This blog post was inspired by the recent viral posts about coconut oil. After about 6 hours of research, I wanted to shut my computer and walk away from this topic. I got so frustrated by the spider web of information out there. Many blog posts and expert opinions are full of statements not well supported by research.
I decided not to give up because I realized that that is the exact problem that everyone is facing and why it is so easy to be swayed by fad diets or industry propaganda. Instead, I chose to dig deep and spend many hours of research figuring out what we know about oil today, and what the research says about how it impacts our health.
Is oil good for us?
Oil is fat stripped from its original source and we do need fat in our diet for our bodies to function properly. Fatty acids are classified as saturated fat and unsaturated fat. Unsaturated fat further separates into monounsaturated fat and polyunsaturated fat.
Polyunsaturated fats (PUFAs) are essential for us to consume in our diet because we cannot make them on our own. PUFAs includes Omega-3’s (also known as alpha-linolenic acid, ALA) and Omega 6’s (also known as Linoleic acid, LA). Omega 6’s are found in the seeds of many plants. Omega 3’s are highly available in fatty fish, with wild salmon being a good source.
Omega-3’s are essential for
Saturated fat is linked to heart disease and the bulk of research supports minimizing saturated fat intake and replacing it with unsaturated fats and whole grains. You will find some claims about how saturated fat is good, but from what I have seen this is largely unsupported by research (Sacks et al, 2017). Saturated fat is found in meat (even chicken), dairy, coconut oil, and palm oil.
Oils are calorie dense and many have little nutrients, which can promote weight gain. Oils found in their original whole food sources such as nuts, avocados, and wild salmon have more nutrients per calorie.
Some oils like coconut oil and palm oil contain a high amount of saturated fat which, again, is linked to heart disease.
There are some additional health concerns related to oil, and we will focus on those with potential links to cancer.
Can oil cause cancer?
I have not found any studies directly linking oil with cancer,
Hexane: The actual process of extracting oil from their whole food sources can cause concern. For example, solvents like n-hexane are used to help extract oil from seeds (example, canola oil), and there have been some research studies and concerns raised around the potential toxicity of hexane. It is unclear whether or not the amount of hexane leftover in cooking oil is harmful.
Cold-pressed or Expeller-pressed: Expeller pressed is a high-pressure technique to remove oil from seeds and involves high heat and often hexane solvent. The high heat causes some of the fats to turn to trans-fat (Hénon et al 1999). Cold-pressed is more expensive but less processed and kept at a lower heat.
Here is a YouTube video which shows how vegetable oil is made.
Many oils are highly refined and most of the nutrients are stripped away. This causes oil to be high in calories but low in nutrients. Oil consumption can lead to weight gain and
Omega 6:3 ratio:
Vegetable oils (including sunflower and safflower oils) have a high proportion of Omega 6 compared to Omega 3 fat. Both Omega 6’s and Omega 3’s use the same enzymes in our bodies so if we are overloaded with Omega 6’s
Excess amounts of Omega 6 may promote inflammation, weight gain, and many diseases including cancer (Simopoulos, 2008; Simopoulos, 2016). Inflammation in itself is a precursor to cancer (check out my blog post on how cancer forms).
The exact ratio of Omega 6 to Omega 3 is uncertain and there needs to be more research around this theory in general (Marventano et al, 2015). Here is an article you can dig into for further reading.
Some oils have a low “smoke point” which means that they break down at high heats. This can contribute to free radicals which are linked to cancer. Additionally, the fumes may increase the risk of lung cancer (Xue et al, 2016).
Many oils, including Canola, Soybean, and Corn oil are mostly made from genetically modified crops. The main concern around GMO products (other than being uncertain of long-term effects of the genetic modification itself) is the use of the herbicide glyphosate (RoundUp weed killer). The crops are modified to be to be able to withstand this herbicide.
Glyphosate is listed as “probably carcinogenic to humans” by the International Agency for Research on Cancer (a branch of the World Health Organization), specifically
If you want to read further on this topic, the Huffington Post wrote an article reviewing the current legal battle with glyphosate and its parent company, Monsanto.
What about that recent news report that said coconut oil is bad for you?
Coconut oil is high in saturated fat compared to other oils which
The paper that the news reports were referencing was not actually heavily focused on coconut oil. To me, this raises a red flag that there may be a “competitive” food industry pushing the direction of this news (for example, the canola oil industry). I do not know if that is true in this case, but it is good to have
The actual focus of the review paper was on how the American Heart Association has reviewed the research and yet again recommends that we minimize our saturated fat intake which includes saturated fat from animal sources (meat and dairy) as well as sources like coconut oil (Sacks et al, 2017). They recommend that we replace these fats with polyunsaturated fats (walnuts and wild salmon are two sources), monounsaturated fats (avocado, tree nuts), and whole grains (not refined/processed).
They do also recommend canola oil and vegetable oils. I’m skeptical of that advice, again given the potential for bias and all of the reasons listed above about these oils.
It is pretty dense, but you can check it out here if you want to read the full report.
Where are oils found in processed foods?
Processed foods like crackers, hummus, chips, dips, salsas, “smart balance”, fried foods, and even in veggie broth. You will commonly find sunflower oil, safflower oil, vegetable oil, and canola oil in many processed foods including organic foods.
What types of oil should we use?
Oil is a processed food, and
For cooking: Cold-pressed Avocado oil. Avocado oil has a high smoke point (can be used for cooking) and also has a lower Omega 6 to Omega 3 ratio and low saturated fat. Personally, I also use cold-pressed coconut oil from time to time when I want coconut flavoring (curries), but I use it sparingly because of the high saturated fat.
For sauces: Extra Virgin Olive Oil. EVOO has a low smoke point so don’t use with heat. It has low saturated fat and a lower Omega 6 to Omega 3 ratio.
Keep in mind, those who choose to eat a vegan diet or plant-based diet without fish may be deficient in omega 3’s and can take an omega 3 supplement (EHA, DHA from wild salmon or algae sources) to prevent issues with brain function. Here is a wild salmon supplement option and an algae option.
- The processing of oil has some concerns that could impact our health
- Oil is a processed food and should be minimized in our diets
- Oil is high in calories and many are low in nutrients, which can contribute to weight gain
- Many vegetable oils have a high omega 6 to omega 3
ratiowhich can lead to inflammation
- We should aim to increase our Omega 3’s and decrease our Omega 6’s
- Vegans should consider taking an Omega 3 supplement
- We should reduce intake of saturated fats including animal fats and oils
- We should be sure to check labels of processed foods for the type of oil used.
- Cold-pressed avocado oil for cooking, extra virgin olive oil or avocado oil for sauces and dressings
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Demark-Wahnefried W, Platz EA, Ligibel JA, et al. The role of obesity in cancer survival and recurrence. Cancer Epidemiol Biomark Prev. 2012;21:1244–1259.
Hénon, G., Kemény, Zs., Recseg, K., Zwobada, F., and Kovari, K., Deodorization of Vegetable Oils. Part I: Modeling the Geometrical Isomerization of Polyunsaturated Fatty Acids, J Am Oil Chem Soc 1999; 76:73-81.
Marventano S, Kolacz P, Castellano S, et al. A review of recent evidence in human studies of n-3 and n-6 PUFA intake on cardiovascular disease, cancer, and depressive disorders: does the ratio really matter?. Int J Food Sci Nutr. 2015;66(6):611-22.
Ritte R, Lukanova A, Berrino F, et al. Adiposity, hormone replacement therapy use and breast cancer risk by age and hormone receptor status: a large prospective cohort study. Breast Cancer Res. 2012;14(3):R76.
Sacks FM, Lichtenstein AH, Wu JHY, et al. Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association. Circulation. 2017;
Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med (Maywood). 2008;233(6):674-88.
Simopoulos AP. An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients. 2016;8(3):128.
Xue Y, Jiang Y, Jin S, Li Y. Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis. Onco Targets Ther. 2016;9:2987-92.
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