Magnesium Absorption: Better Use Tablets Than Caps

The Internet is full of bro-scientific advice on which form of supplemental minerals is the best for you. The form, i.e. tablet or capsule, of the supplement is yet hardly ever discussed. Researchers from Bonn (Germany) (Siener. 2010) have now found that magnesium from effervescent tablets is better absorbed than from capsules:

With standardized conditions, urinary magnesium excretion increased by 40% after ingestion of the effervescent tablets, and by only 20% after intake of the capsules. The results indicate better bioavailability of magnesium from the effervescent tablets than from the capsules. This may be attributed to the fact that the tablets have to be dissolved in water before ingestion so that magnesium becomes ionized, which is an important precondition for absorption.

Bottom line, when you purchase your next magnesium supplement consider its form as well as its content; and prefer tablets over caps.