Seed oils first emerged in the late 1900s as an alternative to partially hydrogenated oils, and there are eight which are most commonly used and discussed: canola or rapeseed, corn, cottonseed, grapeseed, soybean, sunflower, safflower, rice bran, and peanut oil (1). While not all of these are necessarily derived from seeds, they are still categorized as seed oils. In recent years, the topic of seed oils and their potentially negative health effects have garnered significant attention. This heightened awareness has led many individuals to question whether all types of seed oils are inherently bad for their health, or if it is rather the processing techniques and added chemicals they are often subject to. It is essential to recognize that not all seed oils are created equal, and their impact on health can vary depending on factors such as processing and refining methods, and omega-3 to omega-6 fatty acid ratios (2). While some seed oils undergo extensive refining processes that may strip away beneficial nutrients and introduce harmful chemicals, others can be minimally processed and are able retain their natural goodness.
Omega-3 to Omega-6 Balance and Other Considerations
It is true that seed oils themselves may contain high levels of omega-6 fatty acids, which can create an imbalance of omega-6 and omega-3, which may lead to inflammation. For more information, refer to the “Omega-3 Fatty Acids- A Nutritional Powerhouse” article (3). If eaten in moderation, and in ideal balance with omega-3 fatty acids, these oils are not necessarily problematic, and can in fact be beneficial for human health. For example, in small amounts, they can help lower cholesterol and protect you from heart disease (1). The misconception about these oils stems from the fact that in modern society, seed oils – high in omega-6 fatty acids – are often both full of chemical solvents and used to make ultra-processed foods. One of the main reasons for this is that seed oils are often the oils of choice for such foods due to their low cost. These factors coupled together can result in processed foods, which are extremely unhealthy and highly inflammatory. However, if seed oils are of high quality, uncontaminated, and consumed in an ideal omega-6 and omega-3 ratio, they can be beneficial for your health.
Processing of Seed Oils
In order to extract the oil from the seeds, seed oils usually undergo a refining process that includes filtering, bleaching, deodorizing with chemical solvents, and overheating. This process is also used as a means to extend the shelf life and reduce the consumer cost of these oils. However, these processing methods contaminate and lower the quality of the oils, as well as destroy much of the oils’ natural flavors and nutrients (4). On the other hand, expeller and cold-pressed refers to mechanical processes used to extract oil from seeds without the use of high heat and chemical solvents. These methods differ in the amount of heat generated. Cold-pressed oils are extracted with minimal heat, which usually does not exceed 122℉. Conversely, expeller-pressing may generate slightly more heat from the friction created during the expelling process. The temperatures can reach up to 140℉ and sometimes can get as high as 210℉. While expeller-pressed and cold-pressed are both good options, cold-pressed is preferable since these oils are pressed at lower temperatures (5). Both of these processes are able to retain much of the seed oils’ nutrients, flavors, and healthy antioxidants, which would have been otherwise destroyed when using high-heat and chemical solvent methods. Antioxidants can help your body fight against free radicals, which can cause chronic inflammation and disease (6). It is recommended that when purchasing seed oils, that they are unrefined, expeller or cold-pressed, and organic whenever possible.
In conclusion, the truth about seed oils lies in the amount consumed, the quality, and the production method. While some may in fact pose health risks depending on their preparation and omega-3 to omega-6 ratio, they can also be beneficial to human health. By being mindful in the types of oils you choose, your consumption, and educating yourself properly, these oils can be enjoyed in moderation and even help support health and well-being.
By Dr. Anthony Salzarulo, DC, PC and Rachel E. Kessler
1. https://health.clevelandclinic.org/seed-oils-are-they-actually-toxic
2. https://www.healthline.com/nutrition/are-vegetable-and-seed-oils-bad#consumption
3. https://www.drsalzarulo.com/holistic-health-blog/nutrition/omega-3-fatty-acids-a-nutritional-powerhouse/
4. https://latourangelle.com/blogs/general/refined-vs-unrefined-oils
5. https://www.centrafoods.com/blog/what-is-the-difference-between-cold-pressed-expeller-pressed-solvent-expelled
6. https://www.goodnature.com/blog/expeller-pressed-vs-cold-pressed-oil