Few ingredients have attracted quite as much controversy in recent years as seed oils. Sunflower oil, rapeseed oil, soybean oil and other commonly used vegetable oils have increasingly been accused of promoting inflammation, damaging our metabolism and contributing to chronic disease. Scroll through social media and you'll find no shortage of people suggesting that eliminating these oils is one of the most important things we can do for our health.

But how much of this is actually supported by scientific evidence?

A new review published in Current Nutrition Reports has revisited the research surrounding linoleic acid, the main omega-6 fatty acid found in many seed oils. And the findings paint a rather different picture from the one frequently presented online.

In fact, the researchers suggest that linoleic acid may have health benefits extending beyond its established effects on blood cholesterol and cardiovascular health.

Why Have Seed Oils Become So Controversial?

Much of the concern centres on the relationship between omega-6 fatty acids and inflammation.

Linoleic acid is an essential polyunsaturated fatty acid, meaning our bodies cannot manufacture it and we need to obtain it from food. It's found in numerous foods, including nuts, seeds and many vegetable oils.

Once consumed, some linoleic acid can be converted into arachidonic acid, another omega-6 fatty acid involved in the production of signalling molecules known as eicosanoids. Some of these molecules participate in inflammatory processes, which has led to the argument that eating more omega-6 fats must inevitably increase inflammation throughout the body.

It's an understandable hypothesis, but there's a problem with it. Human physiology is considerably more complicated than that.

Arachidonic acid also contributes to signalling pathways involved in normal immune function and the resolution of inflammation. Furthermore, only a relatively small proportion of dietary linoleic acid is converted into arachidonic acid, and increasing linoleic acid intake doesn't necessarily produce a corresponding rise in tissue arachidonic acid.

Most importantly, a plausible biochemical mechanism doesn't automatically tell us what happens when people actually eat these foods.

For that, we need human studies.

What Does the Human Evidence Show?

When researchers have examined the effects of increasing linoleic acid intake in controlled dietary intervention studies, they generally haven't found the increase in inflammatory markers that the popular seed oil narrative would predict.

Studies examining markers such as C-reactive protein, interleukin-6 and tumour necrosis factor-alpha have not consistently demonstrated that higher linoleic acid consumption increases systemic inflammation in healthy adults.

This doesn't mean that omega-6 fatty acids have no relationship with inflammatory biology. They clearly participate in numerous signalling pathways. But participating in inflammatory processes is not the same thing as causing harmful, persistent inflammation when consumed as part of an ordinary diet.

The distinction matters because much of the controversy has developed from taking a complex biochemical pathway and treating it as though it establishes a direct clinical outcome.

The new review also highlights evidence suggesting that linoleic acid may have favourable effects in several other areas of health.

Could Linoleic Acid Actually Have Benefits?

One particularly interesting area involves liver fat.

Several controlled trials have compared diets higher in saturated fat with diets containing more omega-6 polyunsaturated fat. Some have found that replacing saturated fat with polyunsaturated fat reduces the accumulation of fat in the liver, particularly in people with abdominal obesity or during periods of excess calorie intake.

This is relevant because excessive liver fat is closely associated with metabolic dysfunction and insulin resistance.

The review also discusses research examining muscle mass, cognitive function and healthy ageing. Several observational studies have reported associations between higher linoleic acid exposure and more favourable outcomes, including aspects of cognitive health.

However, it's important not to get carried away. Much of this newer evidence is observational, meaning it cannot establish that linoleic acid itself is responsible for the benefits. The authors acknowledge that it's too early to draw firm conclusions about many of these proposed effects.

Nevertheless, the findings certainly challenge the idea that linoleic acid should automatically be regarded as harmful.

The Most Important Question: What Are You Replacing?

One of the most useful concepts in nutritional science is that we rarely change one nutrient in isolation.

If somebody reduces their intake of seed oils, what are they eating instead? This is particularly important when discussing cardiovascular health.

Controlled dietary studies consistently show that replacing saturated fat with polyunsaturated fat, including linoleic acid, lowers LDL cholesterol. And because LDL-containing particles play a causal role in atherosclerosis, this is an important physiological effect.

But replacing seed oils with butter or other fats rich in saturated fatty acids may have quite different implications from replacing them with extra virgin olive oil.

Likewise, replacing highly processed snack foods with nuts, seeds and other minimally processed foods could improve overall dietary quality, regardless of whether those snacks contained seed oils.

This is why simplistic advice to eliminate an entire category of fats can be misleading. The health implications depend on what those fats replace and the wider nutritional composition of the diet.

What About Ultra-Processed Foods and Cooking Oils?

There's another complication worth addressing.

Seed oils are frequently found in ultra-processed foods, including biscuits, crisps, pastries and various packaged snacks. These foods can also contain substantial amounts of refined starch, added sugars, salt and excess calories.

But the presence of seed oils doesn't establish that they're responsible for the health problems associated with diets high in ultra-processed foods.

It's also reasonable to distinguish between consuming fresh vegetable oils and repeatedly heating oils to high temperatures. Prolonged or repeated heating can produce oxidation products and other compounds, particularly when oils are used under demanding commercial frying conditions.

That is a legitimate food chemistry consideration, but it shouldn't be confused with evidence that ordinary consumption of seed oils causes chronic inflammation.

Different questions require different evidence.

So, Should We Be Avoiding Seed Oils?

Based on the available human evidence, there's little justification for treating ordinary dietary consumption of seed oils as an established cause of chronic inflammation.

That doesn't mean we should start adding unlimited quantities of vegetable oil to everything we eat. Oils are energy-dense, and overall dietary quality still matters enormously.

Personally, I think extra virgin olive oil remains an excellent everyday choice, particularly because of its combination of monounsaturated fats and naturally occurring polyphenols. But that doesn't mean we need to fear sunflower or rapeseed oil when they're used sensibly as part of a balanced diet.

And if we want to improve the quality of the fats we eat, replacing some saturated fat with unsaturated fats from foods such as nuts, seeds, olive oil and suitable vegetable oils is a much more evidence-based strategy than simply eliminating anything labelled a seed oil.

Perhaps the most important lesson here is that nutrition science cannot be reduced to a single biochemical pathway or a frightening social media headline.

What matters is what actually happens in the human body, under real dietary conditions, and what the totality of the evidence tells us about long-term health.

References

Messina, M., Nagra, M., Goldman, D. and Nechuta, S. (2026) ‘Evidence Suggests Linoleic Acid Exerts Health Benefits Beyond Cardiovascular Disease: A Brief Review of Clinical and Observational Studies’, Current Nutrition Reports, 15, article 87. https://doi.org/10.1007/s13668-026-00806-9

Johnson, G.H. and Fritsche, K. (2012) ‘Effect of dietary linoleic acid on markers of inflammation in healthy persons: a systematic review of randomized controlled trials’, Journal of the Academy of Nutrition and Dietetics, 112(7), pp. 1029–1041. https://doi.org/10.1016/j.jand.2012.03.029