Do vitamins actually work?

Most brands have way too much of what the RDI (recommended daily intake) requires. From my experience the only two supplements you really need are Vitamin D and Omega 3's. Some guidlines for both would be: Vitamin D 3,000-5,000 I.U.'s and for Omega 3's 3-5 grams. Most fish oils have only 650-1000 mg of Omega 3's as well as Omega 6's and Omega 9's. Find a fish oil that has significantly more Omega 3's than the other Omega's. Capsules are ok, but the actual fish oil is better and is usually higher in the Omega 3's. Try a few different brands out first, taste can vary but are way better than in years past.

When it comes to multivitamin/mineral supplements, the key question is, "how good is your diet". Obviously, it is better to get all your nutrients from a diet high in a variety of foods - especially meats, fish, fruits and vegetables. However, we live in the real world. A world in which very few people get enough of each essential vitamin and mineral.

As Josh says, vitamin D is very commonly under-consumed, especially in people who don't get outside much or live in cloudy or intemperate climates, so if this applies to you, go with Josh's suggestion of a high-dose vitamin D supplement. It is actually not an exaggeration to say that there is a vitamin D epidemic and experts are presently considering increasing the vitamin D recommended intakes by several times!

However, getting back to diet, if you don't eat AT LEAST 5 servings of fruit and vegetables (and don't count potatoes and corn and other veg that are mostly starch) per day, along with servings of dairy and meat/fish/eggs/nuts/seeds, then you will probably benefit from a multi.

In my experience, most people don't eat high levels of a variety of these foods and studies back up my first-hand experience, so if you can clean up your diet, then you should be ok but if not, a multi is good nutritional insurance. If your diet is pretty good but not great, just take a multi every other day.

Also, keep in mind that a multi will "gradually" address any nutrient deficiencies that you may have, so you are not likely to "feel" better right after the first few days of taking one.