The lining of the small intestine plays a central role in digestion and nutrient absorption. Researchers are investigating whether certain plant compounds, including those found in oregano essential oil, can influence this lining, digestive enzymes, and the body's antioxidant defenses.
One 2016 study offers an interesting look at these effects. It examined oregano essential oil in chickens with experimentally induced intestinal infection and found changes in several intestinal and antioxidant measurements.[1]
The 2016 Oregano and Intestinal Health Study
Published in Poultry Science, the study by Bozkurt and colleagues examined oregano essential oil and monensin, a conventional veterinary parasitic drug, in chickens challenged with Eimeria parasites. The researchers compared diets containing oregano oil, monensin, both together, or neither supplement.[1]
The researchers were interested in whether the combination could provide a greater effect than either substance alone. It did not show a useful synergistic or additive effect. Monensin was more effective than oregano oil at reducing parasite shedding and supporting growth after infection. However, oregano oil was associated with changes in intestinal morphology, digestive enzyme activity, and antioxidant markers.[1]
How the Small Intestine Supports Nutrient Absorption
The small intestine is lined with tiny finger/hair like projections called villi. These structures help increase the surface area available for absorbing nutrients. Between the villi are small indentations called crypts, which contain cells involved in maintaining and renewing the intestinal lining.
In the infected chickens, oregano-oil-supplemented diets were associated with favorable measurements of intestinal tissue development. The authors interpreted these findings as evidence of improved intestinal absorptive capacity during infection.[1]
Intestinal structure can influence how efficiently nutrients reach absorptive cells. changes in villus or crypt measurements suggests that vitamins, minerals, or calories may have more absorption potential.
Changes in Digestive Enzyme Activity
Digestion relies on enzymes that help break carbohydrates, proteins, and fats into smaller pieces. The 2016 researchers measured several digestive enzymes in the pancreas and intestinal contents of the chickens.
Some enzyme activities differed between the oregano-oil groups and untreated controls, including certain measures of amylase, chymotrypsin, and lipase.[1]
These results suggest that dietary oregano oil can influence digestive physiology in this animal model.
Antioxidant Measurements: MDA and SOD
The researchers also measured indicators related to oxidative stress. Oxidative stress occurs when reactive molecules and the body's protective systems become imbalanced.
- Malondialdehyde (MDA): A marker of oxidative damage to fats. Serum MDA decreased in groups receiving oregano oil or monensin.
- Superoxide dismutase (SOD): An enzyme involved in antioxidant defense. SOD activity increased in response to the dietary treatments.
- Total antioxidant status: This overall measure of antioxidant capacity also improved in the treated birds.[1]
These biochemical findings are noteworthy, especially in the context of intestinal infection.
What About Human Studies?
Although large, well-controlled human trials are still lacking, smaller studies have investigated oregano-containing treatments for certain intestinal microbial conditions.
In a 2000 study involving 14 adults, six weeks of supplementation with 600 mg emulsified oil of oregano daily, resulted in a complete disappearance of Entamoeba hartmanni (four cases), Endolimax nana (one case), and Blastocystis hominis in eight cases. Also, Blastocystis hominis scores declined in three additional cases. Gastrointestinal symptoms improved in seven of the 11 patients who had tested positive for Blastocystis hominis.[2]
A separate 2014 study followed 104 patients with small intestinal bacterial overgrowth (SIBO) who completed treatment and repeat breath testing. Some patients received multi-herb products, including a formulation containing oregano oil; others received rifaximin. Negative follow-up breath tests occurred in 46% of the herbal-treatment group and 34% of the rifaximin group.[3]
Scientific References
- Bozkurt, M., Ege, G., Aysul, N., Akşit, H., Tüzün, A. E., Küçükyılmaz, K., et al. (2016). Effect of anticoccidial monensin with oregano essential oil on broilers experimentally challenged with mixed Eimeria spp. Poultry Science, 95(8), 1858–1868. https://doi.org/10.3382/ps/pew077 · PubMed.
- Force, M., Sparks, W. S., & Ronzio, R. A. (2000). Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytotherapy Research, 14(3), 213–214. PubMed.
- Chedid, V., Dhalla, S., Clarke, J. O., et al. (2014). Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Global Advances in Health and Medicine, 3(3), 16–24. DOI · Full text.
