Phytosterols are plant compounds that resemble cholesterol. The highest concentrations are found in vegetable oils, beans and nuts. There are over 200 different phytosterols, including steryl glucoside and other sterol derivatives. Phytosterol derivatives have been scientifically proven to lower plasma and LDL cholesterols by competing with cholesterol for absorption in the digestive tract.
The authors of a study recently published in the Journal of Agricultural and Food Chemistry compared different olive cultivars, orchard locations, farming methods and sampling times in a bid to determine which elements influence steryl glucoside levels in olive oils. Initial findings suggest that pedoclimate – meaning soil water, nutrients, and aeration – could have the most significant impact on steryl glucoside concentrations.
Researchers at the Instituto de la Grasa, CSIC (Institute of Fats and Fat Derivatives of the Spanish National Research Council) analyzed virgin oils obtained from the Cornicabra, Manzanilla Cacereña, Manzanilla Castellana, and Picual olive varieties grown in eight different orchards situated around the outskirts of Madrid near the Manzanares River. The orchards were typically planted with 300 trees per hectare and both traditional and organic farming methods were included in the study. Fruit was handpicked and oil was extracted within 24 hours of harvesting to ensure high quality. An Abencor® hammer mill was used to crush the olives, with 700 g of oil paste processed per hour. Forty-four oil samples were analyzed.
Fruit variety and farming method proved less significant than characteristics of the soil – the pedoclimate – on levels of steryl glucosides. Another interesting finding was the presence of a wider variety of steryl glucoside derivatives in the olive oils than has previously been observed. The methodology used in the study was efficient and cost-effective, and thus could easily be applied to the routine testing of steryl glucoside levels in olive oils.
Because they prevent the absorption of regular dietary cholesterol while remaining not easily absorbed themselves, steryl glucosides together with other phytosterols induce lower total cholesterol levels, which in turn can reduce risk for heart disease, stroke and heart attack. This study contributes to the mountain of evidence demonstrating that olive oil, with its concentrations of essential fatty acids and minor compounds including phytosterols and antioxidants, is a strategic food element for managing and reducing cholesterol levels and associated health risks, as well as many other ailments.