>I find it interesting that the two different recent posts have such
>different content for sea vegetables.; one lists laver with 2 vs 378 mg
>of magnesium; the other says 121 vs 900 mg in kelp; both are supposed to
>be for 100 grams.  I wonder why it is such an obscure piece of
>information with such a variance.

I emphasize that the values I gave for the magnesium content of seaweed refers
to non-dried seaweed.

Laver contains 85% water, so dry laver would contain 2/(100-85)*100=13 mg
magnesium per 100 grams.

For kelp, it would be 121/(100-81.58)*100=657 mg

Now, that's still very different from the values given by Main Coast Sea Vegs
Perhaps it's due to the amount of sea salt (dried seaweed contains some
crystallized salt).

The Mg content of unrefined sea salt is variable, but Celtic sea salt contains
about 1% Mg. See

http://www.healthfree.com/celtic/seasalt1.htm

and more particularly

http://www.healthfree.com/celtic/celtsalt4.htm

Lynton:
>But heat doesn't destroy magnesium.  Perhaps its the bio-availability of it
>that's destroyed? If so, how do they know?

The data I gave, from the USDA database, have been determined by the following
method:

"Calcium, iron, magnesium, zinc, copper, and manganese were determined by
atomic absorption and plasma emission spectrophotometry"

"Analytical mineral values represent the total amount of the nutrient present
in the edible portion of the food, including any added to the product in
preparation for the retail market. The values do not necessarily represent
the amounts of the mineral elements available to the body."

Thus, some foods might seem to have a high Mg content, but in reality that
magnesium could be poorly available. It is known, for instance that phytates
bind to magnesium, zinc, perhaps iron. Grains and seeds contain phytates, but
the process of soaking usually eliminates most of the phytates. Oxalates
(present in rhubarb and spinach) decrease calcium bioavailability. Fiber can
also decrease absorption of various minerals. On the other hand, ascorbic acid
enhances iron absorption, calcium in the presence of phytic acid increases zinc
absorption (by chelation process, etc.). Availability depends on numerous
factors.

Now, why roasted sunflower has less magnesium than raw sunflower, I really
don't understand why. Minerals are normally indestructible [they are
usually roasted with the hulls; is it important, i.e. can minerals be
released and deposit in the hulls??]


Best wishes,

Jean-Louis
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