Trends in vitamin, mineral and dietary supplement use in Switzerland. The CoLaus study

Vitamin/mineral (VMS) and dietary supplements (DS) use is common in Switzerland, but nothing is known regarding the factors associated with their initiation, discontinuation or continuation of intake.

Prospective study conducted between 2003-2006 and 2009-2012 in Lausanne, Switzerland among 4676 participants (2525 women, age range 35-75 years). VMS were defined as single or multivitamin/multimineral preparations; DS were defined as any dietary supplement.

VMS use was 20.6% at baseline and 20.3% at follow-up (P=0.69): 559 (12.0%) participants discontinued; 545 (11.7%) initiated and 404 (8.6%) continued VMS use. On multivariable analysis, men had a lower relative risk ratio (RRR) of discontinuing, initiation or continuing; older age and being physically active were associated with a higher RRR of initiation or continuing; lower education and higher body mass index were associated with a lower RRR of discontinuing or continuing of VMS. DS use decreased from 10.4 to 6.8% (P<0.001): 405 (8.7%) participants discontinued; 239 (5.1%) initiated and 81 (1.7%) continued DS use. On multivariable analysis, men had a lower RRR of discontinuing, initiation or continuing; older age had a higher RRR of initiation, discontinuing or continuing; being physically active was associated with a higher RRR of initiation or continuing; Swiss citizens and former smokers had a higher RRR of discontinuing.

VMS use is stable in the Lausanne population, whereas DS use appears to be decreasing. Individuals can be categorized either as users or non-users depending on the study period, and consistent users are only a small fraction of prevalent users.