Design a study to evealuate use of multivitamins?

fortunate asked: As a nutriotional scientist I am asked this question in one of my calsses. I need help here to build the answer.
” Design a study to evaluate use of multivitamins and mineral(MVMs)in attenuationg risk of cardiovascular disease.Discuss…
1. discuss limitations of previous mVM trials
2. Design a study to overcome these limitations.
3.Hypthesize [...]