If you follow any natural health accounts on social media, you’ve likely heard by now that seed oils are damaging to your body. Seed oils, and especially the foods in which they are commonly found, may contribute to chronic inflammation. Chronic inflammation can increase your risk for many serious systemic conditions, from diabetes to cancer, and even infertility. So if you’re trying to conceive, read on for everything we know about seed oils and how they may impact health and fertility.
What is a ‘seed oil’?
Before we explore how seed oils affect fertility, let’s dive into what seed oils are.
The term seed oil (or vegetable oil) refers to a plant-based cooking oil derived from seeds. Some of the most common seed oils used in today’s standard American diet include canola, corn, cottonseed, soybean, sunflower, safflower, grapeseed, and rice bran oils. For decades, these oils have been touted as “heart-healthy” alternatives to butter or olive oil because they contain less saturated fat and cholesterol. The downside, however, is that these oils can contribute to increased inflammation in the body, which is linked to a whole host of health issues [1] (more on this in a bit!).
What’s the problem with seed oils?
Now, we’ve probably all heard that nuts and seeds are part of a healthy diet, so why are seed oils so problematic? It all starts with how the oils are manufactured [2]. First, the seeds are heated to extremely high temperatures, which oxidizes the unsaturated fatty acids, creating harmful byproducts and destroying natural antioxidants contained within the seeds [2]. Later on, the oil is deodorized with chemicals using a process that produces trans fats, which are proven to have adverse effects on the body. The whole process results in an oil that is tasteless and colorless as desired, but also undesirably dense in calories while being low in nutrients.
The connection between seed oils and inflammation
Questionable manufacturing processes aside, the main reason why seed oils are said to be harmful to the body is because they may contribute to chronic inflammation. That’s because they contain high levels of an omega-6 fatty acid called linoleic acid. It’s true that the body needs some omega-6 fatty acids, since they contribute to the body’s vital inflammation response, which kicks in to help us heal when we’re cut or bruised.
The sheer amount of seed oils consumed today may be the issue: some estimates suggest that linoleic acid now makes up 6-10% of the average person’s caloric intake, while a metabolically appropriate level would be around 1-2%. Ideally, these omega-6 fatty acids should be consumed through whole foods, like nuts and seeds, as opposed to in highly concentrated form as found in seed oils. Again, consuming high levels of omega-6s and linoleic acid can lead to chronic inflammation, which is linked to health conditions like arthritis, heart disease, diabetes, weight gain–and yes, infertility [6].
The rise of seed oil-containing processed foods (and the misguided vilification of animal fats) is partly to blame for the dramatic uptick in our linoleic acid consumption. For many Americans, their standard diet consists, in large part, of processed foods such as frozen or premade dinners, packaged breads, chips, crackers, and other snacks, plus bottled sauces, dressings, and condiments, rather than whole foods like fruits, vegetables, and meat. Typically, these processed foods are laden with seed oils–the fat of choice for most conventional food manufacturers thanks to its low price and easy accessibility.
Is butter bad (and are seed oils good?) when it comes to cardiovascular disease?
Of note, some prominent medical organizations suggest that people with cardiovascular disease (CVD) should consume seed oils instead of oils that are richer in saturated fats like butter fat [3]. However, there are compelling challenges being made to the belief that saturated fat consumption causes CVD (and the corollary that decreasing saturated fat intake will decrease cardiovascular disease and death). Here’s an easy-to-understand explainer from the British Journal of Sports Medicine on why saturated fat may not actually be the cause of CVD [4], and here is another research-backed, more academic read on why reducing saturated fat intake isn’t the answer to combatting CVD [5].
It’s not me, it’s the other guy…
Some argue that it’s the high levels of sodium, nutritionally “empty” carbohydrates, and sugar in these foods–not the seed oils–that make frequent consumers of processed foods sick. It’s certainly the case that the excessive sugar and sodium added to these foods in order to make them hyperpalatable are also damaging to the body.
But it’s also possible that high levels of omega-6 consumption can cause inflammatory issues on their own. This may especially be the case when a person eats foods high in omega-6 but doesn’t consume adequate omega-3 fatty acids. Some research suggests a link between chronic health problems and diets with high omega-6 to omega-3 ratios [6][7]. As one example, this 2012 study shows the level of omega-6s vs omega-3s in common cooking oils, ranging from butter to soybean oil [1]. The ratio between omega-6s and omega-3s is just under 2:1 in butter fat, compared to almost 8:1 in soybean oil.
Our friend Lily sums up what’s not to love about seed oils
If you’ve been following our Natural Womanhood Book Review series, you might already know we’re big fans of Registered Dietitian Lily Nichols, author of Real Food for Fertility, Real Food for Pregnancy, and Real Food for Gestational Diabetes. In a brief video interview, Nichols summed up the issue with seed oils:
“An excessive amount of the omega-6-rich vegetable oils can be an issue… It throws off our omega-6 vs. omega-3 balance in the body, and it also tends to cause inflammation. They’re just really sensitive to an exposure to air and light, and they’ve also undergone a ton of processing before they make it into the bottle at the grocery store… So I really encourage people to do their best to minimize the amount of those oils that they’re consuming… any of these really high omega-6 oils, which tend to be the ones in a lot of our processed foods. They’re really not doing our bodies a lot of favors.”
But how might seed oils be connected to infertility?
Infertility is a complicated and devastating condition that affects millions of couples in the US. When a couple is infertile, it may be related to male factors, female factors, or both. Any number of health conditions factor into whether or not a couple is able to conceive, including (but not limited to) PCOS, endometriosis, and hormone disorders in women, and sperm count and sperm quality issues in men. Chronic inflammation, which can negatively impact every body system, in turn may contribute to the development of, or further exacerbate, these infertility-causing conditions.
In women, chronic inflammation can worsen endometriosis and impact ovulation, menstrual cycle regularity, implantation of a newly conceived embryo, and likelihood of miscarriage [8]. As for men, a study published in 2010 showed a link between male infertility and elevated omega-6 to omega-3 ratios [9].
Reduce inflammation, improve fertility
Reducing inflammation in the body, on the other hand, can improve fertility. A 2007 study of over 17,000 women found that subjects who followed a “fertility diet” –that is, a diet rich in anti-inflammatory monounsaturated fats, vegetable protein, high fat dairy, and iron–were more likely to conceive [10]. Most importantly, from the study’s conclusion “Further, the majority of infertility cases due to ovulation disorders may be preventable through modifications of diet and lifestyle” (emphasis added).
If you’re ready to swap out your seed oils…
The single most impactful way to reduce your seed oil intake is to cut down on your consumption of store-bought processed foods. Unless you’re intentionally seeking out seed oil-free options, it’s likely that many of your favorite packaged foods contain some sort of seed oil (and a surprising amount of excess sugar and sodium, to boot!). Some of the biggest culprits of seed oil-laden foods include salad dressings, sauces, crackers, and chips.
If you’re avoiding seed oils, it’s important to become a label reader when you’re grocery shopping. Be on the lookout for seed oil-free alternatives to your favorite snacks. Packaged chips, crackers, and sweets made with olive oil, coconut oil, or butter may be less inflammatory and have fewer adverse effects on your fertility. These cleaned-up swaps are few and far-between, but they do exist–so don’t throw in the towel if you can’t find them right away!
Better yet, learn to make your own sauces and snacks, like the Creamy Avocado Lime Dressing featured here (perfect for taco salads) or this Creamy Roasted Garlic Dip (guaranteed to be the star of the appetizer table at your next gathering). Finding recipes for your favorite previously-store-bought treats is a fun way to get in the kitchen and sharpen your culinary skills–and your homemade versions may taste better and be easier on your wallet.
What to do when you go out to eat
Most restaurants cook with canola oil or peanut oil because they’re relatively cheap, which makes avoiding seed oils difficult when going out to eat. If you’re serious about eliminating seed oils to improve your chances of conceiving, consider cutting back on restaurant outings. And when you do go out to eat, avoid fried foods and opt for simple entrees–think a steak or chicken breast with a side salad (with olive oil and vinegar for dressing) or veggies with real butter on top. You may even be able to request that your meal be cooked in butter or olive oil. Not all restaurants will be able to accommodate, but it never hurts to ask!
As far as home-cooking goes, using vegetable or canola oil from time to time isn’t the worst thing in the world–especially considering you’re probably using less than food manufacturers do, and your oil is likely cleaner than the oil used in restaurant deep fryers, which is seldom changed. But if you’re buying cooking oil anyway, perhaps prepare your meals with a less-inflammatory fat like butter, tallow, olive oil, avocado, or coconut oil. When it comes to baking, use butter or coconut oil in recipes that call for seed oils. (It’s usually a simple 1:1 swap.)
Closing thoughts on seed oils and fertility
Cutting down on seed oils is not the be-all, end-all solution to conceiving. But it certainly can’t hurt–especially if it gets you to cut down on your consumption of processed foods, which are also usually high in sugar, too. There’s a slew of evidence linking high seed oil (and sugar) consumption to inflammation in the body. And since we know that chronic inflammation is linked to fertility problems, it’s worth it to try to cut down on inflammatory foods. Since seed oils are so prevalent in the modern American diet, cutting down on them may feel like a daunting task, especially if you’re not used to cooking or preparing your own food. But doing so will undoubtedly improve your health, and it may even help you and your spouse start a family, making the effort more than worth it.
