Vitamin D Supplementation

Vitamin D has two forms which include ergocalciferol and cholecalciferol. Whereas ergocalciferol is derived from ergosterol in plants, usually yeast, by irradiation, cholecalciferol is usually derived from fish, from the irradiation of 7-dehydrocholesterol from lanolin, or by chemically converting cholesterol.

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Recommended vitamin D intake

Some research shows that vitamin D3 is somewhat more effective at higher doses in boosting the concentrations of vitamin D prohormone in the body. As a result of this evidence, vitamin D3 is usually used to fortify milk and milk products, as well as to prepare supplements.

The normal supplementation dosage ranges from 400 IU/ mL to 400 IU/drop. Care must be enjoined and demonstrated to avoid overdosage, especially with the higher concentration, in infants. However, some current research indicates that 800-5,000 IU/day improves musculoskeletal health in the elderly, preventing up to 50% of falls.

In those who have vitamin D deficiency, up to 600,000 IU administered in several divided doses over a few weeks, such as 50,000 IU/week for 8 weeks, has been recommended. This is sufficient to bring the tissue and serum levels back to normal. Following this, 800-1,000 IU may be taken daily, either from dietary sources or as a supplement.

Do You Need Vitamin D Supplements?

Forms of vitamin D supplementation

Most people maintain a normal vitamin D concentration provided they get 10-15 minutes of sunlight a day on exposed skin. In such a case, supplements are not usually necessary. Indications for vitamin D supplements should be based on the measurement of 25-hydroxy-D levels.

Vitamin D supplements may interact with various medications. Corticosteroids like prednisone, for example, which are widely prescribed for their anti-inflammatory actions, also reduce both calcium absorption and the metabolism of vitamin D, exacerbating bone loss and speeding up the development of osteoporosis with long-term use.

Comparatively, cholesterol-lowering agents such as cholestyramine can impair the absorption of vitamin D as well as other fat-soluble vitamins by interfering with fat absorption. Phenytoin and phenobarbital, both of which are anticonvulsants, both induce the hepatic metabolism of vitamin D, leading to increased inactivation, which leads to lower calcium absorption.


Further Reading

Last Updated: Apr 8, 2021

Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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