We’ve known for a long time that people who consume more olive oil – as opposed to other sources of dietary fat – are protected in certain ways from heart disease. And some recent research has started to uncover the reasons why.
One compelling and unappreciated way that olive oil prevents cardiovascular disease has to do with its impact on blood pressure.
High blood pressure is often characterized as a “silent killer” because it can cause permanent damage throughout the body without any obvious symptoms. Tragically, by the time the problem becomes obvious, it is sometimes too late to reverse the damage.
About 70 million adults in the US have hypertension – that’s 1 in every 3! And only around 52% of people with hypertension have it under control. It is also likely that many are walking around with the condition who don’t even know they have it.
Remarkably, it seems that just consuming olive oil lowers blood pressure, and the effect can be impressive, as you’ll soon see.
To begin, let’s go over what blood pressure actually is, and why it’s worthy of your attention – even if you feel perfectly fine.
Blood Pressure and Why it Matters
Blood pressure refers to the force pushing outward on the walls of your arteries. The more forcefully that the blood pumps, the more that the arteries are required to stretch to allow the blood to easily flow. Over time, if that force is too great, the tissue that makes up the arterial walls can become stressed and damaged.
This insult to the vasculature can lead a wide range of problems. For example, it makes arteries more vulnerable to infiltration and accumulation of cholesterol. It also can destabilize any existing arterial plaques – which increases the risk of them rupturing and inducing heart attacks.
So, high blood pressure is a really big deal, and it’s probably better to nip it in the bud early.
Don’t get me wrong – pharmaceutical interventions definitely have their place. But unless you have very high blood pressure, anti-hypertensive medications are not necessarily an ideal solution.
Users sometimes report feeling persistently drowsy or light-headed, and some classes of these drugs have been associated with adverse effects on glucose metabolism. Furthermore, a Cochrane review found that the benefits of these medications may not outweigh the risks and side effects associated with them for patients who exhibit mild hypertension. So, if you can avoid going on these drugs, so much the better.
Fortunately, there is evidence that certain lifestyle choices – and specifically certain foods – may protect us from the perils of rising blood pressure.
The Power of Food & Dietary Patterns
Around the 1950s, nutrition researchers recognized that people living in Southern Europe, near the Mediterranean sea, historically experienced very few heart attacks relative to other populations around the world. This has been attributed to a constellation of different lifestyle factors that are common to the region.
But that lifestyle pattern comprises a vast range of different behaviors and foods. How can we determine which variables really matter?
To solve this very complicated puzzle, large studies like the European Prospective Investigation into Cancer and Nutrition (EPIC) were started to investigate the relationship between diet and chronic disease. An analysis of participants in the Greek arm of this study, comprised of more than 20,000 people, found that greater adherence to a Mediterranean diet was inversely associated with arterial blood pressure. This would certainly contribute to better cardiovascular health.
When the researchers looked more closely at the specific dietary components that appeared to be responsible for this link, they found only a couple of items were truly relevant.
One was – of course – olive oil, which is a dietary staple of the region. Higher intake was linked to lower systolic and diastolic blood pressure.
Several controlled trials have also supported this correlation. One such study in Italy randomly assigned 23 hypertensive patients to the addition of a few spoonfuls of either 1) olive oil or 2) PUFA-rich sunflower oil to their daily diet for a period of six months. Their blood pressure and other values were measured and compared at various intervals.
During the study, the participants in the olive oil group experienced significant reductions in blood pressure, which enabled them to dial way back on their daily drug regimen. Even better, 8 of them were able to quit drug therapy entirely!
Meanwhile, those who were in the sunflower oil group did not enjoy such declines in blood pressure, and none were able to discontinue their pharmaceutical treatment.
So it looks like there is something special about olive oil that helps protect our ability to maintain healthy blood pressure, and we are starting to figure out why.
How Olive Oil Lowers Blood Pressure
Nitro fatty acids
We usually don’t consume olive oil by itself – unless, of course, you’re this guy.
Historically, it has been used as a dressing for leafy vegetables, which are rich in natural nitrates. This obviously makes otherwise boring green salads tasty. But that fusion of ingredients might also produce some interesting synergistic effects in the body.
We have recently discovered that the combination of nitrogen compounds – from vegetables – and unsaturated fatty acids from oil promotes the formation of a compound called nitro fatty acid.
Nitro fatty acids, which have been identified in blood plasma and urine, have a wide range of effects on the cardiovascular system. Specifically, they relax the lining of blood vessels and reduce arterial inflammation – which would be expected to lower blood pressure.
A study of genetically engineered mice revealed that administration of these nitro fatty acids inhibits an enzyme called epoxide hydrolase. Through a cascade of chemical reactions, this results in dilation of the blood vessels. After a five-day intervention, the mice in the experiment exhibited higher nitro fatty acid levels and lower blood pressure. It appears likely that this mechanism also works similarly in humans.
This would certainly explain the association of the Mediterranean diet with reduced blood pressure, since olive oil and veggies are a pretty classic pairing. Indeed, the EPIC study that I cited earlier found that both olive oil and vegetables were linked to lower blood pressure. As is often the case in nutrition, context matters!
Vanillic acid – A phenol in EVOO (Servili M et al. Antioxidants, 2014.)
We usually think of olive oil as a source of monounsaturated fatty acids, and a lot of research has fixated on that primary component. But olive oil also contains a wide range of phenols – secondary metabolites that occur naturally in olives.
These compounds serve a wide range of protective and signaling functions in plants, but they have also been shown to be highly bioavailable when they are consumed (See Table 1 below for a list of phenols in EVOO). So it’s not too surprising that they also affect our bodies in distinct ways when we eat them. And it appears that these compounds are potentially relevant to blood pressure control, though the precise molecular mechanisms at play are still being elucidated.
The authors of the Italian study of hypertensive patients that we discussed earlier observed that phenolic content was a major distinguishing feature of extra virgin olive oil. Most other sources of fat in the diet – such as the sunflower oil that was also tested – are devoid of polyphenols. But there are approximately 5 mg of phenols for every 10 g of extra virgin olive oil – meaning that the subjects in the EVOO group were receiving between 15-20 mg of olive phenols per day.
These olive polyphenols have been demonstrated to have potent antioxidative activity in cell culture studies. There is some evidence that they may help the body to generate LDL cholesterol that is resistant to oxidative modification.
This is important because oxidized LDL appear to elevate blood pressure by several different mechanisms. Perhaps most importantly, oxidized LDL particles seem to suppress the production of nitric oxide in the lining of the blood vessels.
A recent study using human subjects further supports this role of olive phenols. A double-blind randomized trial of 24 young women with elevated blood pressure compared two different dietary regimens: one using olive oil that was rich in polyphenols, and one using olive oil that was stripped of phenols.
When compared to baseline values, only the group consuming the polyphenol-rich oil experienced drops in their blood pressure. Notably, the polyphenols were also associated with an increase in plasma nitrites / nitrates and a decline in oxidized LDL.
So, to sum up, it looks like antioxidants and polyphenols from olives can reinforce the effect of dietary nitrate that I described earlier by increasing the availability of nitric oxide in the blood vessels. And studies suggest that the more phenols you get, the bigger the impact on your endothelial function.
Olive oil is a simple product, however, what you see in grocery stores will vary considerably in quality.
The major difference across products does not lie in the types of olives, but rather in how they are made. Some reports have suggested that the majority of “olive oil” that is commercially available may actually be diluted in unknown proportions with cheaper refined oils, like soybean or canola.
These aren’t necessarily bad, but using them means that you’re missing out on a lot of the awesome olive phenols and monounsaturated fatty acids that have been associated with heart health in the aforementioned research.
As we established above, the benefits of olive oil are associated at least in part with the natural olive phenols. To maximize your phenol intake, you want to go with extra virgin olive oil, which is mechanically extracted from olives via cold pressure. This retains a lot of the bioactive components of the olive fruit. So-called “light” olive oil, in contrast, is subjected to a refining process that strips away those phenols.
And research shows that it matters. A trial with 40 older men compared refined olive oil with few phenols to extra virgin olive oil with 161 mg / kg of phenols and found that the group consuming EVOO experienced a significant decrease in systolic blood pressure compared to refined oil.
Additionally, these phenols are kind of fragile. They deteriorate when exposed to high heat, light, and over the passage of time. To preserve the phenolic content, extra virgin olive oil should therefore ideally be stored in a cold dark place, or in a dark container.
Finally, to optimize the effects on blood pressure, evidence suggests that olive oil has synergistic effects when consumed together with green veggies. The oil also enhances the absorption of carotenoids and other fat-soluble vitamins in the salad, as an added bonus. A salad, or just green veggies dressed with a modest amount of extra virgin olive oil, is probably a good way to take advantage of this.
Enhanced nitric oxide levels, stimulated by plant-derived polyphenols, can help you to maintain healthy blood pressure throughout your life without drugs – and maybe even help you to get off them.
Phenols in Olive Oil
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