Vitamin D

Laboratory studies have found that Vitamin D is actually a complex of ten compounds, each of which can treat rickets. Each complex is individually identified and they are labeled D-1, D-2, etc. The two most important are D-2 and D-3. Vitamin D-2 (Ergocalciferol or its three forms) exists in fungi and yeast and is the form generally added to milk, food, and vitamin supplements. It is the form used to combat hypocalcemia (low blood calcium). Vitamin D-3 (Cholecalciferol) is found in fish oils, egg yolks, and milk. The body produces Vitamin D-3 in the presence of ultraviolet sunlight. Many factors, including smog, fog, smoke, clothes, and glass, can block ultraviolet light and interfere with the production of this vitamin.

Vitamin D has the dual identity of being a fat-soluble vitamin and a hormone. As a vitamin it promotes calcium absorption from the intestines, calcium resorption from the bone, and calcium deposition into osseous tissue. Its active metabolites are produced in two tissues, but have their effects on other tissues, just like other hormones. They also, like other hormones, have a feedback mechanism that controls the rate of synthesis and secretion of Vitamin DŐs active form.

Various research indicates the importance of Vitamin D as a potential anti-cancer nutrient, proving particularly effective against breast and colon cancer.1 These two cancers occur more frequently in areas with less sunlight, and consequently less Vitamin D-3 production. Breast, lung, colon and cervix tumor cells and leukemia cells contain receptors for Vitamin D. These receptors present an avenue for the vitamin to possibly exert its anti-cancer effects. A synthetic and stronger form of Vitamin D-3 called OCT has been developed for use against cancer. This version contains the anti-cancer properties of the nutrient without the harmful possibility of hypercalcemia.

High doses of Vitamin D have been generally discouraged as side effects can include calcification of soft tissue and kidney failure. It is also speculated that a sustained overconsumption of this vitamin may play a negative part in the escalation of atherosclerosis, heart disease, and decreased magnesium absorption.

The prevalence of rickets, a bone deformity common during the 17th and 18th centuries, led to the discovery of Vitamin D. It was speculated that this disease was caused by lack of sunshine and insufficient diet. Cod liver oil was found to be an effective cure. In 1922 Elmer McCollum identified the curative property in cod liver oil as Vitamin D. It was later learned that this vitamin is essential for the metabolism of calcium and phosphorous, which make for strong bones. Deficiency of the nutrient is associated with osteomalacia in adults and celiac disease.

1 Abe J, Nakano T, Nishii Y, et al., A novel vitamin D-3 analog, 22-2oxa-1,25-dihydroxyvitamin D-3, inhibits the growth of human breast cancer in vitro and in vivo without causing hypercalcemia. Endocrinology 1991; 129:832-837; and Thomas M, Tebbutt S, Williamson R: Vitamin D and its metabolites inhibit cell proliferation in human rectal mucosa and a colon cancer cell line. Gut 1992; 33:1660-1663.

VITAMIN D: SOURCES

• Butter
• Cod-liver oil
• Egg yolks
• Halibut-liver oil
• Herring
• Mackerel
• Salmon
• Sardines
• Sunlight
• Vitamin D-fortified milk

Available as:

• Capsules or tablets. Take with or immediately after food to increase absorption.
• Oral solution: Take with meals or 1 to 1-1/2 hours after meals unless otherwise directed by your doctor.
• A constituent of many multivitamin/mineral preparations.
• Vitamin D is also called cholecalciferol. Other forms of Vitamin D include calcifidiol, calcitrol, and dihydrotachysterol. These forms are also called ergocalciferol.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: PROVEN BENEFITS

• Regulates growth, hardening and repair of bone by controlling absorption of calcium and phosphorus from small intestine.
• Prevents rickets.
• Treats hypocalcemia (low blood calcium) in kidney disease.
• Treats post-operative muscle contractions.
• Works with calcium to control bone formation.
• Promotes normal growth and development of infants and children, particularly bones and teeth.
• Calcifidiol, calcitrol, and dihydrotachysterol are forms of Vitamin D primarily used as additional medicines to treat hypocalcemia (not enough calcium in blood). They are also frequently prescribed to treat bone disease in people undergoing renal dialysis and those with hypoparathyroidism.

What this vitamin does:

• Absorbs and uses calcium and phosphorous to make bone.
• Essential for normal growth and development.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: UNPROVED SPECULATED BENEFITS

• Cures arthritis.
• Prevents colon cancer.
• Treats aging symptoms.
• Treats acne.
• Treats alcoholism.
• Treats herpes simplex and herpes zoster.
• Treats cystic fibrosis.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: SPECIAL CONSIDERATIONS

• Children who live in sunshine-deficient areas.
• Anyone with inadequate caloric or nutritional dietary intake or increased nutritional requirements.
• Older people (over 55 years), especially women after menopause.
• Pregnant or breast-feeding women.
• Those who abuse alcohol or other drugs.
• People with a chronic wasting illness, excess stress for long periods or who have recently undergone surgery.
• Those with a portion of the gastrointestinal tract surgically removed.
• People with recent severe burns or injuries.

Miscellaneous information:

• Put liquid Vitamin D directly into mouth or mix with cereal, fruit juice or food.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: DEFICIENCY SYMPTOMS

• Rickets (a childhood deficiency disease): bent, bowed legs, malformations of joints or bones, late tooth development, weak muscles, listlessness.
• Osteomalacia (adult rickets): pain in ribs, lower spine, pelvis and legs, muscle weakness and spasm, brittle, easily broken bones.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: UNPROVED SPECULATED SYMPTOMS

Muscle diseases (myopathies)1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: LAB TESTS TO DETECT DEFICIENCY

• Reduced levels of Vitamin D forms in blood.
• Decreased serum phosphate, decreased calcium, increased alkaline phosphatase, urinary hydroxyproline, PTH levels.
• Bone X-ray.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: OPTIMAL LEVELS

200-400 IU

VITAMIN D: MINIMUM DOSAGE

Recommended Dietary Allowance (RDA):

Estimate of adequate daily intake by the Food and Nutrition Board of the National Research Council, 1989.

Age RDA

0-6 months 7.5mcg

6-12 months 10mcg

1-10 years 10mcg

MALES

11-18 years 10mcg

19-24 years 10mcg

25+ years 5mcg

FEMALES

11-18 years 10mcg

19-24 years 10mcg

25+ years 5mcg

Pregnant 10mcg

Lactating 10mcg

VITAMIN D: WARNINGS AND PRECAUTIONS

Don't take if you:

• Are allergic to Vitamin D, ergocalciferol or any Vitamin D derivative.

Consult your doctor if you have:

• Any plans to become pregnant while taking Vitamin D.
• Epilepsy.
• Heart or blood-vessel disease.
• Kidney, liver, pancreatic disease.
• Chronic diarrhea.
• Intestinal problems.
• Sarcoidosis.

Over age 55:

• Adverse reactions and side effects are more likely. Supplements are often necessary.

Pregnancy:

• Taking too much during pregnancy may cause abnormalities in fetus. Consult doctor before taking supplement to ensure correct dosage.
• Don't take megadoses.

Breast-feeding:

• Important for you to receive correct amount so enough Vitamin D is available for normal growth and development of baby. Consult doctor about supplements.
• Don't take megadoses.

Effect on lab tests:

• May decrease serum alkaline phosphatase.
• May increase levels of calcium, cholesterol and phosphate in test results.
• May increase level of magnesium in test results.
• May increase amounts of calcium and phosphorous in urine.

Storage:

• Store in cool, dry place away from direct light, but don't freeze. Avoid overexposure to air.
• Store safely out of reach of children.
• Don't store in bathroom medicine cabinet. Heat and moisture may change action of vitamin.

Others:

Absence of sunlight prevents natural formation of Vitamin D by skin. Sunshine provides sufficient amounts of Vitamin D for people who live in sunny climates. Those who live in northern areas with fewer days of sunshine and extended periods of cloud cover and darkness must depend on dietary sources for Vitamin D.

Avoid megadoses.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: OVERDOSE/TOXICITY

Signs and symptoms:

High blood pressure, irregular heartbeat, nausea, weight loss, seizures, abdominal pain, appetite loss, mental and physical-growth retardation, premature hardening of arteries, kidney damage.

What to do:

For symptoms of overdosage: Discontinue vitamin, and consult doctor. Also see ADVERSE REACTIONS OR SIDE EFFECTS.

For accidental overdosage (such as child taking entire bottle): Call your local poison control center.

For toxic symptoms: Discontinue vitamin and seek immediate medical help. Hospitalization may be necessary.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: ADVERSE REACTIONS OR SIDE EFFECTS

Reaction or effect What to do

Appetite loss Discontinue. Call doctor when convenient.

Constipation Discontinue. Call doctor when convenient.

Diarrhea Discontinue. Call doctor immediately.

Dry mouth Discontinue. Call doctor when convenient.

Headache Discontinue. Call doctor immediately.

Increased thirst Discontinue. Call doctor when convenient.

Mental confusion Discontinue. Call doctor immediately.

Metallic taste Discontinue. Call doctor when convenient.

Nausea Discontinue. Call doctor immediately.

Unusual tiredness Discontinue. Call doctor when convenient.

Vomiting Discontinue. Call doctor immediately.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN D: INTERACTION WITH OTHER SUBSTANCES

Antacids with aluminum decreases absorption of Vitamin D and fat-soluble vitamins A, D, E, K.

Antacids with magnesium may cause too much magnesium in blood, especially for people with kidney failure.

Anti-convulsants may reduce effect of Vitamin D from natural sources and require supplements to prevent loss of strength in bones.

Barbiturates may reduce effect of Vitamin D from natural sources and require supplements to prevent loss of strength in bones.

Calcitonin reduces effect of calcitonin when treating hypercalcemia.

Calcium (high doses) increases risk of hypercalcemia.

Cholestyramine impairs absorption of Vitamin D. May need supplements.

Colestipol impairs absorption of Vitamin D. May need supplements.

Digitalis preparations increases risk of heartbeat irregularities.

Diuretics, thiazide increases risk of hypercalcemia.

Hydantoin may reduce effect of Vitamin D from natural sources and require supplements to prevent loss of strength in bones.

Mineral oil increases absorption of Vitamin D. May need supplements.

Phosphorous-containing medicines increases risk of too much phosphorous in blood.

Primidone may reduce effect of Vitamin D from natural sources and require supplements to prevent loss of strength in bones.

Vitamin D derivatives, such as calciferol, calcitrol, dihydrotachysterol, and ergocalciferol: Additive effects may increase potential for toxicity.

Chronic alcoholism depletes liver stores of Vitamin D.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

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