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0:51 Introduction

7:41 What are seed oils?

10:26 Are corn and peanuts by themselves harmful?

11:52 Is it the processing of the oil harmful?

14:50 Is it the contents of the seed oils (e.g., omega 6s)?

24:17 Is it the cooking process with the oils?

28:41 Is there enough added seed oil that it matters?

30:06 Are we blaming the wrong food? A cheap happenstance

31:35 Is it worth the cost to switch?

32:58 Is it time for an N-of-1 trial in yourself?

33:36 Where I net out on seed oils

In recent years, seed oils have become a hot topic, with many claiming they cause inflammation, heart disease, diabetes, and other chronic health conditions. Social media is flooded with warnings about the so-called “hateful eight” oils—corn, canola, safflower, cottonseed, grapeseed, rice bran, soybean, and sunflower oils. But are these concerns valid? Let’s dive into the evidence to explore whether seed oils are truly harmful or just another food fear fad.

What Are Seed Oils?

Seed oils are extracted from various seeds and have become a staple in the modern diet due to their affordability and versatility in cooking. When saturated fats were deemed unhealthy in the 20th century, seed oils became a popular alternative. However, many now claim that these oils are dangerous due to their polyunsaturated fats (PUFAs), specifically omega-6 fatty acids like linoleic acid. But does consuming seed oils actually lead to health problems, or is this concern overblown?

A Historical Perspective on Nutrition Myths

Before jumping into the specifics of seed oils, it’s helpful to look at past nutrition fads that were later debunked. Eggs and shrimp were once considered harmful due to their cholesterol content, but it turns out dietary cholesterol has little effect on blood cholesterol levels. Butter was demonized in favor of margarine, but we later learned that margarine’s trans fats were far worse. Similarly, for years, we avoided peanuts in infant/toddler diets to prevent later food allergies, only to find that early peanut exposure actually reduces the risk. These examples remind us to approach new dietary health claims with caution and wait for solid evidence.

The Basics of Seed Oils

Seed oils are a mixture of saturated, monounsaturated, and polyunsaturated fats. The main concern revolves around the polyunsaturated fats (PUFAs), specifically omega-6 fats like linoleic acid. Some argue that these fats promote inflammation and lead to chronic diseases. However, the situation is more nuanced.

First, omega-6 fats are essential fatty acids, meaning our bodies need them but can’t produce them. They play a vital role in skin health and cell membrane function. The concern some “experts” make is the changing balance between omega-6 and omega-3 fats in our diet. Historically, humans consumed roughly equal amounts of omega-3 and omega-6. Today, due to the prevalence of seed oils, we consume much more omega-6, which some fear may promote inflammation. But is there any evidence to support this?

The Evidence on Seed Oils and Health

1. Inflammation: Some argue that omega-6 fats from seed oils cause inflammation. However, multiple human studies tell a different story. In 15 randomized controlled trials, participants who replaced saturated fats with PUFAs, including those from seed oils, showed no significant increase in markers of inflammation. While lab studies (in vitro) have suggested that linoleic acid can cause inflammation in cells, these results haven’t been replicated in humans.

2. Heart Disease: If seed oils truly promoted inflammation, we might expect higher rates of heart disease in people who consume them. However, a meta-analysis of 30 observational studies across 13 countries found that higher levels of linoleic acid in the blood were associated with a lower risk of heart disease and stroke. Furthermore, a large randomized trial from the Minnesota Coronary Survey showed no difference in cardiac mortality between people consuming a diet rich in seed oils and those who didn’t.
3. Diabetes: Concerns about seed oils causing diabetes have also been refuted by large-scale studies. In the Nurses’ Health Study and the Health Professionals’ Follow-Up Study, people with higher linoleic acid intake actually had a lower risk of developing diabetes.

The Real Problem: Processed Foods, Not Seed Oils

While the evidence suggests that seed oils themselves are not harmful, the issue may lie elsewhere. Seed oils are inexpensive to produce, which has allowed the food industry to create a wide range of ultra-processed, calorie-dense foods like chips, cookies, and fried snacks. These highly processed foods may be the real culprits behind the rising rates of obesity, heart disease, and diabetes—not the seed oils themselves.

Processed foods are designed to be irresistible, and their excessive consumption contributes to weight gain and poor health. So, while seed oils are a convenient and cost-effective ingredient, it’s their role in the creation of unhealthy, processed foods that’s likely the real problem.

What About Cooking with Seed Oils?

Some concerns also revolve around what happens when you cook with seed oils. When oils are heated to high temperatures, they can produce harmful compounds like aldehydes and polycyclic aromatic hydrocarbons (PAHs). However, this occurs mainly at very high temperatures—above 450°F. Most cooking, including frying chicken, happens at much lower temperatures, typically around 325°F to 375°F, where the formation of harmful compounds is minimal.

Additionally, these harmful compounds aren’t unique to seed oils. Grilling meat at high temperatures can produce the same compounds. The issue of concern is that when oils are reused repeatedly at high temperatures, as is often the case in restaurant deep fryers those molecules can accumulate.

Should You Avoid Seed Oils?

For the average person cooking at home, there’s little reason to fear seed oils. The amount of oil used in cooking is relatively small, and as long as you’re not reusing oil repeatedly at high heat, the risk of harmful compounds forming is minimal. That said, if you prefer to use olive oil or avocado oil, there’s no harm in switching—just be prepared for the higher price tag.

Conclusion: Seed Oils Are Not the Enemy

Based on the available evidence, seed oils are not the health hazard they’ve been made out to be. They do not cause inflammation, heart disease, or diabetes.   Their role in processed foods is where the real concern lies. If you’re looking to improve your health, the best approach is to minimize ultra-processed foods, focus on whole, nutrient-dense options, and maintain a balanced diet.

In the end, the fear surrounding seed oils appears to be more of a food fad than a legitimate health concern. So, feel free to enjoy your sauteed vegetables and your salad dressing—just don’t overdo it on the processed snacks.