I've been taking Nature Made Multi Daily vitamin for as long as I can remember. It wasn't until today (after about a month of being Paleo) that it dawned on me to look at the ingredients in this stuff. Was less than thrilled with what I saw. Here is the ingredient list, what are your thoughts?
Ingredients: Calcium Carbonate, Cellulose Gel, Ascorbic Acid, Ferrous Fumarate, Maltodextrin, Croscarmellose Sodium, Mono & Diglycerides of Fatty Acids, Corn Starch, dl-Alpha Tocopheryl Acetate, Niacinamide, Zinc Oxide, d-Calcium Pantothenate, Hydroxypropyl Methylcellulose, Magnesium Stearate, Pyridoxine Hydrochloride, Thiamin Mononitrate, Riboflavin, Vitamin A Acetate, Polyethylene Glycol, Folic Acid, Vitamin D3 (Cholecalciferol), Cyanocobalamin.
No Artificial Colors. No Artificial Flavors. No Preservatives. No Yeast. No Gluten.
Good? Bad? All of the unpronounceables and corn starch send off red flags in my mind.
As Alvaro said, some of those ingredients are the names of the vitamins. Others are the inert ingredients used to aid manufacturing, hold the tablet together, and aid in dissolving in the gut. I don't think any are a real problem although croscarmellose Na can be if you have SIBO. To get optimal amounts in a multi you'd have to swallow a horse pill so I would take the individual vitamins of what you need rather than a multi.
Here's what I'd consider questionable:
DL-alpha-tocopheryl acetate. This is a form of vitamin E, one of several, including gamma. The alpha form tends to do some negative things when used as a supplement in studies. According to Chris Masterjohn: "alpha-tocopherol alone causes gamma-tocopherol deficiency by saturating alpha-tocopherol transport protein and thus preventing gamma-tocopherol’s transport in the blood. Since a major portion of the oxidative stress vitamin E is needed to prevent is nitrative in nature and alpha-tocopherol is useless against nitrative stress, alpha-tocopherol can worsen oxidative stress".
Folic acid. In this post, Chris Kresser discusses the potential risks associated with synthetic acid
supplementation, including increased cancer risk.
Paul Jaminet from The Perfect Health Diet seem to think supplementing with niacin (niacinamide) might be dangerous. See this post to read more.
I personally believe people shouldn't supplement iron unless they're an iron deficient anemic. I've seen this opinion, including the dangers of iron supplemented infant cereal, written about at Robb Wolf's website and a number of others. The main arguments presented tend to be that iron promotes oxidative stress and the growth of bad bacteria.
I don't think your multi vitamin is seriously hurting you or anything like that, I just think you're getting some bad with your good. I think you would be better off looking into your diet for what nutrients you might be low in and taking those specifically. Or, put another way "supplement wisely".
Most of the ingredients on the list are the scientific names of Vitamins. I don't think this is bad, but if you have a balanced whole food, clean diet and you get enough sunlight daily, I don't think you need supplementation.