Influence of Phenol-Enriched Olive Oils on Human Intestinal Immune Function

Abstract

Olive oil (OO) phenolic compounds (PC) are able to influence gut microbial populations and metabolic output. Our aim was to investigate whether these compounds and changes affect the mucosal immune system. In a randomized, controlled, double blind cross-over human trial, for three weeks, preceded by two-week washout periods, 10 hypercholesterolemic participants ingested 25 mL/day of three raw virgin OO differing in their PC concentration and origin: (1) an OO containing 80 mg PC/kg (VOO); (2) a PC-enriched OO containing 500 mg PC/kg from OO (FVOO); and (3) a PC-enriched OO containing a mixture of 500 mg PC/kg from OO and thyme (1:1, FVOOT). Intestinal immunity (fecal immunoglobulin A (IgA) and IgA-coated bacteria) and inflammation markers (C-reactive protein (CRP) and fecal interleukin 6 (IL-6), tumor necrosis factor α (TNFα) and calprotectin) was analyzed. The ingestion of high amounts of OO PC, as contained in FVOO, tended to increase the proportions of IgA-coated bacteria and increased plasma levels of CRP. However, lower amounts of OO PC (VOO) and the combination of two PC sources (FVOOT) did not show significant effects on the variables investigated. Results indicate a potential stimulation of the immune system with very high doses of OO PC, which should be further investigated.

State of the Art on Functional Virgin Olive Oils Enriched with Bioactive Compounds and Their Properties

“…The normal gut microbiota is involved in several functions [101] such as nutrient metabolism, xenobiotic and drug metabolism, antimicrobial protection, integrity of the gut barrier and structure of the gastrointestinal tract and development of gut-associated lymphoid tissue (GALT) which establishes the most extensive part of the immune system in the body. The crosstalk between GALT and the microbiota is critical for mucosal tissue homeostasis, maintenance of mucosal barrier function and protection against infectious and inflammatory diseases occurring at mucosal sites [102,103]. …”

“…For this reason, Martín-Peláez et al, 2016 [103] evaluated the influence of En-VOO on human intestinal immune function in hypercholesterolemic participants establishing the following biomarkers in faecal samples: faecal immunoglobulin A (IgA) and IgA-coated bacteria as intestinal immunity biomarker; faecal protectin and cytokines—interleukin IL-6 and TNF-α—as intestinal inflammatory markers and plasma samples; and C-reactive protein (CRP) as a systemic inflammation marker. According to their results, the VOO intervention increased IgA-coated bacteria by 18.7%, followed by FVOO (51.6%), and FVOOT (94.3%) with respect to pre-intervention values (taking pre-values as 100%).…”

Flavonoids, Inflammation and Immune System

“…This issue provides an opportunity to update current knowledge about some examples of the six subclasses of the flavonoid compounds and their effects—even at molecular level—on immunity and inflammation, but also in inflammatory-mediated diseases such as insulin-resistance obesity, cardiovascular disease and even in cancer. The Special Issue contains six review papers [13,14,15,16,17,18] and eight research papers [19,20,21,22,23,24,25,26] on the current knowledge in the field. Contributions are from countries in Africa (South Africa), America (Brazil), Asia (China, Korea, Japan and Taiwan) and Europe (Germany, Spain and Switzerland).…”

“…This study, focused on acquired immunity, reveals the changes produced by cocoa intake on mesenteric lymph nodes, which eventually prevent oral immunization to a food allergen. Gut-associated lymphoid tissue is also evaluated in the study by Martín-Peláez et al [20], who included a clinical trial with olive oil phenolic compounds. This randomized, controlled, double-blind, cross-over human trial demonstrates that the consumption of a virgin olive oil containing 500 mg/kg olive oil phenolic compounds increases the proportion of intestinal bacterial coated to IgA [20].…”

“…Gut-associated lymphoid tissue is also evaluated in the study by Martín-Peláez et al [20], who included a clinical trial with olive oil phenolic compounds. This randomized, controlled, double-blind, cross-over human trial demonstrates that the consumption of a virgin olive oil containing 500 mg/kg olive oil phenolic compounds increases the proportion of intestinal bacterial coated to IgA [20]. Another clinical study (open, prospective, randomized, cross-over, controlled feeding trial) includes the effect of tomato and olive oil on cardiovascular disease risk factors [19].…”