We recently heard that the attorney general just did an investigation on several well-known retailers of vitamins and accused them of “mislabeling, contamination and false advertising”. The investigation was set off by an article in the NY Times which referred to research done at the University of Guelph in Canada that found that as many as a third of herbal supplements tested did not contain the plants listed on their labels — only cheap fillers instead. They used a DNA probe, which can identify sequences unique to each organism.
They found some surprising substances in the bottles of herbals. Some had none of the ingredient they were supposed to have in them. A physical endurance remedy contained only powdered garlic and rice and the Ginkgo biloba contained powdered radish, houseplants, and wheat!New York Attorney General Targets Supplements at Major Retailers Feb 3, 2015

Well, with so much fraud going on, you need a foolproof way to tell the difference between a cheap, toxic, useless multivitamin, and a quality product. 
Obviously, I can’t tell if the herbals in the supplements are fraudulent and that is precisely why I always use professional products for my patients, but I can give a few hints as to what I look for in a multivitamin.
1. Look at the minerals. Minerals should be chelated with amino acids such as glycine, lysine, or aspartic acid, or at least complexed with an organic substance such as citrate or malate.
If you see oxides in the vitamin, put it down and try another one.
Does everyone know what iron oxide is? Yes, it is rust. Does anyone think that you can treat your iron deficiency anemia with rust?
Mineral oxides are rust. Magnesium oxide is magnesium rust, zinc oxide is zinc rust and so on. Rust is irreversibly bound to oxygen and cannot be used by the body. The next question I am always asked is: ”Then why do they put them in there? You know the answer, because they are cheap!
2. The next thing to look at is vitamin E (D-alpha tocopherol). Vitamin E comes in 2 varieties, synthetic and natural. Synthetic is DL-alpha tocopherol and natural is D-alpha tocopherol. When vitamin E is made in a laboratory, it is made in both the D (dextro-right) and L (levo-left) forms. In nature, we only see D-alpha tocopherol, never the L form. The L form cannot be used and can even block the D-alpha from binding and doing all the antioxidant work that vitamin E does. Since only half of it is really vitamin E, it takes more of it to raise blood levels. In one experiment, It took 300 mg synthetic vitamin E to equal the blood levels achieved by a 100-mg dose of natural vitamin E (Am J Clin Nutr 1997 (Mar); 65 (3): 785-9). Also, the body must not like synthetic vitamin E because it excretes it 3 times faster than the natural form. (FEBS Letters 1998 (Oct 16); 437: 145-8) Therefore, if you see DL- alpha tocopherol on the bottle, put that one down also and move on.
3. The third thing to look at the B12. Vitamin B12 comes in 2 major forms: cyanocobalamin and methylcobalamin. Up to 1/3 of people have some degree of difficulty absorbing and using the cyano kind because it has to be made into the methyl form. If you are one of the 1/3, then you have wasted your money on this. I feel that everybody should take the methylated form because unless you’ve been tested, you don’t know if you’re one of the ones who have difficulty absorbing this. So if you see cyanocobalamin on the label, put that down also
4. The same goes for folate. The toxic synthetic form is folic acid. The same 1/3 of people who can’t use the cyanocobalamin, also have difficulty absorbing the folic acid, for the same reason, it has to be activated first. However, the folate story is more complicated. Grains in this country are stripped of all vitamins and one vitamin is added back, folic acid. Blood levels of folic acid are more than twice the predicted amount (Am J Clin Nutr. Vol 77, pp221-5, 2003.) and people’s bodies are being flooded with this synthetic form of folate. If you’re one of the people who can’t absorb folic acid and cant convert it into methyl folate in the body, you will build up toxic levels of folic acid. And you don’t even have to take a multivitamin for this to occur. It can happen with just bread products. (gluten isn’t the only problem with refined wheat products) High levels of unmetabolized folic acid suppress the immune system, especially natural killer cell activity. (J Nutr, Vol. 136, pp. 189-194, 2006). Several years ago, articles began appearing that excessive intake of folic acid was being associated with colon cancer. In fact a study published in the Journal of the American Medica Association showed that folic acid suggested that folic acid actually promoted the growth of colon polyps over a 10 year period. (The Journal of the American Medical Association 297.21 (6 Jun. 2007): 2351-2359.) This is because of the toxic synthetic form that builds up in any dose larger than 200 mcg, and in some at an even lower dose. Methylated forms do not have that effect. See folic acid on the label, you know what to do.
5. Last, check if there are dyes in there or toxic metals such as aluminum. A very popular vitamin that many people take is loaded with aluminum. In fact, the first 3 ingredients on the list are aluminum in several forms including “aluminum lake”. Why they put Aluminum and dyes in there is anybody’s guess. Dyes and aluminum, not good!
I hope this has been helpful and good luck in your quest for the perfect multivitamin!