Seed oils are the talk of the town these days. They have become such a point of contention and confusion in our society. So, are they good, bad, or somewhere in between?
The answers to these questions are anything but straightforward. Even the research literature on this topic is conflicting.
As a concerned and unbiased Dietitian that has no skin in the game, my goal is to provide you with a nuanced and balanced approach to seed oils. I want you to walk away from this blog post with clear steps on how to eat for health, and on how to wisely utilize seed oils, without having to avoid them entirely.
Canola Oil, and the Rapeseed plant it comes from
What are seed oils?
Seed oils are edible oils that have been extracted from seeds. Several of them have existed for thousands of years, like sesame oil, with evidence of ancient civilizations mentioning them. Examples include:
- Grapeseed
- Cotton seed
- Canola (Rapeseed)
- Sunflower
- Safflower
- Corn
- Soybean
- Rice Bran
Oils, like seed oils, are composed of fatty acids. Fatty acids are long chains of molecules, like carbon and hydrogen, that are linked together. When there is one double bond in the molecular chain, that makes it a monounsaturated fatty acid, or a MUFA for short.
When there are multiple double bonds, then it is called a polyunsaturated fatty acid, or a PUFA. When there are no double bonds, then that is a saturated fatty acid. Seed oils are a mix of mono and polyunsaturated fats, as well as small amounts of saturated fat.
MUFAs and PUFAs are liquid at room temperature. Saturated fats, like beef tallow or coconut oil, are solid at room temperature.
Omega-3 and Omega-6 fatty acids are both PUFAs. They are essential, which means our bodies can’t produce them on their own. We must acquire them from our diet.
Did you know that some seed oils, like canola oil, are composed mostly of MUFAs, just like olive oil? Canola oil’s fatty acid breakdown is: 64% MUFAs, 28% PUFAs (including a significant amount of omega-3s), and 7% saturated fats. Same as olive oil, canola oil is considered a heart healthy fat.
Are seed oils bad for your health?
No, seed oils are not bad for you. However, this statement is multi-faceted. We don’t want to be overconsuming seed oils. We want to make sure that something that is helpful for us doesn’t morph into something hurtful, because we are having too much of it. The dosage should be accounted for.
In small to moderate amounts, seed oils are not just ok, they can be very good for us. Are you shocked?
How come so many people are vilifying seed oils?
Here is what anti-seed oil enthusiasts say, and why it doesn’t hold up:
- Seed oils have been accused of causing inflammation. It is believed that the omega-6 fatty acids convert to arachidonic acid in our bodies which can potentially increase inflammation. In reality, only tiny amounts turn into to arachidonic acid.
Research studies show that tissue levels of it remain almost unchanged after ingesting omega-6 fatty acids. In fact, arachidonic acid is needed for good brain and cognitive health, and is necessary for inflammatory responses.
- They say the way seed oils are processed makes them toxic. Yes, some seed oils do go through a bleaching, refining, and deodorizing procedure that sometimes involves hexane. But, the minute amounts of hexane, if any, left in the final products are far below the limits that are considered safe. What’s more, is the finished products have comparable or lower levels of trans fats in relation to beef tallow. Refined seed oils have a higher smoke point, so they are useful for high heat cooking.
- They blame seed oils for causing everything from obesity, to hormone imbalances, to chronic health conditions. These are just opinions, and they are not backed by any real scientific data, or literature. It’s frightening how something can be plucked out of thin air to be a scapegoat.
Correlation is not causation
As someone who has a Master of Public Health in Epidemiology from UCLA, I hope to make my professors proud when I recall the first epidemiological rule they taught me: correlation does not equal causation. Just because something is going up, while another thing happens to be increasing at the same time, doesn’t mean they are related to each other. There’s not enough evidence to prove that one is causing the other.
Has seed oil consumption gone up significantly over the past century? Yes. Is that behind all of the rising chronic health woes in the US? No. It’s just not that simple.
Anti-seed oil healthcare providers and influencers may disagree with me, but I think there are many other factors, known and unknown, that are behind America’s health problems. Issues like our stressful lifestyles, nutritional deficiencies, circadian rhythm disruption, toxins in our food and environment, untreated trauma and ACEs (adverse childhood experiences), poor access to preventative medical care etc.
Like with any food, people’s individual responses to seed oils will vary
Some people have an inherent allergy, intolerance, or sensitivity to seed oils. In this case, it is best for them to strictly limit or avoid seed oils completely.
Moreover, research has shown that different ethnicities metabolize seed oils uniquely because of genetic variations. Thus, every person will have their own distinct reaction, and way of processing seed oils, based on their physiology and genetic makeup.
Is their suggestion of replacing seed oils with saturated fats better for us?
No, their solution to replace them with saturated fats like beef tallow, lard, and butter is really problematic. Especially for those with genetic predispositions to heart disease, or high cholesterol.
Excessive consumption of saturated fats can increase LDL cholesterol, and the risk of developing cardiovascular disease. It can also cause insulin resistance, and a fatty liver. Only time will tell what the public health fall out will be from the baseless calls to eradicate seed oils.
Do seed oils have any health benefits?
MUFA-rich oils: Avocado, Olive, and High-Oleic Sunflower Oil
Yes, seed oils provide essential PUFAs that make up every cell wall, help balance blood lipids, and that decrease inflammation while also supporting the immune system. They reduce cardiovascular disease risk, and risk of mortality.
Many seed oils contain substantial amounts of MUFAs too. MUFAs have similar health-promoting attributes to PUFAs. In addition to these, they provide Vitamin E and other antioxidants, can increase insulin sensitivity, support blood sugar management, prevent certain cancers, and enhance blood vessel health.
It’s often glossed over that seed oils supply omega-3 fatty acids, albeit in lesser amounts. Canola oil’s 9-11% omega-3 fatty acid content, provides 1.26-1.54 grams of omega-3 fatty acids per tablespoon (14 grams.) It’s hard to overstate the dozens of health benefits that omega-3 fatty acids give. They help brain and mood health, lower inflammation, support cardiovascular and eye health, aid digestion, can prevent certain cancers, is useful in pain management and sleep, and so on.
The campaign against seed oils is harmful, and here’s why:
It’s pulling attention away from more pressing issues with Americans’ diets
Hyperfocusing on single ingredients, like seed oils, is a troubling distraction from more massive problems. Less than 5% of Americans are meeting the recommended 3-5 servings of fruits and vegetables a day, or the required 25 grams of fiber per day. Some Americans live in food deserts where fresh produce is either not available, or inaccessible. Furthermore, many Americans experience food insecurity on a daily basis.
These are the bigger issues with our dietary intake that need to be addressed. Solving these food and nutrition deficiencies will make a vastly larger impact on health outcomes than the type of oil someone uses to cook with, or that is found in foods.
It can lead to disordered eating
Food shaming, and food fear can lead to disordered eating patterns in people. Orthorexia, the eating disorder related to being preoccupied with eating healthfully, is on the rise, unfortunately. Demonizing seed oils only adds fuel to this distorted relationship with food fire.
It’s another toxic diet culture scam
Diet culture scams always involve some kind of quick fix. This same strategy crosses over to the anti-seed oil propaganda. Anti-seed oil proponents think that removing big, bad seed oils will banish all our troubles. But, the diet culture scams weren’t true, and neither is this claim.
It makes eating healthier harder to do
Seed oils are present in many nutritious processed foods. Things like prepackaged salads, frozen meals, and canned foods etc. This doesn’t make those foods unhealthy though.
They are easy and convenient ways for people to get their macro and micro nutrients. Excluding them because they have seed oils means people are missing out on nourishing foods that can improve their health.
Is an example of nutrition elitism
The debate about seed oils is one of privilege. Those that can access and afford pricier oils like avocado, olive, beef tallow etc. are the loudest voices in these conversations. Sometimes they are even the ones manufacturing them, or who have financial ties to them. Bold and scary sound bites sell. Follow the money.
Seed oils are cheaper, and more accessible for a majority of people. They provide nutrients, and are a way to cook and enjoy foods at home. They are found in many inexpensive processed foods that supply good sustenance for people.
Americans are overfed, and undernourished
Americans are obtaining too much of the wrong things in their diets. They are eating too much sodium, sugar, calories, fats, and refined carbohydrates.
Oftentimes, these are coming from ultra-processed foods. These foods aren’t bad for us because of seed oils. They are unhealthy because of their overabundance of all of the things I listed above, along with their lack of nutrients.
Here’s a list of common ultra-processed foods:
- Sugary cereals
- Soda
- Candy
- Potato chips
- Crackers
- White bread
- Fast food
- Pre-packaged Instant foods
- Processed meats like sausage, hot dogs, lunch meats, and jerky
Meanwhile, their bodies are starving for what they actually want: vitamins, minerals, phytochemicals, fiber, and macronutrients like protein, and complex carbohydrates. We’re missing the forest for the trees, when we focus solely on seed oils.
The Omega-6 to Omega-3 ratio
Research studies reveal that the ideal ratio of omega-6 to omega-3 fatty acids varies per person depending on their ethnicity, physical activity levels, gender, age, chronic illnesses, and body composition. They explain that omega-6 and omega-3 fatty acids compete for the same binding sites in our bodies, and thus too much of one will edge the other out, potentially leading to unfavorable results.
Across all the research literature I reviewed, the consensus for the ideal ratio is somewhere between 4:1 to 10:1. Most Americans have a ratio of 16:1. This is definitely not great. It’s likely caused by an omega-3 fatty acid deficit, paired with the overconsumption of omega-6 fatty acids.
This prospective cohort study published by Zhang et al. in 2024, illustrated that both omega-6 and omega-3 fatty acids are protective for human health. But the health support and protection that omega-3s deliver is stronger than omega-6s’. They concluded that a higher ratio of omega-6 to omega-3 fatty acids was tightly associated with an elevated risk of mortality from cancer, CVD, and all-cause mortality.
Bringing the omega-6 to omega 3 proportion down closer to the top end of optimum, 10:1, would be a huge public health accomplishment. Cutting out all seed oils is not the way to do it, however.
Studies show that Americans are not meeting their daily requirements for omega-3s. Therefore, closing this gap will be accomplished by choosing more omega-3 fatty acids and MUFAs, along with being judicious about the kind, and amount of seed oils we are consuming.
How much fat, Omega-6, and Omega-3 Fatty acids should we aim for everyday?
The recommended range for fat is 20-35% of total daily calories, but I generally recommend that most people get around 30%. Using a standard 2,000 calorie diet for these calculations, that is about 67 grams/day.
5-10% of our total daily calories should come from omega-6 fatty acids, or 11-22 grams on a 2,000 calorie diet. There are no set guidelines for daily omega-3 fatty acid intake. I usually recommend that my clients obtain 1-3 grams per day, from a combination of food and/or supplements. Please defer to your healthcare provider for the quantities that are tailored for you.
Wild edible food Purslane, one of the richest plant sources of omega-3 fatty acids
Do the following, instead of eliminating seed oils:
Consume more Omega-3 Fatty acids, and MUFAs
Make an effort to receive enough Omega-3 fatty acids in your day, as they are critical for your health.
Foods and oils loaded with omega-3 fatty acids are:
- Hemp, chia, and flax seeds
- Flaxseed oil
- Canola oil
- Walnuts
- Fatty fish and shellfish
- Fish oil, and sea vegetables
- Wild foods, like purslane
You can use a fish or algae oil supplement as well, to meet your personal needs.
Foods and oils loaded with MUFAs are:
- Almonds, cashews, pistachios, macadamia nuts, and hazelnuts
- Pumpkin and sunflower seeds
- Olive and extra virgin olive oil
- Avocados and avocado oil
- Canola oil
- High-Oleic Sunflower oil
- High-Oleic Safflower oil
- Sesame oil
- Peanut oil
Limit seed oils that are disproportionately high in Omega-6 Fatty acids
Corn, regular sunflower and safflower, grapeseed, and cottonseed oils all have bigger proportions of omega-6 fatty acids in comparison to the other fatty acids it contains. It’s prudent to have them sparingly.
Don’t rely on seed oils alone – use a variety of oils for different purposes
In nutrition, food diversity is king.
Use coconut oil, ghee, avocado oil, beef tallow, or lard for high-heat cooking.
For low to medium-heat cooking, look to oils like olive, sesame, or unrefined canola oil.
For cold preparations, you can use flaxseed, sesame, extra virgin olive, olive, or unrefined canola oil.
Choose unrefined seed oils, that are cold or expeller-pressed
Cold-pressed and expeller pressed oils retain more of their nutrients, omega-3s, and antioxidants. They are a more healthful product. Their minimal processing decreases their smoke point though, so they cannot be employed for high-heat cooking.
Reduce ultra-processed foods, and lean into minimally processed, or unprocessed whole foods
Cutting down on these foods is a smart move. Again, it isn’t the seed oils that make them unhealthy per se, but it’s because they are nutrient-poor, while being overloaded with refined ingredients.
Eating more whole and minimally processed fruits, vegetables, whole grains, nuts, seeds, legumes, complex carbohydrates, lean proteins, and omega-3s, will always serve you well.
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