Learning about the magic inside olive oil
As innovative and exciting as so many reports in nutrition can be, often there’s a long history behind it. For example, the relationship between the Mediterranean diet and heart disease goes back to the 1950s when it was first described by Ancel Keys, an early pioneer in the field nutrition epidemiology. Dr. Keys made an observation that residents of Naples, Italy had a relatively low incidence of coronary heart disease, which he suggested was due to their unique diet. Generally speaking, this diet was low in saturated fats and high in green leafy vegetables, tomatoes, and olive oil.
As the research has continued to develop over the years, some of the individual foods were found to have unique health benefits. Olive oil in particular is believed to impart a health benefit, with previous work showing that it can reduce negative markers of heart health. Recent research is confirming these findings. Violi and colleagues conducted a randomized crossover-controlled trial in which subjects were given a Mediterranean diet with either 10g extra virgin olive oil (EVOO) or 10g corn oil, and a laundry list of metabolic parameters were measured 2 hours after the meal. EVOO had a significantly lower rise in cardiovascular risk markers such as LDL (bad) cholesterol and oxidized LDL, which is consistent with much previous work. What’s really interesting, however, is that for the first time, they showed that the rise in blood glucose following the meal was significantly lower and that the concentration of insulin in the blood was significantly higher in those receiving EVOO, suggesting a potential benefit for EVOO in glycemic control. Just another piece of evidence demonstrating the valuable role that EVOO plays in providing the health benefits of the Mediterranean diet.
To me, the most interesting part about nutrition isn’t just showing that certain foods provide benefits – but answering the question of what’s inside the food that is providing a benefit? For years people assumed that the monounsaturated fats in olive oil were responsible for the observed effects, but more recent research suggests some of the polyphenols within EVOO, such as hydroxytyrosol, may actually play a large role. So here we are, still trying to prove that Dr. Keys was right, and now we’re finding out that he stumbled onto something potentially much bigger than he realized. This latest study by Violi and team makes me wonder, not just what new benefits of EVOO will be found next, but what components of the EVOO are doing the work?
Violi F, Loffredo L, Pignatelli P, et al. Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects. Nutr Diabet 2015; 5(e172): doi:10.1038/nutd.2015.23
Keys A. Mediterranean diet and public health: personal reflections. Am J Clin Nutr 1995; 61(suppl): 1321S-1323S.
Martin-Lelaez S, Covas MI, Fito M, et al. Health effects of olive oil polyphenols: Recent advances and possibilities for the use of health claims. Mol Nutr Food Res 2013; 57(5): 760-771.