When deciding to take vitamin and mineral supplements, one should know which are needed, what amounts to take, and where to get quality products.
In my opinion, it makes sense to determine vitamin, mineral, and overall nutritional deficiencies before supplementing. Through simple blood, urine, feces and hair tests, one can determine their true deficiencies. If deficiency does exist, and a supplement is incorporated into the diet, then repeat testing is necessary to determine the effectiveness of that supplement.
Now, take it one step further...with today's genetic testing, we are able to see the 'hand that we were dealt'...and with that valuable information, we can conquer our weaknesses!