According to the Centers for Disease Control and Prevention (CDC), approximately half of adults in the U.S. take at least one daily dietary supplement – the most popular being a multivitamin.  This translates into about $28 billion per year spent on vitamins, supplements, and minerals.

It is important to understand the difference between these dietary add-ons. Vitamins are naturally occurring, organic nutrients (coming from plants and animals) and include vitamins A, B, C, D, E, and K. Minerals are inorganic compounds (coming from natural processes) and include calcium, magnesium, iron, and sodium. “Supplement” is a catch-all term, which includes vitamins, minerals, herbs, botanicals, etc.  

Another important distinction between vitamins and minerals is that vitamins are either fat or water soluble, whereas minerals are not soluble.  Fat soluble vitamins, as their name suggests, can be stored in fat and can be dangerous in large doses.  In excess, water soluble vitamins can be excreted in the urine and rarely pose danger when consumed in large amounts.

A new study published in the Journal of the American Medical Association (JAMA) found that taking a daily multivitamin can reduce the risk of cancer by 12 percent in men aged 50 and older and appears to have no dangerous side-effects; no benefit was seen for risk of prostate cancer.  The take home from this study is that a multivitamin regimen seems to be more beneficial than increasing daily intake of one vitamin.  

As far as vitamin supplementation goes, few people in the U.S. are deficient in vitamin A.  The retinol form is found in eggs, liver, whole milk, dark green leafy vegetables and orange/yellow fruit and is more readily absorbed than the beta-carotene version.  Most people get plenty of the B vitamins through their diet.  Evidence is mixed for whether vitamin C can help you avoid or reduce cold symptoms.  Vitamin D can be activated just with some sun exposure and is also found in fatty fish, eggs and fortified dairy products.  

As a urologist, I do not support vitamin E or selenium usage in older men based on the findings of the SELECT Prostate Cancer Prevention Trial.  This study was stopped prematurely in 2008 after men taking 400 international units (IU) of the vitamin showed an increased risk of developing prostate cancer.  Moreover, vitamin E may inhibit blood clotting, so it shouldn’t be taken with blood thinners.  

Multivitamins could be beneficial in certain populations – such as women who are pregnant, breast-feeding, or trying to conceive; dieters consuming fewer than 1,200 calories a day or cutting out an entire food group (i.e. carbs); and those with medical conditions that affect digestion and food absorption.

Unless your physician recommends an intake of more than 100 percent of the recommended daily intake of a particular nutrient, you probably don’t need it.  If you are already getting the recommended amount of nutrients by eating a variety of fruit, vegetables, cereals, dairy, and protein, there’s little, if any, additional benefit from ingesting nutritional supplements.  One important finding from the JAMA study is that while you may not receive additional benefits, there doesn’t appear to be any harm by taking supplements.  A word of caution, however: Excess fat soluble vitamins (A, D, E, K) will be stored and can pose toxicity risks if you ingest too much.  

As always, speak with your physician before beginning any supplementation program. It is important to rule out any possible interactions between drugs and supplements.  Furthermore, don’t assume vitamins or supplements are completely safe just because they are labeled as “all natural.”  The FDA does not rigorously test supplements for safety or effectiveness as they do for drugs.  The best way to ensure you meet the standards for vitamins and minerals is to eat healthy foods (especially fruits, vegetables and whole grains).  Combined with a healthy lifestyle, including exercise and not smoking, a healthy diet should help you meet all nutritional requirements.