The nutrition media often tries to pinpoint a villain, thinking it will simplify everything! As a society, we’re constantly on the lookout for a single food or nutrient to blame for every gut issue, the rise in metabolic disorders, heart disease, mental illness – you name it. Spoiler alert: our bodies are complex, and a balanced diet filled with a variety of nutrients will always be the unsung hero. As registered dietitians, we want to help people understand and interpret nutrition messages they see in the media – like the topic of today’s post: seed oils!
Table of Contents
- A Quick History on Fats
- What Are Seed Oils?
- Seed Oil Processing
- Seed Oil Nutrient Composition
- Fat and the Gut Microbiota
- Are Seed Oils Inflammatory?
- Olive Oil and Inflammation
- But what if my gut just feels better after removing seed oils?
- Seed Oils and Heating
- Final Word
- Tips for Choosing and Using Oils
A Quick History of Fats
Many of us remember the 1980s and ’90s when the villain of the day was fat—specifically saturated fat, found in foods like bacon, butter, cream, and eggs. The advice back then was to replace these foods with seed oils. Fast forward to today, and now seed oils are in the hot seat. There are even apps warning you about which restaurants use seed oils. But what does the science actually say and do these oils cause issues for our gut health specifically?
What Are Seed Oils?
When you think of a sunflower seed—a common snack at baseball games and on road trips— 25% of that seed is oil.1 Oilseed plants have a high amount of fat in their seeds. The oil from commonly consumed seeds like sunflower, safflower, soybean, corn, canola, grapeseed, rice bran and cottonseed can be extracted through mechanical and chemical mechanisms to create the edible golden-yellow oil you see on supermarket shelves.2 We commonly see these oils added to products for their affordability, ability to be cooked at high temperatures, stability, taste, and nutrient profiles.2
Seed Oil Processing
Much of the negative perceptions of seed oils starts with their production, claiming that seed oils are subject to extreme temperatures and chemical contamination that make them unsafe to eat.
In reality, seeds are crushed which removes 80% of the oil. To derive the last 20%, temperatures are safely increased, and the oil is rinsed with a water soluble solvent, hexane.3 Hexane is then removed and is not at all present in the oil you find on the shelf.3 Just because a food undergoes processing, doesn’t mean it’s unhealthy or unnatural. Mold is natural, yet unsafe to eat.4 Processing often increases shelf-life and in many cases, makes foods safe.4 We wouldn’t eat unprocessed wheat straight from the earth – ie. processing is often necessary to make something edible! This is also the case with seed oils – so, the oil processing is not an issue!
Seed Oil Nutrient Composition
Every food is a combination of different nutrients, and seed oils are no exception. They primarily consist of different types of fats – like omega-6 and omega-3.5 Each oil you find in the grocery store has a slightly different amount and type of fat present in it. For example, canola oil has a lower amount of saturated fat than sunflower oil.5
Fun fact: amongst all common oils, canola oil has some of the best health properties due to the fats, vitamins, and phytosterols present in the oil.2
In addition to fats, seed oils also contain beneficial compounds (yes that’s right!) like carotenoids, phenolics, phospholipids, vitamins and minerals.5 All these complicated science terms refer to compounds from plants that are important to human health. For instance, phenolic compounds have antioxidant actions (prevent the harmful effect of free radicals) in the body.5
Fat and the Gut Microbiota
If you’ve been following our blog for a while, you know that a diverse gut microbiome is key to a healthy gut! Fiber plays a very important role in supporting the diversity of our gut, as it provides our gut bacteria with food. Our community of gut bacteria can be quite picky eaters, so a diverse array of plant-based foods is key to ensure a healthy gut microbiota in the long-run.
Alternatively, excessive fat intake coupled with low fiber intake, can alter the balance of beneficial microbes in the gut. Additionally, a high fat diet, where more than 35% of your daily calories comes from fat intake can increase inflammation.6 While complications of the gut can certainly be linked to a diet higher in fat, it can not be tied to consuming seed oils specifically. So, enjoy your seed oils in moderation and don’t forget to eat enough fiber!
The Inflammation Debate
The number one argument against seed oils is the claim that they cause inflammation. A common misconception is that inflammation is inherently bad. In reality, inflammation is how our body responds to injury or invading pathogens.4 Problems begin when inflammation becomes prolonged and can lead to digestive diseases like Inflammatory Bowel Disease (IBD).
Are Seed Oils Inflammatory?
Seed oils are rich in omega-6 fatty acids, which are often painted as another villain. When digested, omega-6 can be converted into something called arachidonic acid (AA), which is a substance involved in inflammation. This association tends to ring alarm bells in the nutrition media. While its true inflammation can play a role in the development of many different diseases, omega-6 is a crucial fat that has many other functions in the body, including roles in bone formation, liver development, regulating immune responses and cognitive health.7
When we consume seed oils, less than 1% of omega-6 gets converted into pro-inflammatory arachidonic acid.8 Therefore, these oils contribute very little to inflammation overall. Lets not forget that these oils are not solely made of omega-6; they also contain compounds that offer benefits to human health when consumed in moderation. Many seed oils, such as sunflower oil, soybean oil and canola oil are good sources of omega-3 fat, as well as other compounds that are anti-inflammatory and can help reduce inflammatory immune cells, providing protection against disease.
Olive Oil and Inflammation
You might be wondering which oil is best for your gut. An interesting study found that in patients with ulcerative colitis, consuming 50 ml of extra virgin olive oil daily could reduce inflammation and improve gastrointestinal symptoms (such as bloating, constipation, and bowel movements) in a significant number of patients.10
Olive oil is high in a type of fat called oleic acid.10 This, along with other compounds found in olive oil, can reduce inflammatory pathways that may contribute to gastrointestinal symptoms. This is why it is known for its anti-inflammatory properties. So, olive oil is an excellent oil choice – but keep in mind, we don’t need to be drinking oil all on its own. Instead, find practical ways to fit it into your diet such as salad dressings or adding it to homemade dips or hummus.
In general, there are many oils with favorable nutrient profiles for managing inflammation – here are 5 of our favorite choices, as they contain high amount of omega-3 and low amounts of saturated fat:
- Flaxseed Oil
- Canola Oil
- Soybean Oil
- Extra Virgin Olive Oil
- Safflower Oil11
But what if my gut just feels better after removing seed oils?
If your TikTok algorithm has picked up on your digestive disorder, you’ve likely seen videos claiming that removing seed oils can improve gut symptoms. And it’s possible that you’ve already removed them and seem to notice an improvement. So, how does this work? Common foods containing seed oils are foods like mayonnaise, fried foods, candy, chips, baked goods, breaded products, snack foods, and more. While these are enjoyable foods, they are generally high in sugar, saturated fat, and sodium, and lacking nutrients like fiber. When people cut back on these foods, they often feel better simply because they’re packing their diets with more nutrient-dense options. Therefore, it’s likely the improvement is due to swapping out nutrient-poor foods and not necessarily the removal of seed oils.
Seed Oils and Heating
Another common concern is that heating seed oils will create compounds that are damaging to the body. Repeated heating of seed oils can cause the formation of free radicals (molecules that can be damaging to the body), but this requires temperatures of 300-400℃, which is not realistic when cooking in the home.12
If you see black smoke and burn your oil, retry the dish on a clean pan. Olive oil (not a seed oil), does have a fairly low smoke point. Therefore, it’s not advised to use this for pan frying at high temperatures, instead try using something like canola oil for hotter temperatures! Below is a chart you can use to help pick the best oil for the heat you’re using or your preferred cooking method!
Final Word on The Current Science
The research on how specific seed oils impact different gut conditions is still quite unclear. As we discussed today, seed oils are often blamed for causing inflammation but the issue likely exists with nutrient-poor foods that include these oils, rather than specific seed oils. There is a lot more nuance to this topic than what we hear in the popular media!
What the evidence does show is that maintaining a balance of omega-3 fat and omega-6 fat can help in managing inflammation as these fats work synergistically in the inflammatory processes.13 Seed oils can certainly be part of a balanced diet, especially when opting for those higher in omega-3s, such as canola and olive oil. Focusing on overall dietary patterns that include fruits, vegetables, whole grains, fish, white meat, nuts, and seeds is usually going to be the winning ticket for gut health. While we don’t have a ton of science specifically on individual oils and the gut microbiota, the vast majority of research shows, consuming these offers benefits to our overall health when considered with other aspects of a balanced diet.
By understanding how to properly use oils, they can be enjoyed without negatively impacting the health of our gut.14
Tips for Choosing and Using Oils:
- Choose oils you enjoy: don’t deprive yourself of oils as they offer health benefits, especially olive oil.
- Buy oils in dark glass containers: this helps protect the oils from undergoing oxidation and spoiling.
- Avoid reusing oils: when oil is repeatedly heated it has a greater chance of creating harmful compounds.
- Choose grilled/ steamed options- when eating out, choose grilled/steamed options most often to reduce oil that has been reused in fryers.
- Go low and slow: cooking at lower temperatures for longer times can reduce the amount of potentially dangerous byproducts made from denatured oils. You can also choose oils that are heat-friendly (avocado oil + canola oil)!
- Variety: experiment with different fats while cooking to promote a variation of nutrients.
- Use up your oil: nothing lasts forever, oil has a shelf life of one year when properly stored at room temperature. If your oil develops an odor or it’s been sitting for over a year, get time to get a new one.
- Think about flavor: Choose oils that make sense within the recipes you’re making. What would taste the best?
To conclude, it turns out the seed oils aren’t the villains they’re often made out to be! In fact, the only “bad guy” in the world of nutrition may be society’s tendency to label certain foods as dangerous without investigating the science. When enjoyed as part of a balanced diet, seed oils can offer a plethora of nutrients important to the body without causing harm to the gut. By using the tips above, you can confidently select oils that best suit your nutrition needs and cooking methods.
Want more? Try the following recipes, which feature different cooking oils and offer essential nutrients for gut health.
Recipes with Canola Oil:
- 35 Minute Low FODMAP Stir Fry with Firm Tofu
- Favorite Low FODMAP Carrot Cake
- Low FODMAP Peanut Pad Thai
Recipes with Olive Oil:
Categorized: Gut Health & IBS
