Sunflower oil is one of the most commonly used cooking oils. Many physicians and health organizations promote sunflower seed oil as a healthy fat, claiming it offers many health benefits, including an ability to improve heart health, reduce inflammation, improve your skin, and even protect against cholesterol[*][*][*].
Unfortunately, the essential fatty acid profile of sunflower oil and other vegetable oils — such as corn oil and canola oil — can be more inflammatory than not.
With one set of health experts applauding this oil and another group saying it’s terrible for you — what should you believe?
Read on for a science-based look into this oil to find out where those health claims come from, and what the long-term adverse effects of sunflower oil consumption really are.
What Is Sunflower Oil?
Sunflower oil comes from sunflower seeds (Helianthus annuus), which are packed with many nutrients, including meaningful amounts of vitamin E, A, folate, and choline[*].
However, sunflower oil is different. First of all, it is extracted from a different type of seed than the one you’ll find in the snack aisle. Secondly, due to the way it is processed, the oil itself ends up losing a great part of its nutrient content[*].
There are two types of processing:
- Cold-pressed to make unrefined sunflower oil — typically used for salad dressings and sauces.
- 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 the oil, manufacturers used to hydrogenate it. Hydrogenation turns liquid oil into a solid or semi-solid at room temperature– like margarine, for instance.
Although hydrogenated fats aren’t the same as partially hydrogenated fast (aka, trans fats), there could still be a small amount of trans fats in hydrogenated sunflower oil.
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[*][*].
Sunflower Oil and LDL Cholesterol
There’s research showing sunflower oil consumption leads to slight reductions in LDL cholesterol (LDL-C) levels[*].
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However, reducing your LDL-C doesn’t lower your risk of heart disease. LDL-C is not a great predictor of cardiovascular disease (CVD) risk in the first place, and nowadays clinicians are looking instead 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 cardiovascular disease[*].
Therefore, this oil isn’t really doing much for your cholesterol levels. In fact, it might be raising your risk of heart disease.
That’s where linoleic acid comes in.
Linoleic Acid and Heart Disease
When it comes to fatty acid content, sunflower oil is made up of the following:
- 60-65% PUFA (polyunsaturated fatty acids) – Linoleic acids
- 20-25% MUFA (monounsaturated fat) – Mid-oleic acids
- 10-15% SFA (saturated fatty acids) – Palmitic acids
Sixty-plus percent is a lot of linoleic acids. Sunflower oil, in fact, has one of the highest linoleic acid contents of vegetable oils[*].
Linoleic acid is an omega-6 fatty acid that can accelerate the progression of heart disease[*].
#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 actually 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, which might mean bad news.
When you cook with a high-linoleic vegetable oils, those fragile PUFAs may oxidize in the hot pan. Once eaten, oxidized lipids interact with free radicals, creating a domino effect of inflammation in your arteries and, in turn, accelerating the formation of arterial plaques. These pro-inflammatory conditions might accelerate not only atherosclerosis, but also heart disease[*][*].
#2: Too Much Omega-6 Fatty Acids
Across the board, polyunsaturated fats are not the best option when it comes to cooking. You might be wondering what the verdict is when it comes to uncooked PUFAs instead, but the answer isn’t as simple as you might imagine.
When it comes to omega fatty acids, it is very important to keep a balance between omega-3s and omega-6s[*].
Omega-3 fatty acids support cognitive health and reduce systemic inflammation[*].
Omega-6 is essential too, but overconsumption, which is very common in the Standard American Diet, can become problematic.
Excess omega-6 consumption throws off your omega-6 and omega-3 ratios (O6:O3). The ratio is supposed to be 1:1, but when omega 6 skyrockets (20:1 is the standard American ratio), inflammation can ensue[*].
#3: DNA Damage, High Triglycerides, and Reduced Antioxidant Capacity
In a European study, rats were fed lifelong diets of either virgin olive oil (high in oleic acid) or sunflower oil (high in linoleic acid)[*].
The results showed more DNA damage, higher triglycerides, and reduced antioxidant capacity in the sunflower oil rodents.
Sunflower Oil and Obesity
Obesity may raise your risk of heart disease, as it can be connected to a host of cardiovascular disease risk factors, from insulin resistance and raised blood pressure to inflammation and dyslipidemia[*][*].
Here are the two main reasons why so many Americans are suffering from obesity these days:
#1: Sugar-Laden Diets
Americans love sugar, which can be linked to obesity. When you constantly eat a high-sugar diet, this can lead to chronically elevated blood sugar, also known as hyperglycemia. The side effect of this condition is called hyperinsulinemia (high insulin)[*].
When your body continuously produces insulin, it can develop insulin resistance and go into “fat storage” mode, which can lead to obesity problems[*].
#2: Vegetable Oil Consumption
Following the guidelines of organizations like the American Heart Association[*], Americans have been eating less saturated fat and more polyunsaturated fats since the 1970s. Unfortunately, this change has led to a rise in obesity[*].
As mentioned, omega-6 PUFAs overconsumption may contribute to obesity due to its imbalanced ratio with omega-3. Aside from this, sunflower oil has a high concentration of arachidonic acid (another O6 PUFA), that when ingested, activates your endocannabinoid system. This activation signals your body to put on weight[*][*].
In one study, mice which were fed a high-linoleic diet became obese, while mice fed a low-linoleic diet remained unaffected. This study showed that the same number of calories, but with different characteristics, can have very different metabolic effects[*].
The Struggle to Make Sunflower Oil Healthy
Excess linoleic acid can have negative health effects. It oxidizes easily, can promote obesity, and may lead to heart disease.
The sunflower industry decided to re-engineer the product in two different attempts:
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 have 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 version might be considered the healthiest choice, since it contains at least 80% MUFA as oleic acid, and not much linoleic acid[*].
However, high-oleic sunflower oil is often refined, stripping it of any vitamins and nutrients that might make it worthwhile. And when it comes to fats, there are many better options than high-oleic vegetable oil.
High oleic sunflower oil is better than the standard version, but it’s far from a superfood.
Tips for Healthy Fats
Now that sunflower oil has been properly dissected, you’ll want some positive tips on bringing healthier fats into your life.
Tip #1: Eat and Cook With Super Fats
Sunflower oil — even the high-oleic variety — is not a superfood. But other fats do qualify, such as:
- 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 (a potent antioxidant)[*]
- Avocado oil: Rich in MUFAs and vitamin E[*]
Cooking with stable, healthy fats — and preventing fatty acid oxidation — is easy. Anything with a high SFA, high MUFA, and low PUFA content will do.
Tip #2: Be Savvy at Restaurants
Most restaurants use high-linoleic vegetable oil to cook your food, which means that 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.
Avoid Sunflower Oil When You Can
Sunflower oil is touted as healthy, but the facts present a different story. Most of the “health benefits” are backed by over-inflated claims about lowering cholesterol. But even that’s not 100% accurate.
Instead, it’s best to avoid this PUFA-rich 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 can lead to higher chances of developing heart disease, obesity, and others.
Therefore, while it is important to be smart about choosing the right fats to boost your health, this becomes essential when you’re following a keto diet. When fat is the bulk of your diet (around 60% of calories from fat), you need to choose your fats wisely.
Continue reading more about good fats and bad fats, and make sure you’re eating the most keto-friendly and healthiest fats possible.