Vitamin D is often misunderstood, for one because it has been the source of some controversy lately due in part by the historically low RDA (Recommended Daily Allowance) and more recently, higher levels recommended by some health practitioners.
Vitamin D Deficiencies
Vitamin D deficiencies are known to be associated with osteoporosis (fragile bones) and osteomalacia (a softening of the bones) due to the fact that calcium absorption is compromised with lower levels of Vitamin D.
It is also known to cause rickets and is thought to be a common cause of depression, cognitive decline such as Alzheimers disease, chronic fatigue syndrome and chronic pain (often mistaken for fibromyalgia).
Vitamin D deficiency has also been associated with insulin deficiency and insulin resistance. A recent study showed that it was likely to be a major factor in the development of type I diabetes in children.
It has also been linked with Multiple Sclerosis, rheumatoid arthritis, Crohn’s disease, and other auto-immune disorders.
Optimum Serum Levels
Serum levels of Vitamin D should be between 25 and 75 ng/ml, however the lower end of this range is believed to be below deficient and would not even support sufficient bone health, and could be a precursor to other diseases.
However, it is also possible to have excessive levels of Vitamin D due to the fact that it is not excreted by the body, but stored in fat cells and so accumulates over time.
Levels of Vitamin D in excess of the 75 ng/ml amount can reduce calcium absorption in the bones and cause deposits elsewhere, in soft tissue and the intestine, and may also cause headaches, itchy skin, nausea, and kidney stones.
Toxicity can occur if amounts above 40,000 IU per day are taken for a period of time. But there has never been a reported vitamin D toxicity from under 10,000 IU per day.
Is Vitamin D Really a Vitamin?
In fact, vitamin D is not actually a vitamin at all but a group of fat-soluble secosteroids which are finally converted to a hormone from calcidiol by the kidneys.
This hormone is a potent neuroregulatory steroidal hormone that influences nearly 3,000 of your 25,000 genes.
It is produced in the skin when exposed to Ultraviolet (UV) B rays from the sun, and has a primary function of maintaining optimum levels of calcium and phosphorus in the blood, and so has a crucial role in the absorption of calcium by the bones.
It also works in concert with other hormones in the absorption of other essential minerals. Vitamin D is a cornerstone to our physical health.
But healthy levels of Vitamin D require regular exposure to sunlight, which, due to seasonal weather or jobs keeping people indoors most of the time, smog, cloud cover, sunscreen and latitude, we do not always produce.
The often recommended 10 to 15 minutes of sunshine, at least three times a week is not enough to maintain levels at the low end of the spectrum.
The body produces about 5,000 IU per day of vitamin D with about 50% of the body exposed for 30 minutes, and as much as 1000 IU per day with 10% exposure for that amount of time.
Vitamin D can be found in some fortified cereals, orange juice and dairy products, as it was added to milk and dairy products in the 1930s in the US when rickets were problematic.
It can also be found in eggs, mushrooms, and some oily fish. Cod liver oil is a widely known source of Vitamin D but the quality of the source must be taken into consideration. Farm raised fish will not have healthy levels of Vitamin D or Omega 3 fatty acids.
But, we only get an average of 250 to 300 IU of Vitamin D per day from dietary sources.
When supplementing, it is wise to avoid synthetic Vitamin D (ergocalciferol), D-2, where the natural form (Cholecalciferol), D3, is preferred because it is not only safer but sustains blood levels for a longer time.
While the RDA has been 5 micrograms (200 IU) per day for decades, it is being raised to 400 IU per day which is still thought to not be enough to maintain healthy serum levels.
It has been recommended by some health practitioners that 1000 to 2000 IU per day for adults, and up to 4000 IU per day during the winter months (except for individuals with kidney stones or sarcoidosis).
Some people with conditions such as Celiac may be advised to take more, particularly when first diagnosed. Aging or dark skinned people should increase their dosages as they are more prone to deficiencies.
It has long been believed that 1000 IU of Vitamin D will raise serum levels by 100 ng/mL, but it is now thought that it will take 2000 IU per day to raise levels by that much.
For adults, 10,000 IU per day may result in toxicity from Vitamin D excess in a few months.
Check Your Levels
It would be wise to be tested so that you stay within the optimal range and determine the dose necessary, and particularly to know whether you are deficient, and prone to many chronic illnesses.
The 1,25-dihydroxy-vitamin D test most commonly used will not show a Vitamin D deficiency, even a severe one. A more accurate test is the 25-hydroxyvitamin D test which provides a better view of your serum level.
The problem is that the test is not often covered by insurance. However, the Vitamin D Council can provide a test, saving you a visit to the doctor and the associated bill.