Do Seed Oils Have A Place In A Healthy Lifestyle?

It’s a popular topic in the US at the moment, as the current Secretary of Health condemns them strongly.

So, what does the science say?

Seed oils are not great.

Let’s consider two most popular seed oils in N. America, canola and sunflower, either of which also get described simply as “vegetable oil”, which is an umbrella term that also covers oils from many other plants, including soybeans and even olives, but it’s rare someone will call olive oil “vegetable oil”, because you get to charge more if you mention it’s olive oil.

Canola oil and sunflower oil are less healthy than almost any other vegetable or nut oil (unless you have an allergy, of course).

But then, as regular participants in our “This or That” feature might remember, grapes are less healthy than almost any other fruit. Are they bad? No! They’re just not as good as most other fruits, that’s all; they simply deliver fewer micronutrients, and their structure allows them to exist with minimal fiber compared to most fruits.

So the question now is: ok, so they don’t score as well as olive oil or avocado oil or such, but are they dangerous?

And the answer is: water is dangerous if consumed much in excess of about 1 liter per hour (that’s how much an average healthy pair of kidneys can process) for some hours. More than that, and toxicity ensues quickly, along with swelling of the brain.

And yet… A lot of people, especially in places whose regional cuisine is “deep-fried everything”, do consume a lot of vegetable oil, and that becomes a health problem.

We may hypothesize that it’s for this reason that they (seed oils as a general umbrella term, but usually mostly meaning canola and sunflower) are often associated with cardiovascular disease in epidemiological studies, while olive oil and avocado oil, for example, are certainly not. The thing is, nobody is deep-frying ice-cream sandwiches in olive oil.

Here’s an example, which ties it to industrially-processed seed oils’ higher omega-6 content:

Omega-6 vegetable oils as a driver of coronary heart disease: the oxidized linoleic acid hypothesis

Now, we do need omega-6! In fact, we typically need more omega-6 than omega-3.

However, while we need 1–4x more omega-6 than omega-3, problems arise when the average American is getting nearer to 16x more omega-6 than omega-3. Hence the common advice to get more omega-3 and less omega-6. It’s not that omega-6 is bad per se; it’s good! Rather, it’s that we need the ratio to be a lot closer, that’s all.

See: The importance of the ratio of omega-6/omega-3 essential fatty acids

Canola oil, by the way, has a 2:1 ratio of omega-6 to omega-3, so if that were your only source of omega-6 and omega-3, then well, you’re probably going to have to consume a lot of calories to get your daily dose in and that’s going to cause different problems, but the ratio itself is fine. Not

In a similar vein, canola oil and sunflower oil are marketed as being a source of vitamin E, which they are, but you’d need to drink a cup of oil to get your daily dose, so please just eat some sunflower seeds instead, or perhaps some almonds.

The other side of cardiovascular disease risk

We mentioned above, and cited a study, for how seed oils are linked to coronary heart disease.

But, remember when we said that this is often in epidemiological studies (as that research review mostly reviewed), which don’t necessarily record how people are using them, so much as how often they use them?

Things get interesting if we look at randomized controlled trials (RCTs) instead. That’s because RCTs typically have small, standardized daily doses, suitable for such studies and consistent with “reasonable health guidelines” that allow that study to pass an ethics board.

And when we do that, we get things like…

❝Canola oil (CO) is a plant-based oil with the potential to improve several cardiometabolic risk factors❞

Read in full: The effects of Canola oil on cardiovascular risk factors: A systematic review and meta-analysis with dose-response analysis of controlled clinical trials

What about vs butter?

This one we covered in detail before, so we’ll share that here:

Butter vs Plant Oils: What The Latest Evidence Shows

…which, after much number-crunching, ultimately concludes that substituting even 10g/intake of total butter with an equivalent amount of plant-based oils yielded 17% lower total mortality.

In summary

Do we recommend seed oils? In honesty, not really, no. There are better oils in general.

Consider, for example: All About Olive Oil

…and for more choices, check out that “Butter vs Plant Oils” link just above, because we back-link to so many articles about different options!

But they’re also (per current scientific consensus, since research is ongoing) absolutely fine in moderation—even potentially healthy in moderation, as those RCTs show.

Take care!