At a guess, presuming you are eating red meat on low-carb... maybe
they feel you will be getting enough from diet and should not add
extra? Just a thought.

Since you are on Atkins your intake of meat will be higher and as meat
is generally high in iron, supplementing with iron may result in high
iron levels (in your body). Excessive iron levels can eventually lead to
many diseases like: arthritis, high blood pressure, heart disease, liver
disease, and many others.

Iron is one of the things added to supplements it's possible to
OD on.  There are men who retain too much of it and without
any tests it's easier to assume I might be and not get extra
from the tablets.

For some Centrum are the line between good and bad
quality multis.  There are so many types that are better that
aren't expensive.  I look for generics that say "Compare
with Theragram-M".

Nitrate free bacon to see if you like it.  Greek yogurt.  Nuts.
Cheese.

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I've come accross two issues with iron (I myself am lacking -
borderline anemic), but my father developed gallstones...the following
I copied and pasted from:  http://adam.about.com/reports/Gallstones-and-gallbladder-disease.htm
as a possiblility - from what I understand, they are painful to move
or have removed.
_____________________________
Diet

Men who consume a diet high in foods containing heme iron, such as
meat and seafood, are at increased risk for developing gallstones.
Gallstones are not associated with diets high in non-heme iron
sources, such as beans, lentils, and enriched grains.

Fruits and vegetables appear to substantially reduce the risk of
symptomatic gallstone formation. The effect holds true regardless of
which fruits or vegetables are consumed. Risk drops in proportion to
the percentage of fruits and vegetables in the diet.
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2.  It's hard to lose weight if you're constipated.  I may be
borderline anemic, but constipation is a big problem with me, without
taking iron suppolements- can't figure that one out, but two products
that I've used for constipation are excellent:  First one called
Smooth Move by Traditional Medicinal - you can purchase at the local
grocery and (if anyone is interested, a weight loss natural detox tea
that I sell....)  I have used both and they are both excellent for
constipation - I haven't used long enough for weight issues so cannot
comment on that.  Yes, I'm spamming....but through experience with
these two excellent products!

Hope this helps!
Cheri Redding