Introduction

Vitamin D is known as the “sunshine” vitamin because it is formed in the body by the action of the sun’s ultraviolet rays on the skin. The fat-soluble vitamin is converted in the kidneys to the hormone calcitrol, which is actually the most active form of vitamin D. The effects of this hormone are targeted at the intestines and bones.

Dosage Info

Dosage Range

Dosages that have been used in clinical studies range from 200IU (5mcg) to 10,000IU (250mcg) daily. (1) , (2) It is important to note that based on the presence of hypercalcemia (2.75mmol/L or 11mg/dL) at a given dose, The Food and Nutrition Board of the National Academy of Sciences states that 95 mcg of vitamin D per day is the lowest observed adverse effect level reported. (3)

Most Common Dosage

400IU (10mcg) daily.

40IU = 1mcg

Dosage Forms

Capsules, tablets, and liquid.

Interactions and Depletions

Depletions

• Anticonvulsants
• Bile acid sequestrants
• Corticosteroid medications
• cimetidine
• isoniazid
• mineral oil
• rifampin
• orlistat

Reported Uses

Vitamin D is important for the growth and development of bones and teeth. (4) For this reason, vitamin D is an important growth nutrient for infants and children. Vitamin D is one of the primary regulators of calcium absorption, which is also important for proper bone health and development. Deficiencies are frequently found in individuals with or at risk for osteoporosis. (5) , (6) , (7) , (8) , (9) Considering this relationship, vitamin D insufficiency may have an effect on bone strength. (10) , (11)

Vitamin D is perhaps best known as a treatment for the disease associated with vitamin D deficiency, rickets. (12) Deficiency has also been linked to Crohn’s disease and hearing loss. (13) , (14) Supplementation may treat the skin disorders psoriasis and scleroderma. (15) , (16) Finally, supplementation may be necessary for epileptics, as medications to treat the disorder may deplete vitamin D. (17)

Toxicities & Precautions

Introduction

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General

Vitamin D can be toxic, but this dietary supplement is considered safe when used in accordance with proper dosing guidelines.

Side Effects

Occasional side effects reported with large doses of this dietary supplement include a disorder known as hypercalcemia, (18) which causes calcium deposits in soft tissues. Signs of the disorder include headache, weakness, nausea, vomiting, and constipation. It may be necessary to reduce the dose of this dietary supplement. Consult a physician before using vitamin D in large doses. Tell your physician if these side effects become severe or do not go away.

Pregnancy / Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Proper nutrition is essential during pregnancy for the healthy development of the fetus. Numerous vitamins and minerals are a vital part of proper nutrition. If you are pregnant, think you might be pregnant, trying to get pregnant, or breast-feeding an infant, talk to your healthcare professional about supplementing your diet with appropriate vitamins and minerals.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Vitamins and minerals are an essential part of proper growth and development. Talk to your healthcare professional about the appropriate use of vitamins and minerals in children. Do not use any vitamin or mineral in children under 2 years of age unless first discussed with your healthcare professional.

References

1. View Abstract: Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. May1999;69(5):825-6.
2. View Abstract: Vieth R, Chan PC, MacFarlane GD. Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level. Am J Clin Nutr. Feb2001;73(2):288-94.
3. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride; Washington, DC: National Academy Press; 1999:282. Book available at: http://books.nap.edu/books/0309063507/html/index.html.
4. View Abstract: Outila TA, Karkkainen MU, Lamberg-Allardt CJ. Vitamin D status affects serum parathyroid hormone concentrations during winter in female adolescents: associations with forearm bone mineral density. Am J Clin Nutr. Aug2001;74(2):206-10.
5. View Abstract: Villareal DT, et al. Subclinical Vitamin D Deficiency in Postmenopausal Women with Low Vertebral Bone Mass. Journal of Clinical Endocrinology and Metabolism. 1991;72(3):628-34.
6. View Abstract: Rassouli A, Milanian I, Moslemi-Zadeh M. Determination of serum 25-hydroxyvitamin D(3) levels in early postmenopausal Iranian women: relationship with bone mineral density. Bone. Nov2001;29(5):428-30.
7. View Abstract: Mezquita-Raya P, Munoz-Torres M, Luna JD, et al. Relation between vitamin D insufficiency, bone density, and bone metabolism in healthy postmenopausal women. J Bone Miner Res. Aug2001;16(8):1408-15.
8. View Abstract: Brot C, Vestergaard P, Kolthoff N, Gram J, Hermann AP, Sorensen OH. Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone. Br J Nutr. Aug2001;86(Suppl 1):S97-103.
9. View Abstract: Grados F, et al. Prediction of bone mass density variation by bone remodeling markers in postmenopausal women with vitamin D insufficiency treated with calcium and vitamin D supplementation. J Clin Endocrinol Metab. 2003 Nov;88(11):5175-9.
10. View Abstract: Mezquita Raya P, Munoz Torres M, Lopez Rodriguez F, et al. Prevalence of vitamin D deficiency in populations at risk for osteoporosis: impact on bone integrity. Med Clin (Barc). Jun2002;119(3):85-9.
11. View Abstract: Trivedi DP, Doll R, Khaw KT. Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial. BMJ. Mar2003;326(7387):469.
12. View Abstract: Takeda E, et al. Vitamin D-dependent Rickets Type I and Type II. Acta Paediatr Jpn. Aug1997;39(4):508-13.
13. View Abstract: Andreassen H, et al. Regulators of Calcium Homeostasis and Bone Mineral Density in Patients with Crohn’s Disease. Scand J Gastroenterol. Oct1998;33(10):1087-93.
14. View Abstract: Brookes GB. Vitamin D Deficiency and Deafness: 1984 Update. Am J Otol. Jan1985;6(1):102-07.
15. View Abstract: Morimoto S, et al. Inverse Relation Between Severity of Psoriasis and Serum 1,25-dihydroxy-vitamin D Level. J Dermatol Sci. Jul1990;1(4):277-82.
16. View Abstract: Humbert P, et al. Treatment of Scleroderma with Oral 1,25-dihydroxyvitamin D3: Evaluation of Skin Involvement Using Non-invasive Techniques. Results of an Open Prospective Trial. Acta Derm Venereol. Dec1993;73(6):449-51.
17. View Abstract: Shafer RB, et al. Calcium and Folic Acid Absorption in Patients Taking Anticonvulsant Drugs. J Clin Endocrinol Metab. Dec1975;41(06):1125-29.
18. View Abstract: Selby PL, Davies M, Marks JS. Vitamin D intoxication causes hypercalcaemia by increased bone resorption which responds to pamidronate. Clin Endocrinol (Oxf). Nov1995;43(5):531-6.