Unpacking the latest science on seed oils

Seed oils (thinking sunflower/rapeseed/canola/palm/soya/'vegetable') . Such a controversial subject in the nutrition world with two sides battling it out regularly. It's near impossible to know the truth really and so often, you may get to the end of a ground breaking study, only to find it's sponsored by the very industry it is promoting. Well that's standard in the scientific community which why for me, makes thousands of years/lived experience anecdotal evidence far more compelling.

From claims that they're inflammatory villains to new studies suggesting potential health benefits, what really is best for our health? A recent study has added a new twist to the debate, proposing that certain seed oils might actually support heart health and reduce inflammation—but the story isn't that simple.

The study: analysing blood markers

In this recent study, nearly 1900 people had their blood markers studied and it was found that higher levels of linoleic acid may help to lower risk of heart disease and type 2 diabetes. Apparently the findings challenge claims that seed oils are harmful....however, this fatty acid is also commonly found in many other foods including unprocessed nuts, seeds, lentils, beans and soya.

Let's have a think about this

Some seed oils when in a minimally processed form may offer health benefits as they can be rich in omega-6 and omega 3. If they come cold pressed and only extracted from mechanical processes, it's a whole different thing. However, omega 3 is an extremely volatile oil that is prone to oxidation especially at higher temperatures.

The problem with processing

Many of the seed oils we encounter in ultra-processed foods, takeaways, and restaurant meals go through industrial refining methods, often involving chemical solvents like hexane. While the hexane is mostly removed before the oil reaches your plate, the refining process also strips away antioxidants and introduces the potential for oxidative degradation, especially when the oil is heated to high temperatures. Let's think about that. In most cases, the oil will always have been heated to high temperatures, think crisps (deep fried), chips (deep fried) etc.

When seed oils are exposed to high heat—(deep frying/roasting)—they can produce compounds that promote oxidative stress in the body, a process linked to inflammation, aging, and chronic disease.

What this study is not clarifying is how they are consuming the omega 6 and in what form. It also does not discuss the conversion of omega 6 linoleic acid to the more pro-inflammatory arachidonic acid which is what the anti-seed oil establishment are often referring to (even if the scientific evidence for it isn't that strong).

Don’t take studies at face value

It’s tempting to see headlines like “Seed oils are healthy!” and take them at face value because behind that title is an extremely invested industry. These seed oils are used in abundance within the junk food industry. Most studies are conducted under specific conditions that don’t always reflect real-world eating habits and I've reiterated in past blogs, using animal experiments which any sane person would regard as misinformation.

Consider these factors

• Serving size and frequency matter—a tablespoon of cold-pressed flaxseed oil on a salad is not the same as consuming multiple servings of deep-fried food daily or ultra processed foods most of which contain these processed oils (take a look at the ingredients next time)

• Type of oil matters—cold-pressed, organic oils contain more nutrients than highly refined versions (which may actually by this point have compounds negatively affecting health).

• Your overall diet matters—a balanced diet rich in whole foods, fibre, and healthy fats is so much more important (obvs)

  
  

Should you use seed oils?

Here’s a balanced takeaway:

• Choose minimally processed, cold-pressed oils when possible and don't overheat them

• Avoid using refined seed oils, especially in deep-frying and in highly processed foods.

• Use oils with higher smoke points (like avocado, butter, ghee, coconut) for high-heat cooking.

• Keep an eye on your omega-6 to omega-3 balance—most people consume too much omega-6 relative to omega-3.

  
  

Final thoughts

Nutrition is nuanced, and studies should always be interpreted within the bigger picture. While this latest research offers a fresh perspective on seed oils, it doesn’t give a free pass to processed foods or deep-fried indulgences.

Your best bet? Stick to whole, minimally processed foods, and be mindful of the kinds of fats you’re including in your diet. As always, the dose makes the poison—and the benefit.