Dr. Terry Diamond and colleagues of St. George’s Hospital in New South Wales just published the first head-to-head comparison of 5,000 IU/day to 2,000 IU/day. Remember, the Food and Nutrition Board says 4,000 IU/day is the upper limit, but Dr. Diamond knows the pharmacology of vitamin D well enough to know that quite a few people will still have inadequate levels at 4,000 IU/day.
He recruited 30 patients with vitamin D levels less than 20 ng/ml and put half on 5,000 IU/day and half on 2,000 IU/day for three months. He measured a number of things, the most important of which was muscle strength.
Diamond T, Wong YK, Golombick T. Effect of oral cholecalciferol 2,000 versus 5,000 IU on serum vitamin D, PTH, bone and muscle strength in patients with vitamin D deficiency. Osteoporos Int. 2012 Mar 16.
After 3 months of 2,000 IU/day the vitamin D levels averaged 30 ng/ml (75 nmol/L), meaning about half the patients were still vitamin D deficient. Not so with the 5,000 IU/day group. The average vitamin D level was 45 ng/ml (114 nmol/L), right in the “natural range.” In addition, 93% of the patients had levels higher than 30 ng/ml compared to the 2,000 IU/day group, where only 45 % had levels above 30 ng/ml. Remember, one of the problems with daily dosing is that you must rely on the patient to take their medication. As an old GP, I am here to tell you not all patients take their meds; the ones that get me are the ones who look me straight in the eye and tell me something I know is not true.
In Dr. Diamond’s well-designed study, changes in grip strength compared to baseline were very significant, while the improvements in timed tests of sitting to standing and the 6-meter walk test also improved, but not significantly. What surprised me was that the improvements did not vary with dosage. That is, the 2,000 IU/day had the same improvements in grip strength as did the 5,000 IU/day, meaning muscle strength improvements are the most dramatic at changes in lower ranges of vitamin D levels. By that, I mean if your level is 5 ng/ml to start out and you get to up to 20 ng/ml, your percentage improvement in muscle strength will be much more dramatic than someone who went from 20 to 35 ng/ml.
I am glad to see Australians using daily dosing of vitamin D. Many of the “Stoss” doses, 100,000 IU/month or 600,000/year are not physiological, and are dangerous. Vitamin D was made every day in the skin of our ancestors and we should strive to replicate such dosing schedules. How much do we need? To quote Dr. Diamond, “This study demonstrates that the administration of oral vitamin D at 5,000 IU daily is superior to 2,000 IU daily for 3 months to treat mild to moderate vitamin D deficiency.”
Key Ingredients found in Isotonix® Vitamin D with K2:
Vitamin D3 (Cholecalciferol): 5000 IU
Vitamin
D is a fat-soluble vitamin that is found in some foods and endogenously
produced when sunlight strikes the skin and activates vitamin D
synthesis. Vitamin D promotes the efficient intestinal absorption of
calcium, primarily in the duodenum and jejunum by supporting the
synthesis of calcium-binding proteins to promote normal calcium
absorption and retention. Vitamin D also promotes the normal formation
of bone and normal bone growth and bone remodeling by osteoblasts and
osteoclasts. Vitamin D deficiency can be caused by factors such as lack
of exposure to sunlight, reduced skin synthesis of vitamin D, lower
dietary intake, impaired intestinal absorption, and reduced metabolism
to active forms of vitamin D by the kidneys, all of which increase with
aging. Deficiency has been linked to numerous health concerns, and
insufficient levels of this vitamin are associated with weak bones and
muscle weakness. In addition to promoting strong bones, vitamin D also
has other roles in health, including supporting the body’s normal
modulation of neuromuscular function and immune function. Vitamin D has
been shown to support immune-modulation, and it is thought that
supplementation promotes immune health by promoting the body’s normal
regulation of T-cell function. In reference to cellular health, Vitamin D
supports the modulation of many genes that are responsible for encoding
proteins that regulate normal cell cycle activity. Vitamin D levels
have been strongly correlated to healthy cells. Lastly, through its
interaction with VDR (vitamin D receptor), vitamin D supports the
healthy expression of the gene encoding renin, thus helping to maintain
healthy blood pressure.*
Vitamin K2: 45 mcg
Vitamin
K is a fat-soluble vitamin found meat, eggs, dairy and natto. Although a
fat-soluble vitamin, the body stores very little K2, and its stores are
rapidly depleted without regular dietary intake. Natural
vitamin K2, also known as menaquinone-7 (MK-7), is the most
bioavailable form of K2 and has the longest half-life in the blood of
any form of vitamin K. The Japanese soy food natto is particularly rich
in menaquinone-7 (MK-7). Studies of natto consumption in Japan have
linked menaquinone-7 to bone and cardiovascular health. The correlation
of vitamin K to cardiovascular and bone health directly focuses on
supporting proper calcium utilization, whereby adequate metabolism of
calcium supports arterial and bone health. This is often referred to as
the calcium paradox. The calcium paradox is explained simply as getting
calcium in the right place (i.e., into the bone structures instead of
the arterial vessel walls). These events are dependent upon the
synthesis of the vitamin K-dependent proteins osteocalcin and matrix Gla
protein in a process called carboxylation. The carboxylation of these
proteins is a post-translational step; that is, osteocalcin and matrix
Gla protein are translated from their respective messenger RNA and then
modified by enzymes to the active forms. These carboxylated forms
support the healthy binding and releasing of calcium. This reaction is
essential for optimal and healthy utilization of calcium. Vitamin K2
promotes the synthesis of proteins involved with calcium utilization,
thereby supporting bone retention and arterial health. While vitamin D
supports the healthy regulation and synthesis of osteocalcin, the
mineral-binding capacity of this protein requires vitamin K-dependent
carboxylation and is thought to be related to bone mineralization. Gas6
is a vitamin K-dependent protein found throughout the nervous system, as
well in the heart, lungs, stomach, kidneys and cartilage. Although the
exact mechanism of its action has not been determined, Gas6 appears to
be a cellular growth regulator involved in cellular activities such as
cell adhesion, cell proliferation and protection against apoptosis.*
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