Several studies have come out with compelling evidence against any benefits of multivitamin or supplement use in benefitting health. Recently, Neuhouser et al  found little or no influence in reducing common cancers, cardiovascular disease (CVD) or total mortality in postmenopausal women, after following them for 8 years. Muntwyler et al (2002) found no benefit from vitamin E, vitamin C, or mulitivitamins in reducing CVD or coronary heart disease (CHD) in males . A review of all clinical trials and observational studies on supplements yielded an overall consensus that they don't significantly reduce mortality or morbidity .
The jury is still out on the benefits of calcium, despite it being the most studied mineral (62,852 Medline articles from 1994-2004) . Sure, we know that calcium helps build strong bones and protects against things like osteoporosis, but other things build strong bones too (e.g. exercise and a healthy diet). Americans have been trained to think we're supposed to be getting more than 800 mg of calcium per day (approx 3 servings a day), but is that the right amount? The National Dairy Council (NDC) has strongly pushed and advocated for increasing calcium intake (i.e. "Got Milk?" campaigns), but we don't know for sure if the science matches up. Recommendations vary widely across countries, ranging from 500-1500 mg for young adults, with the US recommending 1000 mg (daily upper limits to avoid adverse effects are about 2500 mg).
The FDA does not regulate vitamins, minerals, and supplements. This is important to remember--anyone can package and sell these things without regulation or proven benefits. Aware of this or not, about 50% of Americans use vitamin or dietary supplements--contributing to a $20 Billion annual industry.
Do I take a MTV or supplements? I currently do take a MTV on days when I'm not eating a particulary wide range of healthy foods. I also take a Calcium/Vit D supplement (Vitamin D assists with absorption of calcium and should be taken in tandem, if taken).
However, as long as the following criteria are met, dietary supplements are probably not adding any benefit (in some cases, adding harm):
1) Get appropriate levels of physical activity
2) Reduce sodium intake
3) Increase fruit and vegetable consumption
4) Avoid smoking
5) Limit alcohol intake
6) Maintain a healthy body weight
This provides more evidence in support of living a healthy lifestyle and stopping the search for magic pills. I'm not trying to dissuade anyone from taking supplements, as they are likely to be helpful for those not getting an adequate range of healthy foods and exercise (e.g. developing countries and "unhealthy" individuals). However, if you live a healthy lifestyle, you're probably wasting your $ on supplements.
As said by Hippocrates (460-377 BC), "Let food by thy medicine and let medicine be thy food."
1. Neuhouser ML, Wassertheil-Smoller S, Thomson C, Aragaki A, Anderson GL, Manson JE, Patterson RE, Rohan TE, Van Horn L, Shikany JM, Thomas A, LaCroix A, & Prentice RL. Multivitamin use and risk of cancer and cardiovascular disease in the Women's Health Initiative cohorts. Arch Intern Med (2009); 169(3):294-304.
2. Muntwyler J, Hennekens CH, Manson JE, Buring JE, & Gaziano M. Vitamin supplement use in a low-risk population of US male physicians and subsequent cardiovascular mortality. Arch Intern Med (2002); 162:1472-1476.
3. Prentice RL. Clinical trials and observational studies to assess the chronic disease benefits and risks of multivitamin-multimineral supplements. Am J Clin Nutr (2007);85(1):308S-313S.
4. Weaver CM & Heaney RP (Eds). Calcium in Human Health. Springer, 2006.