oops, sorry I didn't finish my thought process.

What I wanted to finish with was, that although some organic salts may absorb slightly better than the inorganic forms of minerals, it is very slight..

So then we get into cost and how many pills you have to take to get the dosage.

You have to take more of the organic salts to get dose of a an inorganic form of a mineral..and it always cost more.

So you are taking more tabs and spending more money for a few more percentage points of absorption...

I should have provided this study as well..mag oxide absorbs in the same range as all others.

Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approach

Magnesium Research. Volume 18, Number 4, 215-23, december 2005, Original article

Full Text

Author(s) : C Coudray, M Rambeau, C Feillet-Coudray, E Gueux, JC Tressol, A Mazur, Y Rayssiguier

Summary : Literature data on the bioavailability of various Mg forms provide scarce information on the best Mg salt to be used in animal and human supplementation. This study aimed to investigate the bioavailability of different forms of Mg in rats using Mg stable isotopes. Eighty male Wistar rats aged 6 weeks were fed a semi-purified Mg-depleted diet for three weeks. The rats were then randomised into ten groups and received, for two more weeks, the same diet repleted with Mg (550 mg Mg/kg) as: oxide, chloride, sulphate, carbonate, acetate, pidolate, citrate, gluconate, lactate or aspartate. After 10 days of Mg-repleted diet, the rats received orally 1.8 mg of an enriched 26Mg. Faeces and urine were then collected for 4 consecutive days. Isotope ratios in faeces and urine were determined. The Mg absorption values obtained varied from 50% to 67%. Organic Mg salts were slightly more available than inorganic Mg salts. Mg gluconate exhibited the highest Mg bioavailability of the ten Mg salts studied. Urinary 26Mg excretion varied from 0.20 mg to 0.33 mg, and feeding with the organic pidolate, citrate, gluconate and aspartate salts resulted in higher urinary 26Mg excretion than with inorganic salts. Ultimately, 26Mg retention was higher in the rats receiving the organic salts such as gluconate, lactate and aspartate than in those receiving the inorganic salts. Taken together, these results indicate that 26Mg is sufficiently bioavailable from the ten different Mg salts studied in the present experiment, although Mg gluconate exhibited the highest bioavailability under these experimental conditions.