I was asked the other day to explain what determines Bio-availibility in a multivitamin. First though what is bioavailibility? Bioavailibility is simply how easily and completely your body absorbs the vitamins and minerals in supplements, or in foods. Something would have excellent bioavailibility if 100% of what you ate ended up in your blood stream. It would have 0% if nothing ended up in your blood stream. Of course few are 100% or 0%, but in-between. Below is a discussion of several different factors which affect bioavailibility
Forms of minerals
Minerals initially come from the earth. So in theory you could eat dirt and get all the minerals you need. But unfortunatly the minerals in dirt are in a from that we can’t readily absorb (low bioavailability).
Plants though can pick up those minerals in the soil and bind them into organic compounds in their fruits, leaves, seeds, etc. this is called chelation. Then when we eat that fruit or vegetable we also bring in those chelated minerals, and since they are part of organic compounds that our bodies are looking for, they are readily absorbed.
If you’re looking at your supplements label how do you tell which it has? Simple is to look at the name. For example if it ends in “ide” like magnesium chloride or calcium chloride, then it is a mineral salt as found in dirt. One exception is Iodine – you’ll often see that as potassium iodide.
What you want to look for are minerals in a supplement which are “Chelated” minerals . These will often end in the “ate” such as chromium picolinate, calcium citrate, calcium carbonate, zinc citrate, copper glutamate, etc.
Unfortunately the huge majority of supplement manufactures use the lower bioavailable mineral salts because they are much cheaper vs. the much more expensive chelated minerals. Like the old saying though, “You get what you pay for”
Here is an earlier post I wrote which goes into more detail Dirt Has All the Minerals You Need.
Forms of Vitamins
Like minerals, there are different forms of some vitamins. As you can guess, then cheaper forms have lower bioavailability than the more expensive forms. The key one you’ll find is Vitamin E. The nature form of vitamin E, as found in nature and much more bioavailability is d-alpha-tocopherol. The cheaper, and less absorbable form is dl-alpha-tocopherol. note the difference is the beginning is either d- or dl-. Both are vitamin E, but the d- form is much more absorbable. the dl- form is the same molecular structure, but just put together slightly differently. Imagine a stack of legos as the d- form. Then take off the single top rectangular block and turn it 90 degrees to the left. that is the difference in the dl- form.
The final piece of the bio availability puzzle is dissolution time. This is the measure of how long it takes a tablet to dissolve after you swallow it. The standard is 30 minutes from swallow to completely dissolved. Many inexpensive products though take much longer to dissolve and some don’t dissolve at all. If it goes straight through without dissolving, you can’t absorb any of the ingredients in it. Ask a nurse about “Bedpan bullets” Some they say you can still read the products name on the tablet. I’ve seen one x-ray showing 3 undissolved tablets moving through the intestine and colon. (These were a very popular grocery store and big box store brand that you see advertised frequently on TV and in print)
Like in the two previous sections, manufacturing cost comes into play. The more tablets per hour a manufacture can press on a very expensive piece of equipment, then lower the per tablet, or per bottle cost is. So how do they increase the production speed? Simple press the ingredients in the tablet under much higher pressures so they can fly down the line faster without breaking.
The product I use and recommend tests the dissolution time of their tables during manufacturing every 30 minutes to insure they dissolve within 30 minutes. I’ve toured other plants where they never test the dissolution time.
How to Check quality
If you find a supplement that has the correct forms of ingredients, how can you tell if it is high quality or not. In a nutshell there are two areas:
- Do they take steps to insure that what is on the label is in the tablet with the proper quantities, and
- Do they insure there isn’t anything in the tablet that shouldn’t be in it such as heavy metal contamination, bacteria, insect parts, etc.
Here is an article that explains How to find a high quality supplement.