OffTopic: IGF-I

[Gaby Rottler]

Hi Shannon,

some background info:
IGF-I is a peptid, that's identical for humans, bovine and porcine
species.
Insulin and the two insulin-like growth factors, IGF-I and IGF2 are
everywhere in the body to be found, the IGFs working on the regulation
of the slow growth processes.
IGF-2 is responsible mainly for the development of fetal cells, IGF-1 is
effective after birth.

Because of the identity the bovine IGF-I in milk (which of course should
promote the grouwth of the calf) will also have influence on humans,
because of the identitiy of the 2 substances.
A recent study shows a growth-promoting effect in fetal cell lines, but
of course many other factors may be involved.
------------------------
J Dairy Res. 2006 Sep 15;:1-8 [Epub ahead of print]

Biological activity of bovine milk on proliferation of human intestinal
cells.

Purup S, Vestergaard M, O Pedersen L, Sejrsen K.
Department of Animal Health, Welfare and Nutrition, Danish Institute of
Agricultural Sciences, Research Centre Foulum, PO Box 50, DK-8830 Tjele,
Denmark.

To evaluate the bioactivity of bovine milk from different stages of
lactation on human intestinal tissue, a human fetal small intestinal
cell line was used as a model system. Milk samples representing six
stages of lactation: days 1, 2-3, 6-7 and weeks 12 and 24 after
parturition, 1 week before drying off, and milk-like secretion from two
stages of the dry period: 7 weeks and 3-4 weeks before expected calving,
were collected from 64 Holstein Friesian cows. The whey fraction of the
milk or milk-like secretion was added to the culture medium in
concentrations ranging from 0.078% to 10%. The growth-promoting activity
of whey was measured by determining the incorporation of [3H]thymidine
into DNA for the last 24 h of the culture period. Whey fractions from
all six stages of lactation stimulated growth of intestinal cells. The
growth-promoting activity of colostrum or milk significantly decreased
within the first week after calving. The growth-promoting activity in
mature milk increased gradually during lactation to reach a level
significantly higher than that obtained with colostrum. The
growth-promoting activity of whey from milk-like secretion collected
after drying off was lower than that of colostrum. Whey from different
stages of lactation contained significantly different concentrations of
TGF-beta1 (0.5-27 ng/ml) and TGF-beta2 (12-1219 ng/ml). However, neither
the differences in TGF-beta1 and TGF-beta2, nor the differences in IGF-I
and IGF-binding proteins could fully explain the differences in
growth-promoting activity of colostrums or milk from different stages of
lactation, suggesting that other factors were also involved. The present
study showed that bovine milk contained a number of biologically active
components that affected growth and development of human intestinal
tissue. The results showed that the growth-promoting activity of
colostrum and milk was dependent on the stage of lactation in accordance
with previous results obtained with mammary epithelial cells. The
changes in growth-promoting activity with stage of lactation were
probably related to changes in concentrations of several growth factors.
-------------------------------

Best,

Gaby

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Gaby Rottler,DVM
Germany
rottler@curantur.de
http://www.curantur.de
***Scriptum homoeopathicum***
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Shannon Nelson]

Thanks, Gaby!
But why is that thought to be bad?
It seems there are *many* reasons why most people should not drink
large amounts of milk (and a significant number should not drink any at
all), but is this factor anything to suggest a problem with, say, 1 or
2 cups daily, in your understanding? (I have to admit that, in the
end, I would continue to choose my foods and my kids' milk intake by
experience rather than by theory, but I am curious.)
Thanks,
Shannon
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