Any discussion of vitamin D must begin withthe discoveries of the Canadian-born dentist Weston A. Price. Inhis masterpiece Nutritionand Physical Degeneration, Dr. Price noted that the diet ofisolated, so-called "primitive" peoples contained "atleast ten times" the amount of "fat-soluble vitamins"as the standard American diet of his day.2
Dr. Price determined that it was the presenceof plentiful amounts of fat-soluble vitamins A and D in thediet, along with calcium, phosphorus and other minerals, thatconferred such high immunity to tooth decay and resistanceto disease in nonindustrialized population groups.
Today another Canadian researcher, Dr.Reinhold Vieth, argues convincingly that current vitamin Drecommendations are woefully inadequate. The recommended doseof 200-400 international units (IU) will prevent rickets inchildren but does not come close to the optimum amount necessaryfor vibrant health.3
According to Dr. Vieth, the minimal dailyrequirement of vitamin D should be in the range of 4,000 IUfrom all sources, rather than the 200-400 currently suggested,or ten times the Recommended Daily Allowance (RDA). Dr. Vieth'sresearch perfectly matches Dr. Price's observations of sixtyyears ago!
VitaminD From Sunlight
Pick up any popular book on vitamins andyou will read that ten minutes of daily exposure of the armsand legs to sunlight will supply us with all the vitamin Dthat we need.
Humans do indeed manufacture vitamin Dfrom cholesterol by the action of sunlight on the skin butit is actually very difficult to obtain even a minimal amountof vitamin D with a brief foray into the sunlight.4,5
Ultraviolet (UV) light is divided into3 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 ofthe UV bands. It will burn human skin rapidly in extremelysmall doses.
Fortunately, it is completely absorbedby the ozone layer. However, UV-C is present in some lights.For this reason, fluorescent and halogen and other specialtylights may contribute to skin cancer.
UV-A, known as the "tanning ray,"is primarily responsible for darkening the pigment in ourskin. Most tanning bulbs have a high UV-A output, with a smallpercentage of UV-B. UV-A is less energetic than UV-B, so exposureto UV-A will not result in a burn, unless the skin is photosensitiveor excessive doses are used.
UV-A penetrates more deeply into the skinthan UV-B, due to its longer wavelength. Until recently, UV-Awas not blocked by sunscreens. It is now considered to bea major contributor to the high incidence of non-melanomaskin cancers.7 Seventy-eight percent of UV-A penetrates glassso windows do not offer protection.
The ultraviolet wavelength that stimulatesour bodies to produce vitamin D is UV-B.
It is sometimes called the "burningray" because it is the primary cause of sunburn (erythema).However, UV-B initiates beneficial responses, stimulatingthe production of vitamin D that the body uses in many importantprocesses.
Although UV-B causes sunburn, it alsocauses special skin cells called melanocytes to produce melanin,which is protective. UV-B also stimulates the production ofMelanocyte Stimulating Hormone (MSH), an important hormonein weight loss and energy production.8
The reason it is difficult to get adequatevitamin D from sunlight is that while UV-A is present throughoutthe day, the amount of UV-B present has to do with the angleof the sun's rays. Thus, UV-B is present only during middayhours at higher latitudes, and only with significant intensityin temperate or tropical latitudes.
Only5 percent of the UV-B light range goes through glass and itdoes not penetrate clouds, smog or fog.
Sun exposure at higher latitudes before10 am or after 2 pm will cause burning from UV-A before itwill supply adequate vitamin D from UV-B.
This finding may surprise you, as it didthe researchers. It means that sunning must occur betweenthe hours we have been told to avoid.
Only sunningbetween 10 am and 2 pm during summer months (or winter monthsin southern latitudes) for 20-120 minutes, depending on skintype and color, will form adequate vitamin D before burningoccurs.9
It takes about 24 hours for UV-B-stimulatedvitamin D to show up as maximum levels of vitamin D in theblood. Cholesterol-containing body oils are critical to thisabsorption process.10 Because the body needs 30-60 minutesto absorb these vitamin-D-containing oils, itis best to delay showering or bathing for one hour after exposure.
The skin oils in which vitamin D is producedcan 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, providesonly 200-400 IU of vitamin D each time or an average of 100-200IU per day during the summer months.
In order to achieve optimal levels ofvitamin D, 85 percent of body surface needs exposure to primemidday sun. (About 100-200 IU of vitamin D is produced foreach 5 percent of body surface exposed, we want 4,000 iu.)Light skinned people need 10-20 minutes of exposure whiledark skinned people need 90-120 minutes.11
Latitude and altitude determine the intensityof UV light. UV-B is stronger at higher altitudes. Latitudeshigher than 30° (both north and south) have insufficientUV-B sunlight two to six months of the year, even at midday.12Latitudes higher than 40° have insufficient sunlight toachieve optimum levels of D during six to eight months ofthe year.
In much of the US, which is between 30°and 45° latitude, six months or more during each yearhave insufficient UV-B sunlight to produce optimal D levels.In far northern or southern locations, latitudes 45° andhigher, even summer sun is too weak to provide optimum levelsof vitamin D.13-15 A simple meter is available to determineUV-B levels where you live.
VitaminD From Food
What the research on vitamin D tells usis that unless you are a farmer, lifeguard or a regular sunbather,you are highly unlikely to obtain adequate amounts of vitaminD from the sun. The balance must be obtained from food.
So-called primitive peoples instinctivelychose vitamin-D-rich foods including the intestines, organmeats, skin and fat from certain land animals, as well asshellfish, oily fish and insects. Many of these foods areunacceptable to the modern palate.
Fish make vitamin D from the precursorof vitamin D found in algae. In the higher mammals, vitaminD is made from precursors in lichen and green grass. Reindeerfat, for example, is a good source of vitamin D because reindeerfeed on lichen.16
Vitamin D will be found in the butterfatof ruminant animals that feed on green grass, and in pigsthat spend time in the sunlight. (Pigs resemble humans inthat they convert sunlight to vitamin D.) Eggs will containvitamin D if the chickens have obtained it from insects orfishmeal. Salmon must feed on algae in order to store vitaminD in their fat. Thus, modernfarm-raised salmon are poor sources of this essential nutrient.
Modern diets usually do not provide adequateamounts of vitamin D2;17 because of the trend to lowfat foodsand because we no longer eat vitamin-D-rich foods like kippers,tripe, chitterlings and lard. Deficiencies are therefore pervasiveand widespread.
FoodSources of Vitamin D
USDA databases compiled in the 1980s listthe following foods as rich in vitamin D. The amounts givenare for 100 grams or about 3 1/2 ounces. These figures demonstratethe difficulty in obtaining 4,000 IU vitamin D per day fromordinary foods in the American diet. Three servings of herring,oysters, catfish, mackerel or sardines plus generous amountsof butter, egg yolk, lard or bacon fat and 2 teaspoons codliver oil (500 iu per teaspoon) yield about 4,000 IU vitaminD-a very rich diet indeed!
Sunlight and vitamin D are critical toall life forms. Standard textbooks state that the principalfunction of vitamin D is to promote calcium absorption inthe gut and calcium transfer across cell membranes, thus contributingto strong bones and a calm, contented nervous system. It isalso well recognized that vitamin D aids in the absorptionof magnesium, iron and zinc, as well as calcium.
Actually, vitamin D does not in itselfpromote healthy bone. Vitamin D controls the levels of calciumin the blood. If there is not enough calcium in the diet,then it will be drawn from the bone. High levels of vitaminD (from the diet or from sunlight) will actually demineralizebone if sufficient calcium is not present.
Vitamin Dwill also enhance the uptake of toxic metals like lead, cadmium,aluminum and strontium if calcium, magnesium and phosphorusare not present in adequate amounts.18
Vitamin D supplementation should neverbe suggested unless calcium intake is sufficient or supplementedat the same time.
Receptors for vitamin D are found in mostof the cells in the body and research during the 1980s suggestedthat vitamin D contributed to a healthy immune system, promotedmuscle strength, regulated the maturation process and contributedto hormone production.
During the last ten years, researchershave made a number of exciting discoveries about vitamin D.They have ascertained, for example, that vitamin D is an antioxidantthat is a more effective antioxidant than vitamin E in reducinglipid peroxidation and increasing enzymes that protect againstoxidation.19;20
Vitamin D deficiency decreases biosynthesisand release of insulin.21 Glucose intolerance has been inverselyassociated with the concentration of vitamin D in the blood.Thus, vitamin D may protect against both Type I and Type IIdiabetes.22
The risk of senile cataract is reducedin persons with optimal levels of D and carotenoids.23
PCOS (Polycystic Ovarian Syndrome) hasbeen corrected by supplementation of D and calcium.24
Vitamin Dplays a role in regulation of both the "infectious"immune system and the "inflammatory" immune system.25
Low vitamin D is associated with severalautoimmune diseases including multiple sclerosis, Sjogren'sSyndrome, rheumatoid arthritis, thyroiditis and Crohn's disease.26;27
Osteoporosis is strongly associated withlow vitamin D. Postmenopausal women with osteoporosis respondfavorably (and rapidly) to higher levels of D plus calciumand magnesium.28
D deficiency has been mistaken for fibromyalgia,chronic fatigue or peripheral neuropathy.1;28-30
Infertility is associated with low vitaminD.31 Vitamin D supports production of estrogen in men andwomen.32 PMS has been completely reversed by addition of calcium,magnesium and vitamin D.33 Menstrual migraine is associatedwith low levels of vitamin D and calcium.81
Breast, prostate, skin and colon cancerhave a strong association with low levels of D and lack ofsunlight.34-38
Activated vitamin D in the adrenal glandregulates tyrosine hydroxylase, the rate limiting enzyme necessaryfor the production of dopamine, epinephrine and norepinephrine.Low D may contribute to chronic fatigue and depression.39
Seasonal Affective Disorder has been treatedsuccessfully with vitamin D. In a recent study covering 30days of treatment comparing vitamin D supplementation withtwo-hour daily use of light boxes, depression completely resolvedin the D group but not in the light box group.40
High stress may increase the need for vitamin D or UV-B sunlightand calcium.41
People with Parkinsons and Alzheimershave 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 contributingcause of "crooked teeth" and myopia. When theseconditions are found in succeeding generations it means thegenetics require higher levels of one or both nutrients tooptimize health.44-47
Behavior and learning disorders respondwell to D and/or calcium combined with an adequate diet andtrace minerals.48;49