"Benefits
of Vitamin D"
Written by
Tessa Jupp RN (from an article by Dr Michael Serafina
NSW) for the Post Polio Network of WA
There is a
vast body of science showing the many health benefits of vitamin D.
Maintains Your Calcium Balance
Maintenance of blood calcium levels within a narrow range is vital for normal
functioning of the nervous system, as well as for bone growth, and maintenance
of bone density. Vitamin D is essential for the efficient utilisation of
calcium by the body.
Boosts Your Immune System
Active vitamin D is a potent immune system modulator. There is plenty of
scientific evidence that vitamin D has several different effects on immune
system function that may enhance your immunity and inhibit the development of
autoimmunity. Studies show that people
with good levels of Vit D are less likely to get
colds and flu.
Insulin Secretion
The active form of vitamin D plays a role in insulin secretion under conditions
of increased insulin demand. Limited data in humans suggests that insufficient
vitamin D levels may have an adverse effect on insulin secretion and glucose
tolerance in type 2 diabetes.
Testing Vitamin D Levels
The form of
vitamin D tested for should be 25 Hydroxy-Vitamin D and must be performed using
the DiaSorin method. According to the Royal Children’s
Hospital in Melbourne - the normal range of 25 Hydroxy Vit
D is 50 - 160 nmol/L however if
you wish to obtain optimal levels for peak performance then you should aim for at least 115 nmol/L.
Vitamin D3 Supplements
It is not always effective and/or practical to get
your vitamin D from sunshine, and quite difficult to get adequate amounts from
your diet so for many people, a vitamin D supplement is a practical way to
ensure adequate levels of this important protector are always available in your
bloodstream.
Some
supplements use synthetic vitamin D2 which has been found to be less effective.
A much better form is natural vitamin D3 (cholcalciferol)
which stays in your system longer and with more effect. Vitamin D3 ideally
should be taken as an oil filled capsule which provides far better absorption.
In many cases powder filled capsules or tablets are unable to raise serum
Vitamin D levels significantly thus oiled filled capsules are recommended.
There are a number of
varying dosage protocols ranging from 2,000IU daily to 25,000IU twice a week.
We recommend to stick with the lower doses unless you
are under medical supervision.
More Vitamin D May Be Better?
Recent
science is showing that doses above these may provide better health. For
example, Professor Robert Heaney has reported in April 2006 in the Journal of
Nutrition his study showing an additional 2,600 IU/day of oral vitamin D3
should be given to older women.
The
American Journal of Clinical Nutrition reported a recommendation of 4,000 IU
per day for adults. He also showed that levels of 10,000 IU per day were normal
from body exposure to the sun and the only published vitamin D toxicity was at
levels exceeding 40,000 IU/day.
It seems
more studies are warranted on proper vitamin D doses. Given that vitamin D3 is
safe at very high levels and may provide extraordinary benefits with no known
risk, we recommend individuals get reasonable sun exposure, eat foods rich in
vitamin D, and supplement with 2,000IU Vitamin D3 in an oil based capsule.
Follow up blood tests will then determine if any dosage adjustments are
required.
Vitamin D Toxicity
It is very rare to have a vitamin D overdose. Research
published since 1997 suggests that this level for adults is overly conservative
and that vitamin D toxicity is very unlikely in healthy people at intake levels
lower than 10,000 IU/day.
Certain
medical conditions can increase the risk of hypercalcemia in response to
vitamin D, including primary hyperparathyroidism, sarcoidosis, tuberculosis,
and lymphoma. People with these conditions may develop hypercalcemia in
response to any increase in vitamin D nutrition and should consult a qualified
health care provider regarding any increase in vitamin D intake.
Vitamin D Drug Interactions
The following medications increase the metabolism of vitamin D and may decrease
serum D levels:
Dilantin, phenobarbital, Tegretol,
(all for epilepsy) and rifampin (for TB).
The
following medications should not be taken at the same time as vitamin D because
they can decrease the intestinal absorption of vitamin D: Cholestyramine
and colestipol (Colestid) for
cholesterol, Xenical for weight loss,
mineral oils, the fat substitute Olestra and the oral anti-fungal medication, ketoconazole (Nizoral) for candida
or thrush. Patients on Digoxin
may experience cardiac arrhythmia if high levels of Vit D increases calcium levels.