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Current recommended daily allowances for Vitamin D are probably too low, particularly when new research shows that higher doses can protect us from several diseases.
Anyone who watches television, stares at a computer screen or listens to a radio already knows the news: Vitamin D not only helps to build strong bones; it probably helps to protect us from heart attacks, cancer, diabetes, and even multiple sclerosis. Alas, many Americans aren’t getting enough of the “sunshine vitamin.”
Vitamin D’s role in preventing rickets (a disease characterized by softened and malformed bones) has long been understood. Misguided attempts to prevent rickets in the 1940s by supplementing foodstuffs with vitamin D led to the overdosing of many children, who subsequently suffered irreversible brain damage. Paradoxically, the ensuing apprehension about vitamin D toxicity resulted in a recommended daily allowance (RDA) that is too low for most people. Indeed, one recent study showed that 40% of American babies and toddlers may have inadequate levels of the vitamin; another study suggests that adolescents can and should be taking as much as five times the latest RDA of 400 units daily.
Vitamin D is unique among the many vitamins that contribute to optimum human health. It is the only vitamin that the human body, in a self-regulated process, can produce on its own via exposure to sunlight. About an hour of sun exposure each week is considered sufficient (and this can be achieved in several, short-term forays into the outdoors) but individual needs vary, depending upon age, skin color, and underlying health problems. However, with the well-documented connection between skin cancer and exposure to ultraviolet light, a lot of people are hesitant to spend much time in the sun; they prefer to take a vitamin D supplement instead. In many cases, these individuals will simply take the form of vitamin D that is recommended by their physicians.
Unfortunately, in spite of some excellent studies revealing the superiority of vitamin D3 (cholecalciferol) as a supplement, the form of vitamin D found in major preparations of prescriptions in the US is vitamin D2 (ergocalciferol). It is noteworthy that vitamin D2 was developed and patented by the pharmaceutical industry and has since been prescribed by physicians for patients who need vitamin D. Many doctors don’t know that vitamin D2 differs radically from vitamin D3 in its physiologic activity. Once in the human body, vitamin D2 is inactivated in the normal metabolic pathway that converts vitamin D3 to an active precursor form of the vitamin. Vitamin D3 is the form that leads to higher levels of serum 25-hydroxyvitamin D, which is converted to 1,25-dihydroxyvitamin D. This is the molecule that confers vitamin D’s benefits. Conversely, the metabolic products of D2 are not efficiently bound to important carrier proteins in the bloodstream, and they don’t effectively activate the appropriate cellular receptors. Finally, vitamin D2 has a shorter shelf life than D3.
In summary, then, it is clear that vitamin D3 is the preferred form of supplemental vitamin D; vitamin D2—in spite of longstanding medical dogma—should not be regarded as an acceptable source for supplementation.
The copyright of the article Is Vitamin D3 Better than D2? in Vitamins & Minerals is owned by Stephen Allen Christensen. Permission to republish Is Vitamin D3 Better than D2? in print or online must be granted by the author in writing.
Comments
Aug 17, 2008 3:57 PM
Guest :
You are not very infomed if you say that D2 was created by the
pharmaceutical industry. Vitamin D2 is found in plants. It is active but
it is less active than D3. And it is even perscribed by many doctors to
decrease D3 and increase D2 in the body because D3 is a steriod. Besides
that you aren't saying the side affects of D3 even in a dose of 500 I.Us
many find that there bones become brittle.
Aug 17, 2008 5:56 PM
Stephen Allen Christensen :
I would refer you to http://www.ajcn.org/cgi/content/full/84/4/694
Physicians prescribe what they're taught to prescribe, and much of
doctors' prescribing practices are dictated by the pharmaceutical industry
in this country. That's just the way it is.
Doctors don't prescribe D2
to decrease levels of D3 in the body; unfortunately, they seldom give it a
thought, because physicians, in the main, aren't well-versed in matters of
nutrition.
I do speak from a position of experience, if not
authority. Aside from getting a middling background in nutrition, I
practiced medicine for nearly two decades. I can attest to the influence of
"Big Pharma", both in medical education and in medical
practice.
By the way, MANY of the molecules that are critical to
cellular function are "steroids." Indeed, the very membranes of
our cells are laden with steroid molecules. Just because a molecule is
classified as a steroid doesn't mean it is detrimental to human health.
Jan 12, 2009 9:12 AM
Guest :
But I've heard that vitamin D3 supplements are animal-derived. if that is
true I would rather take D2..
Jan 15, 2009 11:15 AM
Stephen Allen Christensen :
Whether D3 is plant- or animal-derived is moot in the minds of many,
because as soon as you step out into the sunshine, you begin to synthesize
D3 in your skin via the interaction of ultraviolet-B light and a derivative
of the cholesterol molecule. So, whether a person takes it or makes it is
an academic question.
Now, for the strict vegan who eschews the
ingestion of all animal products, this could certainly become a
philosophical issue.
Feb 1, 2009 7:29 AM
Guest :
Thank you for the information, Dr. Christensen. I am a 45 yr. old female
and have had basal cell CA 3 times, so the sun is not an option for me. Do
you recommend 1000 units of D3 daily...is this enough? I know more is not
necessarily better, but in this case, would 5000 units daily be optimal?
Thanks,
Michele
Feb 1, 2009 5:27 PM
Stephen Allen Christensen :
Michele,
The maximum daily dose recommended by the Food and Nutrition
Board of the Institute of Medicne is 2000 IUs daily. However, this may be
an overly conservative recommendation. Vitamin D toxicity is unlikely below
10,000 IUs daily. Personally, I take 2000 IUs daily during the winter and
when I'm not able to get out into the sun during the summer.
I hope
that helps.
Feb 12, 2009 6:44 PM
Guest :
Thank you! off to get some cholecalciferol.
Mar 13, 2009 2:11 PM
Guest :
Does it help if the D3 supplement comes in gel form versus the dry form?
Mar 14, 2009 7:55 AM
Stephen Allen Christensen :
Different vehicles for vitamins (i.e., gel, liquid, tablet, powder,
capsule) may confer different levels of absorption. In the pharmaceutical
industry there are quality standards that require certain levels of
availability for given agents. Unfortunately, the supplement industry is
not so carefully constrained. All else being equal, a gel may provide a
more readily-absorbed nutrient than a tablet or powder, simply because it's
already in a semi-liquid form. However, just because a product is offered
in gel form doesn't guarantee its quality. My advice would be to consult
with a nutritionist that you trust (that person might be your favorite
vitamin retailer) and find a good-quality form of every supplement that you
take. Once you find the ones you like, stick with them.
Sep 22, 2009 4:34 AM
Guest :
I started taking a multi-vitamin which contains 600 UI a few months ago and
then this past weekend I started adding Vitamin D3 pills which contains
1000 UI. I started getting a small rash on the inside of my elbow and on my
shoulder. Can this be the cause? Also my neck is very irritated - I can't
wear scarves, turtlenecks, neckalces, or put on perfume. This has been this
way since the winter. Could the multi-vitamin have this affect?
Sep 22, 2009 1:16 PM
Stephen Allen Christensen :
One easy way to find out if the vitamin is the culprit is to stop taking it
for a couple of weeks. As long as your diet is reasonably well-balanced,
stopping the multivitamin won't hurt you a bit. If the rash and skin
sensitivity go away, it could be something in the vitamin that's causing
the problem. You could always restart the same multivitamin to see if the
problem returns-- thus clinching it--but I'd just get a different
vitamin...if you think you really need it.
If the rash and sensitivity
persist after you've been off the vitamin for two to three weeks, I'd start
looking for other possible causes (i.e., perfumes, cosmetics, soaps and
detergents, etc.) or have a doc take a look.
Sep 24, 2009 4:03 AM
Guest :
Thanks - I'll do that. I just never thought a multi-vitamin would have that
affect. Who would have thought that something which is supposed to help
with your health can cause this sort of problem?
Oct 2, 2009 2:26 PM
Guest :
Because I do not get much exposure to daylight (I go to sleep and wake up
late), I began taking 3000-4000 IUs of D3 earlier this year. I too noticed
a rash around my neck and shoulders, which seems to have intensified when I
recently began taking the pills twice a day (2 x 1000 IUs) instead of 3 or
4 times (3 or 4 x 1000 IUs).
I attributed this rash initially to
irritation from laundry products or perfume, but the only thing that
changed in the weeks prior to the rash's intensification was the doubling
of the amount of D3 I was taking at one time. I also find it interesting
that another reader here has experienced a similar rash in the
neck/shoulder area.
As an experiment, I will cut back to 2000
IUs per day, taken in two installments, and report back here in a week or
two with an update on the state of the rash.
Oct 2, 2009 2:32 PM
Guest :
Because I do not get much exposure to daylight (I go to sleep and wake up
late), I began taking 3000-4000 IUs of D3 earlier this year. I too noticed
a rash around my neck and shoulders, which seems to have intensified when I
recently began taking the pills twice a day (2 x 1000 IUs) instead of 3 or
4 times (3 or 4 x 1000 IUs).
I attributed this rash initially to
irritation from laundry products or perfume, but the only thing that
changed in the weeks prior to the rash's intensification was the doubling
of the amount of D3 I was taking at one time. I also find it interesting
that another reader here has experienced a similar rash in the
neck/shoulder area.
As an experiment, I will cut back to 2000
IUs per day, taken in two installments, and report back here in a week or
two with an update on the state of the rash.
Oct 3, 2009 3:59 PM
Guest :
Rereading my post of yesterday, I realized that when I wrote:
"...when I recently began taking the pills twice a day (2 x 1000
IUs)..."
it was not clear that I meant 2000 (2 x 1000) IUs,
twice a day (total 4000 IUs), an amount which I shall now be halving.
Oct 12, 2009 5:44 PM
Guest :
For the past 3 years I have been taking calcitroil .25 mcg's 2x/day. I
have also been taking Calcium Citrate plus Vitamin D (ergocalciferol)
Vitamin D 400 IU plus Calcium 1000 mg (1500 mg a day) and recently was told
to take 1000 IU's of Vitamin D. I took one each day and noticed numbing
and tingling in my lips, left side of face, fingers and toes. After the
first day, I stopped taking it and symptoms went away. Next day I took it
again and same symptoms appeared. My multivitamin, and Calcium Citrate
both have Vitamin D in it, perhaps it was too much or I am allergic to the
brand of Vitamin D, I am not sure which. I just realized that there was
two types of Vitamin D (ergocalciferol and Cholecalciferol). One is D2 and
the other is D3. I was never told there was a difference and have been
taking D2 all along and then switched to another brand which apparently is
D3. I don't know which is better. Any help would be appreciated.
Oct 12, 2009 7:11 PM
Stephen Allen Christensen :
Rocaltrol (calcitriol) is usually recommended for people suffering from
renal failure, osteoporosis, or hypoparathyroidism. Calcitriol is a potent
form of vitamin D, and anyone taking it in conjunction with other forms of
vitamin D should be closely monitored. I assume your calcium and vitamin D
levels are being checked periodically; one side effect of vitamin D
intoxication could be the sensory disturbances you have described.
However, to ensure that no stone is unturned, I would recommend medical
evaluation to ensure that nothing else is going on. Citrate toxicity, for
example, can cause the symptoms you report; it is a common side effect of
blood transfusion or in people who donate platelets. I've also heard of it
happening in dialysis patients.
Additionally, although your symptoms
are unusual for someone suffering from TIAs ("ministrokes"),
there might be something neurological going on that is unrelated to your
vitamin D intake.
By the way, I always recommend vitamin D3 over D2,
for the reasons I mentioned in the article.
17 Comments
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Jun 22, 2008
