Olive Oil and Health

 

Olive Oil & Health

E.Roehm, M.D. 

Olive oil is a major component of the Mediterranean diet. (See Mediterranean diet video) The Cretan Mediterranean diet, as described in the Seven Countries Study, had 31% of the total calories derived from olive oil.1 The Cretan Mediterranean diet in the Seven Countries study was associated with the lowest rates of heart disease and cancer of any of the populations studied.2

Olive oil is predominantly composed of the following fats: 73% monounsaturated fat, 14% saturated fat and 11% polyunsaturated fat.3  In addition to the fats present, olive oil contains beneficial phenol compounds. (Phenols are a diverse class of chemical compounds.) Extra virgin olive oil is high in phenol content (150-1000 mg/L), while totally refined olive oil has no phenols.4-6 Much of the olive oil sold is a combination of refined olive oil and other types of olive oil that results in varying levels of phenol content being present.

The types of phenols present in olive oil are beneficial in reducing the oxidation of LDL cholesterol.7 (Oxidized LDL cholesterol is a harmful form of cholesterol found in fat and cholesterol deposits in the body.)  Extra virgin olive oil has been found in human studies to lower inflammatory markers in the body and down-regulate genes that are thought to promote fat and cholesterol deposition in the body.8

A diet high in extra virgin olive oil reduced the development of breast cancer in rats.9 In humans, high conformity to a Mediterranean diet was associated with less breast cancer in post menopausal women.10 High olive oil intake has been associated with a reduction in heart disease in a recent study of Italian women as well.11 High olive oil intake has also been associated with a reduction in stroke rate in a study of French women.12  In a pilot study of overweight breast cancer survivors trying to lose weight, an olive oil plant based diet was more effective and provided greater satiety compared to a diet with recommendations for similar calories following a National Cancer Institute diet  not emphasizing olive oil and plant based foods.  (80% of the women losing ≥ 5% of their weight with a plant based olive oil diet vs. 31% on a National Cancer Institute diet)13

A highly refined olive oil has a much lower level of the beneficial phenols. Though with the ingestion of only small quantities of olive oil, this issue would be less important, for larger quantities, a cold pressed extra virgin olive oil is advisable. The production of cold pressed extra virgin olive oil is more consistent with traditional olive oil production techniques and would be expected to have the highest phenol levels.

In summary, olive oil is predominantly a monounsaturated fat and contains beneficial phenol compounds if processed optimally. A cold pressed extra virgin olive oil is advised, particularly if significant quantities of olive oil are ingested.

References:

  1. Keys A, Aravanis C, Sdrin H. The diets of middle-aged men in two rural areas of Greece. Voeding 1966;27:575-86.
  2. Keys A, Menotti A, Karvonen M, et al. The diet and 15-year death rate in the seven countries study. Am J Epidemiology 1986:124:903-915.
  3. USDA National Nutrient Database for Standard Reference, SR-23. 2010.
  4. Visioli F, Caruso D, Grande S, et al. Virgin Olive Oil Study (VOLOS): Vasoprotective potential of extra virgin olive oil in mildly dyslipidemic patients. Eur J Nutr. 2005;44:121–7.
  5. Servili M, Selvaggini R, Esposto S, et al. Health and sensory properties of virgin olive oil hydrophilic phenols: agronomic and technological aspects of production that affect their occurrence in the oil. J Chromatogr A. 2004;1054:113–2
  6. Angerosa F, Dalessandro N, Konstantinou P, et al. Gc-Ris evaluation of phenolic-compounds in virgin olive oil. J Agric Food Chem. 1995;43:1802–07.
  7. Elevated circulating LDL phenol levels in men who consumed virgin rather than refined olive oil are associated with less oxidation of plasma LDL. de la Torre-Carbot K, Chávez-Servín J, Jaúregui O, et al. J Nutr. 2010:140:501-508
  8. Konstantinidou V, Covas MI, Muñoz-Aguayo D, et al. In vivo nutrigenomic effects of virgin olive oil polyphenols within the frame of the Mediterranean diet: a randomized controlled trial. FASEB J. 2010:24:2546-57.
  9. Costa I, Moral R, Solanas M, et al. High corn oil and extra virgin olive oil diets and experimental mammary carcinogenesis: clinicopathological and immunohistochemical p21Ha-Ras expression study. Virchows Arch. 2011;458:141-51.
  10. Trichopoulou A, Bamia C, Lagiou P, Trichopoulos D. Conformity to traditional Mediterranean diet and breast cancer risk in the Greek EPIC (European Prospective Investigation into Cancer and Nutrition) cohort. Am J Clin Nutr. 2010;92:620-5.
  11. Bendinelli B, Masala G, Saieva C, et al. Fruit, vegetables, and olive oil and risk of coronary heart disease in Italian women: the EPICOR Study. Am J Clin Nutr. 2011;93:275-83.
  12. Samieri C, Féart C, Proust-Lima C, Peuchant E, et al. Olive oil consumption, plasma oleic acid, and stroke incidence: the Three-City Study. Neurology. 2011 77:418-25.
  13. Flynn MM, Reinert SE. Comparing an olive oil-enriched diet to a standard lower-fat diet for weight loss in breast cancer survivors: a pilot study. J Womens Health (Larchmt). 2010;19:1155-61.