The Study Where Corn Oil Beat Olive Oil
This site will not cherry-pick. A genuine human trial found corn oil beat extra virgin olive oil on one cholesterol marker. Facing that honestly — caveats and all — teaches more about nutrition headlines than any comfortable result could.
In a randomised, double-blind, crossover feeding trial published in a peer-reviewed lipids journal, 54 adults with elevated cholesterol ate four tablespoons a day of either corn oil or extra virgin olive oil for 21 days each, as part of a low-saturated-fat diet. The corn-oil phase produced bigger drops in LDL cholesterol (a reduction of about 11% versus roughly 3.5% for the olive oil) and in total cholesterol. On that specific marker, over that short window, corn oil won. There is no honest way around it, so let us not try.
Why corn oil moved LDL more
The likely reason is not mysterious. Corn oil is high in polyunsaturated fat and unusually rich in plant sterols — plant compounds that partly block the gut from absorbing cholesterol. Both of those tend to push measured LDL down. Extra virgin olive oil is instead dominated by monounsaturated fat and its own polyphenols, which act on the body in different ways. Different fats, different levers — and on this one lever, corn oil pulled harder.
The honest caveats
Two things must be said plainly, and neither is spin. First, this was a short feeding study measuring a single blood marker, not a long-term test of who lives longer or has fewer heart attacks — and it is worth noting the trial was supported by a maker of corn oil, which does not invalidate it but does belong on the label. Second, LDL is not the whole of health. Olive oil’s reputation does not rest on one cholesterol number; it rests on the whole dietary pattern it anchors — monounsaturated fat, polyphenols and decades of population and outcome data linking a Mediterranean way of eating to better heart health.
| Design | Randomised, double-blind, crossover feeding trial |
|---|---|
| Participants | 54 adults with elevated cholesterol |
| Dose | 4 tbsp/day of each oil, 21 days each |
| Key result | Corn oil lowered LDL more (~11% vs ~3.5%) |
| Main limits | Short; single marker; industry-supported |
| Olive oil’s real case | The whole Mediterranean pattern, long-term |
The grown-up takeaway
The useful lesson is bigger than corn versus olive. It is this: be sceptical of every single-study headline — including the ones that flatter your favourite. One short trial on one marker does not overturn a mountain of long-term evidence, in either direction. If your goal is a lower cholesterol number this month, plant-sterol-rich oils may help; talk to your doctor. If your goal is a way of eating tied to long-term heart health, the case for good olive oil as part of a Mediterranean pattern remains strong. Both can be true. This is general information, not medical advice.
How to read a nutrition headline
- Ask how long the study ran and how many people it followed.
- Ask whether it measured a marker (like LDL) or a real outcome (like heart attacks).
- Check who funded it — not disqualifying, but worth knowing.
- Weigh it against the whole body of evidence, not in isolation.
Corn oil vs olive oil: common questions
Did corn oil really beat olive oil?
On one marker, in one short trial, yes — corn oil lowered LDL cholesterol more than extra virgin olive oil over 21 days. That single result does not settle which oil is better for long-term health.
Why did corn oil lower LDL more?
Corn oil is rich in polyunsaturated fat and plant sterols, which reduce cholesterol absorption and tend to push measured LDL down. Olive oil works through monounsaturated fat and polyphenols instead.
Does this mean I should switch to corn oil?
Not on one study. LDL is only part of health, and olive oil’s evidence rests on the whole Mediterranean dietary pattern over decades. For your own numbers and medications, ask your doctor.
Was the study biased?
It was a real, peer-reviewed trial, but it was supported by a corn-oil maker — worth knowing, though it does not by itself invalidate the result. Its bigger limits are its short length and single marker.
What’s the real lesson?
Be sceptical of every single-study headline, including flattering ones. Judge oils and diets by the whole weight of long-term evidence, not one short trial. This is general information, not medical advice.
I am an olive man, so you might expect me to bury a result like this. I will not. It was a real trial, and on that one cholesterol marker corn oil won — pretending otherwise would make me exactly the kind of cherry-picker I distrust. But the honest reading cuts both ways: a short study of one number, part-funded by a corn-oil maker, does not undo the long-run case for olive oil inside a Mediterranean way of eating. The grown-up habit is to be sceptical of every headline, especially the ones you want to believe. Good oil earns its place on decades of evidence, not one press release.
Drawn from the Maki et al. randomised crossover trial in the Journal of Clinical Lipidology (2014/2015) and on the wider literature on dietary fats and heart health.