Like vitamin D deficit [11], Mg deficit is considered to be a risk factor for cardiovascular disease [12]. Thus, the presented interactions between Mg, vitamin D and cardiovascular mortality fit well together. Nevertheless, for several reasons, data should be considered preliminary. First, associations are based on oral Mg intake. The assessment of oral Mg intake does not take into account inter-individual differences in intestinal Mg absorption and renal and cutaneous Mg loss. It would have been more appropriate to use biochemical data, such as plasma Mg levels (levels of 0.79 to 0.76 mmol/l have been classified as inadequate and levels <0.76 mmol/l as deficient), to assess individual Mg status. Unfortunately, plasma levels of Mg are still rarely assessed, whereas measurement of circulating 25OHD levels has exploded in the clinical setting in recent years [13]. Second, total Mg intake, 25OHD status and physical activity level were clearly interrelated [5]. High Mg intake may thus only be an indicator for high physical activity, which is known to influence 25OHD status (and cardiovascular mortality). Even adjustment for physical activity may not completely solve the problem of potential bias. Third, no data on circulating levels of the biologically active form of vitamin D, 1,25(OH) 2 D, were presented. Circulating 1,25(OH) 2 D is probably a better predictor of total mortality compared with circulating 25OHD, at least if mid-term mortality is assessed [14]. Circulating 1,25(OH) 2 D declines significantly (and parathyroid hormone levels increase substantially) at 25OHD levels below 10 ng/ml, whereas levels of both hormones seem to plateau at 25OHD levels of 20 ng/ml [15]. Notably, three out of the four 25OHD categories in the mortality analysis of the present investigation were above 20 ng/ml, and none covered the range that the IOM has classified as deficient. It would have been interesting to see whether the combination of inadequate Mg intake with 25OHD levels below 12 ng/ml is associated with a further mortality increase.