Seed Oils: Harmful or Harmless
Meg Volley, PostGlo Intern
October 2023
Does it feel like you can’t go a day without hearing about a new food or ingredient that’s “bad for you”? Whether it’s high fructose corn syrup, allegedly cancerous diet soda, or even conventional produce being labelled as toxic in comparison to organics, it can almost feel like there’s nothing left that’s considered safe and healthy to eat. It’s hard to sort out fact from fiction in nutrition claims, so here at PostGlo, we’re here to do just that! Follow along for our next series of blog posts where we dish out the truth on popular nutrition claims.
Let’s get right into it with one of the nutrition world’s most controversial ingredients: seed oils. A subset of vegetable oils, seed oils are derived from the seeds of crops including canola, peanut, safflower, sunflower, rice bran, cottonseed, grapeseed, and soy. They’re commonly found in foods such as salad dressings, nut milks, granola bars, chips, and cookies. Discourse over their usage stems from claims that their high omega-6 fatty acid and linoleic acid content causes inflammation and increases risk of chronic disease (1).
Consumption of omega 6 fatty acids and seed oils has increased since the 1970s. A common, but possibly outdated metric of nutrition analysis is the ratio of omega 6 to omega 3 fatty acids in the diet. While the USDA guidelines recommend a ratio of about 4:1, the standard Western diet looks more like a 20:1 omega 6 to omega 3 ratio, or higher (2). Omega 3 fatty acids are found in foods such as fish (specifically salmon, tuna, and sardines), and nuts such as flaxseed, chia seeds, and walnuts. Omega 3s are found in seed oils as well! In addition to seed oils, omega 6 fatty acids are found in walnuts, sunflower seeds, tofu, eggs, mayonnaise, and almonds.
So, if omega 6 fatty acids are apparently unhealthy, does that mean those foods we just mentioned, like eggs, tofu, and almonds are unhealthy too? Absolutely not. That’s because omega 6 fatty acids actually ARE healthy! Linoleic acid (from which all other omega 6 fatty acids can be derived) consumption is associated with lower blood cholesterol and reduced risk of chronic disease (1). Yes, this goes exactly against claims we discussed earlier about the dangers of linoleic acid, and the secret lies in the AMOUNT consumed.
An important principle in toxicology and nutrition is the idea that “the dose makes the poison”. The NIH recommends omega-6 fatty acids contribute to 5 to 10% of energy intake (1), and if you consume a balanced diet of mostly whole foods, you most likely fall into this range. Just look at the facts: a systemic review of 15 randomized control trials found no impact of various levels of linoleic acid intake on inflammation (1), another meta-analysis observing 660 participants found no statistically significant effects of increased or decreased linoleic acid intake on risk of cardiovascular disease (3), and another study even identified the omega 6 to omega 3 ratio as “both on theoretical and evidential grounds, of little value” (4).
So, what can we do with this information? As always, balance and moderation are key. Instead of avoiding seed oils and foods high in omega 6 fatty acids, try increasing the amount of omega 3 fatty acids in your diet by incorporating foods like fish (specifically salmon, tuna, and sardines), and nuts such as flaxseed, chia seeds, and walnuts.
You can enjoy a healthy and happy life, AND you can consume foods with seed oils, omega 3s, and 6s. These are not mutually exclusive events, and don’t let nonscientific claims convince you otherwise! Be sure to keep up with our blogs and social media for the truth behind more nutrition trends!
References