Effects of Olive Oil on Intestinal Health

Bioactive Compounds of the Olive Tree

Recent research has explored how bioactive compounds derived from the olive tree, such as polyphenols, secoiridoids, and triterpenes, modulate the gut microbiota and promote gut health. A study published in the journal Foods synthesized the evidence on the effects of these compounds on microbiota composition and function.

The olive tree, native to the Mediterranean region, is valued for its oil and fruit. Its various parts contain functional ingredients and bioactive compounds.

• Olive Oil: Main source of monounsaturated fatty acids (MUFAs), especially oleic acid. It also contains phytosterols, tocopherols, polyphenols, and squalene, associated with multiple health benefits.
• Olive Fruit: Contains phenolic compounds, dietary fiber, and triterpenes.
• Olive Leaves: A byproduct of olive cultivation, rich in secoiridoids and flavonoids with anti-inflammatory and antioxidant properties.
• Olive water (wastewater from olive milling): A concentrate of water-soluble phenols with antimicrobial, anti-inflammatory, and antioxidant potential, making it a valuable source for the recovery of functional ingredients.

Phenolic compounds, such as flavonoids, phenolic acids, and polyphenols, are the most studied for their diverse biological activities. The olive tree contains more than 170 polyphenols, known for their antioxidant properties and prebiotic effects.

• Oleuropein: A secoiridoid with neuroprotective, anticancer, anti-inflammatory, and antimicrobial actions. Modulates intestinal and skin microbiota.
• Tyrosol: A prominent phenol in wine and olive oil, recognized for its neuroprotective and cardioprotective properties.
• Oleocanthal: Anti-inflammatory properties similar to ibuprofen.
• Oleacein: Another secoiridoid with potent antioxidant effects.
• Terpenoids: Like maslinic acid and oleanolic acid, they show potential in modulating intestinal health.

Oleacein: Therapeutic Potential

Oleacein exhibits antioxidant, anti-inflammatory, and anti-atherosclerotic properties. It is one of the most abundant and chemically active phenols in EVOO.

This compound is formed by hydrolysis of oleuropein during olive processing, transforming it into an amphiphilic molecule capable of dissolving in both aqueous and lipid environments. Its dual solubility allows it to integrate into particles such as low-density lipoproteins (LDL), protecting them from oxidation, a crucial step in the formation of arterial plaques.

Unlike oleocanthal, oleacein does not inhibit COX enzymes, but rather modulates the inflammatory response by reducing the expression of proinflammatory cytokines such as TNF-$\alpha$ and interleukins.

Clinical studies have linked the consumption of oleacein-rich EVOO with improvements in metabolic health (reduced BMI and glucose) and decreased inflammation. Furthermore, preclinical research suggests neuroprotective potential, with anti-inflammatory and antioxidant activity observed in multiple sclerosis models, as well as a positive impact on neuroplasticity.

Effects of Olive Oil and Its Components on the Gut Microbiota

Olive oil contributes to health not only through its high MUFA content but also through its diverse bioactive compounds. These compounds interact bidirectionally with the gut microbiota. Microbes transform olive oil constituents into new metabolites, and these compounds in turn reshape the microbial community, promote beneficial taxa, increase the production of short-chain fatty acids (SCFAs), and restrict harmful microbes.

The lipid matrix of olive oil facilitates the intestinal absorption of phenolic compounds and fosters microbial communities associated with reduced inflammation. The bioactive compounds in olive oil modulate the gut microbiota, promoting a balanced microbial ecosystem, increasing the integrity of the gut barrier, and reducing inflammation.

These compounds have demonstrated therapeutic potential in gastrointestinal (GI) disorders such as colitis, intestinal inflammation, and obesity.

• Hydroxytyrosol: Derived from the biotransformation of oleuropein in the GI tract. Activates the Nrf2 pathway, counteracting oxidative stress by producingAntioxidant enzymes. It also modulates transporters and enzymes in the synthesis, conversion, and excretion of bile acids, improving their metabolism and intestinal health. It decreases levels of proinflammatory cytokines, relieves intestinal inflammation, and modulates the synthesis and function of tight junction proteins in the intestinal epithelium, strengthening the intestinal barrier.
• Tyrosol: Another olive polyphenol with therapeutic potential for various GI disorders due to its interactions with the intestinal barrier. It mitigates the symptoms of colitis, reduces mucosal damage by improving the integrity of the intestinal barrier, and promotes the expression of tight junction proteins. It may also enhance the proliferation of beneficial bacteria, especially Bifidobacteriaceae and Lactobacillaceae.

It is important to note that these benefits may derive from the synergistic action of several compounds, not from a single component in isolation.

Challenges and Future Perspectives

Despite the promising findings, there are significant challenges before these results can be translated into clinical recommendations. Much of the current evidence comes from animal studies, and the results may not be directly applicable to humans due to genetic, dietary, and physiological differences. The researchers also point out the difficulties in standardizing olive oil composition for studies and the natural variability of the human gut microbiota, which makes it difficult to draw universal conclusions. Well-designed, long-term human clinical trials are needed to confirm these results and better understand individual responses.

Conclusions

In summary, secoiridoids, polyphenols, and triterpenes derived from olive oil establish a two-way communication with the gut microbiota. This interaction shapes the production and balance of microbial metabolites, including SCFAs, neurotransmitters, phenolic derivatives, and secondary bile acids. Translating this knowledge into functional products and dietary recommendations will require multidisciplinary studies integrating clinical trials with systems biology and multi-omics approaches. Deepening mechanistic knowledge and addressing these research gaps could fully unlock the therapeutic potential of olive bioactives for metabolic, inflammatory, and gut-brain axis-related disorders.