Key Points:
- The omega-6 fatty acid linoleic acid, found in vegetable oil, primes LDL for triggering heart disease, according to one hypothesis.
- Vegetable oils have been the primary driver of aging and chronic disease in the past 50 years, according to another hypothesis.
- When compared to saturated fats, the fats within vegetable oils reduce the risk of heart disease, according to a mainstream hypothesis.
In a recent video, physician Paul Saladino, M.D., explained the origin of CANOLA — CANadian Oil Low Acid. He says that Canada produced massive amounts of seed oil during World War II to make it into a lubricant for ships. The oil came from the seeds of the rapeseed plant, which gets its name from the Latin word for turnip. However, once the war ended and the lubricant wasn’t needed, Canada had to create a demand for its huge supply of rapeseed oil.
In order to sell rapeseed oil to the public, Canada started to produce genetically modified rapeseeds that contain less erucic acid, which is toxic to humans. Hence, Canadian oil low acid (canola) was born and is now the second most consumed vegetable oil in the United States after soybean oil. However, physicians like Saladino have argued that canola oil and other linoleic acid-containing vegetable oils cause atherosclerosis.
How Vegetable Oils May Cause Heart Disease
Atherosclerosis is the leading cause of death in the United States, characterized by plaque buildup in the arteries that can lead to heart attacks and stroke. While high LDL cholesterol is a risk factor for atherosclerosis, LDL may not play a causal role. Indeed, pharmacist James DiNicolantonio, Pharm.D, and cardiologist James O’Keefe, M.D., like Saladino, have argued that vegetable oils cause atherosclerosis.
In an article published in Open Heart, DiNicolantonio and O’Keefe describe how vegetable oils may cause atherosclerosis. A key element to understanding their hypothesis is a process called oxidation. Oxidation is a chemical reaction that damages molecules like DNA and fatty acids. Importantly, LDL can fall victim to oxidation. Moreover, studies have shown that oxidized LDL more accurately predicts atherosclerosis than non-oxidized LDL.
Furthermore, it is now generally accepted that oxidized LDL, not normal LDL, triggers atherosclerosis. But what causes LDL to become oxidized? DiNicolantonio and O’Keefe point out that linoleic acid, an omega-6 fatty acid found in vegetable oils, is the most common oxidized fatty acid in LDL. When linoleic acid becomes oxidized, it alters the structure of LDL in a way that promotes the formation of plaques in the arteries.
In other words, linoleic acid makes LDL more susceptible to oxidation, leading to higher levels of oxidized LDL and atherosclerosis, according to DiNicolantonio and O’Keefe.
Vegetable Oils are the Primary Driver of Aging
Another physician, Chris Knobbe, M.D., has advocated against vegetable oils for many years. In one of his recent talks, he presented data showing the correlations between the rise in vegetable oil consumption over time and age-related conditions like heart disease, high blood pressure, cancer, type 2 diabetes, obesity, and Alzheimer’s disease. He argues that vegetable oil consumption, and not sugar and flour consumption is the primary contributor to these diseases.
Dr. Knobbe points out that vegetable oils often have a label saying “heart healthy.” However, the reason for this label is that vegetable oils have been shown to lower LDL cholesterol. He jokes, saying, arsenic also lowers LDL cholesterol. The point is that LDL cholesterol has been inappropriately represented as the main indicator of heart disease. In truth, Knobbe believes, vegetable oil consumption is the core reason for heart disease and other chronic diseases of aging.
The Mainstream View: Vegetable Oil Reduces the Risk of Heart Disease
In an episode of Nutrition Made Simple, Kevin Maki, Ph.D., a scientist who studies fat metabolism, explains the mainstream view of vegetable oil consumption and heart disease. He points out that several observational studies have shown that consuming unsaturated fats like linoleic acid in place of saturated fats, like those found in meat and dairy, reduces the risk of heart disease. It follows that the mainstream view runs completely opposite to the views of physicians like Saladino, O’Keefe, and Knobbe.
Maki goes on to describe randomized trials where replacing saturated fats with unsaturated fats reduces LDL cholesterol, which he says is an imperfect indicator of heart disease. He also mentions that there are a few randomized trials showing that replacing saturated fats with unsaturated fats leads to less incidence of cardiovascular disease events, like heart attacks, and cardiovascular-related death.
Overall, when considering both fringe and mainstream arguments, which are both based on scientific evidence, it would seem that reducing intake of both saturated fat and polyunsaturated fat from vegetable oil is optimal. This would leave a diet rich in monounsaturated fat from food like olive oil and avocados, as well as omega-3 fats from foods like fish. These type of fats are included in the Mediterranean diet, which has repeatedly been shown to be advantageous for longevity.
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