Proanthocyanidin-rich grape seed extract improves bone loss, bone healing, and implant osseointegration in ovariectomized animals.

The purpose of the present study was to confirm if proanthocyanidin-rich grape seed extract (GSE) had the ability to improve bone health such as bone loss, bone healing, and implant osseointegration (defined as the direct connection between bone tissue and an implant) in ovariectomized (OVX) animals. We demonstrated that daily oral administration of GSE prevented bone loss in the lumbar vertebrae and femur in OVX mice. In addition, osteoclastogenesis in the lumbar spine bone of OVX mice, as assessed by histological and histomorphometric analyses, was accelerated but GSE prevented this dynamization, suggesting that GSE could counteract OVX-induced accelerated osteoclastogenic activity. In rats, OVX clearly impaired the healing of defects created on the calvaria, and GSE overcame this OVX-impaired healing. In the same way, osseointegration of a tibial implant in rats was retarded by OVX, and GSE counteracted the OVX-induced poor osseointegration, likely promoting bone healing by preventing imbalanced bone turnover. These results suggest that orally administered GSE improved implant osseointegration by mitigating the impaired bone health induced by OVX as a model of estrogen deficiency.

Proanthocyanidin-Rich Grape Seed Extract Modulates Intestinal Microbiota in Ovariectomized Mice.

Grape-seed extract (GSE) is rich in proanthocyanidins (polymers of flavan-3-ols). GSE is well known to have various beneficial effects to health. The objective of this study was to examine the effect of dietary GSE on the intestinal microbiota in ovariectomized (OVX) mice as a model of menopause. Phylum-level analyses using 16S rRNA-targeted group-specific polymerase-chain reaction primers in fecal samples collected 8 weeks postoperatively from OVX mice revealed that the proportion of Firmicutes and Bacteroidetes populations became imbalanced as compared with that in sham-operated control mice. That is, the ratio of Firmicutes:Bacteroidetes populations in the OVX group were increased significantly. When OVX animals were given dietary GSE, the imbalanced proportion of Firmicutes and Bacteroidetes populations was normalized to that seen in control mice. In addition, the body weight of OVX animals measured at 6 weeks postoperatively was significantly higher than that in sham-operated control animals. Dietary GSE also prevented OVX animals from increasing body weight. Thus, we postulated that GSE can improve imbalanced populations of intestinal microbiota, leading to prevention of obesity under conditions of not only menopause but morbidity. PRACTICAL APPLICATION: The GSE has a great potential to be a functional food to improve dysbiosis in post-menopausal women.