The Oils that Everyone Loves to Hate May Not be So Bad After All…
Omega 6 seed oils get a ton of bad press.
Fitness influencers shoot them with guns, making a dramatic point and ensuring those all-important social media views. Graphs showing increased seed oil consumption alongside obesity rates – heavily implying a causal link – contribute to the narrative.
I went deep down the research rabbit hole, fully expecting to find evidence that seed oils including rapeseed (canola), sunflower and soybean oil were catastrophic for our health.
What I found was far more nuanced.
There are major positives to Omega 6 oils, especially for heart disease outcomes.
Charges against Omega 6 oils include oxidative properties, chemicals used in production and toxic by-products of continual heating. The good news is that, as long as you have a good ratio of Omega 3 to Omega 6 in your diet, there are no clinically significant effects.
After my two day deep-dive into this topic, I’m far more relaxed about seed oils. Omega 3 oils are excellent, with both antioxidant and anti-inflammatory properties. The balance between them (and other healthy oils) is far more important than completely avoiding Omega 6.
Omega 3 Omega 6, Saturated, Monounsaturated and Polyunsaturated Oils
Edible oils come in three chemical types, Omega 3 and 6 oils are polyunsaturated.
The difference is in the way that carbon atoms are linked. Knock-on effects on how the oils are broken down and used by our cells. A by-product of fat metabolism is cholesterol. While the ‘good’ and ‘bad’ labels have given way to a more nuanced view of cholesterol – there are clinically proven links to atherosclerosis.
- Saturated: With no double-chemical bonds, saturated fats come from animal sources. You find these fats in meat, dairy, and in palm oil. Hydrogenated oils can also be saturated.
- Monounsaturated: This category has a single double bond. Liquid at room temperature, popular examples are olive oil, avocado, peanut oil, and nuts.
- Polyunsaturated: With multiple double bonds, polyunsaturated fats come from fish, nuts, and seeds including sunflower and flax.
Oils can contain more than one chemical type. For example, sunflower oil has both monounsaturated and polyunsaturated fatty acids. It also contains a mix of Omega 6 and 3 (in a 40:1 ratio).
Overview: The Case Against Omega 6 Oils
- Oxidation: Omega 6 metabolise into Linoleic acid. This oxidises LDL cholesterol, which leads to arterial plaques – a significant risk factor in coronary heart disease.
- Industrial Chemicals: The production of omega 6 oils uses chemical solvents including Hexane, and chemical deodorants.
- Reheating O6 Oils: Restaurants reheat oils continually, creating toxic by by-products including aldehydes and polycyclic aromatic hydrocarbons.
- New and Unnatural: Seed oil consumption was virtually unheard of a century ago, and the increase as a percentage of calories clearly trends upwards with obesity and chronic diseases.
Note that the type of foods (fried food, deserts and so on) that contain seed oils are also high in simple carbohydrates and sugars.
Little Evidence of Oxidation in People
Our cells are constantly repairing damage caused by oxidation. DNA repair, recycling of damaged cells and breakdown of glycated messenger molecules are just three example mechanisms.
A major charge against O6 is that it breaks down into Linoleic acid, which in turn metabolises into arachidonic acid – which is known to be oxidative. There is no clinical evidence that this is a risk factor. In fact, only 0.2% of Linoleic acid is metabolised this way – more than balanced by the antioxidative properties of the Omega 3 part of the seed oils.
This meta-analysis concludes that there is little evidence that O6 oils create oxidative stress in people.
Fumes from Cooking with Seed Oils
The other charges against are petrochemical use and carcinogenic fumes.
Ventilation in commercial kitchens ensures that fumes from all sorts of cooking are removed. A study from China followed up women working in high burn-point food production without ventilation. It showed a higher incidence of lung cancer, regardless of smoking status.
Data on what was being cooked, with what oils and under what processes is not recorded.
Burning foods of any type risks polluting the air with toxic compounds. Choose seed oils with higher smoke points – and make sure you don’t burn them.
Heart Healthy: Omega 6 Oils and Lower Coronary Heart Disease
At a population level, clinical evidence shows that seed oil consumption leads to lower incidence of heart disease.
This is no hear-say, or correlation – meta analysis of large samples clearly shows a significant reduction in heart attacks, strokes and other forms of heart disease with Omega 6 oil consumption.
If the oxidisation of LDL cholesterol is a contributory factor (there is no evidence of this), then other benefits from seed oil consumption overcome this. Reduction in saturated fat consumption is frequently highlighted.
This analysis covers the controversy.
The Right Ratio of Omega 3 and Omega 6 Oils
A ratio of 4:1 between Omega 6 and Omega 3 oils is ideal.
This gives you the best of all worlds, with heart protection and plenty of antioxidants to repair damage to your DNA and cellular components.
The problem is that most of us are way off – by a factor of three or more.
A ratio of 10:1 (typical for the western diet) means you are missing out on the benefits of using Omega 3 oils as building blocks for cellular health.
On the positive side, this is easy to solve.
A little less Omega 6 means you’ll be skipping foods which are unhealthy in other ways. I’m talking pastries with wheat and sugary fillings, dressings which are loaded with preservatives and artificial flavourings and deep-fried simple-carbohydrate foods. Cutting down on vegetable oils by replacing them with olive oil is another quick win for your long-term health.
Adding oily fish like salmon or mackerel, and chia seeds to your diet will provide plenty of nutrients and minerals – while boosting your omega 3 levels. If you prefer, a simple supplement will help balance your O6 / O3 ratio.
Olive Oil: The Heart of the Mediterranean Diet
I use olive oil for cooking, and on my salads.
Olive oil is high in monounsaturated fat (oleic acid) with some Omega 3 and 6.
It has both antioxidative and anti-inflammatory qualities. Papers and meta-analyses show significant reduction in cardiovascular disease, reduces markers of inflammation (c-reactive protein and others) and improved immune function.
Best of all, by cooking with olive oil, you will reduce the overall volume of Omega 6 oils in your diet, skewing that ratio with Omega 3 back in the right direction.
Wrapping Up: Focus on Your Ratio – Not on Avoiding Omega 6 Oils
Scare stories and extreme opinions get the clicks, but after my deep-dive into the clinical papers, I’m far more relaxed about industrial seed oils than when I started.
That graph showing obesity moving up in parallel with increased seed oil consumption is compelling.
An increase in simple carbohydrate consumption, sugars and hyper processed foods goes along with the seed oil boost. Add to that the lack of compelling clinical evidence (and plenty of positives).
The key factor is to make sure you get Omega 3 oils. Preferably direct from naturally sourced fish, though supplements or chia seed oils work too.
By cutting down on those simple carbs (especially snacks like cakes, pastries, or French fries) you’ll naturally move your 06 / 03 ratio in the right direction.
With an overall healthy diet, I won’t be worrying about the occasional salad dressing or visit to a restaurant.
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