Seed Oils: Sinister or Overhyped?

In this brief newsletter, I review 6 Critical Points about Seed Oils, among the most controversial topics of the day. Get ready for some Provocatively Moderate Positions.

This letter now has a video to go with it. If you prefer watching to reading, here it is. Otherwise, read on!

Seedless to say there’s controversy on the topic of “seed oils.” Call it a trend, fad, or scientific awakening... Whatever you call it, it’s clearly a matter of interest and debate.

In this letter, I’ll highlight 6 Critical Points I think you should know about Seed Oils.

1. Defining Seed Oils

It’s important to clearly define “seed oils.”

Highly oxidized, refined heated/damaged oils, e.g. French Fry Oil at MacDonald’s, is NOT the same as the oil in a raw sesame seed or walnut.

That should be obvious but it deserves emphasis.

2. Do Not Equate Seed Oils to Omega-6/Linoleic Acid

Building on the prior point, “seed oils” should not be equated with polyunsaturated fatty acids (PUFA), omega-6, or linoleic acid.

(*Note: For those who aren’t aware, PUFA are fatty acids with multiple double bonds, making them fragile and prone to oxidation or damage. PUFA include omega-3 (as from fatty fish) and omega-6 fats. The most prevalent omega-6 fat is “linoleic acid,” found at high levels in what are commonly referred to as “seed oils.”)

The conflation and confusion of these overlapping but distinct terms (Seed Oils vs. PUFA vs Omega-6 and linoleic acid) is one major reason it has been impossible to resolve this issue.

We can’t come to consensus if we aren’t talking about the same topic.

3. Overload of Omega-6 Can Cause Inflammation. However…

That said, an imbalance of omega-6 and 3 in the body can create problems, contributing to inflammation. (*See Nuance Note, below)

And because omega-6 are so prevalent in “seed oils” and in the Western Diet, you can see how people would be led to believe avoiding seed oils would be beneficial.

I think there is some reason here.

However, dietary omega-6 and 3 intake does not directly translate into blood/membrane omega-6/3 levels.

In other words, if your dietary intake of omega-6 is 10X and dietary intake of omega-3 is X, the ratio of these fatty acids in your body is unlikely to be 10:1.

The body’s ratio is determined, in part by dietary intake, but also by various metabolic processes that makes the calculus far more complicated.

In truth, the only way to know what your body’s ratios are is to measure.

Taking myself as an example, my absolute intake of Omega-6 is fat greater than intake of Omega-3, on account of the fact that I consume some higher Omega-6 foods like tahini, walnuts, and pecans. However, my measured Omega-6/3 ratio is a “perfect” 1:1, with 17.2% EPA/DHA index. These are hard metrics to beat.

* Nuance Note: The direct impact of omega-6/3 ratio can be best assessed through transgenic animal since, in humans, omega-3 and 6 can't be synthesized de novo. So, in order to manipulate 6/3 ratio, you need to change other dietary variables. This can be overcome in animal models with genetic manipulation.

4. Real Foods for the Win… Thanks Nature!

Real whole foods area often “packed” with compounds that may compensate for and/or protect against oxidation of fragile fats. For example, sesame oil and sesame products (tahini, etc.) contain ~40% omega-6 linoleic acid, but in the context of the lignans in the sesame, the rate of oxidation of this fragile fat is much lower than that of the “naked” omega-6.

Shown above is are the antioxidant effects of sesame lignans on the peroxidation of the omega-6 linoleic acid. The tall line is the control and the graph shows how the natural compounds in the sesame protect omega-6 linoleic acid from oxidation.

5. Randomized Controlled Trials are Not Up To the Task

Short-term randomized controlled trials (including “calorie- and macro- controlled” trials) are not equipped to properly assess the potential harms of “seed oils.”

Whether you define seed oils here as highly oxidized oils or just very high omega-6 content vs control, the physiological changes induced by an omega-6/3 “imbalance” and/or oxidative stress take many months and more likely years to manifest.

Thus, a “negative” finding in a relative short-term RCT can pose a false negative for health effects.

6. Metabolic (Macronutrient) Context Matters

As mentioned earlier, the degree to which omega-6 and omega-3 end up getting stored in your body and/or used for structural purposes depends on many metabolic factors.

As an example, macronutrient context matters. In the context of very low carbohydrate ketogenic diets, PUFA and omega-6 are very efficiently converted into ketone bodies (beta-hydroxybutyrate). Thus, consuming foods rich in omega-6 (like sesame oil) can, in this context, be used as a “biohack” to increase ketone levels, potentially with therapeutic effect.

For more on this:

In summary of my perspective

Based on basic physiology, it’s reasonable to believe “seed oils” (see point 1-2) are harmful beyond the calorie load, and paucity/absence of human RCT data is not all that meaningful (see point 5).

However, it’s also not reasonable to claim, as many do, “seed oils are poison and/or THE reason for the obesity epidemic.” It’s also not reasonable to claim all high omega-6/LA foods are “bad” because of their PUFA content.

My Practices

Personally, I do the following:

• Prioritize whole foods, be that walnuts or ribeye steak.

• Cook with fats and oils stable at higher heats, including Ghee, Macadamia Oil, Avocado Oil.

• Prioritize omega-3 rich foods, especially lower mercury fatty fish, e.g. sardines, sockeye salmon.

In the end, you can do as you please.