Understanding Seed Oils

Seed oils are oils extracted from the seeds of certain plants. While research suggests that a diet including seed oils is healthful, these oils have been blamed for conditions such as eczema, weight gain and inflammation, especially on social media. So, are these oils actually bad for your health?

When people talk about seed oils, eight specific oils get the most attention: canola, soybean, safflower, corn, cottonseed, grapeseed, rice bran and peanut oils. However, there are a wide variety of seed oils available, including those from sesame, flaxseed and walnut.

Omega-3 and Omega-6 Fatty Acids

Seed oils are composed of differing amounts of saturated, monounsaturated and polyunsaturated fats. Polyunsaturated fats, or PUFAs, are often present in the highest amounts and are the focus of most seed oil debates. PUFAs include omega-3 and omega-6 fatty acids, which may help to decrease inflammation in the body when consumed in appropriate ratios. Research on the ideal ratio is unclear. Most seed oils have a much higher amount of omega-6 fatty acids compared to omega-3s. However, there is a lack of research to suggest that omega-6 fatty acids cause inflammation.

Omega fatty acids are often categorized as omega-3s are "good" and omega-6s are "bad," but it’s not that simple. Omega-3 fatty acids (found in foods such as fatty fish, walnuts, chia and flax-seeds) are known for their role in supporting brain and heart health. Meanwhile, research suggests that omega-6 fats are beneficial for lowering the risk of heart disease, with recent research suggesting a decreased mortality rate for those who replace butter with plant-based oils, including those from seeds.

How Seed Oils Are Produced

Besides being a source of omega-6, seed oils have been criticized for how they are produced. Some oils are expeller-pressed or cold-pressed, meaning that heat or chemicals are not used during the process of oil extraction. These oils are produced in small batches, can have a cloudy appearance and can go rancid quickly. In order to yield a clear, shelf-stable oil, producers use heat in extracting the oil from the seed.

Chemical solvents may be used to make the extraction process more efficient with less waste. Concerns exist about the potential for chemicals, such as hexane, to remain in oils after processing. However, residue levels are well below safety limits, even among adults with some of the highest levels of daily fat intake in the United States.

Should Some Seed Oils Be Avoided?

It’s important to consider a variety of factors when choosing what to eat. Tops sources of seed oils for many Americans come from ultra-processed foods, such as baked goods, chips, frozen meals, convenience items and fried food, which lack nutrition.

If you find a seed oil listed in the ingredients of foods like whole-grain bread or peanut butter, review the Nutrition Facts label to see if the food provides other beneficial nutrients and fits into your healthy eating routine.

Including more omega-3 fats in your day may be beneficial. Try sandwiching tuna fish between two slices of whole-grain bread or spreading the bread with peanut butter and sprinkling with ground flaxseed ─ another source of omega-3.

Cooking and Baking

Seed oils such as grapeseed, canola and soybean (labeled as vegetable) have a high smoke point, which means they don’t degrade during cooking. In addition, they are good substitutes for solid fats like butter, lard or shortening, which contain more saturated fats. There are many healthy ways to use seed oils:

• Substitute for some of the solid fat in baked goods, such as whole-grain muffins
• Season a cast iron skillet
• Oil grill grates to keep food from sticking
• Roast vegetables in the oven to get a toasted flavor
• Stir-fry meat and vegetables
• Pop popcorn on the stove
• Make salad dressings — the fat in oils increases the absorption of the fat-soluble vitamins A, E and K that are in leafy greens.
• Make recipes featuring these healthy fats

Using seed oils to prepare wholesome food at home can be beneficial to your health, especially when they are used to replace sources of saturated fat. This substitution promotes healthful eating and can help to reduce total cholesterol and the risk of heart disease. In general, limit packaged dessert and snack items, which may contain seed oils and lack in nutrients. However, there's no need to avoid nutrient-dense foods, such as nut butter and whole-grain breads, that contain seed oils.