Benefits
Gut bacteria: no human data, and no change in the pig study
No human study has measured what this extract does to gut bacteria. In the piglet study Natac cites, colonic microbial ecology was not altered by the olive extract, and the paper's title says its effects were independent of the gut microbiota. Natac points instead to an unpublished in vitro microbiota project, which is not a measurement in a living gut.
Digestive regularity has not been measured
Stool frequency, stool form and transit time have not been measured with this extract in people or in animals. At 200 mg/day it supplies no appreciable fibre, so the stool bulking mechanism that applies to fermentable prebiotic fibres does not apply here at all.
Gut barrier markers: piglet data only, untested in people
In piglets given repeated endotoxin injections, the olive extract raised ileal gene expression of tight and adherens junction proteins and plasma recovery of an oral mannitol dose, though the challenge itself had not impaired permeability and intestinal inflammation was unchanged. A related olive extract raised goblet cell density in farmed sea bream. None of this has been tested in a person.
Mechanism of action
Anti-inflammatory signalling by olive triterpenes and polyphenols
In cultured macrophages stimulated with endotoxin, the olive extract from the piglet study lowered inflammatory cytokine output. In animals, an olive bioactive extract prevented the endotoxin-driven rise in circulating interleukin 1 beta in piglets and lowered interleukin 6 and haptoglobin in challenged heifers. This is animal and cell work.
Tight junction and barrier gene expression
In endotoxin-challenged piglets the extract increased ileal messenger RNA for tight and adherens junction proteins and raised plasma recovery of an oral mannitol dose compared with both control groups. In Caco-2 cells it improved transepithelial electrical resistance. The same study found no change in colonic microbiota, so the barrier effect in that model was not explained by any shift in bacteria.
Immune signalling, shown only in animals
In heifers given rising endotoxin doses, an olive bioactive extract lowered monocyte CD14 expression. In newborn dairy calves an olive extract increased the glucagon-like peptide 2 response but did not improve intestinal permeability or diarrhoea. In Atlantic salmon fed AQUOLIVE, a different Natac olive fruit extract, head kidney gene expression shifted. No human study of this ingredient has been run.
Clinical trials
Double-blind, controlled parallel trial of 90 g/day of olive pomace enriched biscuits, delivering about 17 mg of hydroxytyrosol and its derivatives per 100 g, or isoenergetic control biscuits for 8 weeks. This is a food made from olive pomace, not Oligut and not a triterpene extract; no human trial of Oligut has been published (PubMed, Europe PMC and ClinicalTrials.gov searched). Four authors list OlioCRU s.r.l. as their affiliation. (Conterno et al. 2019, Eur J Nutr)
62 otherwise healthy adults with mildly raised total cholesterol (180 to 240 mg/dl).
Faecal microbial diversity did not change. Lactobacilli and Ruminococcus were lower than with control biscuits, and bifidobacteria showed only a trend upward. Hydroxytyrosol breakdown products rose in urine and blood, but there was no statistically significant effect on cardiovascular markers, including oxidised LDL. It says little about a 200 mg olive triterpene and polyphenol capsule.
30-day feeding study in 31 male weaned piglets in three groups: unchallenged controls, endotoxin-challenged controls, and challenged pigs fed 500 mg/kg of an extract from pomace olive oil standardized to 10% maslinic acid, 4% oleanolic acid and 2% hydroxytyrosol. Rising doses of E. coli lipopolysaccharide were injected over the final 10 days; Caco-2 cell and macrophage experiments were added. The paper does not use the Oligut name; Natac cites it as Oligut evidence. Lucta S.A. supplied the extract, and Kiel University, Lucta and ProNutra Solutions funded the work, including author salaries. (Liehr et al. 2017, PLoS One)
Weaned male piglets (n = 31) plus cell culture. No people.
Challenged control pigs had higher interleukin 1 beta and lower feed intake and weight gain; these responses were not seen in extract-fed pigs. The extract raised ileal gene expression of tight and adherens junction proteins and plasma recovery of oral mannitol versus both control groups. Intestinal inflammation and colonic microbial ecology were not altered by treatment.
Generalized randomized block design: 36 newly weaned beef heifers received saline or six rising intravenous doses of lipopolysaccharide over 10 days, the challenged animals fed no extract or an olive oil bioactive extract at 0.04 or 0.16 percent of diet dry matter. The abstract does not name Oligut; Natac cites the study as Oligut evidence. (Cangiano et al. 2019, J Anim Sci)
36 newly weaned beef heifers. No people.
The extract improved dry matter intake and lowered intravaginal temperature on some, but not all, challenge days, and lowered circulating interleukin 6 and haptoglobin and monocyte CD14 expression. No gut outcome in people was studied.