Should We Avoid Seed / Vegetable Oils?

highly processed seed oil

What are seed or vegetable oils?

Seed oils, such as soy, canola (rapeseed), corn, cottonseed, safflower, sunflower, and grapeseed oils, are typically highly processed oils extracted from the seeds of plants (1).

The oil extraction process includes heating, filtering, bleaching, and deodorizing before the oil is packaged and sold commercially (1).

https://extension.psu.edu/processing-edible-oils

Processed foods, such as corn chips, salad dressing, and baked goods, contain various types of oils, and many processed foods list more than one type of seed or vegetable oil used in a product.

How seed oil consumption affects the body

The refinement and processing of commercial seed oils can destroy nutrients, resulting in an energy-dense, yet nutrient-deficient, product (1).

Seed oils are high in omega-6 fatty acids, and consuming a diet high in seed oils can create an imbalance in the omega-3 to omega-6 ratio in the diet, which can lead to increased inflammation in the body (2).

The polyunsaturated fatty acids in seed oils are highly susceptible to oxidation when exposed to heat and light, which can lead to the formation of peroxides and harmful molecules that damage the body (3).

Today, the Standard American Diet is replete with seed oils, leading to excessive intake of these highly processed, energy-dense, and nutrient-deficient products, which can contribute to weight gain, dysfunction, and disease processes (4).

Conditions related to seed oil consumption

An Open Heart systematic review summarized that industrial seed oils promote oxidative stress, chronic inflammation, and atherosclerosis, which can lead to coronary heart disease (2).

Studies also show an increased risk of obesity when the level of omega-6 fatty acids or the omega-6 to omega-3 ratio increases in the blood (5).

Furthermore, an imbalance in the omega-6 to omega-3 ratio, favoring omega-6, is proinflammatory and contributes to conditions such as atherosclerosis and diabetes (5).

What to use instead

When cooking, unrefined or virgin coconut oil can be used at low to moderate heat with the added benefit of trace nutrients and polyphenols (6).  Avocado oil can be used for broiling, grilling, and high-heat or roasting applications, as its high smoke point makes it a versatile all-purpose cooking oil.  Butter and ghee (clarified butter) can also be good choices for cooking.

For cold food preparations, extra virgin olive oil, unrefined flaxseed, sesame, hemp, and walnut oils can all be healthy options.