I am frequently asked by clients,
‘What about olive oil? Shouldn’t I include it in my diet? Isn’t it heart-healthy?’
Recently many have been asking me the same questions about coconut oil, thanks to a slew of websites and popular books touting its (alleged) benefits. I will keep the science to a minimum here so you don’t all drop off to sleep, because this is an incredibly important subject.
What’s wrong with oils – any kind – is that they impair endothelial function. What’s endothelial function? It’s the ability of the thin layer of cells that line your blood vessels, known as the endothelium, to regulate the flow of blood through those vessels, and to prevent the formation of atherosclerotic plaque – a build-up of fat, cholesterol, calcium, white blood cells engorged with cholesterol (known as ‘foam cells’) and other substances found in the blood on the inside of your arteries. Endothelial function is a strong predictor of your risk of having a heart attack.
Over time, this plaque hardens and narrows your arteries, reducing the flow of oxygen-rich blood to the part of the body supplied with blood by the affected artery. This can lead to:
- Angina (chest pain on exertion);
- Intermittent claudication (pain in the calf muscles after walking for a short distance);
- Chronic kidney disease and eventually kidney failure;
- Cognitive impairment and eventually dementia;
- Erectile dysfunction; and
- Numbness, pain, poor wound healing and even dangerous infections.
Eventually, an atherosclerotic plaque may rupture, causing a clot to form. Depending on the location, you may suffer a heart attack or stroke.
A well-functioning endothelium produces substantial amounts of the gas nitric oxide, which
- Keeps your blood vessels reasonably dilated, in turn lowering your blood pressure;
- Decreases the ‘stickiness’ of platelets, preventing them from forming clots;
- Stops white blood cells from adhering to the blood vessel walls, which is one of the first steps in the formation of atherosclerotic plaque;
- Destroys foam cells – white blood cells which have ingested so much cholesterol that they become non-functional, and become part of the plaque;
- Prevents smooth muscle cells from the artery wall from migrating into the plaque;
- ‘Smoothes’ the flow of blood, minimising the risk of microscopic injuries to the blood vessels. These injuries are ‘patched up’ with cholesterol, like you would patch up a damaged plasterboard wall with Spakfilla. If the injuries are infrequent, the cholesterol ‘patch’ is soon reabsorbed and the artery wall is repaired with normal, healthy endothelial cells. If there are repeated injuries, the cholesterol patches aren’t reabsorbed, but instead start to form an atherosclerotic plaque.
When you ingest extracted oils and fats – especially those with a higher saturated fat content – you impair the function of your endothelial cells for several hours (the duration of effect varies with the type of oil) and during this time period, the growth of atherosclerotic plaques accelerates dramatically.
On the other hand, nuts do not impair endothelial function in spite of their high fat content, because they contain arginine, which endothelial cells use to make nitric oxide, the gas whose functions I described above.
The benefits of the so-called Mediterranean diet are due to the high consumption of antioxidant-rich fruits and vegetables, and are impaired by the addition of olive oil.
The bottom line: extracting an oil from the nutritional matrix that it is packaged in by nature is asking for trouble. If you want to minimise your risk of cardiovascular disease, enjoy plant foods that are naturally high in fats, such as avocado, nuts and seeds, in moderation, but leave the extracted oils out of your diet.
2 replies to "Oils ain’t oils"
This is really interesting, thanks!
Yeah, a lot of vegans really cheat themselves out of the benefits of the vegan diet by adding oil to their food or using vegan convenience foods that contain oil.