Supplementation for six months demonstrated protective effects by increasing whole-body bone mineral density (BMD) in early peri- and postmenopausal women.
Protective effects emerged after high (784 mg) and low (392 mg) intake, compared to the control, but only those on the higher dosage experienced significantly decreased bone loss, according to findings published in Nutrients.
Furthermore, observed benefits were greater for women with lower baseline BMD, which suggests intake may be more effective in individuals at greater risk of bone loss and postmenopausal osteoporosis (PMO), stated researchers from University of Connecticut.
“Recent research has identified delphinidin-3-rutinoside, a major anthocyanin (44%) in blackcurrant, affects osteoblast differentiation by activating the fibroblast growth factor (FGF) pathway, demonstrating its potential as a bone stimulating agent for the prevention of PMO.
“The findings of our study indicate the potential for blackcurrant supplementation to serve as a prophylactic against PMO.”
Antioxidant mechanism
Osteoporosis generally affects women over 50 years of age, with incidence comparable to other major chronic diseases, like hypercholesterolemia and hypertension. Standard treatment includes hormone replacement therapy (HRT) or other medication, such as bisphosphonates for example, however, safety concerns have increased demand for natural compounds as alternative therapies.
The protective effects of antioxidant-rich fruits such, as blueberries and dried plums, have been explored but the effects of blackcurrants on bone health and mechanisms of action are unknown.
Therapeutic tendency
Blackcurrants (Ribes nigrum) contain more anthocyanins than other commonly consumed berries such as blueberry, blackberry, raspberry, and cranberry, and are known to effectively inhibit production of tartrate-resistant acid phosphatase (TRAP) (+) osteoclasts and lipopolysaccharide (LPS)-induced inflammation, the authors explain.
In vitro studies on female adult mice showed that blackcurrant attenuated ovariectomy-induced (age-associated) bone loss. Supplementation lowered inflammation and osteoclastogenesis, and curtailed oestrogen-induced or age-related bone loss, they write.
“The bone protective effects might be through enhancing bone formation as well as suppressing bone resorption as demonstrated by the tendency of bone formation markers and bone formation/resorption index to increase with blackcurrant supplementation.”
On this basis, they hypothesised that sufficient blackcurrant intake may reduce bone resorption in adult women. Given that peak bone mass and bone loss is age-dependent, the study targeted early intervention on women aged 45-60 years.
Trial protocol
The 40 participants were randomised to one of three treatment groups for six months. The low dose blackcurrant group comprised 16 women, the high dose 11, and the placebo 13.
Inclusion criteria included age and absence of HRT treatment one year prior to the intervention. Medical history and dietary behaviour were recorded.
Bone density was measured at baseline and six months, using dual-energy X-ray absorptiometry (DXA). The bone condition of all participants was good at baseline.
Participants were required to take 400 mg calcium and 500 IU vitamin D during the study, to avoid bone deterioration from deficiency, and had to record dietary intake and physical activity.
The low BC group consumed one 392 mg capsule of blackcurrant powder daily (equivalent to 142 fresh blackcurrants) and the high BC two capsules.
Key findings
The study revealed similar mitigating effects on bone formation and resorption as the mouse trial. More specifically, supplementation reduced sclerostin that inhibits osteoblastic bone formation.
Supplementation protected bone integrity, while subjects in the control continued to lose bone density. BMD of ribs was significantly greater in the high BC group and there was a positive trend for increased pelvis BMD after high and low treatment.
Markers of bone formation and resorption with were not significant but researchers observed an increase in the bone-specific isoenzyme of alkaline phosphatase (BALP) and cross-linked C-telopeptide of type 1 collagen (CTX1) index.
“We also found that the bone protective effects of blackcurrant supplementation might be different by the degree of progression of postmenopausal bone loss,” they comment.
“Our results imply that blackcurrants may reduce the risk of PMO, and, therefore, could serve as a preventive agent in women who still retain adult bone mass or as a therapeutic agent in women whose bone loss has substantially progressed.”
Source: Nutrients
Published online, November 23, 2022: http://doi.org/10.3390/nu14234971
‘Blackcurrants Reduce the Risk of Postmenopausal Osteoporosis: A Pilot Double-Blind, Randomized, Placebo-Controlled Clinical Trial’
Authors: B.M. Nosal, et al.