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Vitamin D is fat-soluble vitamin requiring bile for absorption, and occurs naturally in animal foods such as salmon, herring, sardines, egg yolks, cod liver oil and dairy products. It can be acquired either by ingestion or by exposure to sunlight.
Vitamin D is actually more like a steroid hormone than it is like the other cofactor-type vitamins. It was listed as a vitamin for its anti-rickets activity in dogs.
The combination of low sunlight and inadequate sources of the vitamin D rich foods has made rickets a large concern. Interestingly, the first discovered "neanderthal men" were diagnosed as "ancient" men who died of rickets. This accounted for the posture and facial features as bone defects. After years of debate about the origin of neanderthals, this is still one of the most viable explanations. As darker skinned men and women left the sunny climates of the southern hemisphere, they were able to convert less Vitamin D from their skin, rickets set in changing bone structure and eventually killing them. It should be noted that most "neanderthals" are found in areas of reduced sunlight. In the United States, milk is fortified with Vitamin D to prevent this from happening, especially in the darker skinned population, where more sunlight is required to convert pre-vitamin D to vitamin D.
Source
This fat-soluble vitamin can be obtained two major ways. The first is through exposure to sunlight. Our skin has pre-vitamin D (7-dehydroxycholesterol) present in the epidermis. As sunlight or ultraviolet light hits the skin, the pre-vitamin D is converted to the vitamin form called D3 (cholecalciferol). Dietary vitamin D can be obtained from salt water fish, and fish oils, although small amounts can be found in eggs, beef, butter and some vegetable oils.
Vitamin D is found primarily in foods of animal origin, unless they are fortified. Vegetables are usually low in vitamin D, except leafy dark green vegetables and mushrooms which are significant sources of vitamin D.
Vitamin D2 (ergocalciferol) is obtained from plants. Vegetables are usually low in vitamin D, but leafy dark green vegetables and mushrooms are significant non-animal sources.
Vitamin D3 (cholecalciferol) is stable to heat, light, and storage and is derived from animal products. It promotes calcium absorption for proper heart muscle function.
Function
The major function of vitamin D is as a regulator of calcium. Cholecalciferol (D3) is converted to active forms by hydroxylation, which then play crucial roles on the absorption, metabolism, and cellular use of calcium. Active forms of vitamin D3 are now known to initiate biological responses via the regulation of protein synthesis at the level of the gene. The health of the human skeletal system is dependent on the proper amount of vitamin D; a lack of which causes weak and brittle bones, bone malformations and rickets.
Directions
The RDA for vitamin D for adults is 200 IU; for children, teens and pregnant or lactating women it is 400 IU; for the elderly or those with poor sunlight exposure or living in high northern or southern latitudes, it is 400 - 800 IU. It can be supplied by eating approximately 1.5kg of beef, 2.0kg of corn oil - or 100kg of cabbage! The RDA can also be supplied by eating roughly 50gm of salmon or 2.0gm of cod liver oil, and since fortified milk contains 400 IU per quart, half a quart of milk provides the RDA. For comparison, human breast milk contains only 4 to 60 IU per quart. One IU (International Unit) is equal to 0.025mcg of crystalline cholecalciferol.
It is estimated that the RDA can be achieved through the exposure of 30% of a persons skin surface to the sun for 30 minutes at moderate latitudes. The darker the skin, the less vitamin D will be produced (up to 95% of UV light is blocked). If longer exposure times are had, even with the darkest skin color, sufficient levels of vitamin D are produced. Glass blocks UV light, so indoor exposure does not help. During the winter months especially, it is advisable to supplement vitamin D if sun exposure is low and dietary sources are in question. The vitamin D in human milk varies with sun exposure and vitamin D intake.
When taking doses of vitamin D3 in excess of 1100 IU per day, regular blood chemistry tests should be taken to monitor kidney function and serum calcium metabolism.
Side-Effects
Care must be taken in treating vitamin D deficiency, since high doses of vitamin D are toxic and can result in the permanent deposit of minerals in the heart, lungs and kidneys. Symptoms of toxicity include nausea, vomiting, joint pain, and lack of interest in eating food. In adults, vitamin D toxicity occurs with eating 50,000 IU or more per day. In infants, toxicity occurs with 1,000 IU per day. The continued intake of toxic doses results in death.
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Vitamin D can help with the following: | | | | | Digestion |  IBS (Irritable Bowel Syndrome)
 Sensitive Teeth |
Environment / Toxicity |
Fluoride Toxicity | See link between Fluorosis and Calcium. |
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Metabolic |
Metabolic Diet Type
Not recommended for:
 Lipo-Oxidative Type |
Musculo-Skeletal |
 Osteoporosis - Osteopenia |
Nervous System |
Exhaustion Caused By Emotional Upsets |
Nutrients |
Vitamin D Requirement| | Rickets heals promptly with 4,000 IU of oral vitamin D per day administered for approximately one month. During this treatment, the doctor should monitor the levels of 25-OH-D in the plasma to make certain they are raised to a normal value. The bone abnormalities (visible by X-ray) generally disappear gradually over a period of 3-9 months. Parents are instructed to take their infants outdoors for approximately 20 minutes per day with their faces exposed. Children should also be encouraged to play outside.
Osteomalacia is treated by eating 2,500 IU per day of vitamin D for about three months. Measurements of 25-OH-D, calcium, and parathyroid hormone should be obtained after the treatment period to make sure the therapy did, in fact, result in normal blood values. |
Calcium Requirement| | Vitamin D is essential for absorption of calcium from the gut. This is because calcium is transported into the body by a special carrier protein which requires vitamin D for its synthesis. |
Vitamin A Requirement |
Skin-Hair-Nails |
Psoriasis| | Vitamin D has been recognised for many years to improve some of the important abnormalities present in psoriasis skin, but ingestion of even only slightly above the daily recommended amount of Vitamin D can lead to problems with calcium metabolism in the body (possible kidney stones and irregular heart beats).
For this reason calcipotriol, a synthetic form of vitamin D, is used instead in ointment form. Calcipotriol has been found to also have the ability to improve psoriasis, but with minimum effects on internal calcium metabolism. It is available in a very greasy, ointment base for twice daily application. There is a risk of facial dermatitis if the ointment is used on the face or neck, so application is only recommended for the trunk and limbs, and it is important that the hands are thoroughly washed after application to avoid inadvertent transfer to the skin of the face. Comparative studies have shown that calcipotriol ointment is at least as effective as topical cortisones and dithranol in the treatment of stable plaque psoriasis. |
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Tumors, Malignant |
Prostate Cancer| | In patients with advanced hormone refractory prostate cancer with bone metastases, 2000 IU of vitamin D with 500mg of calcium per day for three months was found to reduce bone pain, increase muscle strength, and improve the quality of life. [J. Urology 2000; 163: pp.187-190] |
Breast Cancer| | According to reseachers, women who have mutations in their vitamin D receptor gene are nearly twice as likely to develop breast cancer as are women who do not have the mutation. These findings support previous studies showing vitamin D may offer protection against the disease. Researchers have found that Caucasian women with certain versions of this gene not only have an increased risk of breast cancer, but also may suffer from a more aggressive form of the disease if it spreads.
If true, this suggests that vitamin D does indeed play a part in protecting the body against breast cancer. It also shows that different versions of the vitamin D receptor gene will influence the way in which vitamin D protects the female body against this disease. [Colston, K., et al. Vitamin D receptor gene polymorphisms and breast cancer risk. Clinical Cancer Research August 14, 2004; 10(16)] |
Non-Hodgkin's Lymphoma| | Administration of activated vitamin D (1,25 dihydroxycholecalciferol) may be beneficial in non-Hodgkin's lymphoma. Experimental Study: In a small trial, patients with non-Hodgkin's lymphoma who were found to have high levels of vitamin D receptors responded to activated vitamin D. [Cunningham D, Gilcrist NL, Cowan RA, et al. Vitamin D as a modulator of tumour growth in low grade lymphomas. Abstract. Scot Med J 30: p.193, 1985] |
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Uro-Genital |
Pregnancy-Related Issues| | The Children's Memorial Hospital in Chicago studied five vitamin D-deficient infants; at least two cases were caused by low vitamin D levels during pregnancy. Health problems ranged from seizures and growth failure to rickets. [Daaboul J, et al. J of Perinat 1997;17(1): 104] Congenital cataracts have also been linked to low levels of vitamin D. [Blau EB. The Lancet 1996;347: p.626] Other research points to vitamin D as a possible adjunct therapy for premature babies with respiratory distress syndrome [Nguyen TM, et al. Am J of Physiol 1996; 271(3): L3929] and for women with gestational diabetes. [Rudnicki PM, Molsted-Pedersen L. Diabetologia 1997; 40(1): 404]
The U.S. RDA is 400 IU or 10mg. |
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Vitamin D can help prevent the following: | | | | | Tumors, Malignant | Cancer, General| | Evidence of vitamin D's protective effect against cancer is compelling. For more than 50 years, documentation in medical literature suggests regular sun exposure is associated with substantial decreases in death rates from certain cancers and a decrease in overall cancer death rates. Recent research suggests this is a causal relationship that acts through the body's vitamin D metabolic pathways. For instance, some evidence points to a prostate, breast and colon cancer belt in the United States, which lies in northern latitudes under more cloud cover than other regions during the year. Rates for these cancers are two to three times higher than in sunnier regions.
Dark-skinned people require more sun exposure to make vitamin D. The thickness of the skin layer called the stratum corneum affects the absorption of UV radiation. Dark human skin is thicker than white skin and thus transmits only about 40% of the UV rays for vitamin D production. Darkly pigmented individuals who live in sunny equatorial climates experience a higher mortality (not incidence) rate from breast and prostate cancer when they move to geographic areas that are deprived of sunlight exposure in winter months. The rate of increase varies, and researchers hesitate to quote figures because many migrant black populations also have poor nutrition and deficient health care that confound statistics somewhat.
Although excessive sun exposure may give rise to skin cancer, researchers as early as 1936 were aware that skin cancer patients have reduced rates of other cancers. One researcher estimates moderate sunning would prevent 30,000 annual cancer deaths in the United States.
Vitamin D may also go beyond cancer prevention and provide tumor therapy. Much has been made of pharmaceutical angiogenesis inhibitors - agents that help inhibit the growth of new, undesirable blood vessels that tumors require for nutrient supply and growth. Laboratory tests have shown vitamin D to be a potent angiogenesis inhibitor.
Vitamin D also works at another stage of cancer development. Tumor cells are young, immortal cells that never grow up, mature and die off. Because vitamin D derivatives have been shown to promote normal cell growth and maturation, drug companies today are attempting to engineer patentable forms of vitamin D for anti-cancer therapy. |
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KEY | | May do some good | | | Likely to help | | | Highly recommended | | | May have adverse consequences |
GLOSSARY
Bile
A bitter, yellow-green secretion of the liver. Bile is stored in the gallbladder and is released when fat enters the first part of the small intestine (duodenum) in order to aid digestion.
Calcium
The body's most abundant mineral. Its primary function is to help build and maintain bones and teeth. The body also needs calcium to carry nerve signals, keep the heart functioning, contract muscles, clot blood and maintain healthy skin. Calcium helps control blood acid-alkaline balance, plays a role in cell division, muscle growth and iron utilization, activates certain enzymes, and helps transport nutrients through cell membranes. Calcium also forms a cellular cement called ground substance that helps hold cells and tissues together.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Cataract (Cataracts)
A steadily worsening disease of the eye in which the lens becomes cloudy as a result of the precipitation of proteins. Most cataracts are caused by the functions of the body breaking down. Eye trauma, such as from a puncture wound, may also result in cataracts.
Cobalamin (B12, B-12, Cobalamine, Vitamin B12)
Essential for normal growth and functioning of all body cells, especially those of bone marrow (red blood cell formation), gastrointestinal tract and nervous system, it prevents pernicious anemia and plays a crucial part in the reproduction of every cell of the body i.e. synthesis of genetic material (DNA).
Colon (Colonic)
The part of the large intestine that extends to the rectum. The colon takes the contents of the small intestine, moving them to the rectum by contracting.
Dermatitis
A general term used to refer to eruptions or rashes on the skin.
Epidermis
The outer layers of the skin, made up of an outer, dead portion and a deeper, living portion. Epidermal cells gradually move outward to the skin surface, changing as they go, until they become flakes.
Gestational Diabetes
Gestational diabetes is defined as any degree of glucose intolerance with the onset or first recognition occurring during pregnancy. Many pregnant women do not notice any symptoms of diabetes, but urine and blood tests may show that they have it. Symptoms of diabetes may include thirst, weight loss, eating too much, urinating in large quantities and unexplained fatigue.
Gram (gm, gms, Gramme, Grammes, Grams)
A metric unit of weight, there being approximately 28 grams in one ounce.
Hormones (Hormone)
Chemical substances secreted by a variety of body organs that are carried by the bloodstream and usually influence cells some distance from the source of production. Hormones signal certain enzymes to perform their functions and, in this way, regulate such body functions as blood sugar levels, insulin levels, the menstrual cycle, and growth. These can be prescription, over-the-counter, synthetic or natural agents. Examples include adrenal hormones such as corticosteroids and aldosterone; glucagon, growth hormone, insulin, testosterone, estrogens, progestins, progesterone, DHEA, melatonin, and thyroid hormones such as thyroxine and calcitonin.
Irritable Bowel Syndrome (IBS)
A condition that causes upset intestines for a long period of time. It is very unpleasant to the sufferer but tends to be harmless and usually does not lead to more serious complaints. The symptoms vary from person to person and from day to day. In order to be diagnosed with IBS, a person must have at least three of the following symptoms: pain in the lower abdomen; bloating; constipation; diarrhea or alternating diarrhea and constipation; nausea; loss of appetite; tummy rumbling; flatulence; mucous in stools; indigestion; constant tiredness; frequent urination; low back pain; painful intercourse for women.
IU (mIU, uIU)
International Unit: An arbitrarily defined but agreed upon unit that depends on what is being measured.
mIU: 0.001 or one thousandth of an IU.
uIU: 0.000001 or one millionth of an IU.
Kidney Stone (Kidney Gravel, Kidney Stones)
A stone (concretion) in the kidney. If the stone is large enough to block the tube (ureter) and stop the flow of urine from the kidney, it must be removed by surgery or other methods. Also called Renal Calculus. Symptoms usually begin with intense waves of pain as a stone moves in the urinary tract. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur. Later, pain may spread to the groin. The pain may continue if the stone is too large to pass; blood may appear in the urine and there may be the need to urinate more often or a burning sensation during urination. If fever and chills accompany any of these symptoms, an infection may be present and a doctor should be seen immediately.
Kidneys (Kidney, Renal)
Bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage. The kidneys are sophisticated reprocessing machines, each day handling about 50 gallons of blood to sift out about half a gallon of waste products and extra water. The waste and extra water become urine, which flows to the bladder through tubes called ureters. The actual filtering occurs in tiny units inside the kidneys called nephrons. Every kidney has about a million nephrons. In a nephron, a glomerulus -- which is a tiny blood vessel, or capillary -- intertwines with a tiny urine-collecting tube called a tubule. A complicated chemical exchange takes place, as waste materials and water leave your blood and enter your urinary system. The kidneys recycle chemicals such as sodium, phosphorus, and potassium and thus regulate their levels. Renal: Pertaining to the kidneys.
Kilogram (kg, kgs, Kilogramme, Kilogrammes, Kilograms)
1000 grams, 2.2lbs.
Liver (Hepatic)
The largest and one of the most complex organs of the body, the liver is responsible for much of the metabolism of fats, proteins and carbohydrates. It is the site of much of the body's detoxification. It is connected very closely with digestion and the regulation of blood sugar, among many other functions. Found behind the ribs on the right side of the abdomen, it has many important functions such as removing harmful material from the blood, making enzymes and bile that help digest food, and converting food into substances needed for life and growth. Hepatic: Pertaining to the liver.
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Lymphoma (Lymphomas)
Any tumor of the lymphatic tissues.
Metabolism (Metabolic, Metabolize, Metabolizes, Metabolizing)
The chemical processes of living cells in which energy is produced in order to replace and repair tissues and maintain a healthy body. Responsible for the production of energy, biosynthesis of important substances, and degradation of various compounds. Also defined as the sum total of changes in an organism in order to achieve a balance (homeostasis): Catabolic burns up, anabolic stores and builds up; the sum of their work is metabolism.
Metastasize (Metastases, Metastasized, Metastasizes, Metastasizing, Metastatic)
Usually in reference to cancer: to spread, especially destructively.
Microgram (mcg, Micrograms, ug)
0.000001 or a millionth of a gram.
Milligram (mg, Milligrams)
0.001 or a thousandth of a gram.
Nausea
Symptoms resulting from an inclination to vomit.
Parathyroid Hormone
A hormone released by the parathyroid glands that acts to keep a constant level of calcium in body tissues.
Prostate
The prostate gland in men that surrounds the neck of the bladder and the urethra and produces a secretion that liquefies coagulated semen.
Protein (Proteins)
Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.
Psoriasis
An inherited skin disorder in which there are red patches with thick, dry silvery scales. It is caused by the body making too-many skin cells. Sores may be anywhere on the body but are more common on the arms, scalp, ears, and the pubic area. A swelling of small joints may go along with the skin disease.
RDA (RDAs, US RDA, USRDA)
Recommended Daily Allowance of vitamins or other nutrients as determined by the FDA. U.S. RDAs are more widely used than RDAs, and focus on 3 age groups: Infants of 0-12 months; Children of 1-4 years; Adults and children of more than 4 years.
Rickets
Vitamin-D deficiency characterized by abnormal calcification of bone tissues.
Serum
The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.
Steroid (Steroids)
Any of a large number of hormonal substances with a similar basic chemical structure containing a 17-carbon 14-ring system and including the sterols and various hormones and glycosides.
Syndrome
A medical condition characterized by a collection of related symptoms (what the patient feels) and signs (what a doctor can observe or measure).
Topical
Most commonly 'topical application': Administration to the skin.
Tumor (Tumors, Tumour, Tumours)
An abnormal growth of tissue resulting from uncontrolled, progressive multiplication of cells and serving no physiological function; a neoplasm. Literally, a swelling; in the past the term has been used in reference to any swelling of the body, no matter what the cause. However, the word is now being used almost exclusively to refer to a neoplastic mass, and the more general usage is being discarded.
Vitamin D
A fat-soluble vitamin essential to one's health. Regulates the amount of calcium and phosphorus in the blood by improving their absorption and utilization. Necessary for normal growth and formation of bones and teeth. For Vitamin D only, 1mcg translates to 40 IU.
X-rays (X-ray)
High-energy radiation used to take pictures of areas inside the body.
Last updated: Aug 02, 2008
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