Which are the Healthiest Oils or Fats to Cook With?

Published on

Choosing which type of oil or fat to use when cooking can feel pretty confusing as there are a lot of mixed messages in the media about this. To answer this question fully we need to look at the overall evidence base and weigh up a few different things, from oxidation and smoke points to the type of fats and antioxidants found in different oils.

 

How Heat Affects Oils

Have you ever had a bottle of oil in your kitchen which has turned dark or cloudy, smelled stronger than usual and tasted funny? This happens when light, heat and air causes oil to oxidise or breakdown which turns the oil rancid, this can also produce aldehydes and destroy vitamin E and vitamin K1Aldehydes are compounds which have been linked with diseases such as: heart disease, cancer and dementia but there is little solid evidence that they cause harm in the human diet2-4.

Some people say that you shouldn’t use vegetable oils for cooking as heating these oils produces trans fat, a harmful type of fat which is associated with an increased risk of heart disease. This is only half true; if vegetable oil are heated to a very high temperature this can form small amounts of trans fat, but it is not possible to form significant amounts of trans fat in home kitchens as hydrogen also needs to be present. So unless you own an industrial kitchen where you can heat a vegetable oil so much that it begins to harden, then there is little chance of producing much trans fat when cooking at home4.

Some vegetable oils such as olive oil, rapeseed oil and sunflower oil contain vitamin E and polyphenols which can protect the oil from oxidation; this makes these oils more stable to heat and light until these antioxidants are used up over time1.

Saturated and monounsaturated fat are slightly more stable to the effects of heat than polyunsaturated fat; so reusing oils high in polyunsaturated fats or using these for deep fat frying is more likely to cause oxidation1.

But one of the most important things to consider about heating oils is the smoke point. This is the temperature where the fat begins to break down and become rancid, so a higher smoke point means that a fat is more stable when it is heated and so it is better to use for cooking at higher temperatures4.

 

Table 1: The Smoke Point of Various Oils5-6

>230 ℃ (high smoke point) –  best for searing, browning and deep-frying:
Avocado Oil 269 ℃ 517 ℉
Refined Olive Oil 241 ℃ 466 ℉
Sunflower Oil 236 ℃ 458 ℉
Ghee 235 ℃ 455 ℉
Refined Coconut Oil 235 ℃ 455 ℉
Peanut Oil 233 ℃ 451 ℉
Corn Oil 233 ℃ 451 ℉
Refined Sesame Oil 232 ℃ 450 ℉
200 – 229 (medium-high smoke point) –  best for baking or stir-frying:
Safflower oil 229 ℃ 445 ℉
Virgin Olive Oil 214 ℃ 417 ℉
Rapeseed Oil 207 ℃ 404 ℉
150 – 199 (medium smoke point) – best for low heat baking and light sautéing:
Virgin Coconut Oil 179 ℃ 353 ℉
Butter 167 ℃ 333 ℉
Extra Virgin Olive Oil 160 ℃ 320 ℉
<150 (low smoke point) – best for making dips or dressings:
Flaxseed Oil 107 ℃ 225 ℉
Pumpkin Seed Oil 107 ℃ 225 ℉

 

As well as choosing the most heat stable oils, it’s important to store and use oils correctly to protect them from becoming rancid.

 

Tips for Preventing Oils Becoming Rancid4
Store away from sunlight in a cool and dry place

Replace the cap after use

Consume within 12 months

Avoid refrigeration (can thicken and become cloudy)

Cook for shorter periods of time and at slightly lower temperatures

Never re-use oil once it has been heated

Choose heat stable oils for high temperature cooking

 

The Health Benefits of Different Oils

There is a lot of controversy about whether saturated fat is good or bad for us7-8. Although the current evidence base shows that replacing saturated fats with refined carbohydrates (like sugar, white bread and white pasta) does not have health benefits, replacing saturated fat with wholegrains or unsaturated fat does seem to reduce the risk of heart disease; with more evidence starting to show that polyunsaturated fat is particularly heart healthy9-10. It is also important to mention that in many Western societies we eat more saturated fat than is recommended10-11. So for our heart health it is best to replace fats or oils high in saturated fat (like butter, palm oil or coconut oil) with those high in unsaturated fat (like olive oil, rapeseed oil, sunflower oil, safflower oil and soybean oil). Check out the comparison of oils chart below for a full breakdown of the types of fats found in different types of oils.

 

Comparison of the Fats in Various Oils

(from The BNF (2009) Culinary Oils and Their Effects)1

And as I’ve already mentioned, some oils also contain vitamins and antioxidants which add further health benefits. For example vitamin E is an antioxidant which protects our cells from damage, and vitamin K is essential for bone health and blood clotting1.

 

Vitamin E and K Levels in Various Oils

(from The BNF (2009) Culinary Oils and Their Effects)1

It is also important to look at the effects of whole-foods rather than just the specific fats or vitamins they contain. For example, olive oil has a lot of good quality evidence to support its health benefits, especially in terms of reducing the risk of heart disease and stroke12-13, and some research has actually found that using virgin olive oil to fry food is still associated with a reduced risk of heart disease14. There is also evidence which supports the benefits of rapeseed oil in terms of heart and metabolic health15-16.

 

But remember that unless you are trying to gain weight all oils should only be consumed in small amounts as they are high in calories; for example one tablespoon of any oil contains roughly 120 calories, which is the same as half a jam donut or two digestive biscuits17-18.

 

Main Points:

  1. Heat and light causes oils to breakdown and become rancid, so store oils away from sunlight, avoid cooking for long periods at very high temperatures and avoid reusing oils
  2. The healthiest oils to cook with have a high smoke point and are high in unsaturated fat and antioxidants; good options include: avocado oil, refined or virgin olive oil, sunflower oil, safflower oil and rapeseed oil
  3. Although ghee and refined coconut oil have a high smoke point, these are not the healthiest fats to consume regularly as they are high in saturated fat
  4. It’s best to use all oils and fats sparingly when cooking, unless you are aiming to gain weight

 

For more information about fats you can read my post: Dietary Fatty Avoids: An Overview 

Or check out my infographic series The Facts About Fats:

Part 1. The Basics

Part 2: Saturated and Trans Fat

Part 3: Unsaturated Fat

Part 4: Coconut Oil Debunked

 

References:

  1. BNF (2009) Culinary oils & their health effects 
  2. Baynes (2007) “Dietary ALEs are a risk to human health-NOT”
  3. Feron et al. (1991) “Aldehydes: occurrence, carcinogenic potential, mechanism of action and risk assessment”
  4. BNF (2009) “Answers to questions commonly asked about oils”
  5. “Oil Well data sheet” (2014) available via: https://docs.google.com/spreadsheets/d/1TCpmlGXaLh4Pi-fzAAvpCDWlsNagGpVBLfG4ekEPtCs/edit#gid=15
  6. “Characteristics of Various Oils” available via: http://www.todaysdietitian.com/newarchives/images/0215-2.pdf
  7. Chowdhury et al (2014) “Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis”
  8. Annals of International Medicine (2014): http://wphna.org/wp-content/uploads/2014/08/2014-03_Annals_of_Int_Med_Chowdhury_et_al_Fat_and_CHD_+_responses.pdf).
  9. Hooper (2015) “Reduction in Saturated Fat Intake For Cardiovascular Disease”
  10. Sacks et al. (2017) “Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association” 
  11. Public Health England (2016) National Diet and Nutrition Survey Results from Years 5 and 6 (combined) of the Rolling Programme (2012/2013 – 2013/2014)
  12. Schwingshackl & Hoffmann (2014) “Monounsaturated fatty acids, olive oil and health status: a systematic review and meta-analysis of cohort studies”
  13. EFSA Journal 2011;9(4):2033)
  14. Sayon-Orea et al. (2015) “Does cooking with vegetable oils increase the risk of chronic diseases?: a systematic review”
  15. Lin Lin et al. (2013) “Evidence of health benefits of canola oil” 
  16. Jones et al. (2014) “DHA-enriched high-oleic acid canola oil improves lipid profile and lowers predicted cardiovascular disease risk in the canola oil multicenter randomized controlled trial” 
  17. McCance & Widdowson’s: The Composition of Foods – Fifth Revised and Extended Edition
  18. FSA (2011) “Food Portion Sizes: Third Edition”

Testimonials

Maeve has been consulting on The Food Medic Educational Hub for 12 months now and has been a huge asset to the team. Her ability to translate some very nuanced topics in nutrition into easy-to-follow, informative articles and infographics is really admirable.

Dr Hazel Wallace

Founder of The Food Medic

Maeve is incredibly talented at sharing scientific information in an easy to understand way. The content she shares with us is always really interesting, clear, and of very high quality. She’s one of our favourite writers to work with!

Aisling Moran

Senior UX Writer at Thriva Health

Maeve has written extensively for NHD magazine over the last few years, producing a wealth of dietetic and nutritional articles. Always evidence based and factual, Maeve creates material that is relevant and very readable. She provides high quality work with a professional and friendly approach. Maeve is a beacon of high quality knowledge and work within the nutrition writing community; and someone NHD magazine is proud to work with.

Emma Coates

Editor of Network Health Digest


Support Dietetically Speaking

More from Dietetically Speaking

Can Type 1 Diabetes Management Contribute to an Eating Disorder?

Can Type 1 Diabetes Management Contribute to an Eating Disorder?

This guest post was written by Eloize Kazmiersky. Eloize graduated has a BSc Nutrition degree from the University of Nottingham …
Your No-Nonsense Guide to Eating Well

Your No-Nonsense Guide to Eating Well

I am SO excited to tell you about this book which I have just released!I was inspired to write Your No-Nonsense …
The Pros and Cons of Low-Carb Diets

The Pros and Cons of Low-Carb Diets

This guest post was written by Dr Harriet Holme (MA Hons Cantab, MBBS MRCPCH, PhD, RNutr). Harriet studied medicine at …
Does Green Tea Live Up To The Hype?

Does Green Tea Live Up To The Hype?

This article was written for NHD magazine, and was published in the February 2020 edition. Green tea is often touted as …
COVID-19 Diet Claims Debunked

COVID-19 Diet Claims Debunked

This article was written by Dietetically Speaking's intern Zachary Wenger. COVID-19 is a respiratory illness that can spread from person to …
Tomato Noodle Soup Recipe

Tomato Noodle Soup Recipe

This recipe is inspired by a delicious tomato broth ramen dish I had when I was living in Fukuoka in …
Is Organic Food The Healthier Option?

Is Organic Food The Healthier Option?

This article was first published in the December 2019/January 2020 edition of NHD Magazine. ‘Organic’ is a common buzzword …
Liquid Diets

Liquid Diets

This article was first published in the December 2019/January 2020 edition of NHD magazine. Liquid diets and meal replacements come …
Tofu, Sweet Potato & Veg Satay

Tofu, Sweet Potato & Veg Satay

This delicious vegan satay serves: 4-5 people. Ingredients: 1 large onion1-2 cloves of garlic1 tbsp rapeseed oil 2 medium sweet potatoes1 block …
Why Weight Stigma Deserves Your Attention

Why Weight Stigma Deserves Your Attention

This guest post was written by Amy Powderham, who is in her fourth year of studying Nutrition & Dietetics at …
The Ultimate Cholesterol Lowering Plan  (UCLP) ©

The Ultimate Cholesterol Lowering Plan (UCLP) ©

This article was written by developed for Nutrilicious as marketing communication. It was written by Dietetically Speaking's fantastic intern, Dietetic …
Food & Mood – Part 3: Drinks

Food & Mood – Part 3: Drinks

Many thanks to Katie O Callaghan for writing this guest post. Katie is a final year dietetics student based in …