Up to 70 Percent of Americans May be Deficient in Vitamin D--Find Out Why You Don¹t Want to be One of Them

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Up to 70 Percent of Americans May be Deficient in Vitamin D--Find Out Why

You Don¹t Want to be One of Them

By Cannell, M.D., executive director of The Vitamin D Council

Vitamin D is a vital nutrient that is unique, both in terms of its

physiology and because humans rely on both endogenous skin production and

exogenous sources to meet biological requirements. Vitamin D is commercially

available as vitamin D2, (ergocalciferol) made from plant products, and

vitamin D3, (cholecalciferol) made from animal products.

Cholecalciferol is also made naturally in the skin by the action of a

specific wavelength of ultraviolet light (UVB) interacting with

precholesterol. Cholecalciferol is then transported to the liver and turned

into calcidiol [(25(OH)D]. In turn, the calcidiol is transported to the

kidney and transformed into the steroid calcitriol, which is excreted into

the blood to help regulate calcium in the body. This is the main endocrine

function of vitamin D.

Meanwhile, many tissues other than the kidney turn calcidiol into calcitriol

to help regulate gene expression locally; this is the newly discovered

autocrine (inside the cell) and paracrine (surrounding the cell) functions

of vitamin D. This autocrine and paracrine function is impaired in vitamin D

deficient subjects. All studies show many Americans are vitamin D deficient,

especially Blacks, where the problem is pandemic.

This use of calcitriol by other tissues as an autocrine and paracrine

hormone is a relatively new discovery that explains its role in human

development as well as the many health benefits of vitamin D in other

illnesses such as diabetes, hypertension, heart disease, autoimmune illness,

at least 13 different cancers and, perhaps, some mental illness.

The Extraordinary Rate of Natural Vitamin D Production

The single most important scientific fact about vitamin D is that young

adult Whites make about 20,000 units of vitamin D in their skin within

minutes of whole-body, summer-sun exposure. This is 100 times the Adequate

Intake (AI) and five times the toxicity maximums (Lowest Observed Adverse

Effects Level or LOAEL) recommended by the Institute of Medicine (IOM) for

young adults. Therefore, many Americans greatly exceed the IOM¹s safety

recommendations by simply spending a few minutes outside in their swimming

suits!

This extraordinary rate of natural vitamin D production in the skin (20,000

IU) leading to the production of a potent endocrine, paracrine and autocrine

steroid hormone leads one (as T.S. Eliot once said), ³to an overwhelming

question.² Why did Nature design such a complex system reliant on rapid and

bountiful production of cholecalciferol? Answer, ³Probably for a very good

reason.²

Because low calcidiol [25(OH)D] levels (less than 35 ng/ml) are associated

with so many chronic illnesses, calcidiol levels are an important part of

any laboratory health evaluation and should be routinely checked by

physicians. Unfortunately, few physicians are aware of this so perhaps as

much as 70 percent of the U.S. population has calcidiol levels below 35

ng/ml. Even when asked to check vitamin D levels, physicians often order

calcitriol levels, instead of calcidiol levels, an error that greatly

misleads both the physician and the patient.

What are Optimum Blood Levels of Vitamin D?

For numerous reasons (optimal calcium absorption, maximal suppression of

PTH, reduction in blood pressure, decreased incidence of various cancers,

retarding the progression of osteoarthritis, reducing the incidence of

autoimmune illness, reduction in CRP, etc), healthful blood levels of

calcidiol [25(OH)D] are between 35 and 50 ng/ml although commercial labs

usually report ³normal² or Gaussian distributions of between 8-72 ng/ml

depending on the latitude of the lab¹s population.

Therefore, commercial reference laboratories also mislead physicians and

their patients by reporting ³normal² (Gaussian distributions of a deficient

population) instead of healthful calcidiol levels. Patients need to know

these facts before asking their physician for the calcidiol [25(OH)D] blood

test.

Until the medical profession becomes knowledgeable on this matter, patients

need to become educated, educate their physicians, get the proper blood test

and then take steps to raise their calcidiol level if it is less than 35

ng/ml. We know of no reason to exceed 50 ng/ml.

Populations around the equator (where man evolved) and groups spending time

outdoors without many clothes (lifeguards), have levels of around 50 ng/ml.

Such observations have important implications for the vitamin D conditions

under which humans evolved.

In other words, it suggests humans have had 25(OH)D levels of around 50

ng/ml for 99.99 percent of the time they have been on earth. Only in the

last several hundred years has urbanization, industrialization, glass (UVB

does not penetrate glass), excessive clothes (UVB does not penetrate

clothes) and sunblock lowered 25(OH)D levels to their current deficient

levels.

Options if Your Vitamin D Levels are Low

Persons with low levels have three choices: the sun, a sun lamp or vitamin D

supplements. At most latitudes in the United States, little or no vitamin D

is made in the skin in the late fall and early winter. In our most northern

states the vitamin D blackout lasts for about six months. In the spring and

summer, Whites can make large amounts (20,000 IU) by sunbathing on both

sides, without sunblock, for a few minutes (about one-third the time it

takes for the skin to begin to slightly redden). Darker skinned persons need

five to 10 times longer depending on the amount of melanin pigment in the

skin.

Vitamin D production occurs within minutes and is maximized long before the

skin turns red or begins to tan. One does not have to get repeated blood

tests when using sun exposure to obtain vitamin D. Toxicity can not occur

even with heavy and continuous sunbathing because ultraviolet light begins

to degrade vitamin D after making about 20,000 IU, thus reaching a steady

state. Overexposure, especially sunburns, is damaging to the skin,

dangerous, and should be entirely avoided.

Some artificial sun lamps contain significant amounts of UVB and have been

shown to raise calcidiol levels into the healthful range. Just like the sum,

one does not have to worry about toxicity or obtain repeated blood levels

when using them. However, just like the sum, care must be taken not to

overexpose the skin. Suntans are not needed to obtain adequate vitamin D.

Sunburns must be avoided. One manufacturer with some vitamin D data is

Sperti. (http://www.sperti.com/products.htm)

Many people are beginning to rely on supplements to raise their calcidiol

levels as they have been told (usually erroneously) to entirely avoid the

sun. However, in the absence of UVB, one must consume 3,000 to 5,000 IU of

cholecalciferol a day to maintain healthful calcidiol levels. Similar

studies have not been done with ergocalciferol but current data indicates

that almost twice as much ergocalciferol would be needed.

Vitamin D repletion is safest when done under a physician¹s care so

calcidiol levels (and perhaps calcium levels) can be monitored. Persons

diagnosed with sarcoidosis, other granulomatous disease, cancer (especially

lymphoma) or hyperparathyroidism should not take vitamin D unless they are

under the care of a knowledgeable physician (and would be well advised to

find one). Patients with these conditions may develop a vitamin D

hypersensitivity syndrome, which is different than vitamin D toxicity.

Vitamin D Toxicity

Persons who do not want to have blood tests would be best advised to rely on

prudent sun exposure. If such persons choose to avoid the sun, they should

never exceed 2,000 IU of cholecalciferol a day [which is the Institute of

Medicine¹s NOAEL (No Observed Adverse Effects Level)].

Cholecalciferol can be obtained at health food stores and on the Internet.

Cod liver oil contains about 1,200 IU of vitamin D per tablespoon but also

contains about 14,000 IU of vitamin A. Therefore, persons with no sun

exposure may exceed safe intakes of vitamin A in order to replete the

vitamin D system. (We know omega-3 nutrition is very important but believe

fish oil to be a safer alternative than cod liver oil).

Vitamin D can be toxic in overdose (probably more than 20,000 IU a day over

a prolonged period of time). We are not aware of any reports in the

literature of deaths from acute overdose, such as suicide attempts, leading

to death. In fact, a 150-pound human would have to take more than 100,000

capsules of the 1,000 IU cholecalciferol capsules to approach the LD50 for

the most sensitive mammal (the male rat at 40 mg/kg).

Such patients would be more likely to die from gastric bloating leading to

asphyxiation than from vitamin D toxicity. In mammals, signs of toxicity

short of death can first be seen at .5mg/kg (20,000 IU/kg or 1,400 capsules

at one time for a 150 pound adult human).

We are unaware of any reports of vitamin D toxicity from supplements except

when manufacturing errors occurred. Most of the reported toxicity is

industrial (dairies putting in the wrong amount into milk or the

concentrated oil being used for cooking). However death from chronic

poisoning has been described and is possible. If you believe ³a little is

good then a whole lot is better,² then you may prove the association between

judgment and natural selection.

http://www.cholecalciferol-council.com/index.htm