Researchers in Brazil and the United States explored whether 12 weeks of nitrate-rich beetroot extract, Sabeet, could improve muscle quality, strength and neuromuscular performance in 20 postmenopausal women between the ages of 60 and 85.
“Findings suggest potential clinical relevance for preventing age-related structural and neuromuscular functional decline in postmenopausal women,” they wrote.
Muscle function and sarcopenia in postmenopausal women
Aging reduces muscle quality and strength while increasing the risk of sarcopenia, contributing to frailty and reduced physical function in older adults. Furthermore, the loss of muscle mass also impairs muscle quality.
Postmenopausal women face a greater risk of decline because reduced estrogen disrupts multiple mechanisms that maintain muscle. Aging also weakens neuromuscular function and reduces the rate of force development (RFD), which can lead to reduced mobility and increase risk of falls.
Dietary nitrate from vegetables like beetroot and spinach may help address these declines through the nitrate–nitrite–nitric oxide pathway. Nitric oxide (NO) availability improves muscle blood flow, oxygen delivery and contractile efficiency, and short-term studies have shown that beetroot juice can enhance endothelial function and muscle contractility in older adults, while longer interventions have increased circulating nitrate levels while improving muscle strength and power in postmenopausal women.
However, as this new study noted, the existing body of research lacks long-term randomized trials that focus on postmenopausal women and clinically relevant muscle quality outcomes.
Can beetroot improve muscle health in postmenopausal women?
Participants consumed either nitrate-rich beetroot extract (548 mg nitrate/day) or a nitrate-depleted placebo twice daily. They were assessed at baseline, week eight and week 12.
The researchers measured knee extensor maximal strength and rate of force development (RFD), assessed quadriceps muscle thickness and morphological muscle quality, and calculated functional muscle quality as the ratio of maximal strength to muscle thickness. Finally, they measured blood nitrate and nitrite concentrations.
Participants who took the beetroot extract showed slight improvement in knee extensor strength over the 12 weeks, though the results were not statistically strong.
Beetroot supplementation significantly improved RFD, however. Participants taking the extract were able to generate force faster after eight and 12 weeks, while the placebo group did not improve.
Muscle thickness also increased over time in the beetroot group, although not significantly, but functional muscle quality and morphological muscle quality increased by week 12, meaning fat and fibrous tissue inside the muscle was reduced.
Finally, participants taking beetroot had much higher blood nitrate and nitrite levels, which the researchers noted confirmed that the supplement worked biologically and increased NO availability, which can improve muscle blood flow and function.
“These adaptations are likely mediated, at least in part, by enhanced nitric oxide bioavailability, which may improve muscle oxygen delivery and contractile properties,” the researchers wrote.
They added that future studies should include larger and more diverse populations and use direct measurements of muscle structure and neuromuscular function to better understand how dietary nitrate supports muscle health in aging women.
Source: Nutrients. doi: 10.3390/nu18050860. “Long-Term Beetroot Extract Supplementation Improves Morphological Muscle Quality and Rate of Force Development in Postmenopausal Women: A Randomized Clinical Trial”. Authors: O.J.F. Ramos Junior et al.
