Many physicians and health organizations promote sunflower oil as a heart-healthy fat. Claims include health benefits like its ability to improve heart health, reduce inflammation, improve your skin, and even protect against cancer.
Unfortunately, the fatty acid content of sunflower oil and other vegetable oils is more inflammatory than not. And it’s much more likely that sunflower oil can hurt your heart, not help it[*].
More current and accurate science suggests that sunflower oil — a polyunsaturated, high-linoleic acid vegetable oil — is not a healthy choice. It’s not healthy to eat and it’s definitely not healthy to cook with.
With one set of health experts applauding sunflower oil and another group saying it’s terrible for you — what should you believe?
Read on for a science-based look into this high-linoleic acid oil, where those health claims came from, and what the long-term adverse effects or sunflower oil consumption really are.
First thing’s first: What is sunflower oil?
Sunflower oil comes from sunflower seeds. Sunflower seeds, in and of themselves, do have a host of nutrient benefits, including meaningful amounts of vitamin E, A, folate, and choline[*].
Sunflower oil is different. First of all, it comes from a different type of seed than you’ll find in the snack aisle[*].
The seeds are then processed into oil. There are two types of processing:
- Cold-pressed to make unrefined sunflower oil — typically used for salad dressings and sauces OR
- Bleached, de-gummed, or chemically extracted to make refined sunflower oil
Refined sunflower oil lacks the vitamin E and polyphenols of its unrefined counterpart, but it’s somewhat more stable for high-temperature cooking.
To further stabilize sunflower oil, manufacturers used to hydrogenate it. Hydrogenation turns the liquid oil into a semi-solid — like margarine, for instance.
Another term for hydrogenated sunflower oil? Trans fatty acid, or trans fat.
Trans fats are linked to chronic diseases like cancer, diabetes, and heart disease, and have been banned in the U.S. since 2018[*]. The World Health Organization (WHO) plans on enforcing a worldwide ban by 2023.
So, you likely don’t have to worry about hydrogenating sunflower oil, unless you have an old bottle in the cupboard.
Still, even non-hydrogenated sunflower oil is suspect due to its high polyunsaturated fat content. And in particular, a PUFA called high-linoleic acid.
So, let’s see what a high-linoleic oil does for your health, exactly. First, a little about sunflower oil and your cholesterol levels.
There’s research showing sunflower oil consumption leads to slight reductions in LDL cholesterol (LDL-C) levels[*].
The problem is — reducing your LDL-C doesn’t lower your risk of heart disease.
That’s because LDL-C — standard on lipid panels — is a lousy predictor of cardiovascular disease (CVD) risk in the first place. These days, savvy clinicians are instead looking at LDL particle number, or LDL-P[*].
LDL-P measures the number of lipoproteins in the bloodstream, as opposed to the number of cholesterol molecules within each lipoprotein (LDL-C).
When there’s a discordance between LDL-C and LDL-P, LDL-P is the better predictor of CVD[*].
Take the person with low LDL-C and high LDL-P. Classic discordance. Their standard lipid panel looks “good” and yet they’re in a very high-risk bracket for heart disease.
Not only can you not rely on LDL-C — reducing LDL-C isn’t necessarily a positive change.
So, sunflower isn’t really doing much for your cholesterol levels. In fact, it might actually be raising your risk of heart disease.
That’s where linoleic acid comes in.
By fatty acid, sunflower oil breaks down like this:
- 60-65% PUFA (linoleic acid)
- 20-25% MUFA (oleic acid)
- 10-15% SFA (palmitic acid)
Sixty-plus percent — that’s a lot of linoleic acid. Sunflower oil, in fact, has just about the highest linoleic acid content of any vegetable oil.
And that’s not a good thing. Linoleic acid is an omega-6 fatty acid that can accelerate the progression of heart disease.
Here are three ways that happens:
#1: Cooking With Sunflower Oil = Oxidized Lipids
Sunflower oil appears to be heat-friendly because it has a high smoke point. But the high smoke point has nothing to do with the stability of the fat.
PUFAs, like linoleic acid, are unstable at high temperatures, which means they’re more prone to oxidation, or damage.
Oxidized (damaged) lipids are bad news. Here’s how they accelerate atherosclerosis, or heart disease[*]:
- You cook with a high-linoleic vegetable oil like sunflower oil
- Fragile PUFAs oxidize in the hot pan
- You eat these oxidized lipids, and they enter your bloodstream
- Oxidized lipids interact with free radicals, creating a domino effect of inflammation in your arteries
- This inflammation accelerates the formation of arterial plaques (heart disease)
And so cooking with vegetable oils creates the pro-inflammatory condition necessary for heart disease.
Does that mean that uncooked sunflower oil is great for you? It has vitamin E and polyphenols, after all.
Unfortunately, it does not.
Researchers have shown that — in a group of 20 Spanish men — a sunflower-enriched diet offered zero protection against LDL oxidation[*].
Why? Probably because linoleic acid — the main omega-6 fat in sunflower oil — is pro-inflammatory.
#2: Too Much Omega-6 Fatty Acids
Across the board, polyunsaturated fats are terrible for cooking. But now you’re wondering: what’s the verdict on uncooked PUFAs?
The answer isn’t as simple as you might imagine.
The truth is, when it comes to omega fatty acids, you need a balance of omega-3s and omega-6s.
Omega-3s support cognitive health and reduce systemic inflammation[*].
Omega-6s are essential too, but the problem is: people eat too much of it. Especially in the Standard American Diet.
Excess O6 consumption throws off your O6:O3 ratio. The ratio is supposed to be 1:1, but when O6 skyrockets (20:1 is the standard American ratio) — inflammation ensues[*].
And inflammation is a major contributor to heart disease.
This isn’t the last you’ll hear of the O6:O3 ratio, but first: one more reason sunflower oil increases your risk of heart disease.
#3: DNA Damage, High Triglycerides, and Reduced Antioxidant Capacity
Okay that’s three reasons, but they’re from one study.
Researchers fed rats lifelong diets of either virgin olive oil (high in oleic acid) or sunflower oil (high in linoleic acid)[*]. You can’t do lifelong diet experiments in humans.
What did they find? You guessed it: more DNA damage, higher triglycerides, and reduced antioxidant capacity in the sunflower oil rodents. Not exactly heart healthy.
There’s one more reason that high-linoleic sunflower oil burdens your heart. But it’s such a big one that it deserves its own section.
Obesity raises your risk of heart disease[*].
Mainly because obesity comes with a host of CVD risk factors, from insulin resistance, to raised blood pressure, to inflammation and dyslipidemia.
So why are Americans so obese these days? Two main reasons:
#1: Sugar-Laden Diets
Americans love sugar. How might this cause obesity? Here’s how:
- Someone eats a high-sugar diet
- Tons of sugar translates to chronically elevated blood sugar (hyperglycemia)
- Hyperglycemia means high insulin (hyperinsulinemia)
- Hyperinsulinemia leads to insulin resistance (“fat storage” mode)
- Fat storage mode leads to obesity
Along with sugar, what’s the other culprit in the wave of obesity?
#2: Vegetable Oil Consumption
Eating more omega-6s PUFAs contributes to obesity in a few ways.
First, the O6:O3 ratio. It turns out that an American-style O6:O3 ratio (20:1) is strongly linked to obesity[*].
Another reason involves the conversion of linoleic acid — high in sunflower oil — to arachidonic acid. Arachidonic acid — another O6 PUFA — activates your endocannabinoid system, which signals your body to put on weight.
In one study, mice fed a high-linoleic (American) diet became obese, while mice fed a low-linoleic diet did not. Same number of calories, different metabolic effect[*].
Some sunflower oils, however, have less linoleic acid — and more oleic acid. A brief word on those now.
Excess linoleic acid is bad for you. It oxidizes, promotes obesity, and leads to heart disease.
Someone in the sunflower industry got the memo and re-engineered the product. Here are two attempts at this redesign:
1) NuSun: NuSun is a patented formulation, higher in oleic acid (MUFAs) and lower in linoleic acid (PUFAs) than regular sunflower oil[*].
Proponents of NuSun like to say it’s good for your heart — pointing to a study published in 2005[*].
In this study, researchers gave people with hypercholesterolemia (very high cholesterol) either NuSun, olive oil, or a standard American diet. Interestingly, the NuSun diet lowered LDL-C more than the other two diets (5.8% more).
But as you already learned, LDL-C isn’t a great marker for heart disease. And since sunflower oil fares worse than olive oil for oxidized LDL protection — any benefits of NuSun are pretty insignificant[*].
2) High oleic sunflower oil: this iteration of sunflower oil is (loosely speaking) the healthiest of the brood. That’s because it contains at least 80% MUFA as oleic acid, and not much linoleic acid[*].
Less linoleic acid, less oxidation, fewer problems.
High oleic sunflower oil, however, still doesn’t deserve a spot at your table. It’s often refined, stripping it of any vitamins and nutrients that might make it worthwhile. And when it comes to fats, there are so many better options than high oleic vegetable oil.
High oleic sunflower oil is better than standard sunflower oil, but it’s far from a superfood.
Fortunately, there are plenty of fats that do qualify for superfood status.
Now that sunflower oil has been properly dissected, you’ll want some positive tips on bringing healthier fats into your life.
Tip #1: Eat Super Fats
Sunflower oil — even the high oleic variety — is not a superfood. But other fats do qualify, like:
- Red palm oil: Rich in SFAs, MUFAs, vitamin E, vitamin A, and carotenoids
- Coconut oil: Rich in medium chain triglycerides (a keto-friendly SFA) and lauric acid
- MCT Oil: Full of MCTs to promote ketosis[*]
- Grass-fed butter: Rich in vitamin K2 and vitamin A
- Extra virgin olive oil: Rich in MUFAs and oleuropein (potent antioxidant)
- Avocado oil: Rich in MUFAs, vitamin E
Fill up on these super fats, and you won’t have room for sunflower oil anyway.
Tip #2: Cook Smart
Cooking with stable, healthy fats — and preventing fatty acid oxidation — is a snap. Anything with a high SFA, high MUFA, and low PUFA content will do.
With this in mind, the best cooking fats are:
- Avocado oil
- Red palm oil
Easy to find, easy to use, and delicious.
Tip #3: Be Savvy at Restaurants
Most restaurants use high-linoleic vegetable oil to cook your food. That means they’re feeding you oxidized lipids.
To avoid damaged fats, find a restaurant that will cook your meal in butter or extra virgin olive oil instead.
The Takeaway: Avoid Sunflower Oil When You Can
Sunflower oil is touted as healthy, but the facts present a different story. Most of the “health benefits” of sunflower oil are backed by over-inflated claims about lowering cholesterol. But even that’s not 100% accurate.
Instead, it’s best to avoid PUFA-rich sunflower oil, which is high in inflammatory linoleic acid and devoid of many nutrients you can find in better fats.
Oxidized lipids, an imbalanced O6:O3 ratio, and higher arachidonic acid levels all lead to heart disease, obesity, or worse.
The fix? Seek out healthier fats like palm oil, MCT oil, butter, EVOO, and avocados.
This is super important if you’re keto, eating some 60% of calories from fat. If fat is the bulk of your diet — you need to choose your fats wisely.
Hopefully this article helps inform those choices.