The old Popeye spinach trick has been used for decades as a way of parents and grandparents to convince children that eating their greens would help them grow muscles. Now, a new study has now found this could also be the case for older members of the community. In fact, eating just one cup of leafy green vegetables rich in nitrate per day may help maintain muscle strength and mobility into old age.
The latest study, conducted by Australian researchers from Edith Cowan University and published in the Journal of Cachexia, Sarcopenia and Muscle, followed the diets of 1,420 West Australian women aged over 70. Participants who consumed more nitrate-rich vegetables including spinach, rocket and lettuce had significantly better muscle strength and physical function.
For the purpose of the study, muscle strength was assessed by measuring participant’s grip strength, while physical function was quantified using the timed-up-and-go (TUG) test. The TUG test assesses how long it takes to rise from a chair, walk three metres then return to the chair to sit down.
In older age, a decline in muscle strength and physical function are associated with a bigger risk of disability and more worrying, premature death. Researchers found a 1kg decline over 12 months in grip strength is linked with a 33 per cent increased mortality risk, while each second slower in TUG time increases mortality risk by 8 per cent over three years.
“Poor strength and function are also associated with other adverse outcomes such as falls and fractures, which substantially compromise an individual’s independence,” lead researcher Marc Sim said in a statement. “In our study we found that eating one cup of spinach, rocket or lettuce a day may increase grip strength by up to 2 kg and improve TUG time by up to 1.6 seconds.”
Researchers aren’t yet clear how nitrate works to positively influence muscle function, but believe it could improve vascular function and blood flow.
“We know from previous research that nitric oxide is a vasodilator, which means that it widens your blood vessels, potentially allowing greater blood flow to your muscles. In fact, nitrate supplements are used by athletes to improve endurance and performance,” Sim added. “It could be that higher daily nitrate intake consistently increases muscle blood flow, thereby facilitating musculoskeletal health.”
The next step for researchers is to conduct an intervention study to evaluate exactly how nitrate-rich vegetable consumption influences muscle function. If found to have health benefits, nitrate would be used to inform future dietary recommendations.
The latest study follows previous research which has linked nitrate-rich vegetables to a lower risk of death from stroke and heart disease. A 2017 study by Edith Cowan University found risk of heart disease and stroke could be reduced by as much as 40 per cent by adding more greens such as spinach, lettuce, and kale to diets. Equally, radish, beetroot, and celery were also high in nitrate. Around 75 g per day (equal to one cup) of green leafy vegetables would provide enough nitrate to achieve these health benefits.