Volume 91, Issue 3, March (2004), pp. 403-409 © The Author 2004
doi:10.1079/BJN20031082

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The silicon content of beer and its bioavailability in healthy volunteers

Supannee Sripanyakorn^1,2, Ravin Jugdaohsingh¹, Hazel Elliott^1,2, Caroline Walker³, Payal Mehta², Sera Shoukru², Richard P. H. Thompson¹, Jonathan J. Powell^1,2,4
1Gastrointestinal Laboratory, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, UK
²Department of Nutrition and Dietetics, King's College London, 150 Stamford Street, London, SE1 8WA, UK
³Brewing Research International, Lyttel Hall, Nutfield, Surrey, RH1 4HY, UK
⁴MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, CB1 9NL, UK

 (Received 26 July 2003–Revised 25 November 2003–Accepted 6 December 2003)

Dietary Si, as soluble orthosilicic acid (OSA), may be important for the growth and development of bone and connective tissue. Beer appears to be a major contributor to Si intake, although the Si content of beer and its bioavailability in human subjects have not been well established. Here we investigated the Si content of different beers and then estimated Si absorption from beer in healthy volunteers. The Si content of seventy-six different beers was estimated using inductively coupled plasma optical emission spectrometry and one of the beers, used in the ingestion study, was ultrafiltered to determine OSA content. Next, following the ingestion of 0·6 litres beer (22·5 mg Si; 4·6 % (v/v) ethanol), serum and urinary Si levels were measured in nine healthy volunteers over a 6 h period. A solution of OSA was similarly investigated as a positive control and water and 4·6 % ethanol as negative controls. The mean Si level of beer was 19·2 (sd 6·6) mg/l; the median Si level was 18·0 mg/l. There was no significant difference in the Si levels of the different beers by geographical origin or type of beer. Serum and urinary Si levels increased considerably following the ingestion of beer or a solution of OSA but not with the ingestion of either 4·6 % ethanol or water. The ultrafilterability of Si from beer (about 80 %) and its absorption in volunteers (about 55 %) was comparable with that of a solution of OSA suggesting that Si in beer is present chiefly in a monomeric form and is readily bioavailable.

Keywords:
Beer Silicon Bioavailability

Abbreviations:
ICPOES, inductively coupled plasma optical emission spectrometry, OSA, orthosilicic acid, UHP, ultra-high-purity