Assessment of dietary nitrate intake in humans: a systematic review

Abstract

Background The nitrate content of foods and water is highly variable, which has implications for the compilation of food-composition databases and assessment of dietary nitrate intake. Objective A systematic review was conducted to ascertain the dietary assessment methods used and to provide estimates of daily nitrate intake in humans. Design Relevant articles were identified by a systematic search of 3 electronic databases (PubMed, Web of Science, and Embase) from inception until February 2018. Observational studies conducted in adult populations and reporting information on dietary assessment methods and daily nitrate intake were included. Ecological analyses were conducted to explore the association of nitrate intake with indexes of economic development [Gross Domestic Product (GDP) and KOF Index of Globalization]. Results A total of 55 articles were included. Forty-two studies investigated associations between nitrate intake and disease risk; 36 (87%) of these studies examined the association between nitrate intake and cancer risk, whereas only 6 studies explored the association of nitrate intake with the risk of diabetes, glaucoma, kidney failure, hypertension, and atherosclerotic vascular disease. The majority of studies used food-frequency questionnaires to assess nitrate intake (n = 43). The median daily nitrate intakes in healthy and patient populations were 108 and 110 mg/d, respectively. We found a significant inverse correlation of nitrate intake with GDP (r = −0.46, P < 0.001) and KOF index (r = −0.31, P = 0.002). Conclusions The median estimated daily nitrate intakes by healthy and patient populations were similar, and these values were below the safe upper intake of daily intake (3.7 mg nitrate ion/kg body weight). However, there is considerable heterogeneity in the application of food-composition tables, which may have implications for the accuracy of estimated daily nitrate intake. The association between nitrate intake and risk of cardiometabolic diseases needs further investigation. The protocol for this systematic review has been registered in the PROSPERO database (https://www.crd.york.ac.uk/prospero; CRD number: 42017060354).

Knowledge and beliefs about dietary inorganic nitrate among UK-based nutrition professionals: development and application of the KINDS online questionnaire

“…Questions where current evidence is ambiguous or where there is no correct response (ie, the answer reflects a belief or opinion on inorganic nitrate) were not included in the Index. Recently published systematic reviews and meta-analyses were used to inform these decisions 17 24 30 31…”

Dietary nitrate and population health: a narrative review of the translational potential of existing laboratory studies

“…It is possible that supplemental NO 3 − is ineffective at eliciting meaningful physiological changes in individuals habitually consuming a high NO 3 − diet. Nevertheless, as population intake of NO 3 − is typically low — Babateen et al [ 93 ] reported a median intake of 108 mg/d in healthy individuals. With very few individuals regularly consuming NO 3 − levels to match those provided through supplementation [ 160 ], high habitual NO 3 − intake is unlikely to explain a lack of response to NO 3 − supplementation in most ‘non-responders’.…”

“…Indeed, an investigation conducted on behalf of the WHO in 2004 found no exposure-response relationship between dietary NO 3 − and methemoglobinemia in infants [ 193 ]. It is also worth noting that although some studies report mild adverse symptoms with high NO 3 − intake such as nausea and sickness, to the authors knowledge, no serious adverse events have ever been reported in clinical trials administering NO 3 − [ 1 , 93 ].…”

In vivo and ex vivo impact of nutritional xenobiotics – acrylamide and sodium nitrates – on plasma antioxidant properties

“…It is known that the antioxidant capacity changes under exposure to various xenobiotics, as well as those derived from foods [21]. The general toxic effects of ACR and SN (V) and (III), and nutritional questionnaires on the intake of these substances in the diet are relatively numerous and well-known [20,22,23,24], but there is still a lack of data evaluating the impact of these compounds on the total cellular pool of free thiols in blood plasma. The aim of this study was to estimate the influence of ACR and SN (V) and (III), derived from the diet, on the total pool of free thiols in blood plasma in young healthy people.…”