Nutritional science is ever-evolving, making it tough to keep up with patients’ latest fads and beliefs. Social media only adds fuel to this fire. Now, a simple task like choosing the right cooking oil can leave patients feeling paralyzed in the grocery store.

Here, we’ll decode the latest on fats for cooking so you can feel confident advising your patients.

An ongoing saga: Saturated fats

Saturated fat has long been considered an enemy of heart health, with the American Heart Association recommending intake should be limited to 6% of a person’s diet.

Eckel RH, Jakicic JM, Ard JD, et al. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129(Suppl. S2):S76–S99.

However, some mixed opinions have left people questioning the merits of such strict restrictions, particularly if the saturated fat comes from natural sources like butter and coconuts. 

For now, medical consensus generally still favors replacing solid cooking fats with unsaturated options. But the health implications of different plant oils can vary widely.

How seed oils became controversial

The unsaturated fats in seed oils earned them a health halo that’s recently come under scrutiny. In their natural state, seed oils are a rich source of beneficial compounds.

In addition, the consumption of flaxseed oil has been demonstrated to reduce systolic blood pressure in multiple randomized controlled trials.

Mahmudiono T, Jasim SA, Karim YS, et al. The effect of flaxseed oil consumption on blood pressure among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized clinical trials. Phytother Res. 2022;36:3766–3773.

Unfortunately, it’s not well-suited for cooking.

Public health organizations commonly recommend rapeseed oil (canola oil) as a superior cooking oil practically on par with olive oil due to its negligible saturated fat. Although research generally favors canola oil, some conflicting observations prevent researchers from drawing a strong conclusion on its health impacts.

Raeisi-Dehkordi H, Amiri M, Humphries KH, et al. The effect of canola oil on body weight and composition: a systematic review and meta-analysis of randomized controlled clinical trials. Adv Nutr. 2019;10(3):419–432.

While extreme views on nutrition should always be taken with a grain of salt, there may be some merit to these emerging concerns.

The seed oils typically found in Western diets are highly refined and stripped of precious antioxidants before they’re added to processed foods. As a result, cutting back on ingredients like corn and soybean oil usually means avoiding unhealthy snacks and treats. Additionally, seeds oils are naturally high in omega-6 fatty acids, which tend to be overrepresented in modern diets.

Seed Oils: Are They Actually Toxic?. Cleveland Clinic. October 3, 2023.

It’s also worth noting that some trans fats are produced when cooking with seed oils, particularly when stir frying at high temps.

Song J, Park J, Jung J, et al. Analysis of trans fat in edible oils with cooking process. Toxicol Res. 2015;31(3):307–312.

Which oils are best for which cooking methods may depend on their smoke point.

Choosing and Using Cooking Oils: What To Use and When. Cleveland Clinic. January 17, 2023.

Sunflower oil has a high smoke point, making it suitable for high-heat cooking like searing, browning, and deep frying. In fact, it has a higher smoke point than canola, grapeseed, and peanut oil. 

Hemp, pumpkin, and sesame oils also have beneficial properties, but are delicate and better saved for the last few minutes of cooking to prevent heat damage. Oils such as flaxseed, walnut, and wheat germ should be reserved for use in dressings, dips, and marinades, rather than for cooking.

Why olive oil is still the gold standard

The Mediterranean diet is frequently named as the best diet for longevity and good health. One hallmark characteristic of the diet is the inclusion of olive oil.

While it may sound like old news, encouraging patients to cook with olive oil is sound nutritional advice.

Avocado oil is another plant-based option with a similar thermal stability to that of olive oil, and it has a higher phytosterol content. However, it has lower levels of vitamin E, slightly more saturated fat, and a lower omega-3 to omega-6 ratio than olive oil.

Flores M, Saravia C, Vergara CE, et al. Avocado oil: characteristics, properties, and applications. Molecules. 2019;24(11):2172.

Certain nut oils, like almond and hazelnut oil, are also very low in saturated fat and stand up well in high temperatures. However, their distinct taste isn’t suitable for every culinary creation.