Lyle, glucosamine (again!) absorption ...

V

virtualcyber

New Member
Hi, Lyle

Sorry for clubbing this dead horse to pulp, but ... just one last time.

It seems that if one takes 1 g of glucosamine sulfate orally, about 11% fails to be absorbed by the digestive tract, 45% is metabolized by the liver, and the remaining 44% appears in the blood stream. So, I'd guess that 44% is bioavailable for use by the body.

I know you felt that glucosamine had relatively poor oral delivery and poor bioavailability ... but would it be possible that the above absorption rate be good enough to raise blood leptin levels?

For rats, it seems that 1 mmol/ml was the amount used to raise leptin. I have no clue how much glucosamine sulfate that translates to, for humans, given the above absorption rate.

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Reference:

"Absorption, distribution, metabolism and excretion of glucosamine sulfate. A review."

by Setnikar I, Rovati LC.
 
1 mmol/ml is a concentration, not a quantity. Was the study done on live rats? You need to know how much was injected.

If it was done on rat cells in vitro, they probably just kept the concentration up to 1 mmol/ml by adding more as needed.
 
Hi, edziu
> 1 mmol/ml is a concentration, not a quantity.

Yes, I know that. What I meant was _that_ was the concentration used to induce leptin.

It doesn't matter anyways -- it seems I misread the abstract. The abstract was talking about in vitro experiment on _human_ adipocytes that were treated with 1 mmol/L glucosamine.

> Was the study done on live rats? You need to know how much was injected.

Well, I am thinking that if 1 g of glucosamine sulfate was ingested and about 40% was found in blood, I'd assume 400 mg was in blood, right?

If you know typical concentration of a glucosamine sulfate pill _and_ average volume of blood in 180 lb person (a typical weight?), one should be able to calculate what would be the resulting blood glucosamine concentration.

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I did not want to try the calculation, as I am not an expert, but ... what the hell.

1 mmol/L = 18 mg / dl = 180 mg / L.

For an average man who weighs 85 kg (187 lb), and 180 cm tall, we have blood of about 5.5 L.

180 mg / L * 5.5 L = 990 mg.

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So, it seems that we need to take about 2 - 3 g of glucosamine sulfate to arrive at that concentration. Of course, the concentration in vitro is _forever_. In vivo, the amount decreases with time.

I am assuming that each pill contains 100% glucosamine, which probably isn't the case.
 
In case I was not clear, let me add a few more comments.

From the preceding calculation, we know that to obtain the concentration of 1 mmol / L, we need 990 mg to be in plasma.

Since our absorption rate is 44%, to get the number of grams we need to ingest,

990 mg / .44 = 2.25 g

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In Setnikar paper, the initial dose was 7.5 g, followed by about 2 g / day. After 7 days, the steady state loss through urine was about 2 %. 1/2 life seems to be 58 h, and the peak blood concentration of glucosamine pill is about 9 h after ingestion.

This means daily dose of 2 - 3 g should be enough to keep plasma glucosamine level relatively steady.
 
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