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Archived Comments for: The silicon supplement ‘Monomethylsilanetriol’ is safe and increases the body pool of silicon in healthy Pre-menopausal women

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  1. Measuring the urinary excretion of silicon

    Chris Exley, Keele University

    27 June 2013

    The data in this paper relating to the urinary excretion of silicon are expressed as mg/L for point samples.

    These are meaningless. Either the data should be normalised to account for differences in glomerular filtration rate and expressed per mmol creatinine or 24h urine samples should have been collected so that the data could have been expressed as per 24h.

    Unfortunately data expressed in this manner are not only useless in comparisons between groups within the same study (what if MMST affected GFR?) they are also useless as they cannot be used to compare with data for urinary Si excretion in other studies.

    This basic error means that this study though potentially very interesting is fundamentally flawed.

    Competing interests

    None declared

  2. MMST ingestion in humans does not affect urinary volume

    Ravin Jugdaohsingh, Medical Research Council

    25 September 2013

    Dr Exley makes a perfectly valid comment concerning the role of urinary creatinine in studies with spot urines. However, to suggest that our entire study is flawed because this is not reported is as dramatic as it is erroneous. Three of the four major outcomes in our work would not have been informed by urinary creatinine. The fourth- the increase in urinary silicon/MMST concentration following supplementation ¿ could have been. Nonetheless, double-blind, cross-over placebo control confirmed the consistency of inter-individual urinary silicon concentrations when matched for time of day. Our previous data have shown that MMST ingestion in humans does not affect urinary volume. So, as Dr Exley states, a supplement induced change to GFR would be required to misinform this outcome. However, as we sought silicon:MMST ratios the proposed artefact would, also, have to favour urinary excretion of one form of silicon over the other (ie disproportionately). We consider this implausible and stand by our original conclusions.

    Competing interests

    The author¿ laboratory has received research funding from the silicon supplement and food industry. The author has no competing interest.