Quercetin makes bones heavier and stronger, says meta-study
Rutin, a form of quercetin, makes bones stronger. This is evident from an animal study about which we wrote a few weeks earlier. There are at least 18 other animal studies in which quercetin has a positive effect on bone health. Chinese scientists have incorporated the results of these studies into a meta-study.
The researchers, who are affiliated with Wenzhou Medical University in China, traced 19 animal studies in the medical literature in which laboratory animals had received quercetin and forms of quercetin, and in which researchers had subsequently studied its effects on the bones.
Oral administration increased the bone density of the test animals [first figure below], and also made the bones stronger [second figure below]. Click on the figures for a larger version.
The experiments in which the researchers did not use quercetin, but analogues thereof (such as rutin), resulted in more bone mass. Trials lasting no longer than 8 weeks were more successful, at least in terms of bone mass, than trials that took longer.
There was no single mechanism by which quercetin made bones stronger. Quercetin was an antioxidant, inhibited inflammation and also stimulated the activity of the bone-building osteoblasts in bone tissue.
Part of the mechanism of action is likely that quercetin increases the activity of steroid hormones. In the animal studies quercetin increased the concentration of estradiol [first figure below], and the weight of the uterus [second figure below]. The uterus grows due to estradiol.
Flavonoids such as quercetin increase the production of steroid hormones in the cells of Leydig. This may be because these substances increase the activity of molecules such as StAR, [Cell Biol Toxicol. 2018 Feb;34(1):23-38.] [Toxicol In Vitro. 2017 Oct;44:111-121.] [J Endocrinol. 2008 May;197(2):315-23.] but perhaps also because they weaken the feedback mechanisms in the hypothalamus. [Evid Based Complement Alternat Med. 2014;2014:781684.]
For this reason, some endocrinologists suspect that they may be able to use quercetin and its analogues as an alternative form of hormone therapy in the near future. [Antioxidants (Basel). 2020 Mar 13;9(3):237.] We ourselves suspect that luteolin could be even more interesting than quercetin for this, but that is a different story.
"The findings reveal the possibility of developing quercetin and its derivatives as a drug or an ingredient in diet for the clinical treatment of osteoporosis", write the researchers.
Oxid Med Cell Longev. 2020 Oct 27;2020:6080597.
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