Is Extra Virgin Olive Oil the Critical Ingredient Driving the Health Benefits of a Mediterranean Diet? A Narrative Review

Long-term stability of extra virgin olive oil: effects of filtration and refrigeration storage on the Kolovi variety

BACKGROUND

The composition of extra virgin olive oil (EVOO) defines its sensory, nutritional, and human health benefits, and distinguishes it as a key component of the Mediterranean diet. Nevertheless, EVOO constituents are susceptible to degradation during processing and storage, which reduces the olive oil's quality and limits its shelf life. The present study investigated the effect of molecular filtration before storage and the effect of cool storage at 4 °C on the stability of 'Kolovi' EVOO, a variety originating from the Greek island of Lesvos, over a 24 month period.

RESULTS

Storing EVOO at 4 °C positively affected free acidity, peroxide value, K268, fruity qualities, and concentrations of hydroxytyrosol, tyrosol, ligstroside aglycone, lutein, and squalene, in comparison with the control sample stored at room temperature, particularly after 1 year. Molecular filtration significantly affected the ratio of unsaturated fatty acids to saturated fatty acids (UFAs/SFAs). Optimal preservation of parameters such as acidity value and lutein content was achieved by combining molecular filtration with refrigeration.

CONCLUSIONS

The present study recommends storing EVOO in the refrigerator for up to 18 months. Based on the regulatory limits of the quality characteristics of acidity, peroxide value, K232 value and fruity sensory attributes, the shelf-life of the protected geographical indication (PGI) 'Kolovi' EVOO can reach 2 years under cool storage (4 °C) and with molecular filtration before storage. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Review article: Evidence-based dietary management of inflammatory bowel disease

BACKGROUND

Dietary management of patients with inflammatory bowel disease (IBD) involves more than defining a therapeutic diet. The profusion of 'expert advice' is not necessarily built on evidence.

AIMS

To provide evidence-based guidance on all clinically relevant aspects of nutritional and dietary management of patients with IBD.

METHODS

A comprehensive review of the published literature was made.

RESULTS

Four pillars of management should be considered in all patients. First, nutritional status should be optimised, since myopenia and visceral obesity are associated with poorer outcomes, which can be improved with attention to their correction. Accurate point-of-care measurement of body composition is advocated to identify problems, guide interventions and monitor outcomes. Second, exclusive enteral nutrition and the Crohn's Disease Exclusion Diet with partial enteral nutrition in reducing intestinal inflammation in patients with Crohn's disease have sufficient evidence to be advocated. Multiple other dietary approaches, while promising, have insufficient evidence to be recommended. Third, dietary approaches are important in symptomatic control in many non-inflammatory scenarios. Finally, guidance on following a healthy diet is fundamental to the general health of patients. Multiple approaches are advocated, but the optimal strategy is unclear. The precarious nutritional status of patients with IBD together with the risks of nutritional inadequacy and maladaptive eating behaviours associated with restrictive diets dictate involvement of expert dietitians in assessment and personalised delivery of dietary interventions.

CONCLUSIONS

Four pillars of nutritional management require specific assessment and interventional strategies that should be chosen by evidence. Optimal delivery requires the skills of a specialised dietitian.

Age-Related Effects of Olive Oil Polyphenol Ingestion on Oxidation of Low-Density Lipoprotein in Healthy Japanese Men: A Randomized Controlled Double-Blind Crossover Trial

BACKGROUND

The function of olive oil polyphenols in suppressing the oxidation of low-density lipoprotein (LDL) is well-known in Europeans. However, it remains unclear whether olive oil polyphenols exert antioxidant effects in Japanese people.

OBJECTIVES

The objective of this study was to determine whether the ingestion of olive oil polyphenols suppresses LDL oxidation in the Japanese population and whether this effect depends on age.

METHODS

This randomized controlled double-blind crossover trial with a 2-week washout enrolled 80 healthy Japanese men aged 35-64 years. Participants ingested either 14 g of extra virgin olive oil containing 5.0 mg of olive oil polyphenols (test food) or 14 g of refined olive oil containing 0.3 mg of olive oil polyphenols (control food) for 3 weeks. The primary outcome was oxidized LDL (malondialdehyde-modified LDL; MDA-LDL). Subgroup analyses based on age (35-50 and 51-64 years) were also performed.

RESULTS

In all of the participants (35-64 years), there were no significant differences in MDA-LDL between the control and test groups. However, in the 35-50 years subgroup, ingestion of olive oil polyphenols led to a significantly larger reduction in MDA-LDL as compared with the control group (p < 0.025).

CONCLUSIONS

The significantly lower dietary total polyphenol intake of the 35-50 years subgroup compared to the 51-64 years subgroup suggests that the suppressive function of olive oil polyphenol intake on LDL oxidation in Japanese men is influenced by dietary habits and is more clearly demonstrated in the younger age population with a relatively low total polyphenol intake.

Effect of a Phytochemical-Rich Olive-Derived Extract on Anthropometric, Hematological, and Metabolic Parameters

BACKGROUND

Extra virgin olive oil is a fundamental component of the Mediterranean diet. It contains several molecules that sustain human well-being by modulating cellular metabolism and exerting antioxidant, anti-inflammatory, and anti-ageing effects to protect normal tissues, and it can exert anti-angiogenic and pro-apoptotic effects on cancer cells. Metabolites found in different parts of the olive tree, including leaves, also possess properties that might help in cancer prevention and promote wellness in aging. Olive mill wastewater (OMWW), a liquid residue produced during olive oil extraction, represents an environmental issue. However, it is rich in phytochemicals with potential beneficial properties. Dietary supplements based on OMWW can be produced for nutritional supplementation with advantages to the ecology.

PURPOSE

This work aims to measure hematochemical, anthropometric, and metabolomic parameters in volunteers taking an OMWW dietary supplement, Oliphenolia® (OMWW-OL).

METHODS

The supplementation of OMWW-OL 25 mL twice daily for 30 days was tested on a pilot cohort of volunteers with characteristics close to metabolic syndrome. Hematochemical, anthropometric, serum biomarkers and serum metabolomic parameters were analyzed before the intervention, at 30 days, and 30 days after stopping consumption.

RESULTS

A total of 29 volunteers were enrolled, and 23 completed the study. The participants' parameters at baseline were measured, and then twice daily at 30 days of treatment and 30 days after assumption discontinuation. Although treatment was with an olive derivative, their weight did not increase. Their body mass index, instead of augmenting, slightly decreased, particularly in the women. Also, hydration increased, especially in the women, while blood pressure, glycemia, and insulin decreased. Cholesterol, high-density lipoproteins, and triglycerides were stable, and LDL levels decreased, while vitamin D levels, alongside calcium, perceptibly increased. Albumin also increased. All the values were in support of an equilibrium, with no damaging effects. By mass spectrometry analysis, we also found favorable changes in the vitamin D/histamine and homocysteine/methionine ratios, an increase in a new metabolite of unknown formula, and the vitamin D/unknown metabolite ratio.

CONCLUSIONS

Supplementation of OMWW-OL has no detrimental effects and might imply the beneficial modulation of several biological parameters. Although this is a small pilot study, with limited potency, it preliminarily suggests that the OMWW extract use could be potentially valuable for people at risk of metabolic syndrome. Some of these parameters could also be relevant in supporting healthy ageing and in cancer prevention.

Editorial Special Issue: 2022 consortium for trans-pyrenean investigations on obesity and diabetes

This Special Issue of the Journal of Physiology and Biochemistry contains 7 contributions that have been elaborated in the context of the mini-network "Consortium of Trans-Pyrenean Investigations on Obesity and Diabetes" (CTPIOD), which is on its 19th year of existence. This scientific community, mostly involving research groups from France and Spain, but also open to participants coming from other countries, is focused on investigating the molecular and physiological mechanisms implicated in the development of obesity, diabetes, non-alcoholic fatty liver disease, and other noncommunicable diseases, as well as new preventive and therapeutic strategies. This special issue covers novel nutritional, molecular, and physiological aspects related to these metabolic diseases. Some of these papers emerge from the lectures of the 19th Conference on Trans-Pyrenean Investigations in Obesity and Diabetes, organized by the University of Zaragoza and celebrated in the town of Jaca (Spain) on 17-18th October 2022, and have been prepared in collaboration between different groups of the network. Many lectures were focused on the preventive role of specific fatty acids, dietary phenolic compounds and other phytochemicals against metabolic disorders. Consequently, we encouraged submission of original research in this field for this special issue.

Extra Virgin Olive Oil and Metabolic Diseases

Over the last few decades, metabolic syndrome coexisting with cardiovascular disease has evolved into a pandemic, making the need for more food-oriented therapeutic approaches and a redefinition of lifestyle imperative, with the Mediterranean diet being the linchpin of this effort. Extra virgin olive oil (EVOO), the key pillar of the Mediterranean diet and one of the most notorious edible oils worldwide, owes its popularity not only to its characteristic aromas and taste but mainly to a series of beneficial health attributes including anti-diabetic, hypolipidemic, anti-hypertensive and anti-obesity actions. In this narrative review, we aimed to illustrate and enlighten EVOO's metabolic properties through a pathogenetic approach, investigating its potential role in metabolic and cardiovascular health.

The Role of Parental Adherence to the Mediterranean Diet and Family Time Together in Children's Weight Status: The BeE-School Project

The family context has been associated with children's weight status. This study aims to investigate the association of parents' adherence to the Mediterranean diet and family time with the weight status of children. The research is part of BeE-school, a cluster-randomized trial implemented in primary schools located in socially vulnerable contexts. A total of 735 children (380 boys and 355 girls) aged 6 to 10 participated in the study. Anthropometrics were assessed during school time, and weight status was categorized, while parents self-reported sociodemographic variables, adherence to the Mediterranean diet (MEDAS questionnaire), and family time. Children from families with higher education levels whose parents have a high adherence to the Mediterranean diet have lower odds of overweight/obesity (odds ratio (OR) 0.301, 95% CI 0.143-0.634, p = 0.002). Also, children from families with lower education levels who have more time together with their family have lower odds of overweight/obesity (OR 0.731, 95% CI 0.573-0.934, p = 0.012). The family environment, mainly family time together and adherence to the Mediterranean diet, exerts a significant influence on children's weight status. Professionals working in children's health should consider the family when fostering health-promoting behaviors.

An Appraisal of the Oleocanthal-Rich Extra Virgin Olive Oil (EVOO) and Its Potential Anticancer and Neuroprotective Properties

Dietary consumption of olive oil represents a key pillar of the Mediterranean diet, which has been shown to exert beneficial effects on human health, such as the prevention of chronic non-communicable diseases like cancers and neurodegenerative diseases, among others. These health benefits are partly mediated by the high-quality extra virgin olive oil (EVOO), which is produced mostly in Mediterranean countries and is directly made from olives, the fruit of the olive tree (Olea europaea L.). Preclinical evidence supports the existence of antioxidant and anti-inflammatory properties exerted by the polyphenol oleocanthal, which belongs to the EVOO minor polar compound subclass of secoiridoids (like oleuropein). This narrative review aims to describe the antioxidant and anti-inflammatory properties of oleocanthal, as well as the potential anticancer and neuroprotective actions of this polyphenol. Based on recent evidence, we also discuss the reasons underlying the need to include the concentrations of oleocanthal and other polyphenols in the EVOO's nutrition facts label. Finally, we report our personal experience in the production of a certified organic EVOO with a "Protected Designation of Origin" (PDO), which was obtained from olives of three different cultivars (Rotondella, Frantoio, and Leccino) harvested in geographical areas located a short distance from one another (villages' names: Gorga and Camella) within the Southern Italy "Cilento, Vallo di Diano and Alburni National Park" of the Campania Region (Province of Salerno, Italy).

Olive Oil Polyphenols Improve HDL Cholesterol and Promote Maintenance of Lipid Metabolism: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

In 2011, the European Food Safety Authority (EFSA) accorded a health claim to olive oil polyphenols in that they protected LDL particles from oxidative damage. However, limited scientific evidence has so far failed to confer any claim of function on the maintenance of normal lipid metabolism. We performed a systematic review and meta-analysis of human RCTs, evaluating the effect of olive oil polyphenol administration on lipid profiles. Previous literature was acquired from six electronic databases until June 2023. A total of 75 articles were retrieved and screened for inclusion criteria, which resulted in the selection of 10 RCTs that evaluated the effect of daily exposure to olive oil polyphenols on serum lipids in adults. Meta-analyses were built by tertiles of outcomes, as follows: low (0-68 mg/kg), medium (68-320 mg/kg), and high (320-600 mg/kg) polyphenols for HDL and LDL cholesterol (HDL-C and LDL-C, respectively), and low (0-59.3 mg/kg), medium (59.3-268 mg/kg), and high (268-600 mg/kg) polyphenols for total cholesterol (TC). The study protocol was registered on PROSPERO (registration code: CRD42023403383). The study design was predominantly cross-over (n = 8 of 10) but also included parallel (n = 2 of 10). The study population was predominantly European and healthy. Daily consumption of olive oil polyphenols did not affect TC levels and only slightly significantly reduced LDL-C, with WMD statistically significant only for high daily consumption of olive oil polyphenols (WMD -4.28, 95%CI -5.78 to -2.77). Instead, our data found a statistically significant HDL-C enhancing effect (WMD pooled effect model: 1.13, 95%CI 0.45; 1.80, heterogeneity 38%, p = 0.04) with WMD by daily exposure level showing a statistically significant improvement effect for low (WMD 0.66, 95%CI 0.10-1.23), medium (WMD 1.36, 95%CI 0.76-1.95), and high (WMD 1.13, 95%CI 0.45-1.80) olive oil polyphenol consumptions. Olive oil polyphenols contribute toward maintaining lipid metabolism. Thus, food labeling regulations should stress this health feature of olive oil, whereby a declaration of the olive oil polyphenol content should be added to products on the market. Consumers need to be aware of the quality and possible health effects of any products they consume, and enforcement of nutrition labels offers the best way of providing this information.

The Protective Role of Oleuropein Aglycone against Pesticide-Induced Toxicity in a Human Keratinocytes Cell Model

The extensive use of agricultural pesticides to improve crop quality and yield significantly increased the risk to the public of exposure to small but repeated doses of pesticides over time through various routes, including skin, by increasing the risk of disease outbreaks. Although much work was conducted to reduce the use of pesticides in agriculture, little attention was paid to prevention, which could reduce the toxicity of pesticide exposure by reducing its impact on human health. Extra virgin olive oil (EVOO), a major component of the Mediterranean diet, exerts numerous health-promoting properties, many of which are attributed to oleuropein aglycone (OleA), the deglycosylated form of oleuropein, which is the main polyphenolic component of EVOO. In this work, three pesticides with different physicochemical and biological properties, namely oxadiazon (OXA), imidacloprid (IMID), and glyphosate (GLYPHO), were compared in terms of metabolic activity, mitochondrial function and epigenetic modulation in an in vitro cellular model of human HaCaT keratinocytes to mimic the pathway of dermal exposure. The potential protective effect of OleA against pesticide-induced cellular toxicity was then evaluated in a cell pre-treatment condition. This study showed that sub-lethal doses of OXA and IMID reduced the metabolic activity and mitochondrial functionality of HaCaT cells by inducing oxidative stress and altering intracellular calcium flux and caused epigenetic modification by reducing histone acetylation H3 and H4. GLYPHO, on the other hand, showed no evidence of cellular toxicity at the doses tested. Pretreatment of cells with OleA was able to protect cells from the damaging effects of the pesticides OXA and IMID by maintaining metabolic activity and mitochondrial function at a controlled level and preventing acetylation reduction, particularly of histone H3. In conclusion, the bioactive properties of OleA reported here could be of great pharmaceutical and health interest, as they could be further studied to design new formulations for the prevention of toxicity from exposure to pesticide use.