An emblem of the Mediterranean diet, extra virgin olive oil is even more valuable for health when it is organic, thanks to the polyphenols present in it in significantly higher quantities. So are olives, to be preferred organic for the same reasons.
Polyphenols and phenolic compounds, as well as carotenoids and other phytocompounds, indeed play a decisive role in the antioxidant action and other health properties of EVO (extra virgin olive oil). As well as affecting its organoleptic properties, stability and nutritional value. (1)
Attention should be paid, however, to both storage and how the oils and olives are used. Some brief tips, with a recipe for making healthy stir-fry and sauces.
Extra virgin olive oil, organic and conventional compared
A recent Catalan study had the main objective of evaluating the difference in polyphenolic substances present in EVO oils obtained from the same olive variety(Hojiblanca). Comparing those of organically and conventionally grown plants under identical environmental conditions. The results showed a significantly higher presence of polyphenols in organically produced oils. (2)
Soil and nutrient management is one of the main aspects related to these results. The practice of nitrogen fertilization (NPK) followed in conventional olive growing is contrasted with the use of elements that come from the mineralized biomass in the soil, in the organic regime. Where, in cases of critical nutritional conditions, the synthesis of secondary metabolites (including polyphenols) is promoted. (3)
Polyphenols, sensory attributes
The Catalan study – like others before it – notes in organic extra virgin oils the higher content of secoiridoids, a class of polyphenols that contribute to the sensory attributes of bitterness and spiciness, while attenuating the hint of fruitiness. (4) Such elements play to taste but also-and more importantly-to health.
Therefore, the all-around goodness of organic extra virgin oil tends to be felt. This also explains the growing success in international markets of organic produce, which motivates the conversion of olive groves. (5) All the more so by the more innovative olive growers who have well understood the usefulness of biostimulants for improving yields and plant resistance.
Polyphenols in extra virgin olive oil, antioxidant and protective action
The antioxidant action of polyphenols in EVO oil-especially the secoiridoids (oleuropein, oleacin, oleocanthal) and constituents (hydroxytyrosol and tyrosol)-
is related to, among other things, DNA protection from oxidative damage and anticarcinogenic activity (6,7).
Indeed, phenolic extracts from EVO oil have been found to be very effective in inhibiting cancer cell lines, with a dose-dependent mechanism. That is, their effectiveness increases in relation to the increase in phenolic concentration (8,9).
Antioxidants, heat treatments and storage
Heat treatments such as cooking, in promoting the release of nutrients from food, cause oxidation of phytocompounds and fatty acids in extra virgin oil. And it is therefore that its use is recommended raw or following cooking. (10)
Preservation of table olives, in turn, can be enhanced by the addition of aromatic plant extracts (e.g., rosemary, oregano, fennel) and also through pasteurization treatments.
Pasteurization however, in extending the
shelf-life
of the product, affects the antioxidant properties (as well as the nutritional and sensory properties) of the olives. (11)
Healthy stir-fry and sauces, the winning recipe
Better preservation of polyphenols and their stability to heat can be achieved by mixing extra virgin olive oil with vegetables that are themselves rich in antioxidants (e.g., onion, shallots, garlic, carrots, and celery). The addition of tomato-raw or in puree or preserves, where the concentration of lycopene is even higher-contributes further to antioxidant activity. (10)
The winning recipe-to make a sauté and/or sauce that is healthier and can reduce oxidative stress-is rooted in the ancient traditions of Cilento, where Ancel Keys studied and developed the Mediterranean diet model. It consists of the
– Mix extra virgin olive oil with water, in equal or slightly larger amounts,
– Cook the stir-fry over low heat, to wilt the vegetables gently, before adding other ingredients.
In fact, the emulsion of EVO oil with water is worth maintaining a relatively low temperature (<100 °C) during cooking, so as to preserve its antioxidant properties. In addition to preventing the ‘smoke point’ (which results in oil degradation and the formation of toxic substances) from being reached, thanks also to the low fire.
Organic and health, the extra reasons
Organic foods, as it turns out, have a higher amount of polyphenols and phytoconstituents and thus an added value for health. Choosing organic products also makes it possible to:
– Minimize inputs of pesticide residues, herbicides (e.g., glyphosate, or glyphosate) and fungicides as well as other agrochemicals. Which in fact disappear from the bodies of consumers who follow an organic diet, (11)
– increase the inputs of microorganisms that interact favorably with the microbiota and thus stimulate, among other things, the immune system. (12) An ever-useful and highly relevant function.
Dario Dongo and Andrea Adelmo Della Penna
Notes
(1) Servili et al. (2014). Biological activities of phenolic compounds of extra virgin olive oil. Antioxidants 3:1-23, https://doi.org/10.3390/antiox3010001
(2) Lòpez-Yerena et al. (2019). Effects of organic and conventional growing sysytems on the phenolic profile of extra-virgin olive oil. Molecules 24:1986, doi:10.3390/molecules24101986
(3) Hunter et al. (2011). Evaluation of the micronutrient composition of plant foods produced by organic and conventional agricultural methods. Crit. Rev. Food Sci. Nutr. 51:571-582, https://doi.org/10.1080/10408391003721701
(4) Barbieri et al. (2015). Do consumers recognize the positive sensory attributes of extra virgin olive oils related with their composition? A case study on conventional and organic products. J. Food Compos. Anal. 44:186–195, https://doi.org/10.1016/j.jfca.2015.09.001
(5) Hurtado-Barroso et al. (2016). Organic food and impact on human health. Int. J. Pharm. Tech. Res. 9:316-324, https://doi.org/10.1080/10408398.2017.1394815
(6) Fabiani et al. (2008). Oxidative DNA damage is prevented by extracts of olive oil, hydroxytyrosol, and other olive phenolic compounds in human blood mononuclear cells and HL60 cells. J. Nutr. 138:1411-1416, https://doi.org/10.1093/jn/138.8.1411
(7) Torić et al. (2020) Biological activity of phenolic compounds in extra virgin olive oils through their phenolic profile and their combination with anticancer drugs observed in human cervical carcinoma and colon adenocarcinoma cells. Antioxidants 9:453, doi:10.3390/antiox9050453
(8) Echeverria et al. (2017). Hydroxytyrosol and cytoprotection: A projection for clinical interventions. Int. J. Mol. Sci. 18:930, https://doi.org/10.3390/ijms18050930
(9) Silva et al. (2010). Oxidative stability of olive oil and its polyphenolic compounds after boiling vegetable process. LWT-Food Sci. Technol. 43:1336-1344, https://doi.org/10.1016/j.lwt.2010.05.013
(10) Ricci et al. (2018). Homemade tomato sauce in the Mediterranean diet: a rich source of antioxidants. Italian Journal of Food Science 30(1):37-49, https://doi.org/10.14674/IJFS-980
(11) Lanza et al. (2013). Effect of pasteurization and storage on quality characteristics of table olives preserved in olive oil. Int. J. Food Sci. Technol. 8:2630–2637, https://doi.org/10.1111/ijfs.12259
(11) Dario Dongo, Andrea Adelmo Della Penna. The organic diet rids the body of glyphosate in a few days. Scientific study. GIFT (Great Italian Food Trade). 25.8.20, https://www.greatitalianfoodtrade.it/salute/la-dieta-bio-libera-l-organismo-dal-glifosato-in-pochi-giorni-studio-scientifico
(12) Dario Dongo, Andrea Adelmo Della Penna. Biological foods and the immune system, scientific evidence. GIFT (Great Italian Food Trade). 11.4.20, https://www.greatitalianfoodtrade.it/salute/alimenti-biologici-e-sistema-immunitario-evidenze-scientifiche
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.
