by Albert Cilia-Vincenti

This series explores Dean Ornish’s 30-year research experience into healing & disease reversal by dietary and lifestyle changes. He is a California University Professor of Medicine in San Francisco. This instalment continues looking into whether it is possible to consume too many ‛good’ fats.

Olive oil has very good public relations.  It is promoted as the healthiest fat and as the basis of a healthy Mediterranean diet. But is this excellent reputation scientifically justified? Olive oil contains 14% saturated (‘bad’) fat, so when you consume a lot of it, you’re loading yourself with a significant amount of saturated fat as well as a lot of calories. One tablespoon of any oil has 14 grams of fat (126 calories), so when you’re pouring any oil on your food, you’re showering it with a lot of liquid calories. For most people, reducing total fat consumption is a good idea. You only need about 5% of calories from fat (about 10 grams per day) to provide the essential fatty acids.  The average American gets almost 40% of calories from fat.

What about studies showing that olive oil lowers blood cholesterol? That only applies when you substitute olive oil for butter or oils (like palm oil) that are higher in saturated fat. In other words, it’s not that the olive oil lowers your cholesterol, it just doesn’t raise it as much. A study in the Journal of the American College of Cardiology found that olive oil significantly reduces blood flow to various parts of your body, whereas canola oil (Canola oil is the American name, the European name is Rapeseed oil) and salmon do not. Similar results were found in another study in which olive oil impaired blood flow, whereas walnuts (contain omega-3 fatty acids) improved blood flow.

The landmark Lyon Study found that a Mediterranean diet significantly reduced the incidence of heart attacks and premature death. Many attribute these beneficial outcomes to an increased consumption of olive oil (good for the olive oil industry!). However, in this study, it was found that increased consumption of rapeseed oil, not olive oil, accounted for these improvements. Also, people in this study consumed more whole-grain bread, more root vegetables and green vegetables, more fish, less red meat (beef, lamb and pork were replaced by poultry), and more fruit every day. Butter and cream were replaced by margarine made from rapeseed oil. Why? Because rapeseed oil has significant amounts of omega-3 fatty acids, whereas olive oil does not.

The omega-3 fatty acids are the ‘good’ fats, with extraordinary health benefits. The omega-6 fatty acids are also essential to your diet, but the problem is that many population groups consume too much of them and not enough of the omega-3 fatty acids. While the omega-3 fatty acids reduce inflammation, the omega-6 fatty acids increase it if you consume too much of them. And inflammation increases the risk of coronary heart disease and other chronic diseases.

The ideal ratio of omega-6 to omega-3 fatty acids should be about 1:1, or no more than 2:1 but, unfortunately, the ratio in the average Western type diet is between 10:1 and 30:1. The best way to improve this ratio is to consume more omega-3 fatty acids and fewer omega-6 fatty acids.  Much of the excessive omega-6 fatty acids come from the wrong kinds of oils. Although olive oil has a ‘good for you’ reputation, it has 13 times the amount of harmful omega-6 fatty acids as beneficial omega-3 fatty acids. Corn oil is even worse, with a 46:1 ratio of omega-6s to omega-3s.

Rapeseed oil has a much more balanced ratio of 2:1 omega-6s to omega-3s.  Flaxseed oil is rich in omega-3 fatty acids with a ratio of 1:3 omega-6s to omega-3s. So, to improve your ratio, one should consume more rapeseed oil or fish oil, and less olive oil. It doesn’t mean you shouldn’t have olive oil – it has the best taste of all oils, is healthier than many others, but it’s not nearly as healthy as fish oil, rapeseed oil, or flaxseed oil.  This nutritional medical science information has important connotations for the Maltese food and the general health scene. Rapeseed oil should be advertised as medically proven to be the healthiest (and considerably cheaper than extra-virgin olive oil). However ironically it is very difficult to find rapeseed oil on the shelves of local supermarkets. The Health Promotion department of our Health Ministry should also be looking into this important food and health connection.

Bibliography

Vogel RA, Corretti MC, Plotnick GD.  The postprandial effect of components of the Mediterranean diet on endothelial function.  J Am Coll Cardiol 2000; 36(5):1455-60.

Cortes B, Nunez I, Cofan M et al. Acute effects of high-fat meals enriched with walnuts or olive oil on postprandial endothelial function.  J Am Coll Cardiol 2006, 48(8):1666-71.

Trichopoulou A, Costacou T, Bamia C, Trichopoulou D.  Adherence to a Mediterranean diet and survival in a Greek population.  N Engl J Med 2003, 348(26):2599-608.