Osteoporosis is a global health problem characterized by low bone mass and an increase in bone fragility. It is now well accepted that dietary factors play a central role in bone development and health. Diet that lacks adequate minerals is considered to be a risk factor for osteoporosis. The food supplement, Aquamin, is a natural, multi-mineral derived from the red algae Lithothamnion corallioides, rich in calcium, magnesium and 72 other trace minerals. The aim of this study was to evaluate the effect of Aquamin on osteoblastic behaviour and mineralisation in a pre-osteoblastic cell line. Cell number and metabolic activity were assessed using Hoescht DNA and AlamarBlue assays respectively. Osteogenic differentiation was measured using an alkaline phosphatase assay while mineralisation was determined using von Kossa and alizarin red staining. It is reported here that Aquamin promotes increased mineralisation in osteoblast cell culture. These data suggest that the nutritional supplement Aquamin plays an important role in promoting bone formation and may be useful in treating bone diseases such as osteoporosis. Copyright © 2011 John Wiley & Sons, Ltd.