Fluoride intake and urinary excretion in 6- to 7-year-old children living in optimally, sub-optimally and non-fluoridated areas.

OBJECTIVES: This study was designed to measure total intake, urinary excretion and estimated retention of fluoride in children under customary fluoride intake conditions, living in either fluoridated or low-fluoride areas of north-east England. Subsidiary aims were to investigate the relationships between the variables measured. METHODS: Using a randomized cluster design with schools as the sampling units, four schools from a non-fluoridated area and two from a fluoridated area were selected from the schools chosen to participate in the study. Fluoride intake from diet and toothbrushing was assessed using a 3-day food diary and fluoride analysis of expectorated saliva during toothbrushing. Samples of all foods and drinks consumed were measured for fluoride content using direct and indirect silicon-facilitated diffusion methods as appropriate. Urinary fluoride excretion and urine volume were measured over 24 h and estimation of fractional urinary fluoride excretion (FUFE) and fluoride retention made from collected data. Following descriptive analysis of variables, Pearson's correlations investigated relationships between fluoride content of home tap water, daily fluoride intake, excretion and retention. RESULTS: Thirty-three children completed the study: 18 receiving non-fluoridated water [mean = 0.08 (+/-0.03) mg F/l], nine sub-optimally fluoridated water [mean = 0.47 (+/-0.09) mg F/l] and six optimally fluoridated water [mean = 0.82 (+/-0.13) mg F/l] at the time of the study. Complete data on F intake, excretion and retention were available for 29 children. Mean fluoride intake from diet and toothpaste ranged from 0.031 (+/-0.025) mg/kg body weight (bw)/day for the low-fluoride area to 0.038 (+/-0.038) and 0.047(+/-0.008) mg/kg bw/day for sub-optimally and optimally fluoridated areas respectively. Contribution of toothpaste to total fluoride intake ranged from 3% to 93% with mean values of 57%, 35% and 47% for children receiving low, sub-optimally and optimally fluoridated water respectively. FUFE ranged from a mean of 32% (+/-13%) for the optimally fluoridated area to 44% (+/-33%) for the low-fluoride area. Fluoride retention was not correlated with the fluoride concentration of home water supply, but was strongly positively correlated (P < 0.001) with total daily fluoride intake. CONCLUSIONS: In an industrialized country, total fluoride intake, urinary excretion and consequently fluoride retention no longer reflect residence in a community with a non-fluoridated or fluoridated water supply. Fluoride toothpaste contributes a significant proportion of total ingested fluoride in children, particularly in low-fluoride areas.

The nutrition knowledge of older adults living in sheltered housing accommodation.

BACKGROUND: Nutrition knowledge enables informed dietary choices. This paper reports on the nutrition knowledge of older adults residing in sheltered housing accommodation in socially deprived areas of north-east England. METHOD: As part of a cluster randomized dietary intervention trial, a validated questionnaire measured the knowledge of current dietary recommendations, nutrient sources, ability to select healthy meal options and knowledge of associations between diet and diseases of older adults aged 60 years and over residing in sheltered accommodation. RESULTS: Completed questionnaires were obtained from 177 (59%) subjects (147 female, 30 male), of whom 76% were overweight/obese and 2% underweight. The mean (SD) age was 76.4 (8.0) years. Of a possible score of 47, the mean score was 23.2, indicating that approximately 50% of questions were answered incorrectly. Knowledge of associations between diet and diseases was particularly poor; 90% of subjects being unaware of the benefits of high fruit and vegetable consumption. Respondents in the highest 10% of the nutrition knowledge score had a significantly higher intake of fruit and vegetables compared with those in the lowest 10%. CONCLUSION: A high proportion of older adults had little basic nutrition knowledge; this presents a barrier to healthier eating that should be addressed.

Is the fluoride/creatinine ratio of a spot urine sample indicative of 24-h urinary fluoride?

OBJECTIVE: The main aim of this study was to determine how representative the fluoride/creatinine (F/Cr) ratio of a spot urinary sample is of the fluoride content of a 24-h urine sample in young children aged 12-36 months. Subsidiary objectives were to: (a) evaluate the use of 24-h urine samples in monitoring fluoride exposure and (b) estimate the retention of fluoride in very young children. METHODS: Seven healthy children residing in a fluoridated area completed the study. Dietary information was obtained using a 3-day estimated food diary followed by an interview on the fourth day. Samples of foods and drinks were analysed for fluoride content. Ingestion of fluoride from toothpaste was also measured. A 24-h urine sample and a morning spot urine sample were collected from each child. RESULTS: The mean age of the children was 32 months (range: 16-36 months). The mean total daily intake of fluoride was 0.71 (+/-0.41) mg or 0.05 (+/-0.02) mg/kg bodyweight, of which 37% came from the diet, the remainder being from toothpaste ingestion. None of the children used any other sources of fluoride such as fluoride tablets or fluoridated salt. The mean F/Cr ratio was 1.49 (+/-0.63) mg F/g creatinine. A positive correlation (Pearson's correlation=0.76, P=0.05) between fluoride excretion estimated using the F/Cr ratio in a morning spot urine sample and fluoride excretion in a 24-h urine sample was found. There was also a positive correlation (Pearson's correlation=0.83, P=0.02) between total daily fluoride intake and 24-h urinary fluoride excretion. Less than half (43%) of the total daily fluoride intake was retained in the body. CONCLUSIONS: The F/Cr ratio of a morning spot urine sample may be used to estimate mean 24-h urinary excretion of fluoride and therefore has potential application for larger-scale epidemiological studies where 24-h samples are impractical. Estimates of 24-h urinary fluoride excretion can be used to gauge fluoride exposure.

Bioavailability of fluoride in drinking water: a human experimental study.

It has been suggested that systemic fluoride absorption from drinking water may be influenced by the type of fluoride compound in the water and by water hardness. Using a human double-blind cross-over trial, we conducted this study to measure c(max), T(max), and Area Under the Curve (AUC) for plasma F concentration against time, following the ingestion of naturally fluoridated hard and soft waters, artificially fluoridated hard and soft waters, and a reference water. Mean AUC over 0 to 8 hours was 1330, 1440, 1679, 1566, and 1328 ng F.min.mL(-1) for naturally fluoridated soft, naturally fluoridated hard, artificially fluoridated soft, artificially fluoridated hard, and reference waters, respectively, with no statistically significant differences among waters for AUC, c(max), or T(max). Any differences in fluoride bioavailability between drinking waters in which fluoride is present naturally or added artificially, or the waters are hard or soft, were small compared with large within- and between-subject variations in F absorption. Abbreviations used: F, fluoride; AUC, Area under the Curve for plasma F concentration against time; AUC(0-3), Area under the Curve for plasma F concentration against time for 0 to 3 hours following water ingestion; AUC(0-8), Area under the Curve for plasma F concentration against time for 0 to 8 hours following water ingestion; c(max), maximum plasma F concentration corrected for baseline plasma F and dose (i.e., F concentration of individual waters); T(max), time of c(max).

Changes in water intake of Northumbrian adolescents 1980 to 2000.

OBJECTIVES: To determine: total water intake in young English adolescents; the relative importance of sources of water intake; and changes in water intake and sources of water between 1980 and 2000. DESIGN: A cross-sectional observational study of the diets of 11-12-year-old children attending seven schools in south Northumberland, UK. The information obtained was compared with results from a similar survey carried out 20 years previously. METHODS: All children attending these schools were invited to participate. They completed a three-day diet diary with an interview on the fourth day, on two occasions during the school year. Standard UK food composition tables were used and water intake from various sources calculated. Anthropometric and social class information was obtained. RESULTS: Four hundred and twenty-four children completed all aspects of the study (64% of those eligible). The mean total water intake was 1,130 g d(-1), approximately the same as that recorded 20 years before. Water intake in relation to energy intake: water intake was 139 g MJ(-1) in boys and 143 g MJ(-1) in girls. Sixty-five per cent of water came from drinks and 35% from foods; very similar to proportions 20 years before. The sources of water in drinks had changed considerably, with a marked increase in consumption of soft drinks (especially carbonated drinks) and a decrease in consumption of hot drinks and milk. There were a few differences between sexes but little difference between social groups. CONCLUSIONS: Total water intake was similar to that recorded 20 years previously and lower than intakes reported in other countries. Changes in the sources of water meant that less water consumed was likely to come from the tap in the house and more from drinks made elsewhere, than 20 years previously. These changes have implications for estimating fluoride intake in fluoridated areas.

Fluoride content of still bottled waters available in the North-East of England, UK.

OBJECTIVE: The aims of this study were to measure the fluoride content of still bottled waters on sale in the UK and to estimate and compare the fluoride intake from tap and bottled water for British children. METHODS: Three bottles of 25 commercial brands of bottled water were purchased from supermarkets, grocery stores and health shops in the North-East of England. All samples were still spring, mineral or distilled waters, sold in plastic bottles. The fluoride content of all samples was determined, in duplicate, using a Fluoride Ion Selective Electrode. RESULTS: The mean (+/- SD) fluoride content of the bottled waters was 0.08 (+/- 0.08) mg L(-1) with a range from 0.01-0.37 mg L(-1) which is below the accepted standard for optimally fluoridated water. The mean fluoride intake for 4-18-year-olds when the source of water intake is solely fluoridated tap water was estimated to be 0.26 mg F per day; compared with 0.16 mg F per day, when a combination of tap and bottled water is consumed. CONCLUSIONS: Bottled water, from those sampled, is unlikely to make an important contribution to total fluoride intake in British diets. Consumption of bottled water containing a negligible amount of fluoride in preference to fluoridated tap water might result in less than optimal fluoride ingestion in young people.

Sources of dietary fluoride intake in 4-year-old children residing in low, medium and high fluoride areas in Iran.

Accurate estimation of fluoride dietary intake is desirable for optimising caries prevention. Little is known about the dietary fluoride intake of children aged 4 years, an age when many permanent teeth are forming. This study was undertaken in Fars Province, Iran, in 1995-1996, where there are big differences in temperature between winter and summer. The aims were to determine: (a) the relative contributions of different components of the diet to fluoride intake, (b) the effect of variation in fluoride concentration in drinking water, and (c) the effect of climate temperature. Temperature varied between +40 degrees C in summer to -5 degrees C in winter. The mean fluoride concentrations in drinking water in the three areas were 0.3, 0.6 and 4.0 mgF/L. Dietary information was obtained by two 3-day diet diaries with interview, validated with reference to international standards. The fluoride content of foods was measured using the silicon-facilitated diffusion method. One hundred and three 4-year-old children completed the study. The mean (and 95% confidence interval) dietary fluoride intakes in each of the three areas, respectively, were 413 (+/- 21), 698 (+/- 89) and 3472 (+/- 557) micrograms/day. Drinks provided 72 to 87% of dietary fluoride--this proportion increased with increasing water fluoride concentration and increasing climate temperature. Tea (infusion) was an important source of dietary fluoride, providing 31 to 38% of total dietary intake. Tap water was a more important source of fluoride than soft drinks. Cooked rice and bread were the most important food source of fluoride and the amount of fluoride they contributed increased as water fluoride concentration increased. The results of this first such survey in the Middle East showed (a) that water (as a drink) and tea were by far the most important contributors to dietary fluoride intake, (b) substantial increases in fluoride intake with increasing water fluoride concentrations, and (c) substantially higher fluoride intakes in summer than in the winter.

Total fluoride intake and urinary excretion in 4-year-old Iranian children residing in low-fluoride areas.

Knowledge of levels of fluoride ingestion and excretion is important in planning optimum fluoride therapy for young children. In previous literature, it has been assumed that only about one-third of ingested fluoride is excreted in young children. The aims of the present study were (a) to measure total fluoride intake, urinary fluoride excretion and fluoride balance, and (b) to investigate the effect of air temperature on fluoride intake and urinary fluoride excretion, in young children. Children (4 years old) living in a city, a small town and rural areas of Fars province, Iran, where drinking water contained 0.30-0.39 mg F/l, were invited to participate. Selection of subjects was by random sampling of kindergartens or health centres. The children were surveyed twice, once in summer and once in winter. Diet was obtained by 3 d diaries with interview. Samples of most foods and drinks were analysed for fluoride content. Ingestion of fluoride from toothpaste was estimated for each child. Each child's urine was collected over 24 h and analysed for fluoride content. Seventy-eight of the 116 volunteers completed all aspects of the study, which was conducted in 1995-6. For all children, the mean fluoride ingestion from diet was 0.390 (SD 0.122) mg/d or 0.028 (SD 0.008) mg/kg body weight per d. Fluoride ingestion from diet was higher in summer and higher in rural areas. The mean ingestion of fluoride from all sources was 0.426 (SD 0.126) mg/d and the mean fluoride urinary excretion was 0.339 (SD 0.100) mg/d. The difference between ingestion and urinary excretion was +0.087 (SD 0.143) mg, equivalent to 80% excretion. Faecal excretion was not estimated. The results indicate fluoride retention at 4 years to be much lower than previously assumed.

Fluoride concentration in foods from Iran.

Knowledge of fluoride intake is important in optimizing the caries-preventive role of fluoride, and the measurement of fluoride intake usually requires information on the fluoride concentration in foods and drinks. Most information comes from developed countries and there are no data on fluoride concentration in foods in Middle Eastern countries including Iran. The aim of the study was to: (a) describe a modification to the silicon-facilitated diffusion method for determining fluoride concentration, (b) provide information on fluoride content of foods in Iran to supplement food tables for the Middle East, and (c) determine the effect of variation in the fluoride concentration of drinking water on the fluoride concentration of prepared foods. Five hundred and ten samples of 84 popular foods and drinks were collected from three areas of Iran where water fluoride concentrations were 0.32, 0.58 and 4.05 mg/L. The mean recovery of fluoride added to food samples before diffusion was 98 +/- 5%. Values for duplicate analysis of 20 food samples were within 0.03 microgram F/g. Most of the samples of foods and drinks came from the area with 0.32 mg F/L in water supplies. For 30 of the 84 items, fluoride concentration was below 0.1 microgram/g. Fluoride concentrations in the cereals group (which constituted much of the diet) were mainly between 0.2 and 0.3 microgram/g, when prepared for consumption. It was concluded that: (a) modification of a published method for determining fluoride concentration of foods appeared to be an advance, (b) values for fluoride concentration of foods commonly consumed in Iran showed variation between groups but were in broad agreement with published data, and (c) concentration of fluoride in water influences positively fluoride concentration in foods cooked in water, but the increase in foods was less than the increase in fluoride concentration in water.