The potential of salivary biomarkers of nutritional status and dietary intake: A Systematic Review

Objectives: To explore whether nutritional salivary biomarkers could be used to aid nutritional status assessment and/or support traditional dietary assessment methods for patients. Data and Sources: Searches were performed using four electronic databases; MEDLINE, EMBASE, Scopus and Web of Science. Trial registers (i.e. Cochrane), grey literature and reference lists were searched. Study Selection: Studies which measured nutritional salivary biomarkers related to nutritional status and/or dietary intake outcome were included. No restrictions on participants' age, study design, publication date, setting or health status. Animal studies, non-English language studies, commentaries, and conference abstracts were excluded. Results: Study titles and abstracts were screened (n = 7982), full-texts assessed (n = 176) and 85 studies were included in a narrative synthesis. The most promising salivary biomarkers for nutritional status included: glucose, where saliva and serum levels were positively correlated in those with type 2 diabetes (T2D), higher salivary calcium levels in post-menopausal women in general and specifically those with lower bone mineral density (BMD), and salivary vitamin D to assess vitamin D status in healthy volunteers. Higher salivary total antioxidant capacity (TAC), nitrate/nitrite and fluoride were observed with increased antioxidant, nitrate/nitrite and fluoride dietary intake, respectively. A meta-analysis found significantly higher mean salivary glucose (n = 12) in T2D compared with healthy controls, but there was substantial heterogeneity (I2=94%) and evidence of publication bias. Conclusions: The most promising salivary biomarkers identified in this systematic review were, glucose, vitamin D, calcium, TAC, nitrate/nitrite and fluoride. However, this was based on a small number of studies of varying quality, with many lacking a salivary assay performance assessment. Clinical Significance: At present, nutritional salivary biomarkers cannot be used alone to assess nutritional status or dietary intake. Further research into the most promising nutritional salivary biomarkers is required.

Automated summary

The study explores the potential of nutritional salivary biomarkers in aiding nutritional status assessment, with promising results in biomarkers such as glucose, vitamin D, calcium, TAC, nitrate/nitrite, and fluoride. However, further research on these biomarkers is needed due to limited studies and varied quality.