Have you heard?! We’re in the midst of a great vegetable oil debate!
The dispute: Is oil healthy? Or is it just a processed, unnecessary, high-fat food that we’re better leaving off of our plates and out of our skillets?
In truth, the debate over oil is nothing new. Confusion about whether or not it’s part of a healthy diet has been around for a long time and I’ve gotten lots of questions about it over the years. So I teamed up with Crazy Sexy Nutrition Director, Jen Reilly, RD, to tackle this debate head on!
You might’ve heard some of your favorite plant-based health gurus recommend eliminating oil completely—even extra virgin olive oil, which has been shown to lower cholesterol levels and help prevent heart disease (study). So, let’s start by breaking down four of the most common criticisms we hear about veggie oils. Then we’ll cover some of the possible benefits of including them in your diet so you can figure out what’s best for you.
But first, let’s do a quick review of the types of fats found in plant oils:
- Trans fats (avoid these completely): These fats have no health benefits and are actually harmful. They’re made by taking healthy vegetable oils and adding hydrogen atoms to make them more shelf-stable. They show up in processed and fried foods and have been shown to increase “bad” LDL cholesterol levels while also decreasing “good” HDL cholesterol (study).
- Saturated fats (try to eat these sparingly): These fats have generally been considered unhealthy, especially when it comes to heart disease risk. But not all types of saturated fats are created equal. The saturated fat in coconut oil, for example, doesn’t tend to increase cholesterol levels and heart disease risk the way saturated fats from animal products do (study).
- Monounsaturated fats: You’ll find these fats in foods like avocados, nuts and the star of today’s show: olive oil! Studies have shown that monounsaturated fats can help lower breast cancer risk (study) and cholesterol levels (source), improve rheumatoid arthritis symptoms (study), and reduce belly fat (study).
- Polyunsaturated fats: These fats are found mostly in vegetable oils (corn, sunflower, safflower, etc.). Omega-3s also fall into this category, and they’re considered the healthiest, most essential fats on the block. They’re known for improving heart health and decreasing risk of stroke (source). They’re also important for building brain cells and supporting a healthy nervous system (source). You’ll find omega-3s in flax, walnut and hemp oils.
Alright, now that we’ve covered the types of fats you’ll find in plant oils, let’s dig into four of the top criticisms you might’ve heard from the anti-oil side of this debate.
Criticism #1: Olive oil constricts blood vessels.
One of the most noteworthy waves of anti-oil hype started in 2000 when Dr. Vogel, a heart specialist at the University of Maryland, published a small study looking at how the various components of the Mediterranean diet might impact endothelial function (aka blood vessel constriction, which is a possible risk factor for heart disease).
Study subjects ate one of three meals containing olive oil, omega 3-fortified canola oil or salmon. Results showed that arteries didn’t constrict at all after subjects ate salmon, but did to some extent when they consumed canola oil (reducing blood flow by 11 percent) and olive oil (reducing blood flow by 34 percent). While blood vessel constriction isn’t a confirmed risk factor for heart disease, this finding still raised alarm.
The good news is that when combined with antioxidant-rich foods like vegetables or even red wine vinegar (hello, yummy salad dressing!), the vessel-constricting effect of olive oil disappears almost completely (study). It’s also worth noting that extra virgin olive oil has more antioxidants than refined olive oil, so I encourage you to opt for that when you can (just be careful using extra virgin olive oil in cooking—more on that later!).
At the end of the day, unless you’re diet is imbalanced and lacks sufficient antioxidants, this blood vessel issue is a non-issue.
Criticism #2: Olive oil has over a 10:1 ratio omega-6s to omega-3s.
It’s important to maintain a 4:1 ratio of omega-6s to omega-3s in your diet to protect your body from inflammation and heart disease, maintain a strong immune system, and support a healthy central nervous system. But because omega-6s are easy to get (they’re in nutrient-rich vegetable oils like sunflower and safflower oil, but also in lots of processed foods, poultry and eggs) and omega-3s aren’t as readily available, this balance can be hard to strike.
Olive oil is made up of far more omega-6s than omega-3s, so some argue that consuming it makes that ideal ratio even harder to achieve. But using it in moderation simply isn’t enough to cause an imbalance because the total amount of omega-6s is still quite small when compared with those other omega-6-rich foods mentioned above.
This is still a good reminder to choose your omega-6 sources wisely. They are essential and while some, like sunflower oil, are rich sources of vitamin E and other nutrients, others are packed with inflammatory nasties (yep, I’m talking about processed foods and animal products). Also, make sure you’re getting sufficient omega-3s by including ground flaxseed, flax oil, chia seeds and walnuts in your meals.
Criticism #3: Vegetable oils are unsafe at high heat.
Prolonged high temperatures can cause certain oils to break down and produce potentially toxic, cancer-causing compounds such as lipid peroxides and aldehydes. Oils high in polyunsaturated fats (flax, canola, soybean, safflower and sunflower) are most prone to this kind of oxidative damage. So while those oils are great for salads, raw meals and dishes that are heated quickly at lower temps (like simmered soups), they’re not the best choice for most cooking.
But this doesn’t mean you can’t cook with oil at all—you just need to use the right kind! Olive, grapeseed and avocado oils are actually quite stable at high heat. The fats in these oils are primarily monounsaturated, making them lower in those polyunsaturated fats we talked about above. They also have high smoke points, making them great choices for the majority of cooking methods. Olive oil has a smoke point between 374-406°F (190-208°C), grapeseed oil has a smoke point of 420°F (216°C) and avocado oil’s smoke point is around 500°F (260°C). Plus, olive oil and avocado oil are rich in antioxidants (vitamin E among others), which actually work to prevent the oxidative damage that can occur when an oil is heated past its smoke point.
Keep in mind: Extra virgin olive oil has a lower smoke point than refined olive oil, so it shouldn’t be used for prolonged cooking over high heat. Some even say that it should be limited to use in salad dressings and simmered dishes like soups and pastas. Not only will extra virgin olive oil smoke more quickly, but its flavonoids and nutrients will degrade faster than those in refined olive oil, which has had its impurities removed.
Criticism #4: Oils may promote weight gain because they’re 100% fat.
Dietary fat contains 9 calories per gram vs. carbohydrates and protein, which have just 4 calories per gram, making it the richest source of calories available. Even a gram of alcohol has fewer calories than fat (seven, to be exact!). For this reason, people often blame fat (and oil by association) for promoting weight gain or getting in the way of healthy weight management.
While it’s true that vegetable oils are processed foods made up of 100 percent fat, that doesn’t make them 100 percent bad for you! Including oils in your diet can make meals more satisfying. Plus, consuming some added fats in the form of oil can help keep hunger at bay longer than if you go oil-free (study). Many of us have personal experience with this—when I was going through my low-fat phase in the 90s (along with the rest of the US!), I was ALWAYS hungry!
When it comes to appetite control, satiety and body weight, coconut oil is especially helpful because it contains something called medium-chain triglycerides (MCTs). MCTs are used almost immediately by the liver for energy and are very rarely stored as body fat. They can also keep your metabolism (your calorie-burning machinery) running faster for a longer period of time than other fatty acids (study). Take that, hunger!
Remember, there’s no one-size-fits-all diet and it’s important to follow a plan that works best for you. Because oil is so calorie-dense, giving it up (or being more conscious about measuring out a moderate amount) is what helps some people maintain or achieve their goal weight—and that’s great! If you do end up going oil-free, just make sure you’re getting those healthy fats elsewhere—I’ve included tips to help you do so later on in this post.