Effects of Chewing Gum on Nitric Oxide Metabolism, Markers of Cardiovascular Health and Neurocognitive Performance after a Nitrate-Rich Meal

Abstract

Objectives

Cardiovascular and neurocognitive responses to chewing gum have been reported, but the mechanisms are not well understood. Chewing gum after a nitrate-rich meal may upregulate the reduction of oral nitrate to nitrite and increase nitric oxide (NO), a molecule important to cardiovascular and neurocognitive health. We aimed to explore effects of chewing gum after a nitrate-rich meal on nitrate metabolism (through the enterosalivary nitrate-nitrite-NO pathway), endothelial function, blood pressure (BP), neurocognitive performance, mood and anxiety.

Methods

Twenty healthy men (n = 6) and women (n = 14) with a mean age of 48 years (range: 23–69) were recruited to a randomized controlled cross-over trial. After consumption of a nitrate-rich meal (180 mg of nitrate), we assessed the acute effects of chewing gum, compared to no gum chewing, on (i) salivary nitrate, nitrite and the nitrate reductase ratio (100 x [nitrite]/([nitrate] + [nitrite]); (ii) plasma nitrite, S-nitrosothiols and other nitroso species (RXNO); (iii) endothelial function (measured by flow mediated dilatation); (iv) BP; (v) neurocognitive performance; (vi) mood; and (vii) anxiety.

Results

Consumption of the nitrate-rich meal resulted in a significant increase in markers of nitrate metabolism. A significantly higher peak flow mediated dilatation was observed with chewing compared to no chewing (baseline adjusted mean difference: 1.10%, 95% CI: 0.06, 2.14; p = 0.038) after the nitrate-rich meal. A significant small increase in systolic BP, diastolic BP and heart rate were observed with chewing compared to no chewing after the nitrate-rich meal. The study did not observe increased oral reduction of nitrate to nitrite and NO, or improvements in neurocognitive performance, mood or anxiety with chewing compared to no chewing.

Conclusion

Chewing gum after a nitrate-rich meal resulted in an acute improvement in endothelial function and a small increase in BP but did not result in acute effects on neurocognitive function, mood or anxiety.

Keywords:

• Chewing
• gum
• nitrate
• nitrite
• nitric oxide
• endothelial function
• blood pressure
• cognition

Acknowledgments

The authors would like to thank Ms Adeline Indrawan for technical assistance, Ms Lisa Rich for performing and analysing the FMDs, and Mr Claude Backory for nursing assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Funding sources

A/Prof Downey is supported by a National Health and Medical Research Council R.D. Wright Biomedical Career Development Fellowship (CDF: 2017-2020). The salary of LCB is supported by a National Health and Medical Research Council of Australia Emerging Leadership Investigator Grant (ID: 1172987) and a National Heart Foundation of Australia Post-Doctoral Research Fellowship (ID: 102498). NPB is funded by a National Health and Medical Research Council Early Career Fellowship (Grant number APP1159914), Australia. JMH was funded by a National Health and Medical Research Council Senior Research Fellowship. This work was funded by a grant from the Wrigley Science Institute to AS.