Tyrosol Bioavailability in Humans after Ingestion of Virgin Olive Oil

Results from epidemiological studies support the relationship between the consumption of phenolic-rich food and a low incidence of coronary heart disease (1)(2). The lower incidences of coronary heart disease and certain cancers in Mediterranean countries have been associated with diet, of which fruits, vegetables, legumes, and grains are the usual components and the major fat component is olive oil (3). The Mediterranean dietary pattern has been also shown to be effective in secondary prevention of coronary heart disease (4). Virgin olive oil is rich in phenolic compounds with strong antioxidant properties that protect olive oil from autooxidation (5). In addition, olive oil phenolic compounds have been shown to delay in vitro metal-induced and radical-dependent LDL oxidation (6)(7). Among the phenolic compounds in olive oil is tyrosol (4-hydroxyphenylethanol), which is also present in other dietary sources (8)(9) and has mild antioxidant properties (10)(11)(12). However, information on the bioavailability of dietary phenolic compounds in humans is scarce (13)(14). In bioavailability studies of phenolic compounds, one of the main problems is the estimation of the dose administered because these substances can be present in multiple forms in food. In the specific case of olive oil, phenolic compounds may be in the form of glycosides, polymers, and esters (12)(15). To our knowledge, the bioavailability of tyrosol from nonsupplemented dietary sources has not been described previously. Eight healthy volunteers were recruited (five men and three women; age range, 25–52 years). The local ethics committee, CEIC-IMAS (register no. 98/798/I), approved the protocol, and participants signed an informed consent. All volunteers could be considered healthy on the basis of physical examination and standard biochemical and hematological tests. Subjects had an mean weight of 75 ± 13.47 kg (men, 83.2 ± 4.4 kg; women, …