Vitamin D supplementation

Vitamin D3 supplementation is an effective alternative to UV exposure, provided adequate doses are taken.

Vitamin D needs

Vitamin D from both capsules and liquid is equally effective in treating vitamin D deficiency.

Much individual variation exists in response to supplemental vitamin D. The amount needed to raise and/or maintain blood serum levels for one person may not be enough for another. This is due to various factors such as age, weight, absorption, overall health, and amount of sun exposure. Recent research has determined that genetic variants are also a factor. 1

The only way to know for sure if a certain dosage is working for you is to have your vitamin D levels tested. Occasional monitoring of these levels will one determine what dose is right for them.
Current US Government recommended amounts

Adequate Intake for vitamin D represents the daily intake established by the Food and Nutrition Board (FNB) as sufficient to maintain bone health and normal calcium metabolism in healthy people. 2
FNB daily Adequate Intake (AI) for vitamin D

Children and adults up to the age of 70 years - 600 IU
Seniors 70+ years - 800 IU

Why these amounts are inadequate

US Government recommended Adequate Intake for vitamin D is too low to receive many of vitamin D's benefits.

The problem with current recommendations is that vitamin D influences a much wider array of physiological processes other than simply maintaining bone health and normal calcium metabolism. 3

For proper functioning, a healthy human body utilizes around 3,000-5,000 IU of vitamin D per day - indicating the current recommended intakes are not high enough to raise and/or maintain the vitamin D levels necessary for proper health. 4
Vitamin D Council recommended amounts

Based on the body's indicated daily vitamin D usage, Vitamin D Council recommends the following amounts of supplemental vitamin D3 per day in the absence of proper sun exposure. Due to the variable response discussed above, these are only estimated amounts.

Healthy children under the age of 1 years – 1,000 IU.
Healthy children over the age of 1 years – 1,000 IU per every 25 lbs of body weight.
Healthy adults and adolescents – at least 5,000 IU.
Pregnant and lactating mothers - at least 6,000 IU.

Additionally, children and adults with chronic health conditions such as autism, MS, cancer, heart disease, or obesity may need as much as double these amounts.
Tolerable Upper Intake Level

The US Government’s Tolerable Upper Intake Level (UL) for vitamin D is set at 4,000 IU per day. While this is a step in the right direction from the previous UL at 2,000 IU per day, in some situations - such as with those who are obese - it may still be too low. An upper limit this low will also result in the prevention of adequate doses from being used in studies, greatly curtailing our understanding of vitamin D’s physiological effects as well as the true extent of its treatment potential. 5 6 7

Experts agree the Upper Limit for vitamin D should be raised to 10,000 IU per day.

Current expert consensus is that the US Government UL for vitamin D is too low and that it should be raised to 10,000 IU per day. 6 7 8 Since this is the amount one would naturally produce in their skin from sun exposure, it is considered safe. 9
Can I take more than 10,000 IU per day?

Wanting to raise vitamin D levels quickly, some people choose to supplement with amounts higher than 10,000 IU per day until target levels are achieved. When using vitamin D in these amounts, frequent monitoring of blood levels (preferably as supervised by your physician) as well as adequate magnesium intake are advised. Once blood serum levels are optimized, daily amount should be lowered to the amount necessary to sustain these levels. How much is needed will be unique to the individual, but it should be somewhere around 5,000 IU per day.
Which type of vitamin D?
Oil vs. powder

Vitamin D3 supplements come in two forms:

oil (cod liver oil-based) - fat-soluble vitamin D, includes liquid drops or gel caps.
dry powder (lanolin-based) - water-soluble vitamin D, includes capsules or tablets.

As far as we know, both water-soluble and fat-soluble vitamin D are equally absorbed and metabolized by the body, and are thus equally effective.
D2 vs D3

Read the Vitamin D Council's full position statement on vitamin D2 vs D3 here.

Vitamin D3 (cholecalciferol) is the type of vitamin D the body naturally produces in the skin in response to sun exposure. Vitamin D2 is produced naturally when fungi (yeast or mushrooms) are exposed to ultraviolet light from the sun or to artificial UV light.

Scientific studies have demonstrated the bioequivalence of vitamin D2 and D3 in forming 25(OH)D when daily consumption of either precursor occurs over a minimum of 6 weeks 10. There is other evidence that the body has preference to D3 over D2, showing in these studies that the body more readily uses D3 when it has both forms in the body, and that D3 is more potent than D2 for producing 25(OH)D 11.

Although both D2 and D3 are effective for raising blood levels of 25(OH)D, the Vitamin D Council believes that vitamin D3, as produced in human skin, is the more natural precursor, and recommends supplementing with vitamin D3. Vitamin D3 supplements are not vegetarian and are not likely to be derived from American products. If an individual has ethical concerns over D3, D2 can be an effective replacement.

How should I take my vitamin D?

Both forms of vitamin D may be taken any time of day with, or without, any other food or supplement and still remain effective. If one is concerned about absorption, they may take their vitamin D at mealtime, though there is no evidence to indicate this is more effective.

Most people take their vitamin D daily, yet there are some who opt to take it weekly at a higher dose. Since the body is designed to store vitamin D for future use, a weekly interval should produce the same results as daily use. 12
Mixing sun exposure and supplements

It is okay to use both sun exposure and intermittent supplementation to receive one's vitamin D. Simply do not take any supplemental vitamin D on the days when proper sun exposure is received. Keep in mind that vitamin D taken orally bypasses the body's built in toxicity protection with that obtained by sun exposure. As with daily use of oral vitamin D, periodic monitoring of levels is advised.
Precautions

People with the following conditions should only take vitamin D with the guidance of a knowledgeable physician:

primary hyperparathyroidism
sarcoidosis
granulomatous TB
some cancers

Those with primary hyperparathyroidism should only use vitamin D when under the care of a knowledgeable endocrinologist.

Interactions with medications

There have yet to be any documented instances of an adverse interaction of vitamin D with any medications. There are, however, medications which have been found to interfere with the body’s proper utilization of vitamin D. They are: 2

Steroids - impair vitamin D metabolism, contributing to bone loss and development of osteoporosis.
Xenical®, alli™, Questran®, LoCholest®, and Prevalite® - reduce vitamin D absorption.
Dilantin®) - increases hepatic metabolism of vitamin D to inactive compounds.

Page last edited: 31 October 2011
References

Wang T.J., et al. Common genetic determinants of vitamin D insufficiency: a genome-wide association study. Lancet. 2010 July 17; 376 (9736): 180-188.
Food and Nutrition Board Dietary Supplement Fact Sheet: Vitamin D. ods.od.nih.gov.
Grant WB, Holick MF Benefits and requirements of vitamin D for optimal health: a review. Altern Med Rev. 2005 Jun; 10 (2): 94-111.
Heaney R.P., Davies K.M., Chen T.C., Holick M.F., Barger-Lux M.J. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr. 2003 Jan; 77 (1): 204-10.
Hathcock, J. N. Shao, A. Vieth, R. Heaney, R. Risk assessment for vitamin D. Am J Clin Nutr. 2007 Jan; 85 (1): 6-18.
Heaney, R. P. The Vitamin D requirement in health and disease. J Steroid Biochem Mol Biol. 2005 Oct; 97 (1-2): 13-9.
Vieth, R. Critique of the considerations for establishing the tolerable upper intake level for vitamin D: critical need for revision upwards. J Nutr. 2006 Apr; 136 (4): 1117-22.
Vieth, R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. 1999 May; 69 (5): 842-56.
Vieth, R. Vitamin D toxicity, policy, and science. J Bone Miner Res. 2007 Dec; 22 Suppl 2V64-8.
Holick MF, Biancuzzo RM, Chen TC, Klein EK, Young A, Bibuld D, Reitz R, Salameh W, Ameri A, Tannenbaum AD. Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. Journal of Clinical Endocrinology & Metabolism. 18/12/2008; 93 (3): 677-81.
Heaney RP, Recker RR, Grote J, Horst RL, Armas LA. Vitamin D(3) is more potent than vitamin D(2) in humans. Journal of Clinical Endocrinology & Metabolism. 22/12/10; 96 (3): 447-52.
van Groningen L., Opdenoordt S., van Sorge A., Telting D., Giesen A., de Boer H. Cholecalciferol loading dose guideline for vitamin D-deficient adults. Eur J Endocrinol. 2010 Apr; 162 (4): 805-11.