Oak Bark health benefit
January 17 2016 by
Ray Sahelian, M.D.

An important healing component in the smooth bark of the oak tree is its tannin, which has astringent and mildly antiseptic qualities. The tannin is what makes oak bark valuable for minor wounds and inflammation, for tightening tissue and lessening oozing.
   As of 2016, I am not aware of human research with oak bark supplements.

Oak Bark antioxidant
Antioxidant activity in medicinal plants associated with the symptoms of diabetes mellitus used by the indigenous peoples of the North American boreal forest.
J Ethnopharmacol. 2002.
Department of Plant Science, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
Thirty-five plant species were selected from the published literature as traditionally used by the Indigenous Peoples of the boreal forest in Canada for three or more symptoms of diabetes or its complications. Antioxidant activities in methanolic extracts support the contribution of these traditional medicines in a lifestyle historically low in the incidence of diabetes. In a DPPH assay of free radical scavenging activity 89% of the methanol extracts had activity significantly greater than common modern dietary components, 14% were statistically equal to ascorbic acid and 23% had activities similar to green tea and a Trolox positive control. Superoxides produced with an NBT/xanthine oxidase assay found scavenging was significantly higher in 29% of the species as compared with the modern dietary components and Trolox. The methanol extracts of Rhus hirta, Quercus alba (oak bark) and Cornus stolonifera performed similarly to green tea's in this assay. Assessment of peroxyl radical scavenging using a DCF / AAPH assay showed 60% of the plant extracts statistically similar to Trolox while R. hirta and Solidago canadensis extracts were greater than green tea, ascorbic acid and Trolox. The majority of the species (63 and 97%, respectively) had scavenging activities similar to ascorbic acid in the superoxide and peroxyl radical scavenging assays.

Oak bark for stomach health
Effects of aqueous extracts from Quercus ilex root bark, Punica granatum fruit peel and Artemisia herba-alba Asso leaves on ethanol-induced gastric damage in rats.
Phytother Research. 1999.
The gastroprotective effect of tannic acid and the aqueous extract of Quercus ilex root bark, Punica granatum fruit peel and Artemisia herba-alba Asso leaves was investigated in the rat against ethanol-induced damage. Tannic acid, Q. ilex and P. granatum extracts gave 100% precipitation of ovine haemoglobin in vitro, whereas A. herba-alba extract was devoid of any protein-binding property. Oral administration of these plant extracts or tannic acid induced a significant decrease in gastric lesions. The observed protection was more pronounced when the test solution was given at the same time with ethanol, except for Q. ilex extract. The acid content of the stomach was significantly increased by P. granatum (368%) and A. herba-alba (251%) extracts prepared in ethanol. It is suggested that monomeric and polymeric polyphenols can strengthen the gastric mucosal barrier.

Molecules. 2012. Extraction of betulin, trimyristin, eugenol and carnosic acid using water-organic solvent mixtures. A solvent system consisting of ethyl acetate, ethyl alcohol and water, in the volume ratio of 4.5:4.5:1, was developed and used to extract, at room temperature, betulin from white birch bark and antioxidants from spices (rosemary, thyme, sage, and oregano) and white oak chips. In addition, under reflux conditions, trimyristin was extracted from nutmeg using the same solvent system, and eugenol from olives was extracted using a mixture of salt water and ethyl acetate. The protocol demonstrates the use of water in organic solvents to extract natural products from plants. Measurement of the free-radical scavenging activity using by 2,2-diphenyl-1-picrylhydrazyl (DPPH) indicated that the extraction of plant material using ethyl acetate, ethyl alcohol and water was exhaustive when carried out at room temperature for 96 h.