Solid vitamin supplements:
the most important ingredients
are not vitamins!

Let's have a look at the most common form of vitamin supplements: the solid form.

Most of vitamin supplements are produced as pills, tablets, caplets or capsules.
During the manufacturing process of solid supplements, the active ingredients are mixed with a variety of excipients (other ingredients).

Excipients are needed for several reasons: to take up space (fillers), to hold the ingredients together (binders), to assist in disintegration (disintegrants), and for other functions. Sometimes it might be necessary to coat the tablet because of the unpleasant taste or odor of its ingredients (coatings).

Fillers are necessary for the manufacturing process, but are only needed to take up the volume of the pill. The pill must be large enough for human fingers to readily handle it. Even small vitamin supplement tablet might be much larger in volume than the vitamins and minerals it contains.

Some common fillers are lactose (milk sugar), cellulose, corn starch, sugars (including sucrose, mannitol, sorbitol, fructose, and dextrose), whey, and yeast.

Binders are used to make the components stick together when the ingredients are compressed to form the pill. Some common binders are povidone, xanthan gum and Carbopol (an acrylic resin). Some fillers may also act as binding agents, and may be referred to as filler/binders.

Disintegrants stimulate the break-up of the tablet in the stomach.

Coatings help to prevent a tablet from dissolving too soon, thus breaking up in your mouth.

There are also other kinds of excipients: lubricants, colorants, flavors and plasticizers.

The acceptable excipients are generally either food products (such as lactose, sugar or starch), or chemically inert ingredients that pass through the body without any effect (such as cellulose).

Overall, the function of excipients is to make sure that vitamins and minerals contained in the tablet will make their way into the stomach. Once the tablet is in the stomach, it is extremely important that excipients do not prevent the disintegration of the pill and absorption of the active ingredients.

Excipients used in low-quality vitamin supplements can prevent the tablet from being disintegrated (dissolved) in the stomach. If this happens, and the tablet leaves the stomach undissolved, its ingredients will not be absorbed in small intestine, and its beneficial effects will not be realized.

In addition to the excipients of poor quality, factors such as high pressure and high temperature during the manufacturing process can also negatively impact a tablet's dissolution characteristics.

This picture is from the medical book "Essentials of Skeletal Radiology", by Terry R. Yochum and Lindsay J. Rowe (ISBN 0781739462).

These non-transparent objects in the lower right-hand corner are undissolved pills in one's intestine, passing through the body intact!

The importance of the dissolution of tablets in the human stomach was understood more than a century ago.

Here is a quote from a book published in 1895 (A Treatise on Pharmacy, Gaspari C, Lea Bros., Philadelphia):
"..it would seem that prompt action of certain remedies must be considerably impaired by firm compression. ...the composition of all compressed tablets should be such that they will readily undergo disintegration and solution in the stomach."

However, the criteria for a tablet's efficiency did not exist for a long time, and up to 1950 tableting technology was rather empirical (per Historical Perspectives on Dissolution Technology by L. T. Grady).

By 1950, disintegration tests for tablets were officially adopted by US Pharmacopeia. Go to the Home page to see a video about vitamin tests conducted by US Pharmacopeia.

The currently accepted standard is that the tablets must dissolve within 15 to 30 minutes of being in the stomach.

To test your vitamin supplements at home, put some warm water with white vinegar (to simulate the stomach acid) in a glass and drop in your pill. It should dissolve within 15 to 30 minutes in order to meet industry standards. If it doesn't, your pill will not work as well as it's supposed to, and you need to change your vitamin supplement!

You can let this test go on for up to 60 minutes. If the pill is not dissolved by then, it is highly unlikely to be of any benefit whatsoever to your body.

So, what you can do to assure that your body benefits from the dietary supplements you're taking?

The best guarantee of quality is a sign "USP Verified" on the package. This means that this particular product passed all tests by US Pharmacopeia and satisfied both dissolution and content tests.

Apart from using solid supplements of high quality, you may consider other forms of supplements, which do not have problems with dissolution.
Liquid vitamins, spray vitamins and gel supplements are not solid, and their ingredients are readily available for absorption.