Jonvik Kristin L, Nyakayiru Jean, van Dijk Jan-Willem, Wardenaar Floris C, van Loon Luc J C, Verdijk Lex B
Int J Sport Nutr Exerc Metab. 2017 Apr;27(2):148-157. doi: 10.1123/ijsnem.2016-0239. Epub 2016 Oct 21.
Although beetroot juice, as a nitrate carrier, is a popular ergogenic supplement among athletes, nitrate is consumed through the regular diet as well. We aimed to assess the habitual dietary nitrate intake and identify the main contributing food sources in a large group of highly trained athletes. Dutch highly trained athletes (226 women and 327 men) completed 2-4 web-based 24-hr dietary recalls and questionnaires within a 2- to 4-week period. The nitrate content of food products and food groups was determined systematically based on values found in regulatory reports and scientific literature. These were then used to calculate each athlete's dietary nitrate intake from the web-based recalls. The median[IQR] habitual nitrate intake was 106[75-170] mg/d (range 19-525 mg/d). Nitrate intake correlated with energy intake (ρ = 0.28, p < .001), and strongly correlated with vegetable intake (ρ = 0.78, p < .001). In accordance, most of the dietary nitrate was consumed through vegetables, potatoes and fruit, accounting for 74% of total nitrate intake, with lettuce and spinach contributing most. When corrected for energy intake, nitrate intake was substantially higher in female vs male athletes (12.8[9.2-20.0] vs 9.4[6.2-13.8] mg/MJ; p < .001). This difference was attributed to the higher vegetable intake in female vs male athletes (150[88-236] vs 114[61-183] g/d; p < .001). In conclusion, median daily intake of dietary nitrate in highly trained athletes was 106 mg, with large interindividual variation. Dietary nitrate intake was strongly associated with the intake of vegetables. Increasing the intake of nitrate-rich vegetables in the diet might serve as an alternative strategy for nitrate supplementation.
尽管甜菜根汁作为一种硝酸盐载体，是运动员中一种受欢迎的提高运动能力的补充剂，但硝酸盐也可通过日常饮食摄入。我们旨在评估大量训练有素的运动员的习惯性膳食硝酸盐摄入量，并确定主要的食物来源。荷兰训练有素的运动员（226名女性和327名男性）在2至4周内完成了2至4次基于网络的24小时膳食回顾和问卷调查。根据监管报告和科学文献中的数据，系统地确定了食品和食物组的硝酸盐含量。然后将这些数据用于根据基于网络的回顾计算每位运动员的膳食硝酸盐摄入量。习惯性硝酸盐摄入量的中位数[四分位间距]为106[75 - 170]mg/天（范围19 - 525mg/天）。硝酸盐摄入量与能量摄入量相关（ρ = 0.28，p <.001），并且与蔬菜摄入量密切相关（ρ = 0.78，p <.001）。相应地，大部分膳食硝酸盐通过蔬菜、土豆和水果摄入，占总硝酸盐摄入量的74%，其中生菜和菠菜贡献最大。校正能量摄入量后，女性运动员的硝酸盐摄入量显著高于男性运动员（12.8[9.2 - 20.0] vs 9.4[6.2 - 13.8]mg/MJ；p <.001）。这种差异归因于女性运动员比男性运动员摄入更多的蔬菜（150[88 - 236] vs 114[61 - 183]g/天；p <.001）。总之，训练有素的运动员膳食硝酸盐的每日摄入量中位数为106mg，个体间差异较大。膳食硝酸盐摄入量与蔬菜摄入量密切相关。增加饮食中富含硝酸盐的蔬菜摄入量可能是补充硝酸盐的一种替代策略。
