerides, and the LDL-to-HDL ratio. One study found that corn oil reduced LDL by nearly 11%, compared to about 3.5% for extra-virgin olive oil over three weeks in individuals with high cholesterol. The polyunsaturated fats in seed oils tend to lower LDL and its counterpart ApoB, more effectively than the monounsaturated fats predominant in olive oil. If lipid levels are a concern for you, this is a significant advantage you forfeit by using only olive oil.

• Omega-3s that olive oil lacks. As mentioned, canola and soybean oils provide ALA, an essential omega-3 fatty acid with few good plant sources. Olive oil contains virtually none. If you’re not consuming fatty fish regularly, seed oils can help fill that nutritional gap.

• A metabolic assist. While the evidence is less robust, some reviews associate canola and sesame oils with modest weight reductions. Canola oil’s fat profile also appears to enhance glucose control, insulin resistance, and insulin production. In a cardiovascular-kidney-metabolic (CKM) context, where lipids, glucose, and weight are interconnected, this is worth considering.

• Better options for high heat. Olive oil can dominate the flavor of dishes where a neutral taste is desired, while many seed oils are more heat-tolerant and flavor-neutral, ideal for searing, stir-frying, roasting, and baking. In certain frying comparisons, high-oleic sunflower oil even performs better under heat than olive oil. Considering the lower cost, there are numerous cooking scenarios where seed oils are simply the more practical choice.

  
  

Olive oil still deserves its place-this is the key point

I am not suggesting you eliminate olive oil. It possesses a unique advantage that no seed oil can match: solid outcome data. In the PREDIMED trial, a Mediterranean diet enriched with extra-virgin olive oil reduced major cardiovascular events by about 30%. Observational studies link it to lower mortality rates, reduced heart disease and stroke, and potentially decreased cancer risk. Additionally, it contains polyphenols, protective plant compounds absent in refined oils and resists oxidative breakdown well under heat.

That’s why the optimal approach is to use both oils, not just one. Olive oil offers the strongest evidence base and distinctive flavor, while seed oils provide enhanced LDL lowering, omega-3s, and high-heat versatility. Relying on just one type of oil means sacrificing one set of benefits in favor of another.

How to effectively use both oils

• Use extra-virgin olive oil as your finishing and low-to-medium-heat oil-for dressings, drizzling, sautéing, and any dish where its flavor is desired.

  
  

• Opt for canola or another seed oil for high heat and baking-such as searing, stir-frying, roasting, and in neutral-flavored dishes, along with the benefits of LDL lowering and omega-3s.

  
  

• Ensure adequate omega-3 intake. This is the most evidence-supported dietary fat strategy, consume fatty fish a couple of times a week or incorporate ALA from canola and soybean oils. This is far more important than avoiding omega-6.

  
  

• Stop viewing canola oil as a threat. The energy spent fearing it would be better directed toward factors that genuinely affect your risk: your ApoB levels, blood pressure, metabolic health, sleep quality, and physical activity.

  
  

Cooking with a combination of oils is not a compromise, it’s the evidence-based choice. The decision to use only olive oil is rooted in a myth. Once you set aside this myth, reintroducing seed oils is one of the simplest enhancements you can make to your cooking.

This article is intended for educational purposes and reflects the current state of the evidence; it is not a substitute for personalized medical advice. Your ideal dietary fat strategy depends on your lipid levels, metabolic profile, and overall risk factors, including whether you have established heart disease, which is precisely the type of situation prevention aims to personalize.

FAQs

• Are seed oils really inflammatory? Research indicates that seed oils like canola and sunflower do not significantly increase inflammation compared to olive oil.

• What is the ideal omega-6 to omega-3 ratio? Current evidence suggests that the total intake of omega-6 and omega-3 is more important than their ratio.

• Can I use seed oils for high-temperature cooking? Yes, many seed oils are more heat-tolerant and flavor-neutral, making them suitable for high-heat cooking.

• Should I completely avoid olive oil? No, olive oil provides numerous health benefits and should be included as part of a balanced diet.

• How can I ensure I get enough omega-3s? Include fatty fish in your diet a few times a week or consider plant-based sources like canola and soybean oils for ALA.

References

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