British Journal of Nutrition

Full Papers

Dietary Surveys and Nutritional Epidemiology

Fractional urinary fluoride excretion of 6–7-year-old children attending schools in low-fluoride and naturally fluoridated areas in the UK

F. V. Zohooria1 c1, R. Wallsa2, L. Teasdalea3, D. Landesa3, I. N. Steena4, P. Moynihana2a5a6, N. Omida1 and A. Maguirea2

a1 School of Health and Social Care, Teesside University, Middlesbrough TS1 3BA, UK

a2 Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, UK

a3 County Durham Primary Care Trust, County Durham, UK

a4 Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK

a5 Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK

a6 Human Nutrition and Research Centre, Newcastle University, Newcastle upon Tyne, UK


F is an important trace element for bones and teeth. The protective effect of F against dental caries is well established. Urine is the prime vehicle for the excretion of F from the body; however, the relationship between F intake and excretion is complex: the derived fractional urinary F excretion (FUFE) aids understanding of this in different age groups. The present study aimed to investigate the relationships between (1) total daily F intake (TDFI) and daily urinary F excretion (DUFE), and (2) TDFI and FUFE in 6–7-year-olds, recruited in low-F and naturally fluoridated (natural-F) areas in north-east England. TDFI from diet and toothbrushing and DUFE were assessed through F analysis of duplicate dietary plate, toothbrushing expectorate and urine samples using a F-ion-selective electrode. FUFE was calculated as the ratio between DUFE and TDFI. Pearson's correlation and regression analysis were used to investigate the relationship between TDFI and FUFE. A group of thirty-three children completed the study; twenty-one receiving low-F water (0·30 mg F/l) and twelve receiving natural-F water (1·06 mg F/l) at school. The mean TDFI was 0·076 (sd 0·038) and 0·038 (sd 0·027) mg/kg per d for the natural-F and low-F groups, respectively. The mean DUFE was 0·017 (sd 0·007) and 0·012 (sd 0·006) mg/kg per d for the natural-F and low-F groups, respectively. FUFE was lower in the natural-F group (30 %) compared with the low-F group (40 %). Pearson's correlation coefficient for (1) TDFI and DUFE was +0·22 (P= 0·22) and for (2) TDFI and FUFE was − 0·63 (P< 0·001). In conclusion, there was no correlation between TDFI and DUFE. However, there was a statistically significant negative correlation between FUFE and TDFI.

(Received March 01 2011)

(Revised July 12 2012)

(Accepted July 12 2012)

(Online publication September 14 2012)

Key Words:

  • Fluoride;
  • Urinary excretion;
  • Dietary intake


c1 Corresponding author: F. V. Zohoori, fax +44 1642 342770, email


  Abbreviations: BW, body weight; DUFE, daily urinary fluoride excretion; FUFE, fractional urinary fluoride excretion; TDFI, total daily fluoride intake