A study commissioned by the UK Department of Health from researchers at the University of Newcastle found no statistically significant difference between the bioavailability of fluoride ingested from artificially fluoridated water and fluoride ingested from naturally fluoridated water. (1)

Bioavailability is measured by the amount of an ingested substance that reaches the bloodstream and the amount that is excreted in the urine.

In addition, the team found no difference in blood plasma fluoride concentrations between individuals who had consumed hard water and those who had consumed soft water.

The study, completed in 2004, involved 20 healthy young adults, with an average age of 25, whose blood fluoride concentrations were measured after they had consumed artificially and naturally fluoridated water samples from four different sources, all containing approximately one part per million of fluoride.  Two were soft waters and two were hard.

The tests were conducted ‘blind’, with neither the subjects nor the researchers knowing which of the four waters had been consumed by whom.

Fluoride levels in blood plasma and urine following ingestion of these different waters were  compared with the levels following ingestion of a ‘standard reference’ water.

During the experiment the subjects all ate the same low fluoride meals and used fluoride-free toothpaste.

In their conclusions, the researchers acknowledged the relatively small number of participants in the study and suggested that any future studies might benefit from a larger sample size.  Nevertheless, they point to the absence of any statistically significant differences in bioavailability between the fluoridated and non-fluoridated waters used on this occasion.

1. Maguire A et al (2004): Bioavailability of fluoride in drinking-water – a human experimental study. Report for the UK Department of Health