Eating just one cup of leafy green vegetables every day could boost your muscles. Poor muscle function is linked to greater risk of falls and fractures.
Researchers at Edith Cowan University (ECU), led by Dr Marc Sim, examined data from 3,759 Australians between the ages of 25 and 85, taking part in Melbourne’s Baker Heart and Diabetes Institute AusDiab study over a 12-year period.
Food intake was estimated by a questionnaire which asked participants to record how often they ate any of 74 different foods.
Foods such as green leafy vegetables and beetroot are naturally high in nitrates. Other sources of dietary nitrate include bacon and other processed meat which are not considered part of a healthy diet.
Dr Sim said cooking reduces the nutritional value of green vegetables as nitrate if lost in the cooking water.
“I am concerned about residential aged care when vegetables tend to be boiled for a long time. To save the good stuff use the water vegetables are cooked in to make soup or for cooking rice,” he said.
The team found those people with the highest regular consumption of green leafy vegetable or beetroot had 11 per cent stronger lower limb strength and four per cent faster walking speeds than those with the lowest intake.
The greatest benefits to muscle function were observed at nitrate intakes of about 90 mg/day. This intake is easily achieved by consuming one cup of nitrate-rich green-leafy vegetables, such as spinach, lettuce or rocket daily. The relation between total nitrate intake and strength was driven predominantly by vegetable-derived nitrate as opposed to non-vegetable-based sources of nitrate.
Muscle function was measured by the strength of knee extension in participants. Walking speeds by the time it took them to get up from a chair, walk eight feet, turn and return to the chair.
Dr Sim said the findings reveal important evidence for the role diet plays in overall health.
“Our study has shown that diets high in nitrate-rich vegetables may bolster your muscle strength independently of any physical activity,” he said.
While leafy greens may be some of our least favourite vegetables, they could be the most important and provide the greatest health benefits.
“Less than one in ten Australians eat the recommended five to six serves of vegetables per day,” he said.
“We should be eating a variety of vegetables every day, with at least one of those serves being leafy greens to gain a range of positive health benefits for the musculoskeletal and cardiovascular system.
“It’s also better to eat nitrate-rich vegetables as part of a healthy diet rather than taking supplements. Green leafy vegetables also provide a whole range of essential vitamins and minerals critical for health.
“A balanced diet rich in green leafy vegetables in combination with regular exercise, including weight training, is ideal.”
Poor muscle function is a key risk factor for falls and is vital for maintaining good overall health, especially bone strength later in life.
“With around one in three Australians aged over 65 suffering a fall each year, it’s important to find ways of preventing these events and their potentially serious consequences,” said Dr Sim.
Presently, mechanisms by which nitrate improves muscle function remain unclear, although other trials have shown beetroot juice can lower blood pressure and improve vascular function.
Dr Sim said the next step of his research will be to explore strategies to increase leafy green vegetable consumption in the general population.
“We are currently recruiting for the MODEL Study, which examines how knowledge of disease can be used to prompt people in making long-term improvements to their diet and exercise,” said Dr Sim.
This research was published in the Journal of Nutrition last month.