Olive oil, the best source of fat for cooking

Olive oil, the best source of fat for cooking

Cardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.30 March 2020

OVERVIEW

  • Over a 24-year period, people who regularly consumed olive oil had an 18% lower risk of coronary heart disease compared to those who never or very rarely consumed it.
  • Replacing only a daily half-serving (5 g) of margarine, butter or mayonnaise with olive oil is associated with a decrease of about 7% in the risk of coronary heart disease.
  • These results confirm that olive oil, especially virgin or extra-virgin olive oil, represents the best source of fat for “healthy” cooking.

It has been known for several years that people who adopt a Mediterranean type diet are less at risk of being affected by cardiovascular diseases. One of the main features of the Mediterranean diet is the abundant use of olive oil, and several studies show that this oil contributes greatly to the protective effect of the Mediterranean diet on cardiovascular health. On the one hand, olive oil has a very high content (70%) of monounsaturated fatty acids, which lower blood LDL-cholesterol levels and improve blood glucose control. On the other hand, virgin and extra virgin olive oils, obtained from the mechanical cold pressing of fruits, also contain significant amounts of several antioxidant and anti-inflammatory compounds such as tocopherols (vitamin E), certain phenolic acids, and several types of polyphenols. In addition to making olive oil much more stable than refined vegetable oils (and reducing the production of oxidized compounds when cooked at high temperature), these compounds certainly contribute to the preventive effects of olive oil, because it has been shown that the reduction in the risk of cardiovascular disease is 4 times greater (14% vs. 3% risk reduction) among consumers of virgin olive oil than among those who use refined olive oil, devoid of these phenolic compounds.

The benefits of preferential use of olive oil have just been confirmed by a study recently published in the Journal of the American College of Cardiology. By examining the eating habits of 92,978 Americans over a 24-year period, a team of researchers at Harvard University observed that those who reported higher consumption of olive oil (> 1/2 tablespoon/day (i.e. >7 g/day) had a risk of coronary heart disease reduced by 18% compared to those who never or very rarely consumed it. The superiority of olive oil over other sources of fat is also suggested by the observation that replacing only half a serving (5 g) of margarine, butter or mayonnaise with olive oil was associated with a decrease of about 7% in the risk of coronary artery disease. There is no doubt: to cook “healthy”, the best source of fat is undoubtedly olive oil.

The cardiovascular benefits observed in this study may seem quite modest, but it should be mentioned that the intake of olive oil in the population studied (inhabitants of the United States) was relatively low, well below what is observed in studies carried out in Europe. For example, the category of the “largest consumers” of olive oil in the U.S. study included anyone who consumed a minimum of 1/2 tablespoon per day, a quantity much lower than that of the participants in the Spanish study PREDIMED (4 tablespoons per day). This higher olive oil intake in the PREDIMED study was associated with a 30% decrease in the risk of cardiovascular events, about double the protective effect seen in the study conducted in the United States. It is therefore likely that the reduction in the risk of coronary heart disease observed in the U.S. study represents minimal protection, which could be even more important by increasing the daily intake of olive oil. In general, experts recommend the consumption of about two tablespoons of olive oil per day to reduce the risk of cardiovascular disease, and to choose virgin or extra-virgin oils because of their polyphenol content.

A new metabolite derived from the microbiota linked to cardiovascular disease

A new metabolite derived from the microbiota linked to cardiovascular disease

Cardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.29 March 2020

OVERVIEW

  • Metabolomic screening has identified a new metabolite associated with cardiovascular disease in the blood of people with type 2 diabetes.
  • This metabolite, phenylacetylglutamine (PAGln), is produced by the intestinal microbiota and the liver, from the amino acid phenylalanine from dietary proteins.
  • PAGln binds to adrenergic receptors expressed on the surface of blood platelets, which results in making them hyper-responsive.
  • A beta blocker drug widely used in clinical practice (Carvedilol) blocks the prothrombotic effect of PAGln.

A research group from the Cleveland Clinic in the United States recently identified a new metabolite of the microbiota that is clinically and mechanistically linked to cardiovascular disease (CVD). This discovery was made possible by the use of a metabolomic approach (i.e. the study of metabolites in a given organism or tissue), a powerful and unbiased method that identified, among other things, trimethylamine oxide (TMAO) as a metabolite promoting atherosclerosis and branched-chain amino acids (BCAAs) as markers of obesity.

The new metabolomic screening has identified several compounds associated with one or more of these criteria in the blood of people with type 2 diabetes: 1) association with major adverse cardiovascular events (MACE: myocardial infarction, stroke or death) in the past 3 years; 2) heightened levels of type 2 diabetes; 3) poor correlation with indices of glycemic control. Of these compounds, five were already known: two which are derived from the intestinal microbiota (TMAO and trimethyllysine) and three others that are diacylglycerophospholipids. Among the unknown compounds, the one that was most strongly associated with MACE was identified by mass spectrometry as phenylacetylglutamine (PAGln).

In summary, here is how PAGln is generated (see the left side of Figure 1):

  • The amino acid phenylalanine from dietary proteins (animal and plant origin) is mostly absorbed in the small intestine, but a portion that is not absorbed ends up in the large intestine.
  • In the large intestine, phenylalanine is first transformed into phenylpyruvic acid by the intestinal microbiota, then into phenylacetic acid by certain bacteria, particularly those expressing the porA
  • Phenylacetic acid is absorbed and transported to the liver via the portal vein where it is rapidly metabolized into phenylacetylglutamine or PAGln.

Figure 1. Schematic summary of the involvement of PAGln in the increase in platelet aggregation, athero-thrombosis and major adverse cardiovascular events. From Nemet et al., 2020.

Researchers have shown that PAGln increases the effects associated with platelet activation and the potential for thrombosis in whole blood, on isolated platelets and in animal models of arterial damage.

PAGln binds to cell sites in a saturable manner, suggesting specific binding to membrane receptors. The researchers then demonstrated that PAGln binds to G-protein coupled adrenergic receptors, expressed on the surface of the platelet cell membrane. The stimulation of these receptors by PAGln causes the hyperstimulation of the platelets, which then become hyper-responsive and accelerate the platelet aggregation and the thrombosis process.

Finally, in a mouse thrombus model, it has been shown that a beta blocker drug widely used in clinical practice (Carvedilol) blocks the prothrombotic effect of PAGln. This result is particularly interesting because it suggests that the beneficial effects of beta blockers may be partly caused by reversing the effects of high PAGln levels. The identification of PAGln could lead to the development of new targeted and personalized strategies for the treatment of cardiovascular diseases.