Cod Liver OIl - How much is too much?

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http://www.thenakedscientists.com/forum/index.php?topic=5065.msg99329

" In spite of high vitamin D intake, overt vitamin-D toxicity has never been

reported in Iceland. Still, long term consumption of relatively large

quantities of cod liver oil might have some adverse effects on the

population. For this reason we decided to perform a small study on a group

of 19 adult Icelanders who had taken more than one tablespoon of cod liver

oil daily for the last 5 years or longer. Seventeen adults of same age and

sex distribution who had not taken any vitamin D preparations during the

previous year were chosen for control purposes. Serum vitamin D metabolites,

25(OH)D and 1,25(DH)2D were measured in all subjects, as well as serum

calcium. All methods have previously been described.

The results were as follows: Consumers of cod liver oil had significantly

higher levels of 25(DH) vitamin-D serum than did the control group, or

34,2ng/ml(+- 9,8 S.D.) compared with 18,0ng/ml(+-6,6 S.D.) amongst controls.

All values in the cod liver oil group were in the high normal range, the

highest value being 59ng/ml. In the control group most values were in the

low normal range, but three individuals were below 10ng/ml, with the lowest

value measured at 5 ng/ml. No significant difference was found in serum 1,25

(DH) 2vitamin-D or serum calcium between the groups, and all values measured

within normal ranges. "

{The question I've always had is which D is in CLO? Since it comes from the

fishes liver I suspected it would be calcidiol, 25-dihydroxycholecalciferol

(25-OH-D3). But labels ae never specific.

The D in a pill indicates D3, cholecalciferol as does that in milk, and a

human might be able to take a S/L without effect because the kidney will

turn it to an inactive form (24,25-[OH]2 - D3.), without the PTH.

This article shows me they can measure the 1,25 (DH), so I suspect there is

a problem in the analyses, and in interpretation of serum D3 tests.

Also, it shows me people can take a tbls per day without A or D

hypervitaminosis.

Regards