Bioavailability and Calcium

What is Bioavailability?

Assuming that you have chosen a reliable brand with a proven track record there still are no guarantees the therapy will work for you. A potential stumbling block to benefiting the most from your chosen herb, vitamin or supplement, is bioavailability.

A big word with big implications- bioavailability represents the amount of active ingredient in the medication or supplement that gets into your blood stream and can be effectively used by your body. You could take pounds of supplements without visible improvement in your condition simply because your body is unable to extract its beneficial ingredients. A perfect example is yam in its natural forms. Although yams contain progesterone- the hormone our body needs- eating yams will never give you that progesterone. That is because our bodies cannot make yams bioavailable, meaning it cannot extract the progesterone from them. How the supplement gets into your system, what the body does with it once it’s in your blood stream, how much of it gets to your cells and how they use it, are only parts of the bioavailability story. When medications are tested for effectiveness, the most important marker is their bioavailability. With supplements and food substances, that are not under FDA scrutiny, bioavailability is not even addressed.

Another example of variable bioavailability is calcium. Calcium is essential to good bone structure. But taking calcium supplements does not insure that more calcium gets into our system, let alone to our bone cells or into our bones. Let’s follow the path of a calcium pill you take in the evening, three hours after your last meal. Your stomach is empty and the pill gets broken down into tiny components by gastric juices. If the components are small enough, the calcium supplement you took gets absorbed into your blood stream. If it isn’t small enough, it goes through the stomach and into the intestine and out the other end- no calcium supplement for your body. If it gets absorbed into your blood stream it has a good chance of getting to your bone cells. But once there, there is no guarantee that the cells that need the calcium have the enzymes, substrates, and all other necessary environmental elements, to absorb the calcium molecules and use them to make strong bones. The path I use to describe the fate of calcium in your body is similar to any other food or medication you take. There are lots of great supplements available with incredible potential benefits. The reason they don’t live up to their promises is because they are not bioavailable. This is one of the key reasons many supplements just don’t work. In an attempt to improve bioavailability, many manufacturers advise taking their supplements on an empty stomach. The reason behind this method of administration is that hypothetically, an empty stomach will be more inclined to digest and absorb a supplement than if mixed with other foods or medications. I stress hypothetically, because there are no studies to substantiate the bioavailability of most supplements on the market today.

Other methods of administration (besides pills and tablets) have better rates of absorption and bioavailability. Pharmaceutical companies have conducted numerous studies that reinforce the increased bioavailability of creams and gels. The reason is primarily that skin is a more predictable absorbent, it is the largest organ in the human body and the blood flow to the skin is high in warm areas, like chest, inner thighs, arms, and pulse points (wrists, ankles, armpits, groin).

From a clinical standpoint, degree of bioavailability of a substance is directly proportional to its expected effect. If you are taking a pill to get rid of a headache and the headache is gone in thirty minutes to an hour after you took the pill, clinically speaking, the pill was bioavailable enough to be effective. When we discuss the bioavailability of natural hormones or supplements we are referring to subjectively measurable effects (like elimination of hot flashes, or night sweats for instance).

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