Article at a Glance
- Vegetable oils contain small amounts of trans fat.
- Vegetable oils are easily damaged, which means most vegetable oils contain free radicals that are bad for our health.
- Sitosterol is a type of plant fat found in vegetable oil and other plant foods.
- Normally, we don’t absorb sitosterol, however, variants in the ABCG8 genes can result in greater absorption of plants sterols like sitosterol.
- Absorbing the oxidized fats found in vegetable oils is especially bad for heart health.
- These oxidized fats bind to certain types of lipoproteins making the particles more atherogenic (bad for your heart).
This is a post about why I don’t eat vegetable oil, not as much a post about why vegetable oil is bad for people in general (although it is), so I hesitate to list the same “dangers of canola oil” bullet points as every other blog on the internet, but in order to set the table for the nerdy journey I am about to take you on, I will briefly list and emphasize a couple of the big ones you’ll need in order to get the most out of this post.
Why vegetable oil is bad for you
Vegetable oil is easily damaged and contains free radicals
Vegetable oil (and you can throw in most seed oils as well), like many polyunsaturated fats, including fish oil, is easily damaged. It oxidizes when exposed to air, heat and light. The oxidation process creates free radicals, which you can think of as little barbed wire molecules that crash into cells and do damage. As we’ll learn in a bit, the heart is especially susceptible to injury from the free radicals in damaged oils. In fact, vegetable oil is one area where plant based cardiologists like Caldwell Esselstyn and paleo advocates, Chris Kresser being one of the most visible, agree. Both will tell you to avoid vegetable oils like the plague, in large measure due to the fact that they’re so delicate.
And in case you think you can pick a vegetable oil that is free radical free, it’s important to understand that the free radical count in vegetable oil spikes when it’s heated, and since the primary purpose of most vegetable oils is cooking, or as an ingredient in a processed food, heating is inevitable. (R) It’s also next to impossible to know what could have happened to the vegetable oil you’re eating before it arrived at your grocery. For example, was the shipment hauled in a truck without A/C? Was the shipment left out in the sun before being fork lifted into a stock room? You’ll never know, and these are the types of events that lead to oxidation. Since we can’t account for the chain of title with vegetable oil, we can’t know for sure how high the free radical count is in any given bottle. This is especially true for the oil used in restaurants. Was the oil kept near a stove for a month before it went into the sauté pan being used to make your dinner?
Vegetable oils contain glyphosate
Vegetable oils contain glyphosate, which is a pesticide used to spray GMO crops and even non-GMO crops to accelerate ripening. Glyphosate wipes out the gut microbiome and is increasingly becoming linked to cancer, especially in workers exposed to it as part of their job. (R)
Omega 3 to Omega 6 ratios
Omega 3 to Omega 6 ratios. You’ve heard this one before, but to repeat, the prevalence of grain fed meat and processed foods, made with omega 6 rich vegetable oils, has pushed the American diet way too far to the omega 6 side of the spectrum. This imbalance has resulted in an increase in chronic conditions caused by inflammation. (R)
Vegetable oil contains trans fat
Vegetable oils contain small amounts of trans fats. (R) Trans fats are the really dangerous fats found in processed foods that are bad for your heart. They reliably raise LDL-C. Due to loopholes in labelling, most vegetable oils have small enough trans fat content that they don’t need to be disclosed, but they are there. When you eat vegetable oil, or foods cooked in vegetable oils, you are eating trans fat, period. (R)
Can eating vegetable oil raise serum trans fat?
If you’re a regular reader of this blog, you’ve heard me mention Boston Heart Diagnostics, which is the lab I use to get blood work done. Boston Heart offers fatty acid profiles which show you how much EPA, DHA, saturated fats, and yes, even trans fat, is circulating in your blood. I have routinely been confounded by my trans fat levels, which are often in the borderline range. They’re not high, but they’re not always in the green, which has been puzzling since I very rarely, if ever, eat pastries, pies, cookies, etc.
I am 100% gluten free and don’t partake in most gluten free desserts, so my chances for ingesting trans fat are quite limited. Or so I thought. What I didn’t realize is that, a few times a week, I was unwittingly pigging out on fried foods and foods high in vegetable oils. The culprit: chips. As a kind of cheat snack, I would have some corn chips and salsa. Or, I would go the grain free route and have some Siete grain free chips. On occasion, I’d do some gluten free bread, or maybe some dried fruit.
The messed up thing about these foods is they’re either fried (corn chips and Siete chips are both fried) or they contain liberal doses of vegetable oils. Yes, they are putting sunflower oil on foods like dried cherries now for some reason.
Since the vegetable oils contain trans fat, these processed foods were the explanation for my above normal trans fat levels.
Are vegetable oils absorbed into the blood?
But, I know what you’re thinking: vegetable oils aren’t absorbed into the blood. The whole reason they’re said to be heart healthy is because the sterol (plant fat) in vegetable oils, called sitosterol, competes for absorption with cholesterol. To the extent sterols are temporarily absorbed, the body kicks out the phospholipids before they reach the blood stream.
This may be true in some cases, but my blood tests showed I was prone to absorbing larger amounts of the sterols I was eating. I wrote previously about why some people seem to thrive on a carnivore diet. My theory is that people who excel on the carnivore diet, which often involves eating nothing but red meat for months at a time, have undiagnosed sitosterolemia, which is a condition marked by hyper absorption of plant sterol. The plant sterols that are supposed to be pushed out of the lumen get in the blood where they cause joint pain, heart disease and a host of other problems. Sitosterolemia is genetic, it is marked by variants in the ABCG8 genes whose job is to kick out sterol from the lumen (gut wall) back into the digestive tract where these plant fats can be excreted by the body. So, in most people, sterol is only temporarily absorbed and most of it doesn’t make its way to the blood. However, just as everyone absorbs different amounts of cholesterol, we also absorb different amounts off sterol. I don’t have sitosterolemia, I don’t have the genes nor do I have the sitoserol levels consistent with that condition. My joints are fine. However, I have blood work which shows my sitosterol levels can get a little high (3.9 mg/dl at highest), especially when I am eating a diet that is higher in sterols from sources like vegetable oils, beans, lots of nuts and seeds, avocado, etc.
What does this mean?
Well, sitosterol is a marker labs use to gauge how much cholesterol someone absorbs, so for starters it means I am absorbing more cholesterol than some others. But it also means my ABCG8 genes aren’t firing at 100%. I don’t have the sitosterolemia SNPs, but I do have two SNPs in the ABCG8 region. When you combine the genetics with the labs, it’s clear that I am prone to absorbing higher amounts of plant sterols, of which vegetable oil is a very potent source.
Since vegetable oil contains ready made doses of oxidized sterol, or to use another term, oxidized phospholipids, I am getting a heavier dose of free radicals when I eat vegetable oil than someone with full ABCG8 function.
But the issue doesn’t stop with ABCG8, the oxidized phospholipids in vegetable oils can bind to lipoproteins, which isn’t a good thing for the heart.
Vegetable oil and lipids
In addition to sitosterol, I also have elevated levels of Lp(a), which is a particularly dangerous type of LDL particle that is known to increase the risk for heart disease. Lp(a) is largely driven by genetics, you can see it on lipoprotein panel like the ones we offer in our custom nutrition plan.
Luckily, I only have a heterozygous mutation for rs10455872 (one of the key Lp(a) SNPs) so my Lp(a) levels are only moderately elevated, they have ranged from between 33 mg/dl to 49 mg/dl which, according to European standards, is considered low risk. However, there is good evidence based on this New England Journal of Medicine study, and some others, that oxidized phospholipids preferentially bind to Lp(a), and it’s the combination of the two that makes Lp(a) so atherogenic (bad for your heart). There is even evidence that ingesting oxidized plant fats goes beyond just binding to Lp(a) and actually increases serum levels of Lp(a) as well. (R)
This makes sense in light of the fact that the LDL-C tests everyone gets reflect not just the cholesterol mass within an LDL particle, but also its phytosertol content as well.
So, boom, that is why I don’t eat vegetable oil. I have ABCG8 SNPs and an LPA SNPs that, when combined, add up to a genetic profile that is best suited to avoiding oxidized fats like vegetable oil and, yes, even fish oil. I absorb these fats at an accelerated rate, and their oxidized bi-products bind to unique lipoproteins in my body making them more dangerous.