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Any discussion of vitamin D must begin with
the discoveries of the Canadian-born dentist Weston A. Price. In
his masterpiece Nutrition
and Physical Degeneration, Dr. Price noted that the diet of
isolated, so-called "primitive" peoples contained "at
least ten times" the amount of "fat-soluble vitamins"
as the standard American diet of his day.2
Dr. Price determined that it was the presence
of plentiful amounts of fat-soluble vitamins A and D in the
diet, along with calcium, phosphorus and other minerals, that
conferred such high immunity to tooth decay and resistance
to disease in nonindustrialized population groups.
Today another Canadian researcher, Dr.
Reinhold Vieth, argues convincingly that current vitamin D
recommendations are woefully inadequate. The recommended dose
of 200-400 international units (IU) will prevent rickets in
children but does not come close to the optimum amount necessary
for vibrant health.3
According to Dr. Vieth, the minimal daily
requirement of vitamin D should be in the range of 4,000 IU
from all sources, rather than the 200-400 currently suggested,
or ten times the Recommended Daily Allowance (RDA). Dr. Vieth's
research perfectly matches Dr. Price's observations of sixty
D From Sunlight
Pick up any popular book on vitamins and
you will read that ten minutes of daily exposure of the arms
and legs to sunlight will supply us with all the vitamin D
that we need.
Humans do indeed manufacture vitamin D
from cholesterol by the action of sunlight on the skin but
it is actually very difficult to obtain even a minimal amount
of vitamin D with a brief foray into the sunlight.4,5
Ultraviolet (UV) light is divided into
3 bands or wavelength ranges, which are referred to as UV-C,
UV-B and UV-A.6 UV-C is the most energetic and shortest of
the UV bands. It will burn human skin rapidly in extremely
Fortunately, it is completely absorbed
by the ozone layer. However, UV-C is present in some lights.
For this reason, fluorescent and halogen and other specialty
lights may contribute to skin cancer.
UV-A, known as the "tanning ray,"
is primarily responsible for darkening the pigment in our
skin. Most tanning bulbs have a high UV-A output, with a small
percentage of UV-B. UV-A is less energetic than UV-B, so exposure
to UV-A will not result in a burn, unless the skin is photosensitive
or excessive doses are used.
UV-A penetrates more deeply into the skin
than UV-B, due to its longer wavelength. Until recently, UV-A
was not blocked by sunscreens. It is now considered to be
a major contributor to the high incidence of non-melanoma
skin cancers.7 Seventy-eight percent of UV-A penetrates glass
so windows do not offer protection.
The ultraviolet wavelength that stimulates
our bodies to produce vitamin D is UV-B.
It is sometimes called the "burning
ray" because it is the primary cause of sunburn (erythema).
However, UV-B initiates beneficial responses, stimulating
the production of vitamin D that the body uses in many important
Although UV-B causes sunburn, it also
causes special skin cells called melanocytes to produce melanin,
which is protective. UV-B also stimulates the production of
Melanocyte Stimulating Hormone (MSH), an important hormone
in weight loss and energy production.8
The reason it is difficult to get adequate
vitamin D from sunlight is that while UV-A is present throughout
the day, the amount of UV-B present has to do with the angle
of the sun's rays. Thus, UV-B is present only during midday
hours at higher latitudes, and only with significant intensity
in temperate or tropical latitudes.
5 percent of the UV-B light range goes through glass and it
does not penetrate clouds, smog or fog.
Sun exposure at higher latitudes before
10 am or after 2 pm will cause burning from UV-A before it
will supply adequate vitamin D from UV-B.
This finding may surprise you, as it did
the researchers. It means that sunning must occur between
the hours we have been told to avoid.
between 10 am and 2 pm during summer months (or winter months
in southern latitudes) for 20-120 minutes, depending on skin
type and color, will form adequate vitamin D before burning
It takes about 24 hours for UV-B-stimulated
vitamin D to show up as maximum levels of vitamin D in the
blood. Cholesterol-containing body oils are critical to this
absorption process.10 Because the body needs 30-60 minutes
to absorb these vitamin-D-containing oils, it
is best to delay showering or bathing for one hour after exposure.
The skin oils in which vitamin D is produced
can also be removed by chlorine in swimming pools.
The current suggested exposure of hands,
face and arms for 10-20 minutes, three times a week, provides
only 200-400 IU of vitamin D each time or an average of 100-200
IU per day during the summer months.
In order to achieve optimal levels of
vitamin D, 85 percent of body surface needs exposure to prime
midday sun. (About 100-200 IU of vitamin D is produced for
each 5 percent of body surface exposed, we want 4,000 iu.)
Light skinned people need 10-20 minutes of exposure while
dark skinned people need 90-120 minutes.11
Latitude and altitude determine the intensity
of UV light. UV-B is stronger at higher altitudes. Latitudes
higher than 30° (both north and south) have insufficient
UV-B sunlight two to six months of the year, even at midday.12
Latitudes higher than 40° have insufficient sunlight to
achieve optimum levels of D during six to eight months of
In much of the US, which is between 30°
and 45° latitude, six months or more during each year
have insufficient UV-B sunlight to produce optimal D levels.
In far northern or southern locations, latitudes 45° and
higher, even summer sun is too weak to provide optimum levels
of vitamin D.13-15 A simple meter is available to determine
UV-B levels where you live.
D From Food
What the research on vitamin D tells us
is that unless you are a farmer, lifeguard or a regular sunbather,
you are highly unlikely to obtain adequate amounts of vitamin
D from the sun. The balance must be obtained from food.
So-called primitive peoples instinctively
chose vitamin-D-rich foods including the intestines, organ
meats, skin and fat from certain land animals, as well as
shellfish, oily fish and insects. Many of these foods are
unacceptable to the modern palate.
Fish make vitamin D from the precursor
of vitamin D found in algae. In the higher mammals, vitamin
D is made from precursors in lichen and green grass. Reindeer
fat, for example, is a good source of vitamin D because reindeer
feed on lichen.16
Vitamin D will be found in the butterfat
of ruminant animals that feed on green grass, and in pigs
that spend time in the sunlight. (Pigs resemble humans in
that they convert sunlight to vitamin D.) Eggs will contain
vitamin D if the chickens have obtained it from insects or
fishmeal. Salmon must feed on algae in order to store vitamin
D in their fat. Thus, modern
farm-raised salmon are poor sources of this essential nutrient.
Modern diets usually do not provide adequate
amounts of vitamin D2;17 because of the trend to lowfat foods
and because we no longer eat vitamin-D-rich foods like kippers,
tripe, chitterlings and lard. Deficiencies are therefore pervasive
Sources of Vitamin D
USDA databases compiled in the 1980s list
the following foods as rich in vitamin D. The amounts given
are for 100 grams or about 3 1/2 ounces. These figures demonstrate
the difficulty in obtaining 4,000 IU vitamin D per day from
ordinary foods in the American diet. Three servings of herring,
oysters, catfish, mackerel or sardines plus generous amounts
of butter, egg yolk, lard or bacon fat and 2 teaspoons cod
liver oil (500 iu per teaspoon) yield about 4,000 IU vitamin
D-a very rich diet indeed!
|Lard (Pork Fat)
|Smoked Chinook Salmon
Egg Yolk (Fresh)
(One yolk contains about 24 IU)
|Pork Liver (Braised)
|Beef Liver (Fried)
|Beef Tripe (Raw)
|Beef Kidney (Simmered)
|Chicken Livers (Simmered)
|Small Clams (Steamed/Cooked
|Blue Crab (Steamed)
Sunlight and vitamin D are critical to
all life forms. Standard textbooks state that the principal
function of vitamin D is to promote calcium absorption in
the gut and calcium transfer across cell membranes, thus contributing
to strong bones and a calm, contented nervous system. It is
also well recognized that vitamin D aids in the absorption
of magnesium, iron and zinc, as well as calcium.
Actually, vitamin D does not in itself
promote healthy bone. Vitamin D controls the levels of calcium
in the blood. If there is not enough calcium in the diet,
then it will be drawn from the bone. High levels of vitamin
D (from the diet or from sunlight) will actually demineralize
bone if sufficient calcium is not present.
will also enhance the uptake of toxic metals like lead, cadmium,
aluminum and strontium if calcium, magnesium and phosphorus
are not present in adequate amounts.18
Vitamin D supplementation should never
be suggested unless calcium intake is sufficient or supplemented
at the same time.
Receptors for vitamin D are found in most
of the cells in the body and research during the 1980s suggested
that vitamin D contributed to a healthy immune system, promoted
muscle strength, regulated the maturation process and contributed
to hormone production.
During the last ten years, researchers
have made a number of exciting discoveries about vitamin D.
They have ascertained, for example, that vitamin D is an antioxidant
that is a more effective antioxidant than vitamin E in reducing
lipid peroxidation and increasing enzymes that protect against
Vitamin D deficiency decreases biosynthesis
and release of insulin.21 Glucose intolerance has been inversely
associated with the concentration of vitamin D in the blood.
Thus, vitamin D may protect against both Type I and Type II
The risk of senile cataract is reduced
in persons with optimal levels of D and carotenoids.23
PCOS (Polycystic Ovarian Syndrome) has
been corrected by supplementation of D and calcium.24
plays a role in regulation of both the "infectious"
immune system and the "inflammatory" immune system.25
Low vitamin D is associated with several
autoimmune diseases including multiple sclerosis, Sjogren's
Syndrome, rheumatoid arthritis, thyroiditis and Crohn's disease.26;27
Osteoporosis is strongly associated with
low vitamin D. Postmenopausal women with osteoporosis respond
favorably (and rapidly) to higher levels of D plus calcium
D deficiency has been mistaken for fibromyalgia,
chronic fatigue or peripheral neuropathy.1;28-30
Infertility is associated with low vitamin
D.31 Vitamin D supports production of estrogen in men and
women.32 PMS has been completely reversed by addition of calcium,
magnesium and vitamin D.33 Menstrual migraine is associated
with low levels of vitamin D and calcium.81
Breast, prostate, skin and colon cancer
have a strong association with low levels of D and lack of
Activated vitamin D in the adrenal gland
regulates tyrosine hydroxylase, the rate limiting enzyme necessary
for the production of dopamine, epinephrine and norepinephrine.
Low D may contribute to chronic fatigue and depression.39
Seasonal Affective Disorder has been treated
successfully with vitamin D. In a recent study covering 30
days of treatment comparing vitamin D supplementation with
two-hour daily use of light boxes, depression completely resolved
in the D group but not in the light box group.40
High stress may increase the need for vitamin D or UV-B sunlight
People with Parkinsons and Alzheimers
have been found to have lower levels of vitamin D.42;43
Low levels of D, and perhaps calcium,
in a pregnant mother and later in the child may be the contributing
cause of "crooked teeth" and myopia. When these
conditions are found in succeeding generations it means the
genetics require higher levels of one or both nutrients to
Behavior and learning disorders respond
well to D and/or calcium combined with an adequate diet and
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