Highlights:
- Seed oils, also known as vegetable oils, are commonly used in cooking and are a significant source of essential fatty acids in the modern diet.
- Industrial seed oils, such as corn, canola, cottonseed, soy, sunflower, safflower, grapeseed, rice bran, and peanut, contain higher levels of linoleic acid and may be harmful to health.
- The shift from traditional fats to seed oils started in the early 20th century and was accelerated by research in the 1950s linking saturated fat to heart disease.
- Seed oils are high in Omega-6 polyunsaturated fatty acids and are prone to oxidation, which generates free radicals and causes oxidative stress and inflammation in the body.
- The best alternatives to seed oils are olive oil, avocado oil, coconut oil, and grass-fed butter, which are less processed and contain higher amounts of antioxidants and anti-inflammatory compounds.
What are Seed Oils?
The world of oils and fats can be confusing, especially when it comes to understanding the differences between industrial seed oils and vegetable oils. Industrial seed oils, such as corn, canola, cottonseed, soy, sunflower, safflower, grapeseed, rice bran, and peanut, are sourced directly from the seeds of crops and contain higher levels of linoleic acid, which may not be ideal for health.
Seed oils, commonly referred to as vegetable oils, are widely used in cooking and are considered a significant source of essential fatty acids in the modern diet. Despite this, recent research has raised concerns about the potential health risks associated with consuming seed oils in excess. This article will explore the dangers of seed oils and why it is essential to limit their consumption and choose healthier sources of fat instead.
On the other hand, vegetable oils are a much broader category, encompassing all oils derived from plant matter, whether it’s fruits, grains, seeds, or nuts. Some of the most common vegetable oils include canola (rapeseed), coconut, corn, cottonseed, olive, palm, palm kernel, peanut, safflower, soybean, sunflower, grapeseed, rice bran, and avocado. With such a wide range of fatty acid ratios, it’s important to be aware of the linoleic acid content of the oils you use for cooking.
What is the History of Seed Oils?
For centuries, fats have played an essential role in the human diet, but it wasn’t until the early 20th century that seed oils made their mark. From soybean oil, corn oil, and canola oil to safflower oil, sunflower oil, and more, these new oils started to replace traditional fats like butter and lard in kitchens across the United States. A flurry of research in the 1950s linking saturated fat to heart disease only accelerated this shift, as people sought to protect their hearts by swapping out saturated fats for polyunsaturated fats found in seed oils.
However, as time passed, this research was called into question and it became clear that seed oils, while low in saturated fat, contain certain types of unstable polyunsaturated fats that may be linked to a host of chronic illnesses, including heart disease, diabetes, autoimmune diseases, and even cancer. With this newfound understanding, it’s crucial to reevaluate the role of seed oils in our diets and consider alternative sources of healthy fats.
What is the Difference between Saturated and Unsaturated Fats?
Saturated fats and unsaturated fats are both types of fats that are present in our diets. Saturated fats are typically solid at room temperature and are found in animal products such as meat, dairy, and butter. On the other hand, unsaturated fats are typically liquid at room temperature and are found in plant-based products such as seeds, nuts, and oils. Saturated fats have long been considered unhealthy due to their association with heart disease, and for this reason, the medical establishment has encouraged people to limit their consumption of saturated fats and switch to unsaturated fats instead.
The error that linked saturated fats to heart disease was a flawed interpretation of observational studies in the 1950s and 1960s that suggested a correlation between the consumption of saturated fat and an increased risk of heart disease. These studies did not establish a causal relationship between the two, but rather observed a correlation between the two factors. The studies did not take into account other factors that could contribute to heart disease, such as lifestyle factors, overall diet, and the presence of underlying health conditions. In addition, the studies did not differentiate between different types of saturated fats and their potential health effects.
In the 1950s, President Dwight D. Eisenhower had a heart attack, which sparked public fear and increased interest in heart disease and its causes. At the time, the medical establishment believed that saturated fat was a major contributor to heart disease, and they encouraged people to switch to unsaturated fats, including seed oils, as a way to reduce their risk of heart disease. The theory was that unsaturated fats, being liquid at room temperature, were healthier than solid, saturated fats.
This led to a widespread belief that all saturated fats were harmful and needed to be reduced in the diet, which led to the promotion of unsaturated fats, including seed oils, as a healthier alternative. As recently as 2015, the medical establishment still recommend reducing saturated fat intake and replacing it with unsaturated fats.
However, as time passed and more research was conducted, it became clear that this was a mistake. The PUFAs in seed oils are prone to oxidation when exposed to heat, light, and air, generating free radicals that can cause oxidative stress and inflammation in the body. Additionally, an overconsumption of Omega-6 PUFAs relative to Omega-3 PUFAs can lead to an imbalanced ratio that has been linked to a range of health issues, including obesity, cardiovascular disease, and certain types of cancer. These findings call into question the previous recommendation to consume large amounts of seed oils and highlight the importance of choosing healthy sources of fat instead.
How are Seed Oils Made?
The food we consume, from bacon and butter to plant-based proteins, undergoes processing before reaching store shelves. While processing isn’t inherently harmful, the type of processing and the addition of certain chemicals and preservatives can pose long-term risks to our health. The production of seed oils, commonly found in many processed foods, is a prime example of this.
To transform seeds into the bottle of oil you find on store shelves, manufacturers subject the seeds to high temperatures and harsh chemicals, resulting in harmful by-products like trans fats. Synthetic antioxidants are also often added to extend the shelf life of the unstable fats in seed oils, but these antioxidants, such as TBHQ, BHA, or BHT, have been linked to cancer.
Here’s a closer look at the process of making most seed oils:
- The seeds, such as corn, soybean, safflower, sunflower, rapeseed, and others, are gathered and subjected to high temperatures, causing oxidative damage and transforming some PUFAs into harmful trans fats.
- The seeds are then extracted using a chemical solvent like hexane for optimal yield.
- The seed oils undergo high-heat deodorization, which may further damage the unstable PUFAs and increase the production of trans fats.
- Finally, chemical preservatives, including the carcinogenic compounds BHT and BHA, may be added to enhance the shelf life of the oils.
What are the Dangers of Seed Oils?
The high levels of Omega-6 polyunsaturated fatty acids (PUFAs) in seed oils are a cause for concern. Omega-6 PUFAs are prone to oxidation when exposed to heat, light, and air, which generates free radicals that can cause oxidative stress and inflammation in the body and brain. In addition, excessive consumption of Omega-6 PUFAs can disrupt the delicate balance between Omega-3 and Omega-6 fatty acids in the body, leading to an imbalanced ratio that has been linked to several chronic diseases, including heart disease, cancer, and autoimmune disorders [*, *, *, *].
Many seed oils are also highly processed and refined using chemicals and high heat, resulting in the formation of harmful compounds, such as trans-fatty acids. Trans-fatty acids have been linked to an increased risk of heart disease and other chronic health conditions. This process also creates toxic by-products, including 4-Hydroxynonenal (HNE), that can cause inflammation and damage to cellular structures. [*, *].
Seed oils are also high in lectins, naturally occurring compounds that can cause an immune response in some individuals and lead to digestive problems, such as bloating, gas, and abdominal pain. A study published in Biochimie found that soybean oil, a common ingredient in many processed foods, is particularly high in lectins [*].
Additionally, an overconsumption of Omega-6 PUFAs relative to Omega-3 PUFAs can lead to an imbalance in the Omega-6 to Omega-3 ratio, which has been linked to a range of health issues, including obesity, cardiovascular disease, and certain types of cancer [*].
Autoimmune Disease
A 2021 study published in the Nutrients found that a diet high in Omega-6 PUFAs has been linked to the activation of immune system pathways that trigger an immune response that attacks the body’s own tissues, leading to autoimmune disease.
Additionally, the high heat and chemical processing that seed oils undergo can create toxic by-products that can further exacerbate autoimmune conditions, as found in a 2015 study published in the Food Chemistry.
Heart Disease
A study published in the journal “Archives of Medical Science” in 2022 found that a high intake of Omega-6 PUFAs was associated with an increased risk of cardiovascular disease. This highlights the importance of choosing healthier sources of fat in order to reduce the risk of heart disease.
Alzheimer’s Disease
A diet high in Omega-6 polyunsaturated fatty acids (PUFAs), commonly found in seed oils, has been linked to an increased risk of Alzheimer’s disease. The pro-inflammatory nature of Omega-6 PUFAs can lead to oxidative stress and inflammation in the brain.
A 2008 study published in Brain Research found that a diet high in Omega-6 fatty acids can disrupt the balance of fatty acids in the brain, leading to the formation of amyloid plaques and neurofibrillary tangles, hallmark features of Alzheimer’s disease.
Furthermore, research has shown that an imbalanced ratio of Omega-6 to Omega-3 fatty acids can increase the risk of developing Alzheimer’s. It is important to limit the consumption of seed oils and choose healthier sources of fat to support overall brain health.
Obesity
Seed oils have been linked to obesity in multiple scientific studies. A 2020 study published in Nutrition Research and Practice found that a higher intake of linoleic acid, which is prevalent in seed oils, was associated with an increased risk of obesity.
The pro-inflammatory properties of Omega-6 fatty acids, found in high amounts in seed oils, can disrupt metabolic processes and contribute to weight gain. This disruption of metabolism can lead to an increase in body weight and ultimately, obesity.
Additionally, processed foods that contain seed oils are often high in calories and low in essential nutrients, leading to overeating and weight gain. To maintain a healthy weight and reduce the risk of obesity, it is recommended to limit the consumption of seed oils and choose healthier sources of fat, such as olive oil, avocado oil, and coconut oil.
Diabetes
Seed oils have been linked to an increased risk of type 2 diabetes. A meta-analysis published in the The Journal of Nutrition found that higher intake of omega-6 fatty acids, which are abundant in seed oils like corn, canola, soybean, and sunflower oil, was associated with a greater risk of developing type 2 diabetes. On the other hand, higher intake of monounsaturated fatty acids found in olive oil was linked to a lower risk.
A separate study published by the British Cardiovascular Society found a link between seed oils and type 2 diabetes. Participants who consumed more linoleic acid, a type of omega-6 fatty acid commonly found in seed oils, had a higher risk of developing type 2 diabetes. However, participants who consumed more alpha-linolenic acid, a type of omega-3 fatty acid found in flaxseed oil and fatty fish, had a lower risk.
Cancer
The link between seed oils and cancer has been studied by various scientific studies. One such study, published in the journal “Public Health Nutrition”, found an association between high levels of linoleic acid, commonly found in seed oils, and an increased risk of breast cancer in postmenopausal women.
Another study, published in the “Nutrition and Cancer”, found a correlation between a high intake of Omega-6 fatty acids, which are abundant in seed oils, and an increased risk of prostate cancer. These findings suggest that seed oils, particularly those high in linoleic acid and Omega-6 fatty acids, may contribute to the development of certain types of cancer.
Common seed oils to avoid include:
- Canola Oil
- Corn Oil
- Cottonseed Oil
- Grapeseed Oil
- Peanut Oil
- Rice Bran Oil
- Safflower Oil
- Soybean Oil
- Sunflower Oil
- Vegetable Oil (often a blend of multiple seed oils)
- Margarine or Margarine-like spreads (often made with seed oils)
- Shortening (often made with partially hydrogenated seed oils)
What are the Best Alternatives to Seed Oils?
It’s important to note that seed oils are commonly used in processed and junk foods, which can contribute to the overconsumption of Omega-6 PUFAs and increase the risk of health problems. In light of these potential health risks, it is recommended to limit consumption of seed oils and opt for healthier sources of fat instead. These include olive oil, avocado oil, coconut oil, grass-fed butter and animal fats. These oils are less processed, contain higher amounts of antioxidants and anti-inflammatory compounds, and are less prone to oxidation when exposed to heat and light.
Fruit Oils
A 2022 study published in Frontiers in Nutrition found that olive oil consumption was associated with a reduced risk of cardiovascular disease. Coconut oil, high in medium-chain triglycerides, has been shown to increase energy expenditure and enhance weight loss compared to other oils, according to a 2022 study published in the PLoS One. Avocado oil, rich in monounsaturated fats, has been shown to improve heart health and reduce inflammation, according to a 2019 study published in Molecules.
Grass Fed Butter
Grass-fed butter is a healthier alternative to seed oils, as it contains higher amounts of antioxidants and anti-inflammatory compounds. Unlike seed oils, which are often highly processed and refined using chemicals and high heat, grass-fed butter is made from the milk of grass-fed cows, which results in a more natural and nutritious product. This type of butter is high in beneficial fatty acids, such as conjugated linoleic acid (CLA), which has been shown to have anti-cancer and anti-inflammatory properties. It is also rich in vitamins A, D, and K2, which are important for maintaining strong bones and overall health. Additionally, grass-fed butter is a good source of medium-chain triglycerides (MCTs), which have been shown to have a positive impact on weight loss and energy expenditure.
Tallow & Ghee
Tallow and ghee are traditional forms of fat that have been used for centuries in cooking and as a source of dietary fat. Tallow is made from the fat of grass-fed cattle and is considered a healthy alternative to industrial seed oils due to its high levels of monounsaturated and saturated fats, which are more stable and less prone to oxidation when exposed to heat. Ghee, on the other hand, is a form of clarified butter that has been used in Indian cuisine for thousands of years. It is made by simmering butter to remove the water and milk solids, leaving behind a rich, flavorful oil that is rich in short- and medium-chain fatty acids, making it easy to digest and a popular choice for those following a ketogenic diet. Both tallow and ghee are less processed than seed oils and are a good source of essential fatty acids and vitamins A, D, and K2.
Conclusion
Seed oils are commonly found in our food and widely used, but it’s important not to overlook the specific types of fats we consume. In particular, those high in linoleic acid can have harmful effects on our health.
To reduce exposure to these dangerous oils, it’s wise to start by examining the fats in our daily diets, from packaged snacks to restaurant dressings, sauces, and deep fryers. If eating out presents a challenge, consider cooking more at home with healthier alternatives like low-linoleic acid fruit oils or traditional animal fats.
Making informed decisions about our fat sources is crucial for reducing the risk of chronic health problems and maintaining overall health and well-being. It’s important to remember that the fats we consume can have a significant impact on our health, and making informed choices based on current research and recommendations is vital.
