Are Seed Oils Bad For Your Gut? An RD's Take
https://mysuperherofoods.com/what-about-sesame-oil/
But First, What are seed oils?
Seed oils (AKA vegetable oils) are extracted from seed crops, such as canola (rapeseed), soy, corn, safflower, and cottonseed. Seed oils only came into play in the last century, with advances in farming and machinery.
The refining process that turns these seeds into oil is pretty intense. The oil is extracted, refined, and deodorized. This gets rid of undesirable substances such as pesticide residues, metal traces, polycyclic aromatic hydrocarbons, and dioxin. During the refining process, the substances that contribute to the touted healthy properties of vegetable oils (stanols, & sterols) are also removed.
Seed oils are high in omega 6 fatty acids, which are extremely vulnerable to oxidation. The refining process increases their risk of oxidation. Cooking these oils past their smoke point and being exposed to light also heightens the risk. Oxidation of these oils = they become rancid and essentially can do more harm then help health-wise.
To get more speific, these oxidized fats contain lipid oxidation products (LOPs) and a carcinogenic compound, acrolein. LOPs are no joke—they're linked to a laundry list of inflammatory diseases, like IBD, atherosclerosis, heart failure, obesity, and more. Plus, they can negatively impact fertility by damaging oocytes and sperm. Acrolein may be linked to heart disease, diabetes, & alzheimers when consumed regularly. Note that oxidation of oil can occur with avocado & olive oils as well if cooked past the smoke point.
A note on high heat cooking vs finishing oils…
Plant oils are easily damaged by heat, so avoid cooking them at high temps, with the exception of coconut oil which is naturally high in heat-stable saturated fat. Plant oils such as olive & avocado are best used for finishing oils or lower heat cooking per my note on oxidation above.
As mentioned, coconut oil is suitable for high heat cooking, as well as ghee (clarified butter) or beef tallow. Ghee actually has a higher smoke point than butter
OK, now that we’ve talked the freaky sh** about seed oils, let’s get to WHAT TO CHOOSE INSTEAD….
Choose these instead of seed oils:
High quality, unrefined oil like extra virgin olive oil
Organic unrefined coconut oil
Ghee or grass fed butter
Grass fed beef tallow (pictured)
The updated deets on the health bennys of butter:
Saturated fat (the fat in butter) is often blamed for heart disease because it can raise LDL cholesterol, which is considered bad for your heart. On the other hand, omega-6 polyunsaturated fatty acids (PUFAs) (the fat in seed oils) are seen as “heart-healthy” because they can lower both total cholesterol and LDL (the bad cholesterol). People often swap out butter for seed oils thinking it's better for their hearts…
BUT here's the thing: focusing only on LDL cholesterol levels is NOT the whole story. Saturated fat seems to lower the levels of small, dense LDL particles (the ones associated with higher heart disease risk) and increase larger, less harmful LDL particles. This means: even though saturated fat might raise overall LDL cholesterol, it does not necessarily increase the risk of heart disease. Another interesting point is that saturated fats have shown to increase LDL and total cholesterol, but also increase HDL cholesterol. On the other hand, unsaturated fatty acids don't raise HDL as much.
PS: Saturated fats are naturally stable and resistant to oxidation, even when heated. Because of their stability, saturated fats like butter and tallow make ideal cooking fats!
Additionally, the research shows us that small, dense LDL particles and oxidized LDL (damaged LDL) may have a bigger impact on heart disease risk than just LDL cholesterol levels alone. What can cause oxidation of LDL? Omega 6 fatty acids that oxidize easily (aka: Seed oils)
A large randomized clinical trial found that participants consuming the highest amount of saturated fat experienced no detrimental effects to their lipid profile while consuming a diet of whole foods and low in refined carbohydrates. This reminds us to focus on the overall quality of our diet.
A note on inflammation & seed oils….
Excessive consumption of omega-6 fats via seed oils can deplete vitamin E stores (a potent antioxidant!), leaving your body defenseless against lipid oxidation. By cutting back on seed oils, we're not only sparing our vitamin E reserves but also preventing them from being used up in the battle against oxidative stress.
Too much omega-6 can also throw off the delicate balance with omega-3 fats. These two compete for the same receptor binding sites, so overdoing it on omega-6 could leave you deficient in omega-3s.
Another problematic seed oil anecdote…
Reheating oil can create various carcinogenic compounds, including polycyclic aromatic hydrocarbons (PAH), which have been linked to various types of cancer. Seed oils are the #1 oil being cooked and cooled repeatedly. Mainly in restaurant settings- anything deep fried. These foods are highest in LOPs.
So what foods are seed oils commonly found in?
They can be sneaky! Seed oils can hide in brands we know and love, ie: Boom Chicka Pop popcorn, Once Again Nut & Seed butters (some, not all!), Made Good bars, etc. It’s super common to find them in things like readymade hummus (even organic!), salad dressings, granola bars, snack foods, the vast majority of chips (this is why we love Siete!) and baked goods. When grocery shopping, check your labels!! PS: I often get asked about the sunflower oil in Simple Mills crackers - they have come out with a statement saying that they use a higher quality sunflower oil that is organic and high oleic - meaning it is not as high in omega 6’s as typical sunflower oil and it never gets near its smoke point in baking. As someone who loves me a Simple Mills cracker, I say vary with other seed-oil free brands and minimize vs. give up completely for joy and sanity-sake.
Seed oils & your gut
Studies have shown that seed oils may have an impact on gut health. One study on mice has shown that a diet high in soybean oil decreased good bacteria, and increased bad bacteria. Another study showed that women with IBS had heightened levels of arachidonic acid (an omega-6 fatty acid prevalent in seed oils), as well as pro-inflammatory PUFA metabolites. What does this mean in plain english? Studies are showing links between seed oils and gut inflammation. In the standard American diet, the omega 6/omega 3 imbalance can be strikingly high, reaching ratios like 20:1. This imbalance can trigger inflammation, leading to health problems like inflammatory bowel disease (IBD).
My realistic TL;DR:
The obvious recco -> Focus on eating mostly whole foods while limiting processed & packaged foods when able.
Read labels, choose brands like Siete, Lesser Evil and Hu crackers to do your best to keep seed oils out of the home.
Give yourself grace when going out to eat. We know that stressing about food itself can have a negative impact on digestion. Enjoy the experience, be present and choose vitamin E-rich foods like pumpkin seed, avocado and wild salmon to buffer the oxidative stress from seed oils.
Opt to cook in the home as much as possible, and when out to eat, enjoy yourself!
Choose roasted/baked/slow cooked foods vs. fried
If you feel comfortable, you can always ask your foods to be cooked in butter instead!
