The inorganic anions nitrate and nitrite are oxidation products from endogenous nitric oxide (NO) generation and constituents in our diet. A nitrate-nitrite-NO pathway exists in which nitrate can be serially reduced to bioactive NO. The first step of this pathway occurs in the oral cavity where oral bacteria convert salivary nitrate to nitrite, whereafter nitrite is reduced to NO systemically by several enzymatic and non-enzymatic pathways. Data are scarce regarding salivary levels and oral conversion capacity of these anions in infants. We measured salivary nitrate and nitrate in infants at 4 and 12 months of age and related values to age, sex, dietary pattern and oral microbiome. Saliva was collected from a total of 188 infants at 4 and 12 months of age. Salivary nitrate, nitrite and nitrite/nitrate ratio as a measure of oral nitrate-reducing capacity were analyzed by HPLC and related to age, sex, type of diet (breast milk or formula) and oral microbiome. There was no difference in salivary nitrate, nitrite or nitrite/nitrate ratio between boys and girls at any age. At 4 months levels of these parameters were lower than what has been described in adults but they had all increased significantly at 12 months of age. At 4 months of age salivary nitrite/nitrate ratio was lower in breast-fed compared to formula-fed infants, but these differences disappeared at 12 months. Several bacterial species were associated with oral nitrate reducing capacity including Prevotella, Veillonella, Alloprevotella and Leptotrichia. We conclude that in infants there is an increase in salivary nitrate and nitrite as well as in oral nitrate-reductase capacity during the first year of life. Differences observed at 4 months of age between breast-fed and formula-fed infants disappear at one year of age.

中文翻译：

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年龄，性别和饮食对婴儿唾液硝酸盐和亚硝酸盐的影响。

无机阴离子硝酸根和亚硝酸根是内源性一氧化氮（NO）生成的氧化产物，也是我们饮食中的成分。存在硝酸盐-亚硝酸盐-NO途径，其中硝酸盐可连续还原为生物活性NO。该途径的第一步发生在口腔中，其中口腔细菌将唾液硝酸盐转化为亚硝酸盐，此后亚硝酸盐通过几种酶促途径和非酶促途径被系统还原为NO。关于婴儿中这些阴离子的唾液水平和口服转化能力的数据很少。我们测量了4个月和12个月大婴儿的唾液硝酸盐和硝酸盐含量，以及与年龄，性别，饮食模式和口腔微生物组有关的值。从4和12个月大的188名婴儿中收集唾液。唾液硝酸盐 通过HPLC分析了亚硝酸盐和亚硝酸盐/硝酸盐比率作为衡量口服硝酸盐还原能力的指标，并且与年龄，性别，饮食类型（母乳或配方奶）和口腔微生物组有关。男孩和女孩在任何年龄段的唾液硝酸盐，亚硝酸盐或亚硝酸盐/硝酸盐比率均无差异。在第4个月时，这些参数的水平低于成人所描述的水平，但在12个月大时均显着增加。与配方奶粉婴儿相比，母乳喂养的婴儿唾液中亚硝酸盐/硝酸盐比率在4个月时要低，但这些差异在12个月时消失。几种细菌与口服硝酸盐的还原能力有关，包括普雷沃氏菌，韦永氏菌，异位丙酸杆菌和细小球藻。我们得出的结论是，婴儿在出生后的第一年中唾液中的硝酸盐和亚硝酸盐含量以及口服硝酸盐还原酶的含量都会增加。母乳喂养婴儿和配方喂养婴儿在4个月大时观察到的差异在1岁时消失。