A higher dietary intake of nitrate — a substance found primarily in vegetables, including many leafy green vegetables — was linked to better leg muscle function in a study published in the Journal of Nutrition.
As noted in an article on the study at Medical Dialogues, muscle function — and especially leg muscle function — is a predictor of whether older adults experience falls and fractures, in addition to being important for general mobility and daily activities. Both type 1 and type 2 diabetes are linked to a higher risk of falling, for reasons that may include vision difficulties, neuropathy affecting the legs, and weakness due to blood glucose fluctuation.
In the new study, 3,759 participants in the Australian Diabetes, Obesity, and Lifestyle Study had their dietary habits assessed over a period of 12 years using a detailed food frequency questionnaire. Based on these responses, researchers calculated their estimated dietary nitrate intake. Participants had their muscle function assessed through two different measures — knee extension strength and the 8-foot time up-and-go test (which measures how long it takes a person to stand from a seated position, walk around a marker 8 feet away, and return to their seat). The researchers then compared dietary nitrate intake with these measures of muscle strength.
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The overall median nitrate intake among participants was 65 milligrams per day, 81% of which came from vegetables. Participants in the top third of nitrate intake — with a median daily intake of 91 milligrams — performed better on both measures of muscle function than those in the bottom third, whose median daily nitrate intake was 47 milligrams. Compared with the bottom third, those in the top third had an average greater knee extension strength of 2.6 kilograms (5.7 pounds) — 11% greater — and an average faster 8-foot timed up-and-go test result 0.24 seconds, or 4%, faster. Similarly, those in the top third for nitrate intake were 31% less likely to have a knee extension strength measurement that fell in the “weak” category, and 37% less likely to have an 8-foot timed up-and-go test result that fell in the “slow” category.
Importantly, the researchers also found that physical activity — as self-reported by participants — did not affect the relationship between nitrate intake and muscle function. In other words, getting more exercise couldn’t make up for the lower muscle function linked to a lower dietary nitrate intake.
The researchers concluded that a higher intake of nitrate from vegetables “could be an effective way to promote lower-limb muscle strength and physical function in men and women.” As noted in a BBC article, nitrate-rich vegetables include spinach, arugula, celery, beets and carrots.
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