1545 THE EFFECTS OF DIETARY NITRATE SUPPLEMENTATION ON PHYSICAL PERFORMANCE IN OLDER PEOPLE – A SYSTEMATIC REVIEW

Abstract Background Dietary nitrate (inorganic nitrate) supplementation has been proposed as an intervention to improve muscle function via increased nitric oxide (NO) availability. Although some studies show benefit in younger adults, the effects in older people are unclear. This systematic review evaluated the effects of dietary nitrate supplementation on physical performance and muscle strength measures in older people. Method The review was conducted according to a prespecified protocol by two reviewers. We included interventional studies using dietary nitrate supplementation, mean participant age 60 and over, with or without sarcopenia or impaired physical performance. Outcomes of interest were physical performance and measures of muscle strength and mass. Risk of bias was assessed using a structured tool. Results were grouped by intervention and outcome measures and were described by narrative synthesis. Results Our search strategy found 1174 titles; 25 studies were included in the review. Study size ranged from 8 to 72 participants. Data on baseline functional status were not available, but 7 studies were in healthy older adults. The intervention duration ranged from a single dose to twelve weeks. Most studies had high or unclear risk of bias; three had low risk of bias. One hundred and nineteen outcomes were reported; 62 were physical performance measures and 57 were muscle strength measures. Twenty-nine outcomes showed significant improvement, two showed significant worsening and 88 showed no statistically significant difference. Results that showed significant improvement did not group together under any particular outcome measure, supplementation product or duration. Meta-analysis was not possible due to heterogeneity of populations, intervention duration and outcome measures. Conclusion Current evidence suggests that increasing intake of dietary nitrates may be beneficial for physical performance and muscle strength in older people, however data are limited. Future studies should be longer, larger and target older people with sarcopenia or impaired physical performance.