Association between the content of intracellular and extracellular fluid and the amount of water intake among Chinese college students

BACKGROUND: Normal distribution of body fluid is important for maintaining health through the balance of water metabolism. Studies have shown that disease states and diuretics perturb the balance and then induce abnormal intracellular/extracellular fluid ratio. However, there are relatively few researches on the associations between water intakes and body fluid. The objective of this study was to explore the association between body fluid and water intake. METHODS: A total of 159 young adults in Baoding, China were recruited in this cross-sectional survey and completeness of follow-up was 98.1%. A 7-day fluid specific diary was used to record total fluid intake (TFI). Water intake from foods (FWI) for 3 days was measured using the methods of weighting, duplicate portion method and laboratory analysis by researchers. Body fluid was measured using bioelectrical impedance analysis. RESULTS: Total body water (TBW), intracellular fluid (ICF) and extracellular fluid (ECF) of participants were 32.8[28.0,39.2], 20.5[17.3,24.5] and 12.4[10.7,14.7], (kg). This represented 55.2 ± 6.2, 34.4 ± 4.0 and 20.8 ± 2.3 (%) of body weight (BW), respectively. ICF, ECF and TBW among male participants who drank more than or equal to adequate TFI was higher than those who drank less (Z = -1.985, p = 0.047; Z = -2.134, p = 0.033; Z = -2.053, p = 0.040). Among both males and females, the values of TBW/BW in participants whose TWI met or exceeded the AI were higher than those with TWI less than AI (t = − 2.011, p = 0.046; t = − 2.716, p = 0.008). Among all participants, there was moderate correlation between water intakes (TFI/BW, FWI/BW and TWI/BW) and body fluid (ICF/BW,ECF/BW and TBW/BW) (p < 0.01 for all). Same correlations were found among both males and females. CONCLUSION: There is a certain degree of association between water intake and body fluid. However, whether TFI or TWI achieve AI or not do not disturb the balance on the distribution of body fluid. More studies should be conducted to find the diagnostic threshold on TFI and TWI which may disrupt the distribution of body fluid so as to prevent related diseases. TRIAL REGISTRATION: Chinese clinical trial registry. Name of the registry: Relationship of drinking water and urination. Trial registration number: ChiCTR-ROC-17010320. Date of registration: 01/04/2017. URL of trial registry record: http://www.chictr.org.cn/edit.aspx?pid=17601&htm=4.