Current RDA for vitamin D responsible in part for epidemic deficiency

[Dwight Hoo]

Subject Vitamin D:

First some background information. 1 U.S.P. = 1 I.U. = 0.025
micrograms. 66 to 165 I.U. per 100 milliliter of serum is the
normal range. Converting the low value of the range 66 to
micrograms per liter yields 16.5 micrograms per liter. The RDA
for women age 23 or older is 200 IU. This value previously was
held to be 400 IU by "authorities." The major storage and
transport form is either 25-hydroxy-ergocalciferol or
25-hydroxy-cholecalciferol from respectively D2 and D3.

Now the discussion. Kelley S. Scanlon et al report in AJCN
find that many women ages 15 to 49 are short on vitamin D. The
study was broken in two populations, African American and
European American. The threshold at which the individuals were
considered deficient was 15 mcg per liter of 25(OH)D. Of the
1546 blacks, 42% were below the threshold. Among the 1426
whites, 4.2% were below the threshold. Both groups were
non-pregnant. To my mind even a 4.2% deficiency is wildly high
given the easy treatment and 42% is utterly outrageous. The
exact 10X seems a little odd given that it is exact:-)

Now an interesting point. In a sub-population of the blacks,
those taking supplement containing 200 to 400 IU qd a full 30%
were still below the threshold!

Hence the comment by Michael F. Holick of Boston Univ. that
those person not getting enough sun (apparently a large
percent of the population) the current RDA should be raised by
four times or more.

Note also, the elderly (of all skin pigmentation levels) have
greatly reduced ability to form vitamin D at the skin. A
population not considered in this study.

It would seem that this value should be screened by GP's, that
way they can not only suggest a supplement by also suggest a
supplement dose. Especially as some individuals are vitamin D
sensitive while others are resistent. It seems that an intake
beginning at 1200 IU qd can increase the risk of heart attack
and kidney stones. How much of an increased risk, I don't
know. Holick is clearly suggesting at least 800 IU qd for many
or even a 1000 IU qd is desirable.

Now a question, can getting lots of sun increase ones chances
of kidney stones? I need to review the negative feedback
mechanisms. I recall one as 25(OH)D is converted to the active
form by 1a-hydroxylase found mostly but not solely in the
kidneys. The result is the major ligand for the D receptors. I
recall there feedback mechanism at the D3 to calcitrol level
but is there one earlier at 7-dehydrocholesterol to D3 level
of formation?

This not a vitamin to go mega on.

DH

[Steve Harr]

Dwight Hooper wrote in message
<45159f7d.0207010212.27bdc387@posting.google.com>...
>Subject Vitamin D:

>It would seem that this value should be screened by GP's,
>that way they can not only suggest a supplement by also
>suggest a supplement dose. Especially as some individuals are
>vitamin D sensitive while others are resistent. It seems that
>an intake beginning at 1200 IU qd can increase the risk of
>heart attack and kidney stones.

Except I still don't believe the heart disease thing, since
the evidence is not good for it. There is one paper from India
in which I found a correlation, but this is a tropical
country, and the science from India is not that good--
certainly not good enough to make life-decisions on. It needs
to be confirmed, and in any case, the vitamin D-25 levels in
these men with coronary disease were very high compared with
anything you see in N. America.

> How much of an increased risk, I don't know. Holick is
> clearly suggesting at least 800 IU qd for many or even a
> 1000 IU qd is desirable.

At least. With the possible exception of people already
known to be renal stone formers, we'd probably all be better
off it we dietarily got 2,000 IU. This is the same kind of
thing as folate.

>Now a question, can getting lots of sun increase ones chances
>of kidney stones?

COMMENT:

Possibly, though the effect is very mild. UV radiating
caucasions in winter does increase their urinary Ca excretion
by 10 to 20%, just as you'd expect. Also, white guys get more
stones in the US the farther South they live. But the effect
is mild with RR of something like 0.82. And a day of sunshine
can give you 10,000 IU of vitamin D, so the dietary equivalent
of this latitudinal sunshine difference I would guess is in
the thousands of units for Caucasians, not hundreds.

Perhaps the answer is that everybody should get at least one
vitamin D-25 level early in life while living the sort of life
style you're going to live, sunwise. Vitamin D is sort of like
iron. Some people are going to have to supplement fairly
heavily with D (well over RDA) to get up to snuff (this is
especially true for non-whites and women living at higher
latitudes), while others won't. For those with the problem,
the 400 IU in your multivitamin probably won't do it. And
again, much as in the case with iron and folate, vitamin D
deficiency is a *much* worse problem epidemiologically than
having too much.

BTW, the direct epidemiological relationship between heart
disease and renal stone is not impressive, and doesn't show up
at all in the best studies. Negative epidemiologic
correlations are much more conclusive than positive ones. This
lack of correlation almost certainly could not hold if vitamin
D status had a large effect on both stone formation AND heart
disease risk, though it might hold if it had a large effect on
either alone, and not the other. As indicated above, I think
there's probably a modest effect of sunlight and diet D on
renal stones in N. America, and little effect on heart
disease, at least at doses common to non-tropical regions.

Am J Epidemiol 1996 Mar 1;143(5):487-95

Relation between geographic variability in kidney stones
prevalence and risk factors for stones.Soucie JM, Coates RJ,
McClellan W, Austin H, Thun M.

Department of Epidemiology, Rollins School of Public Health of
Emory University, Atlanta, Georgia, USA.

To determine whether geographic variability in rates of kidney
stones in the United States was attributable to differences in
personal and environmental exposures, the authors examined
cross-sectional data that included information on
self-reported, physician-diagnosed kidney stones collected
from 1,167,009 men and women, aged > or = 30 years, recruited
nationally in 1982. Information on risk factors for stones
including age, race, education, body mass, hypertension, and
diuretic and vitamin C supplement use was obtained by self
administered questionnaire. Consumption of milk, coffee, tea,
soft drinks, and alcohol was based on food frequency data.
Indices of ambient temperature and sunlight level were
assigned to subjects based on state of residence. Stones were
nearly twice as prevalent in the Southeast as in the Northwest
among men and women. Ambient temperature and sunlight indices
were independently associated with stones prevalence after
controlling for other risk factors for stones. Regional
variation was eliminated for men and greatly reduced for women
after adjustment for temperature, sunlight, and beverage
consumption. Other factors appeared to not contribute to
regional variation. These results provide evidence that
ambient temperature and sunlight levels are important risk
factors for stones and that differences in exposure to
temperature and sunlight and beverages may contribute to
geographic variability. PMID: 8610664 [PubMed - indexed for
MEDLINE]No.

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