Dietary supplement use in the older population of Iceland and association with mortality

Dietary supplements are often used by the elderly to improve their nutritional status. However, intake above the recommended dietary levels may be detrimental, and uncertainty exists on the potential health benefits of supplementation in this population. The aim of this study was to describe supplement use among Icelandic older adults and to assess its association with total mortality and CVD-related mortality. This study used data from the Age Gene/Environment Susceptibility-Reykjavik study, which recruited 5764 participants aged 66-98 years in 2002-2006. Intake of vitamins and minerals from dietary supplements was estimated from interviews. Hazard ratios (HR) for mortality were estimated in multivariate analyses with follow-up ending in 2009. The results showed that most (77 %) of the participants used supplements. Overall, the consumption of vitamins and minerals from supplements was moderate although 22 and 14 % of users exceeded the upper recommended intake levels for vitamin B6 and Zn, respectively. Supplement users followed in general a healthier lifestyle than non-users. There were 1221 deaths including 525 CVD-related deaths during the follow-up period. When comparing multivitamin users with non-users in multivariable models, no associations with total mortality (HR 0·91; 95 % CI: 0·77, 1·08) or CVD-related mortality (HR 0·91; 95 % CI 0·70, 1·18) were observed. In conclusion, users of supplements generally lead healthier lifestyles than non-users and supplements did not confer any added advantage or harm relative to mortality risk. However, the intake of vitamin B6 and Zn from dietary supplements exceeded the recommended daily intake for almost a quarter of the supplement users.