Olive Oil
The olive tree (Olea europaea) has been cultivated since ancient times in Persia, Mesopotamia and the Mediterranean, and some trees have been known to live for more than a thousand years. The olive tree has silvery-green leaves, a gnarled trunk and an oily, bitter fruits which are either prepared whole for the table, or the oil is extracted using cold-pressure or steam. Olives should preferably be cold-pressed in order to preserve the phenolic compounds in the oil, a process that produces extra-virgin olive oil. The production of oil reaches around eleven million tons per year.
While the fruit is mostly grown for its healthy oil, the leaves are also used to prepare medicinal extracts. The oil and leaves contain a large number of phenolic compounds with antioxidant, antihypertensive, hypoglycaemic, hypo-cholesterolemic, cardioprotective, anticancer and anti-inflammatory properties.1 Furthermore, olive oil contains iron as well as vitamins E and K.
The type of oil eaten as a staple in a diet not only determines how we metabolise energy, but also the make-up of important lipid components in the cells of the body. Olive oil contains a high percentage of monounsaturated oleic acid (omega-9) which, like all dietary fatty acids, is incorporated into the membrane of every cell in the body, helping to regulate cellular function and protect the body against the development of chronic diseases. Oleic acid is actually the most common fatty acid in nature and is beneficial to health because of its favourable effect on blood lipids, its ability to lower blood pressure, and the fact that it can reduce levels of toxic amyloid-β peptide in neuronal cells, a process associated with dementia.2
This gives us an indication of the importance of eating the best oil that we can on a daily basis, while avoiding hydrogenated trans fats such as margarine and canola oil. These inferior oils are associated with lipid irregularities in tissues linked to degenerative diseases such as cardiovascular disease, Alzheimer’s disease and diabetes, and unfortunately are a key fat in the modern urban diet.3
By comparison, the traditional Mediterranean diet was rich in polyphenols obtained from fruits, vegetables, seeds as well as natural olive oil, and in Crete the olive oil intake was actually in excess of 30% of dietary calories.4 This high olive oil intake was once associated with exceptional heart health; however, the Greeks have lost their former advantage over other nations since the 1960s, by replacing butter and olive oil with factory fats on the misguided recommendation of health authorities.
The benefits of olive oil also derive from its non-oil constituents, and these are affected by crushing, malaxation, filtering and pressing temperatures. These constituents include tocopherols, squalene, carotenes, triterpenic acids, lignans, secoiridoids and oleuropein. The most significant benefits of these compounds is their antioxidant activity which protects, for example, against lipid oxidation which is the major contributor to the development of plaque in arteries. These valuable constituents are beneficial because they ‘modulate gene expression towards a protective mode for proteins participating in cellular mechanisms involved in oxidative stress resistance, inflammation or lipid metabolism.’5
Just one of these non-oil constituents, oleuropein, is a potent antioxidant and anti-inflammatory compound, and has marked anticancer activity on the endometrium and breast. In addition, oleuropein is protective of the cardiovascular system while also assisting with blood sugar regulation. This means that it has plenty to offer in a clinical context for treating metabolic syndrome, as well as by being part of a broad dietary strategy for promoting health in general.6
As mentioned, the leaves of the olive tree also have medicinal properties and extracts can contain higher amounts of polyphenols than the oil. These offer the same benefits as the oil for support of the cardiovascular system, and olive leaf extracts have in fact been shown to reduce both systolic and diastolic blood pressure. The mechanisms are thought to be angiotensin-converting enzyme inhibition (ACE), calcium channel-blocking and the restoration of endothelial function—actions similar to those of modern pharmaceutical drugs but without the side-effects. This is also the case with olive leaf extract’s anti-inflammatory activity, resembling that of non-steroidal anti-inflammatory drugs (NSAIDs). Extracts can also lower total cholesterol and triglycerides as well as raise protective HDL cholesterol, while imparting a protective effect against potential damage from actual heart attacks without resorting to statins. In addition, oleuropein can regulate fat synthesis and fat cell size, contributing to the treatment of obesity.1
Another common metabolic disease is diabetes, and the traditional Mediterranean diet has been found to be broadly protective against this modern disease because of its low sugar consumption as well as the high intake of olive oil. In fact, olive leaf has been traditionally used to treat diabetes and one recent trial of overweight middle-aged men found that supplementation with olive-leaf polyphenols significantly improved insulin sensitivity and pancreatic β-cell function.7
Olive leaf constituents have also drawn the attention of cancer researchers because of the antioxidant properties of these polyphenols. These compounds, such as oleocanthal, have been found to exhibit selective antitumour activity in several cancer cell lines including breast, colon, prostate, pancreas, myeloma and leukaemia. In this respect, they inhibit malignant cells or cause them to die, while leaving non-cancer cells viable.8 This selective effect is advantageous in treatment, something we don’t get from conventional drugs which induce a general state of toxicity by damaging DNA and healthy cells, and thereby producing the severe side-effects that we associate with chemo-therapy.9 Olive leaf extract can therefore be part of a comprehensive supportive regime of wholefoods, herbal medicine and lifestyle change that contributes to holistic treatment.
Furthermore, constituents in olive oil or the leaf extract are neuroprotective, helping to protect the aged against dementia. Impressively, olive oil can also help treat other age-related conditions such as nutrient deficiency and bone fracture. In fact, osteoporosis was formerly a rare condition in the Mediterranean region and this is because olive oil aids in the maintenance of bone mineral density.6 This mean that dietary intervention using olive oil and calcium-rich legumes can replace the consumption of extra milk for those people who react adversely to dairy products. (By the way, calcium supplements are not currently recommended).10
When applied externally, olive oil is antiseptic, anti-inflammatory and demulcent, which means it is soothing to irritation.11 It nourishes the skin and body, and can be used safely on children. You can mix it with a little garlic or cod liver oil and rub it into their feet or chests as a constitution builder, tonic, and immune system enhancer. It can also be made into various ointments and lotions, when medicinal herbs such as calendula, comfrey and St. John’s wort are infused into it by placing them in a jar of olive oil for a couple of weeks in warm place.
References:
1. Vogel P, Kasper Machado I, Garavaglia J, Zani VT, de Souza D, Morelo Dal Bosco S. Polyphenols benefits of olive leaf (Olea europaea L) to human health. Nutr Hosp 2014;31:1427–33.
2. Lopez S, Bermudez B, Montserrat-de la Paz S, et al. Membrane composition and dynamics: a target of bioactive virgin olive oil constituents. Biochim Biophys Acta 2014;1838:1638–56.
3. Micha R, Mozaffarian D. Trans fatty acids: effects on cardiometabolic health and implications for policy. Prostaglandins Leukot Essent Fatty Acids 2008;79:147–52.
4. Lam C. The Traditional Mediterranean Diet: Lessons Learned. J Orthomol Med 2011;26:109–16.
5. Kalogeropoulos N, Tsimidou MZ. Antioxidants in Greek Virgin Olive Oils. Antioxid Basel Switz 2014;3:387–413.
6. Liu H, Huang H, Li B, et al. Olive oil in the prevention and treatment of osteoporosis after artificial menopause. Clin Interv Aging 2014;9:2087–95.
7. de Bock M, Derraik JGB, Brennan CM, et al. Olive (Olea europaea L.) leaf polyphenols improve insulin sensitivity in middle-aged overweight men: a randomized, placebo-controlled, crossover trial. PloS One 2013;8:e57622.
8. LeGendre O, Breslin PA, Foster DA. (-)-Oleocanthal rapidly and selectively induces cancer cell death via lysosomal membrane permeabilization. Mol Cell Oncol 2015;2:e1006077.
9. Samet I, Han J, Jlaiel L, Sayadi S, Isoda H. Olive (Olea europaea) leaf extract induces apoptosis and monocyte/macrophage differentiation in human chronic myelogenous leukemia K562 cells: insight into the underlying mechanism. Oxid Med Cell Longev 2014;2014:927619.
10. Michaëlsson K, Wolk A, Langenskiöld S, et al. Milk intake and risk of mortality and fractures in women and men: cohort studies. BMJ 2014;349:g6015.
11. Grieve M. A Modern Herbal. London: Tiger Books International; 1994.