Seed oils have been dominating recent internet debates. Everywhere you turn, there’s another claim about their health implications. But, with the overwhelming amount of information out there, what’s truth and what’s myth? Is there any substantial evidence that seed oils are bad for you? Dive deep with us as we debunk the myths and provide you with clear, evidence-based answers. It’s time you finally got peace of mind on this topic.
Seed oils have become the newest food debate sensation across social media. As I pen this down, the hashtag #seedoils boasts a staggering 50 million views on TikTok. A lot of these trending videos shout about the “evils” of seed oils, linking them to inflammation, obesity, and a slew of other ailments. Confused about separating the real deal from the hype about seed oils? Worry not! We’ve sifted through the noise just for you.
What Are Seed Oils?
Seed oils refer to those vegetable oils sourced directly from a plant’s seed. While many vegetable oils you know fall under this category, olive oil is an exception as it’s derived from the fruit. The “hateful eight,” a recent tag given, consists of the more prevalent seed oils: canola, corn, cottonseed, grapeseed, rice bran, safflower, soy, and sunflower oils.
Seed Oil Nutrition Facts
Every seed oil showcases its unique nutritional composition, but a unifying feature is their rich content of omega-6 fatty acids. Omega-6s stand as one of the two primary types of polyunsaturated fats, with the other being the much-adored omega-3 fatty acids.
Contrary to popular belief, no seed oil is purely composed of omega-6s. Each oil offers a mix of fatty acids. Typically, for seed oils, the composition ranks from the highest to the lowest in this manner: omega-6s (primarily linoleic acid), monounsaturated fats, saturated fats, and then traces of omega-3s.
Linoleic acid – what is it? Within the family of omega-6 fatty acids, linoleic acid stands out as the most prominent. Especially in seed oils, it’s the most abundant fatty acid, contributing to around 40 to 80% of their total fatty acid makeup. Notably, canola oil is an outlier with its linoleic acid content at around 20%.
Why Are Seed Oils “Bad?”
Alright, so let’s settle this: are seed oils truly bad for you? To dive into that, it’s crucial to know where all the shade thrown at seed oils comes from. Critics frequently wave around charts and statements highlighting the skyrocketing consumption of seed oils over the past century. This, they claim, parallels the alarming rise in ailments like obesity and heart disease. (Yes, shouty shirtless dude at the supermarket, we’re looking at you.)
Indeed, throughout the 1900s, we did see a surge in seed oil consumption, especially soybean oil. This was influenced by various reasons – health advice nudging people towards polyunsaturated oils over animal fats and the advancements in seed oil processing techniques, like solvent extraction and partial hydrogenation.
Because of this, our diet witnessed a significant bump in linoleic acid intake – that major omega-6 we’ve been discussing – to roughly 7% of our total dietary energy. For context, this is in harmony with the American Heart Association’s guidance of 5 to 10% and the World Health Organization’s recommendation of 2.5 to 9%. Still, this high omega-6 content, with linoleic acid in the spotlight, continues to be a hot topic when discussing seed oils’ possible contribution to inflammation and chronic illnesses.
It’s true that chronic diseases have been on an upward trajectory. But remember the golden rule: just because two things happen together doesn’t mean one caused the other. Let’s dive deeper into that…
So, Are Seed Oils Inflammatory?
When you delve into the debate on seed oil consumption, you’ll come across a series of compelling arguments that often center around some or all of the following points:
- Within our bodies, the linoleic acid derived from seed oils undergoes a transformation, becoming arachidonic acid. This particular acid is a known precursor to compounds that trigger inflammation.
- A heavy tilt in the balance of fatty acids, particularly when omega-6s greatly outnumber omega-3s, can set the stage for a state of persistent, low-level inflammation, which some believe may have long-term health implications.
- The techniques and procedures used to process seed oils aren’t always benign. In fact, there’s concern that these methods might lead to the creation of byproducts that aren’t exactly friendly to our health.
- A characteristic of many seed oils is their instability, especially when subjected to heat. They have a tendency to oxidize, a process that can render them potentially harmful when ingested.
Now, as with many widely circulated claims, there’s usually an element of truth nestled within. It’s important not to take things at face value, but to dissect and scrutinize each claim. Let’s embark on that journey, analyzing each point against the backdrop of scientific evidence.
Claim: linoleic acid in seed oils is converted to inflammatory compounds
Here’s the perspective: Inside our bodies, linoleic acid from seed oils gets transformed into arachidonic acid. This is another type of omega-6 fatty acid, which serves as a foundational material for various compounds, including some that are known to instigate inflammation.
While it’s accurate that linoleic acid can evolve into arachidonic acid in our system, it’s crucial to note that arachidonic acid can birth a wide spectrum of bioactive compounds. Interestingly, some of these compounds play an anti-inflammatory role.
Yet, according to specific tracer studies, the conversion rate from dietary linoleic acid to arachidonic acid is quite minimal, hovering around just 0.2%. Further, a comprehensive review that investigated the connection between the consumption of dietary linoleic acid and the consequent shifts in tissue concentrations of arachidonic acid revealed something telling. When our intake of linoleic acid exceeds the bare minimum required to ward off essential fatty acid deficiency, it doesn’t significantly spike the levels of arachidonic acid in tissues. The body maintains arachidonic acid quantities at a fairly stable range, irrespective of substantial upticks in linoleic acid consumption.
Claim: seed oils throw the omega 6 to 3 ratio out of whack
You’ve probably stumbled upon health enthusiasts raising a hue and cry about the “unbalanced” ratio of omega-6 to omega-3 in our diets. They often stress that an excessive intake of omega-6, compared to omega-3, fosters a state of inflammation in our bodies, potentially raising the risk of chronic ailments. (Remember, omega-3s are the ones everyone sings praises about.)
Many compare our modern-day omega-6 to omega-3 ratio, which is approximately 10:1, with an assumed ancient ratio of 1:1 to 2:1. Based on this, they suggest that this shift in ratio parallels the rising tide of chronic conditions like heart diseases and obesity. But, should we single out omega-6-rich seed oils as the primary culprits? Or could it be more about the broader Western Diet, characterized by a surge in ultra-processed foods and a noticeable decline in the intake of fruits, veggies, and fiber?
Consider this: While seed oils are a prominent source of omega-6 fats in the typical Western menu, most people aren’t consuming these oils while cooking wholesome meals. Instead, they’re ingesting them through fast-food orders and pre-packaged snacks. Many of these foods are calorie-dense, packed with fats (including the saturated kinds) and sugars, and often lack beneficial nutrients like fiber. It’s not just about the skewed omega ratio; these foods also substantially up the calorie count.
Here’s food for thought: Is the problem truly that our omega-6 levels are soaring, or could it be that our omega-3s are dwindling? Why is there such a rush to cut down omega-6s instead of potentially ramping up our omega-3 intake?
Regardless, the use of the omega-6 to omega-3 ratio as a reliable gauge for the inflammatory potential of one’s diet has been met with skepticism by many experts. And their reservations aren’t without foundation. Pinning down and accurately determining this ratio is a Herculean task, fraught with inaccurate assumptions, including the ones we’ve previously explored.
One of the prevailing beliefs is that a high intake of linoleic acid could thwart the conversion of omega-3 alpha-linolenic acid into its potent, anti-inflammatory derivatives, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Now, while it’s a fact that linoleic acid and alpha-linolenic acid vie for the same enzymes to give birth to either arachidonic acid or EPA/DHA, the true degree to which linoleic acid hinders this transformation remains a bit foggy. It seems to impact the EPA conversion more than DHA. However, it’s important to note that the body’s conversion rate of alpha-linolenic acid to EPA/DHA is inherently limited. So, curbing linoleic acid consumption doesn’t magically amp up EPA and DHA levels. For noticeable boosts, direct dietary sources, like fatty fish, are the way to go.
The takeaway: Having adequate omega-3 intake in conjunction with adequate omega-6 intake is essential. That said, don’t subscribe to this distracting and misguided “ratio-thinking”. Instead, focus on increasing intake of dietary sources of omega-3s, which are traditionally less emphasized in the diet.
Claim: seed oil processing results in toxic byproducts
Many seed oils available for purchase undergo a refining process. This involves the use of solvents and heat to glean the oil from seeds, resulting in a light-colored and mildly flavored end product.
There’s some apprehension about minuscule remnants of the chemical solvent, hexane, which is utilized during extraction, possibly lingering in the finished oil. Yet, if there are any residuals, they are incredibly minute (believed to be under 1 ppm), and current research suggests no adverse health implications from such trace amounts. Moreover, a significant portion of the hexane we’re exposed to daily doesn’t stem from our diet. Instead, it’s from environmental sources like car exhausts.
Another point of contention is the potential formation of trans fats when oils undergo extremely high temperatures during processing. This is a potential concern for all vegetable oils. However, industry practices have evolved over the years to curtail this occurrence. Research into various cooking oils suggests trans fat formation might be slightly more prevalent in corn oil. In contrast, some others like soybean, rapeseed, and sesame oil typically have undetectable trans fat levels.
Yes, refining diminishes the quantity of some beneficial nutrients, including omega-3s, vitamin E, and assorted antioxidants. But it’s vital to remember that our primary sources of these nutrients are whole foods, and so the reduction in oils isn’t terribly impactful. And by diversifying the oils you use, you can balance things out. For instance, the robust flavor of extra-virgin olive oil stands out in salad dressings and marinades, whereas canola oil, with its subtle taste, may be preferable for baking.
For those keen on skipping the solvents and high heat, unrefined, “cold-pressed” seed oil variants are available. They offer a richer flavor and deeper color and retain a higher nutrient content. However, they can be a bit elusive on store shelves and usually come with a heftier price tag.
Claim: seed oils are highly unstable and oxidize easily when heated
When seed oils are subjected to high heat for extended durations, they can produce significant amounts of inflammatory polar compounds. This fact often gets spotlighted, sometimes misrepresentative, to denounce seed oils. Let’s dive deeper to gain a clearer perspective.
A particular research project that delved into the oxidative stability of widely-used cooking oils observed a unique behavior in canola oil. When canola oil was heated at approximately 464°F for 20 minutes, it exhibited a total polar compound percentage of 27.5%, crossing the accepted 25% threshold for human intake. It’s pivotal to understand that canola oil is somewhat distinct. It possesses a reduced omega-6 count and an elevated omega-3 count, with the latter being more susceptible to oxidation and the former following suit. Other seed oils in this study remained within the acceptable range after the same time period.
In the same investigation, when canola oil was exposed to around 356°F—akin to the heat settings of most home cooking—it showed a polar compound percentage of merely 7% after 20 minutes. Even after an extended heating time of 6 hours, the percentage was a still-acceptable 17%. To draw a parallel, both coconut oil and extra virgin olive oil had percentages hovering around 10% at the 6-hour mark.
Another key observation from this study was that the tests were conducted devoid of food. The researchers highlighted that the absence of food might have intensified the oxidation effects on the oil.
The conclusions are straightforward: Utilizing seed oils for everyday home cooking activities, like pan-frying or sautéing, is probably not worrisome since we typically employ milder heat. However, it’s wise to moderate consumption of fried items, particularly from eateries, and refrain from reusing cooking oils.
To further guard against the buildup of inflammatory agents, store oils correctly—ideally in a shaded, cool spot shielded from sunlight and heat. Also, buy oil amounts you can reasonably consume within a few months after opening.
Bottom Line: Are Seed Oils Inflammatory?
Even if we were to entertain the various theories and mechanistic arguments presented, they would still need to resonate with actual outcomes observed in humans. Contrary to popular belief, available human data does not corroborate the idea that these seed oils, brimming with omega-6, incite inflammation.
A comprehensive meta-analysis, which encompassed 15 randomized controlled trials (RCTs) focused on the impact of linoleic acid on inflammatory indicators, deduced that the bulk of RCT data from healthy adults didn’t demonstrate an increase in inflammatory markers upon adding linoleic acid to their meals. In a parallel vein, another meta-analysis delving into the prolonged effects of polyunsaturated fatty acids on markers of inflammation and inflammatory bowel disease deduced that omega-6 PUFAs appeared to exert no discernible effect on inflammatory markers among IBD patients.
Even more intriguing, certain research points to elevated linoleic acid concentrations being linked with a diminished inflammatory state. Quite the plot twist!
Seed Oils and Heart Disease
Linoleic acid is known to diminish key risk factors for coronary heart disease (CHD), especially total and LDL cholesterol when it substitutes saturated fat in our meals. This understanding has led organizations like the American Heart Association to endorse consuming 5% to 10% of energy from omega-6s, especially linoleic acid, in conjunction with other health-oriented lifestyle and dietary guidelines, to mitigate heart disease risk.
However, some critics of seed oils argue that such guidelines might actually elevate the risk of heart disease. Their reasoning suggests that since heart disease is linked to inflammation, curbing linoleic acid intake would minimize diet-induced inflammation, thus lowering the associated risks. Given seed oils are a primary dietary source of linoleic acid, the recommendation then is to sidestep these oils to foster cardiovascular health.
Supporters of this viewpoint often lean on previously discussed mechanistic hypotheses about seed oils and inflammation. They also reference contentious meta-analyses of RCTs that indicate neutral to possibly adverse coronary outcomes from increased omega-6 consumption. Yet, one must approach these studies judiciously. Some included RCTs, notably the Sydney Diet Heart Study and the Minnesota Coronary Experiment, bear significant design imperfections like short study durations, inconsistent treatments, high drop-out rates, and potential confounding factors. An expertly executed meta-analysis, accompanied by an advisory from the American Heart Association, which excluded these problematic RCTs, concluded that upping linoleic acid intake, chiefly via polyunsaturated vegetable oils, in lieu of saturated fats notably reduces cardiovascular disease occurrences.
Given the inherent challenges in executing and interpreting vast intervention trials, such as those referenced above, observational studies employing linoleic acid intake markers also play a crucial role in discerning its cardiovascular impacts.
A contemporary meta-analysis encompassing 30 forward-looking cohort studies found that higher levels of linoleic acid in circulation and stored in fat tissues correlated with reduced chances of significant cardiovascular incidents. Similarly, another expansive meta-analysis, which covered 44 prospective cohorts, deduced that elevated linoleic acid intake, measured either through biomarkers or dietary assessments, was linked to a slightly reduced risk of cardiovascular mortality.
Bottom Line: Are Seed Oils Bad For You?
Suggestions to entirely cut out seed oils from one’s diet, in an effort to combat inflammation and heart disease risks, largely hinge on scarce direct proof. In fact, existing data often points to either benign or positive outcomes linked to the consumption or blood presence of linoleic acid—the dominant fatty acid in most seed oils—when it comes to inflammation indicators and the threat of chronic ailments. Yet, despite these insights, misleading narratives about seed oils persist, especially on platforms like social media.
So, where does that leave you? Given the pre-existing abundance of omega-6s in the typical Western diet and considering that oils are naturally rich in calories and provide fewer health-boosting nutrients compared to whole fat sources, there’s likely no pressing reason to actively seek higher seed oil consumption. However, if your current diet is saturated (pun intended) with saturated cooking fats, transitioning partly to omega-6-laden oils might substantially slash your cardiovascular disease vulnerability.
In essence, based on prevailing data, there’s absolutely no cause for alarm if seed oils are listed among the ingredients of your cherished food items or if you utilize them in culinary endeavors where a mild-tasting oil fits the bill.
Also, considering the importance of a balanced omega-3 and omega-6 intake, a more valuable dietary goal would be to bolster your omega-3 consumption, which tends to be underrepresented in most diets.
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