Why is food supplement use declining?
The population-based study suggested that whether individuals continued taking food supplements depended on whether reported benefits were being met.
Overall the researchers found that vitamin/mineral supplementation (VMS) user numbers remained stable as those discontinuing were offset by those starting off.
Findings from the study clash with claims that VMS use is increasing in Europe.
This increase has been shown in a number of socio-demographic categories such as female gender, older age and lower body mass index.
Here, VMS use was shown to be more consistent with individuals with a favourable lifestyle and healthier diet.
Swiss study
The study, which was funded by GlaxoSmithKline (GSK), was conducted between 2003–2006 and 2009–2012 in the city of Lausanne and involved 4,676 participants aged between 35 and 75.
The team from Lausanne University Hospital (CHUV) in Switzerland also recorded body weight and height.
For both the VMS and food supplement groups, subjects were characterised as never (absent at the starting point and follow-up), initiators (absent at starting point but present at follow-up), discontinuers (present at starting point but absent at follow-up) and continuers (present at starting point and follow-up).
VMS and food supplements included omega-3 and combinations of calcium and vitamin D.
As calcium and vitamin D supplements might have been prescribed for osteoporosis prevention and iron and vitamin B12 for anaemia, participants taking such combinations were excluded.
Results found that occurrence of food supplement use was 10.4% at the beginning of the study, which decreased to 6.8% at follow-up.
During the 5.5 year study period, 405 (8.7%) subjects discontinued; 239 (5.1%) initiated and 81 (1.7%) continued supplement use.
Additionally, 3951 (84.5%) did not use any supplement at the starting point and at follow-up.
VMS prevalence was 20.6% at the beginning of the study and 20.3% at follow-up. During the study period, 559 (12.0%) participants discontinued; 545 (11.7%) initiated and 404 (8.6%) continued VMS use, whereas 3168 (67.8%) did not use any VMS at baseline and follow-up.
Conflicting research
Decreased supplement use is a finding that contradicts a study conducted in the US but is in agreement with research conducted in Scandinavia.
“The prevalence of [food supplement] users decreased with one possible explanation being the tighter regulations regarding their health claims,” the researchers said.
While they thought that supplement adoption was initially based on health claims, supplement discontinuation when benefits were not met or when side effects occur was also a possibility.
The team acknowledged that as reasons for discontinuing were not collected, these explanations remained speculative.
Meanwhile, women and older participants were significantly more likely to start and continue VMS use.
“Women and elderly people tend to be more health-conscious and to adopt health-promoting behaviours such as VMS use,” the team said.
“Another explanation is the prevention of osteoporosis in elderly women by calcium and vitamin D combinations. Our results suggest that most women VMS initiators did so for a medical and not for a personal reason.”
Source: European Journal of Clinical Nutrition
Published online ahead of print, doi:10.1038/ejcn.2016.137
“Trends in vitamin, mineral and dietary supplement use in Switzerland. The CoLaus study.”
Authors: P. Marques-Vidal, P. Vollenweider and G. Waeber
