Are Seed Oils Really Bad For You? I Asked A Nutritional Therapist

Those who like to stick to a Mediterranean-style diet will have already heard about the beneficial polyphenols in fresh, high-quality olive oil (though these degrade faster than you might think). 

But depending on which corner of social media you inhabit, you might have seen quite a lot of claims about the “bad” effects of seed oils on your health, too. 

Some people argue that an omega-6 fatty acid (linoleic acid) in seed oils, including canola, sunflower, soybean, grapeseed, safflower, and peanut oil, contributes to inflammation in the body. 

But some research says that the ingredient, which is found in “virtually all commonly consumed foods,” does not seem to alter the arachidonic acid levels people suspect it of raising (blamed, arguably inaccurately in this case, for inflammation). 

Harvard writes that not only does linoleic acid create less arachidonic acid than you may think, but that the supposedly inflammatory acid may be misunderstood; the body turns it into molecules that calm inflammation and fight blood clots, too.

So, we spoke to Kerry Beeson, a qualified nutritional therapist at Prep Kitchen, about her thoughts on the topic. 

The nutritional therapist isn’t convinced

“Seed oils are objectively quite healthy, in that they’re typically low in saturated fats,” the expert told us.

They “contain beneficial nutrients like antioxidants, linolenic acid (an essential omega-6 fatty acid), and some contain small amounts of omega-3,” Beeson said.

“We don’t make these fats in the body, so we must obtain them from our diet.” 

The NHS says that omega-6s, which people say are to blame for inflammation, contain polyunsaturated fats which can help to lower “bad” LDL cholesterol.

While the seed oils are often present in processed foods, which tend to provide little nutritional benefit thanks to high levels of salt and, typically, less fibre and protein, this is not due to the oil in and of itself (though too much fat may be included in some of these products).

Some worry that the ratio of omega-6 to omega-3s in our diet, which has shifted towards most of us eating more omega-6s without healthy omega-3s to balance them, gets thrown off further by the consumption of seed oils.

But Beeson, the American Heart Association, and Massachusetts General Hospital agree that we don’t yet know for sure what an ideal ratio is.

And the expert says that eating more omega-3s, which experts agree the majority of us are lacking, is as simple as eating “oily fish, flaxseeds, chia seeds, or walnuts.”

As Harvard Health wrote, “To improve the ratio of omega-3 fats to omega-6 fats, eat more omega-3s, not fewer omega-6s.”

Does that mean I should go ham on all the oils I want?

The NHS says that fats (found in all oils, butters, and ghee) are bad for us when eaten in excess. 

“Too much fat in your diet, especially saturated fats, can raise your cholesterol, which increases the risk of heart disease,” they shared. 

But coconut oil has some of the highest saturated fat levels of all common cooking oils (86% to butter’s 52%), while the British Heart Foundation recommends a seed oil (rapeseed) as their best pick alongside olive oil.

With that said, fats of any kind should not make up more than 35% of our diet. 

As Benson told us, we should “aim to eat a wide variety of healthy fats in your diet [and] avoid eating lots of processed foods.”

Eating enough fruit, vegetables, and oily fish (or other sources of omega-3) will go far, the British Heart Foundation says.