Abstract
Introduction
Dietary consumption of inorganic nitrate (NO3) in vegetarians has been suggested to be higher than in omnivores as the main dietary sources of this anion are vegetables. Given the potential role of NO3 in lowering blood pressure, it has been suggested that this can explain, at least partially, the lower levels of blood pressure of vegetarians compared to omnivores. However, no previous study has investigated this question. Thus, the main aim of this study was to estimate dietary NO3 consumption in vegetarians and omnivores, to analyse plasma and salivary levels of NO3 and nitrite (NO2), and to investigate whether NO3 and NO2 bioavailability in vegetarians was associated with lower blood pressure compared to omnivores.
Methods
22 healthy subjects following a vegetarian diet (V) for at least a year (16 F + 6 M) and 19 omnivores (O) (11 F + 8 M) of similar age (V= 26 ± 6; O= 26 ± 6 y/o), BMI (V= 22.9 ± 3.8; O= 22.1 ± 2.9) , gender and physical activity levels (V= 315 ± 221; O= 334 ± 208 min/week) completed this study. Following a single-blind and non-randomized protocol participants were given a mouthwash placebo (water) for one week. Additionally, they recorded all their food consumption during that week using food diaries. Dietary NO3 was estimated using the European Food Safety Authority database (European Food Safety Authority, 2008). They visited the laboratory on the seventh day in order to provide a saliva and blood sample under fasting conditions and for measurement of blood pressure in triplicate using an automated sphygmanometer. Then, participants were given antibacterial mouthwash (Corsodyl, UK) for seven more days in order to inhibit the oral NO3/NO2 pathway. They were also encouraged to replicate their food intake from the previous week. The same measurements were taken under fasting conditions on the fourteenth day.
Results
Results are expressed as mean ± SD. Dietary NO3 intake by vegetarians (97 ± 79 mg/day) was 19 mg/day higher than in omnivores (78 ± 47 mg/day), but this was not statistically different (P>0.05). Plasma NO3 (V= 43 ± 33 µM; O= 40 ± 18 µM) and NO2 (V= 84 ± 41 nM; O=74 ± 21 nM) and salivary NO3 (V= 525 ± 698 µM; O= 542 ± 571 µM) and NO2 (V= 329 ± 340 nM; O= 319 ± 283 nM) were also similar between both groups after using placebo. Blood pressure was also not different (P> 0.05) between both groups (V SBP= 104 ± 8 mmHg, DBP 64 ± 6 mmHg; O SBP= 103 ± 6 mmHg, DBP 61 ± 7 mmHg). A significant reduction (P<0.05) of plasma NO2 (V= 65 ± 15 nM; O= 61 ± 16 nM) and salivary NO2 (V= 155 ± 171 nM; O= 133 ± 214 nM) was observed in both groups after using antibacterial mouthwash, but, this was not associated with any change in blood pressure.
Conclusion
A vegetarian diet was not associated with higher dietary NO3 intake or increased NO3/NO2 bioavailability compared to a healthy omnivore diet. This study also challenges previous literature as blood pressure was not lower in vegetarians compared to omnivores in healthy and young adults.
Dietary consumption of inorganic nitrate (NO3) in vegetarians has been suggested to be higher than in omnivores as the main dietary sources of this anion are vegetables. Given the potential role of NO3 in lowering blood pressure, it has been suggested that this can explain, at least partially, the lower levels of blood pressure of vegetarians compared to omnivores. However, no previous study has investigated this question. Thus, the main aim of this study was to estimate dietary NO3 consumption in vegetarians and omnivores, to analyse plasma and salivary levels of NO3 and nitrite (NO2), and to investigate whether NO3 and NO2 bioavailability in vegetarians was associated with lower blood pressure compared to omnivores.
Methods
22 healthy subjects following a vegetarian diet (V) for at least a year (16 F + 6 M) and 19 omnivores (O) (11 F + 8 M) of similar age (V= 26 ± 6; O= 26 ± 6 y/o), BMI (V= 22.9 ± 3.8; O= 22.1 ± 2.9) , gender and physical activity levels (V= 315 ± 221; O= 334 ± 208 min/week) completed this study. Following a single-blind and non-randomized protocol participants were given a mouthwash placebo (water) for one week. Additionally, they recorded all their food consumption during that week using food diaries. Dietary NO3 was estimated using the European Food Safety Authority database (European Food Safety Authority, 2008). They visited the laboratory on the seventh day in order to provide a saliva and blood sample under fasting conditions and for measurement of blood pressure in triplicate using an automated sphygmanometer. Then, participants were given antibacterial mouthwash (Corsodyl, UK) for seven more days in order to inhibit the oral NO3/NO2 pathway. They were also encouraged to replicate their food intake from the previous week. The same measurements were taken under fasting conditions on the fourteenth day.
Results
Results are expressed as mean ± SD. Dietary NO3 intake by vegetarians (97 ± 79 mg/day) was 19 mg/day higher than in omnivores (78 ± 47 mg/day), but this was not statistically different (P>0.05). Plasma NO3 (V= 43 ± 33 µM; O= 40 ± 18 µM) and NO2 (V= 84 ± 41 nM; O=74 ± 21 nM) and salivary NO3 (V= 525 ± 698 µM; O= 542 ± 571 µM) and NO2 (V= 329 ± 340 nM; O= 319 ± 283 nM) were also similar between both groups after using placebo. Blood pressure was also not different (P> 0.05) between both groups (V SBP= 104 ± 8 mmHg, DBP 64 ± 6 mmHg; O SBP= 103 ± 6 mmHg, DBP 61 ± 7 mmHg). A significant reduction (P<0.05) of plasma NO2 (V= 65 ± 15 nM; O= 61 ± 16 nM) and salivary NO2 (V= 155 ± 171 nM; O= 133 ± 214 nM) was observed in both groups after using antibacterial mouthwash, but, this was not associated with any change in blood pressure.
Conclusion
A vegetarian diet was not associated with higher dietary NO3 intake or increased NO3/NO2 bioavailability compared to a healthy omnivore diet. This study also challenges previous literature as blood pressure was not lower in vegetarians compared to omnivores in healthy and young adults.
| Original language | English |
|---|---|
| Title of host publication | 23rd Annual Congress of the European College of Sport Science, 4th - 7th July 2018, Dublin - Ireland |
| Subtitle of host publication | Book of Abstracts |
| Editors | M. Murphy, C. Boreham, G. De Vito, E. Tsolakidis |
| Place of Publication | Cologne |
| Publisher | European College of Sport Science |
| Pages | 132 |
| Number of pages | 1 |
| ISBN (Print) | 9783981841411 |
| Publication status | Published - Jul 2018 |
| Event | 23rd Annual Congress of the European College of Sport Science: Sport Science at the Cutting Edge - University College Dublin and Ulster University, Dublin, Ireland Duration: 4 Jul 2018 → 7 Jul 2018 http://ecss-congress.eu/2018/18/index.php (Conference website) |
Conference
| Conference | 23rd Annual Congress of the European College of Sport Science |
|---|---|
| Abbreviated title | ECSS 2018 |
| Country/Territory | Ireland |
| City | Dublin |
| Period | 4/07/18 → 7/07/18 |
| Internet address |
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