Relationship of hair calcium concentration to incidence of coronary heart disease

This study was designed to evaluate whether hair calcium concentration reflects the mortality from coronary heart disease on a UK-wide basis and to determine the effect } if any } of environmental factors which might affect calcium metabolism on this relationship. The study was based on our earlier findings of an inverse relationship between hair calcium concentration and that in the intima of the aorta and the association of high aorta calcium with severe alterations to the vessel walls which was found never to co-exist with hair calcium concentrations greater than 700 ppm. Hair samples were collected from 4393 males in an ethically approved study in 40 different health districts. These covered the range in known prevalence of heart disease as reflected in the published standardised mortality ratios SMR.. Data on water hardness were obtained from the Water Authorities and on mean annual sunshine hours from the Meteorological Office. Statistical analysis was by regression and multivariate regression techniques. Hair calcium was determined by XRF analysis and the accuracy validated by means of certified reference samples. Significant relationships were found between health district and county SMR and their respective mean hair calcium concentrations accounting for 37 and 55% of their respective variances in SMR. Water hardness and sunshine hours accounted for 39 and 49% of the variance in mortality from CHD. In combination they accounted for 54% of the variance and with the inclusion of hair calcium 65%. South-east England had the highest hair calcium, the hardest water and the most sunshine hours and the lowest mortality from CHD. The converse was true of Scotland. Hair calcium concentration did reflect the risk of CHD on a population basis and was strongly influenced by both the hardness of the water supply and the annual sunshine hours which also independently affected the SMR for CHD.