The Vitamin D Council advises that most healthy people can receive
5,000-10,000 IU of vitamin D3 a day without harm. But high dose vitamin D
must be accompanied by sufficient calcium and magnesium...and people
with certain diseases should only take supplements under the supervision
of a knowledgeable doctor. Vitamin D is essential for the absorption of
calcium and the prevention of osteoporosis. Recent studies have shown
that it may also boost the immune system and help to prevent cancer.
Our
body will automatically regulate how much vitamin D it produces from
sunshine. Studies show that sunbathing in the summer for about 30
minutes can result in the production of over 10,000 IU of vitamin D and
that once our skin makes about 20,000 IU, the ultraviolet light begins
to degrade the vitamin so that we do not "overdose" on the sun. Vitamin D
expert Dr. Vieth reports that there is no practical difference between
vitamin D acquired from the sun and that acquired from food and
supplements.
The Vitamin D Council reports that doses of 5,000 IU
per day from all sources (sun, diet and supplements) are safe for most
healthy people and that there are no reports of toxicity up to 10,000 IU
per day. But the Council also warns that without calcium and magnesium
in sufficient quantities, vitamin D supplementation will withdraw
calcium from the bone and will allow the uptake of toxic minerals. As
everyone metabolizes vitamin D differently, the best way to identify the
optimal level of supplementation is to adjust the dosage to maintain
target blood levels. The Vitamin D Council recommends that optimal
health is supported by blood levels of 50-80 ng/mL (125-200nmol/L) as
identified in a 25(OH)D vitamin D blood test.
HIGH DOSE VITAMIN D FOR TREATMENT OF SEVERE DEFICIENCY
High
dose vitamin D treatment is broadly accepted in the medical community
for people who are suffering from a severe deficiency but are otherwise
in good health. There are two views on the best way to receive high dose
vitamin D. The most common form of high dose vitamin D in the US is a
prescription form of ergocalciferal also known as vitamin D2. But as
vitamin D2 is less potent than vitamin D3, many doctors now recommend
high dose vitamin D3 which can be purchased in a health food store or
on-line.
VITAMIN D2 (50,000 IU/week)
Dr. Michael
Holick of the Boston University School of Medicine recommends high dose
vitamin D2 treatment for people whose 25(OH) blood levels are below 10
ng/mL (25 nmol/L). He proposes an oral dose of 50,000 IU/wk of vitamin
D2 for 8 weeks followed by another blood test to check serum levels. If
the levels are still inadequate, another 8-week course of 50,000 IU/week
may be prescribed until blood levels reach 30 to 50 ng/mL (75-125
nmol/L). Once these target blood levels have been attained, patients
prone to developing vitamin D deficiency may be encouraged to take
50,000 IU of D2 every 2 weeks to sustain their blood levels...or 1,000
IU a day of vitamin D3. He also suggests that exposure to direct
sunlight for 5-10 minutes on the arms and legs between 10am-3pm during
the spring, summer and fall can prevent further deficiency.
Ergocalciferol
is available to U.S. doctors in prescription strength of 50,000 units
in the brand names of Drisdol and Calciferol. As it is derived from
plants rather than animals, ergocalciferol is considered Kosher.
VITAMIN D3 (4,000 IU/day)
Dr.
Vieth (Mount Sinai Hospital in Toronto Canada) recommends that vitamin
D3 is the preferred choice for supplementation. In 2001, a study
involving 61 healthy men and women resulted in healthy increases in
blood levels following daily intake of 4,000 IU of vitamin D 3-without
an increase in blood calcium or urinary calcium excretion. After 2-5
months, the blood levels of participants increased to a range of
28-50ng/ml (69-125 nmol/L). Dr. Vieth has proposed a rule of thumb, that
4,000 IU of vitamin D3/day will increase 25(OH)D blood levels by
100nmol/L (40ng/ml) after 8 months of use and that any surplus vitamin D
will remain in the body for approximately 2 months.
Dr. Vieth
recommends a daily dose of 4,000 IU/day in order to maintain blood
levels above 100nmol/L. He also clarifies that published cases of
vitamin D causing elevated blood calcium (hypercalcaemia) have involved
daily intake of 40,000 IU. Hypercalcaemia due to excessive vitamin D is
generally accompanied by blood concentrations greater than 88ng/ml (220
nmol/L).
Dr. Vieth also suggests that high and infrequent dosing
may result in blood level fluctuations without producing sustainable
improvements in blood levels. Intake of lower doses of 2,000-4,000 IU
daily rather than 100,000 IU once a month are more likely to produce the
desired results.
CALCITRIOL
Calcitriol is a steroid
that is produced after vitamin D passes through the liver and kidneys.
The Vitamin D Council warns against treating vitamin D deficiency with
calcitriol (or its analogs) as it poses risks of hypercalcaemia (high
blood calcium) and fails to replenish the body's stores of vitamin D.
HIGH DOSE VITAMIN D TREATMENT GETS SILLY (500,000 IU)
Non-compliance
(failure to take medications) is common both with prescription drugs
and vitamins. Pharmaceutical companies and researchers often seek to
address this problem with a "one shot a year" approach to osteoporosis
medication and occasionally with vitamins.
In 2010, professors at
the University of Melbourne reported results of a study involving 2,256
women (aged 70 years or older and considered to be at high risk of
fracture) who received an annual dose of 500,000IUs of D3 supplements
for three to five years. They were surprised that the recipients of this
high dose vitamin D regime had 26% more fractures and 15% more falls
than the placebo group. Treatment of non-compliant people with mega
doses of vitamin D does not seem to be the solution....as suggested by
earlier research that lower doses ingested daily produce the best
results.
There are a number of diseases for which vitamin D
supplements can cause elevated blood calcium and possibly compromise the
immune system. In these cases, supplements should only be taken under
the supervision of a knowledgeable doctor. By
Darlene Varaleau
