The Great Oil Debate: Are Seed Oils the Enemy, Or is There More to the Story?
- Nichole Dandrea-Russert
- 1 hour ago
- 10 min read
There is considerable debate around fats and oils—and which ones are considered “good” or “bad” for health. With an overwhelming amount of nutrition chatter on social media, mixed messages online, and ever-changing food trends, it can be difficult to separate evidence-based guidance from misinformation.
In recent years, seed oils have been widely criticized for their alleged negative health effects, while animal-based fats like beef tallow and butter have surged in popularity as so-called “healthier” alternatives. Some interpretations of recent dietary guidance and visual food models have further fueled this confusion, leaving many people unsure about which fats truly support long-term health.
If you’re feeling uncertain about what’s accurate, misleading, or simply oversimplified—you’re not alone.
The goal of this article is to cut through the noise by explaining the science behind different types of fats, clarifying common misconceptions about seed oils, and offering practical guidance to help you make informed choices that align with your health goals.
In this article, we’ll explore:
What seed oils are and how they’re produced
The different classifications of dietary fats (saturated, trans, and unsaturated)
A comparison of commonly used oils, including seed oils, olive oil, and avocado oil
How dietary guidelines and food models address fat consumption
How to make a fat choice that works best for you
Exploring Seed Oils
Seed oils have recently become a hot topic, with some voices claiming they are inherently harmful to health. As with most nutrition topics, the reality is more nuanced.
Seed oils are derived from plants, but the way they are produced and used can vary widely—and those differences matter.
Seed oils are extracted from the seeds of plants and include oils such as canola, corn, cottonseed, flaxseed, grapeseed, hempseed, rice bran, safflower, sesame, soybean, sunflower, walnut, and others. Most commercially available seed oils are refined and processed, though the degree of processing depends on the oil and its intended use.
There are two primary methods used to extract oil from seeds:
Mechanical extraction, which involves pressing the seeds to release their oils
Chemical extraction, which uses hexane—a petroleum-derived solvent—to extract a higher yield of oil
After extraction, many seed oils undergo additional steps known as refining, bleaching, and deodorizing (RBD). This process removes strong odors, pigments, and impurities, resulting in a neutral-tasting oil with a longer shelf life and higher heat stability. These qualities make refined seed oils particularly appealing for commercial cooking and food manufacturing.
Some seed oils—such as sunflower, peanut, sesame, almond, and castor oil—may be cold-pressed initially but later refined to tolerate higher cooking temperatures or meet industrial demands.
Others, like flaxseed oil, are more commonly found cold-pressed and unrefined, preserving their natural flavor and nutrient profile but making them unsuitable for high-heat cooking.
Seed oils are widely used in restaurants and fast-food chains due to their high production yield, affordability, long shelf life, and ability to withstand high frying temperatures.
They are also common ingredients in processed and ultra-processed foods. While these foods are often associated with poorer health outcomes, it’s important to note that this is typically due to the overall nutritional profile of ultra-processed foods, rather than the presence of seed oils alone.
Next, we’ll take a closer look at the different types of dietary fats and how they function in the body.
Breaking Down the Composition of Fat
Dietary fats are classified based on their chemical structure and how they behave in the body. The three main categories are saturated fats, trans fats, and unsaturated fats, the latter of which includes monounsaturated and polyunsaturated fats.
Saturated Fats
Saturated fats are typically solid at room temperature and are most commonly found in animal-based foods, though some plant oils also contain higher levels. Examples of foods and fats that are primarily saturated include coconut oil, palm oil, beef tallow, butter, lard, chicken fat, full fat dairy, eggs, and some commercially produced vegan butters, cheeses, and pastries.
Research shows that saturated fat intake can increase low-density lipoprotein (LDL) cholesterol by affecting blood lipid levels. When consumed in excess, saturated fats have also been associated with increased inflammation and insulin resistance, both of which can contribute to chronic disease risk.
Trans Fats
Trans fats exist in both naturally occurring and industrially produced forms. Naturally occurring trans fats are formed in the digestive systems of ruminant animals and can be found in foods made from these animals.
Industrially produced trans fats are created through a process called hydrogenation, in which liquid oils are treated with hydrogen to make them more solid. This process improves shelf life, stability, and texture, making these fats attractive for food manufacturing. Artificial trans fats have been consistently linked to increased cardiovascular disease risk and are now largely restricted or banned in many countries, including the U.S.
Unsaturated Fats
Unsaturated fats are typically liquid at room temperature and are generally associated with positive health outcomes. They are divided into monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) based on their chemical structure. Without getting too technical, monounsaturated fats have one “flex point” in their structure, while polyunsaturated fats have more than one—which affects how they behave in the body.
Most fats and oils contain a mix of fat types but are categorized based on the predominant one.
Monounsaturated fats (MUFAs):
Olive oil
Canola oil
Peanut oil
Polyunsaturated fats (PUFAs):
Omega-6 fatty acids: safflower oil, sunflower oil, corn oil, soybean oil, cottonseed oil
Omega-3 fatty acids: flaxseed oil, walnut oil, fish oil
Omega-3 and omega-6 fats are known as essential fatty acids, meaning the body cannot produce them on its own and they must be obtained through the diet.
Omega-6 fatty acids are often portrayed as harmful, but they are not inherently bad. As with any nutrient, health concerns arise primarily with excessive intake—particularly when omega-6 fats significantly outweigh omega-3 fats in the diet.
Research consistently shows that replacing saturated fats with unsaturated fats can help lower LDL cholesterol, reduce inflammation and oxidative stress, lower blood pressure, and reduce the risk of heart rhythm disturbances.
Claims Against Seed Oils
In recent years, seed oils have increasingly become the focus of criticism in health and wellness conversations. Much of the concern centers on their omega-6 fatty acid content and how it relates to overall inflammation and chronic disease risk.
Omega-3 and omega-6 fats are both essential fatty acids, meaning they must be obtained through the diet. Research suggests that health outcomes may be influenced not only by the absolute intake of these fats, but also by their balance. Many experts suggest that a lower omega-6 to omega-3 ratio—often cited as somewhere between 1:1 and 4:1—is associated with better health outcomes, particularly in relation to inflammation.
Some seed oils naturally have a more favorable omega-6 to omega-3 ratio, such as:
Canola oil: ~2:1
Hempseed oil: ~3:1
Walnut oil: ~4:1
Soybean oil: ~8:1
Other seed oils contain much higher amounts of omega-6 relative to omega-3.
Examples include:
Corn oil: ~50:1
Cottonseed oil: ~257:1
Grapeseed oil: ~696:1
Rice bran oil: ~21:1
Safflower oil: ~75:1
Sunflower oil: ~66:1
Concerns arise when diets are consistently high in omega-6 fatty acids while being low in omega-3s, a pattern common in diets heavy in ultra-processed foods. In this context, excessive omega-6 intake has been associated with increased inflammation and oxidative stress, which may contribute to conditions such as atherosclerosis (plaque buildup in artery walls). In the Western diet, the typical omega-6 to omega-3 ratio is around 15:1, but it can reach 20:1 or higher. This is primarily because more than 50% of the diet consists of ultra-processed foods and excessive consumption of refined oils.
It’s important to note that these outcomes are influenced by overall dietary patterns, not the presence of seed oils alone.
Why Seed Oils Can Still Be Part of a Healthy Diet
Not all seed oils have an unfavorable omega-6 to omega-3 ratio. Some—such as flaxseed oil and walnut oil—are actually rich in omega-3 fatty acids, while hempseed oil and canola oil offer more balanced ratios of omega-6 to omega-3, approximately 3:1 and 2:1, respectively.
When used in place of saturated and trans fats, certain seed oils have been associated with improved cardiovascular health outcomes. Research suggests that replacing animal fats and industrial trans fats with polyunsaturated fats—including those found in seed oils—can help lower LDL cholesterol, reduce the risk of heart disease, and support overall metabolic health.
Some studies have also linked higher intake of unsaturated fats to modest reductions in body weight and improvements in conditions such as migraine frequency, though individual responses varied.
Seed oils are classified as polyunsaturated fats, a category that is generally associated with better heart health compared to saturated fats when consumed as part of a balanced diet.
Additionally, the processing method matters. Seed oils that are cold-pressed and unrefined retain more of their natural nutrients and antioxidants and do not require chemical solvents during extraction. These oils are best used in low-heat applications, such as salad dressings or finishing oils, where their nutritional integrity can be preserved.
Looking at Other Popular Oils: Olive and Avocado
Now that we’ve explored seed oils, let’s take a closer look at two widely used cooking oils—olive oil and avocado oil—and how they compare in terms of nutrition, processing, and health impact.
Olive Oil
Pros
Can be produced cold-pressed and unrefined, helping preserve natural nutrients
Extra virgin olive oil (EVOO) and virgin olive oil are cold-pressed and retain the highest levels of beneficial compounds
Rich in polyphenols and antioxidants, which help combat oxidative stress
High in oleic acid (omega-9), a monounsaturated fat associated with anti-inflammatory benefits
Naturally low in omega-6 fatty acids
EVOO has been extensively studied and associated with reduced inflammation and lower risk of cardiovascular disease, type 2 diabetes, certain cancers, and neurodegenerative conditions
Enhances the absorption of fat-soluble compounds, such as carotenoids found in carrots and leafy greens, when used in dressings or meals
Cons
Not all olive oil is created equal—refined olive oils (those not labeled “extra virgin” or “virgin”) contain fewer antioxidants and health-promoting compounds
Some products labeled as olive oil may include olive pomace oil, which is extracted from the pits and pulp left after pressing and is more heavily processed
Quality and purity can vary; some olive oils are blended with other oils to reduce production costs
As with any oil, excessive intake can contribute excess calories, which may impact blood lipid levels in certain individuals
Avocado Oil
Pros
Can be produced cold-pressed, preserving nutrients and beneficial compounds
Naturally low in omega-6 fatty acids
Contains antioxidants, including vitamin E
Rich in oleic acid, similar to olive oil, supporting heart health
Provides additional bioactive compounds such as phytosterols, which may help lower LDL cholesterol, and lutein, which supports eye, skin, and brain health
Has a higher smoke point than EVOO, making it suitable for higher-heat cooking when minimally refined
Cons
Like olive oil, avocado oil can also be refined and highly processed, reducing antioxidant content
Quality varies widely, and some products labeled as avocado oil may be diluted or oxidized
What the 2025–2030 Dietary Guidelines for Americans Say About Saturated Fat
The 2025–2030 Dietary Guidelines for Americans include updated visual food models and messaging that have sparked confusion and debate—particularly around dietary fat. Some interpretations of these visuals suggest that foods such as steak, beef, cheese, whole milk, butter, and beef tallow are being emphasized as preferred or “healthy” fat choices.
However, it’s important to look beyond graphics and examine the language of the Guidelines themselves.
The Dietary Guidelines state:
“In general, saturated fat consumption should not exceed 10% of total daily calories. Significantly limiting highly processed foods will help meet this goal. More high-quality research is needed to determine which types of dietary fats best support long-term health.”
This recommendation aligns with decades of nutrition research linking high saturated fat intake to increased LDL cholesterol and elevated cardiovascular disease risk. A substantial body of peer-reviewed research already exists demonstrating that replacing saturated fats with unsaturated fats—particularly polyunsaturated fats—is associated with improved heart health outcomes.
The Guidelines also note that butter and beef tallow are options for cooking fats, though they remain significant sources of saturated fat. This distinction is important: being listed as an option does not imply that these fats should be consumed freely or without consideration of overall dietary patterns.
Understanding how dietary guidelines compare with the broader body of scientific evidence—and how they apply to real-life eating habits—can help consumers make informed decisions that support long-term health rather than relying on simplified visuals or trending interpretations.
Tips for Swapping Saturated Fats with Unsaturated Fats
So how do you put all of this information into practice? The key is preparation—especially before stepping into the grocery store. Small, intentional choices can add up to meaningful health benefits over time.
Smart Grocery Store Strategies
Know your fats. Identify which oils are higher in saturated fat and which provide more unsaturated fats, particularly those with balanced omega-6 to omega-3 ratios.
Read ingredient labels. Saturated fats such as coconut oil and palm oil commonly appear in vegetarian and vegan packaged foods, including nondairy creamers, vegan butters, and cheeses.
Choose quality oils. Look for extra-virgin or unrefined oils, opt for certified organic when possible, and select oils packaged in dark glass bottles to protect against oxidation.
Prioritize whole foods. Meet more of your daily fat needs through whole foods like nuts, seeds, olives, and avocados and use oils sparingly.
Preparing your own dressings, sauces, baked goods, and snacks can help reduce reliance on packaged foods that tend to be higher in saturated fats.
Best Oils to Use at Home
For everyday use:
Olive oil
Avocado oil
Flaxseed oil (best used unheated—try it drizzled over salads or vegetables)
For higher-heat cooking (as alternatives to butter, lard, or shortening):
Canola oil
Soybean oil
Making the RIght Choices for YOU
Navigating nutrition advice—especially around fats and oils—can feel overwhelming, particularly when messaging is conflicting or overly simplified. When it comes to seed oils, their health effects depend on the specific oil, how it’s processed, how it’s used, and what it replaces in the overall diet.
Cooking at home gives you greater control, clarity, and confidence in the choices you’re making.
Rather than relying on oils as the main fat source, prioritize whole foods first and use oils thoughtfully when they serve a purpose. Avocados, nuts, and seeds deliver healthy unsaturated fats along with fiber, vitamins, minerals, and protective plant compounds.
If you’re looking to reduce oil use altogether, try sautéing with vegetable broth or water and finishing dishes with a drizzle of oil for flavor.
Ultimately, the best choice is one that supports your health, preferences, and lifestyle—because sustainable habits matter more than perfection.
Kandace Wormsby, MS, is a highly experienced Exercise Physiologist with a strong background in cardiac rehabilitation, neurological rehabilitation, and special populations training. She holds a Master of Science in Kinesiology and a Bachelor of Science in Marketing, bringing both clinical expertise and a well-rounded approach to patient care. Kandace is currently a student in the Coordinated Program at Georgia State University, pursuing her second Masters degree to become a Registered Dietitian. With over seven years in the health and wellness industry, she specializes in creating individualized, evidence-based exercise programs for individuals with various health conditions, in addition to working with the general population. She is committed to empowering patients and clients to improve their health, confidence, and overall quality of life through movement and nutrition education.
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