What is the toxicity level of Vitamin D?

[DerickVonD]

I was wondering, since vitamin D is fat soluble, what is the max dose someone can take. I ask this, because I have Vitamin D gel caps and there is Vitamin D in my multivitamin. I've been taking both. I don't go out in the sun much. In my nutrition book for college they recommend 400IU and state the "Upper Limit" someone can take is 4,000IU. This is based on a government standard, so I know it's wrong.

 

[JudoJosh]

http://www.ncbi.nlm.nih.gov/m/pubmed/21378345/

Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention.

Abstract
BACKGROUND: Studies indicate that intake of vitamin D in the range from 1,100 to 4,000 IU/d and a serum 25-hydroxyvitamin D concentration [25(OH)D] from 60-80 ng/ml may be needed to reduce cancer risk. Few community-based studies allow estimation of the dose-response relationship between oral intake of vitamin D and corresponding serum 25(OH)D in the range above 1,000 IU/d.

MATERIALS AND METHODS: A descriptive study of serum 25(OH)D concentration and self-reported vitamin D intake in a community-based cohort (n = 3,667, mean age 51.3 ± 13.4 y).

RESULTS: Serum 25(OH)D rose as a function of self-reported vitamin D supplement ingestion in a curvilinear fashion, with no intakes of 10,000 IU/d or lower producing 25(OH)D values above the lower-bound of the zone of potential toxicity (200 ng/ml). Unsupplemented all-source input was estimated at 3,300 IU/d. The supplemental dose ensuring that 97.5% of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d.

CONCLUSION: Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity.

 

[mcc23]

http://www.ncbi.nlm.nih.gov/m/pubmed/21378345/

Wow ~10,000 IU/d= 40 ng/ml.. Should be no issues with toxicity here

 

[DerickVonD]

Wow ~10,000 IU/d= 40 ng/ml.. Should be no issues with toxicity here

I'm been taking about 8,000-9,000IU a day.

 

[elegua]

It's worth pointing out that many nutrients not only start having diminishing returns, but can actually lose effectiveness as you get higher in dosage -- irrelevant of toxicity. The current predominant hypothesis as to "why" has to do with gene expression -- certain ranges of nutrients aid in gene expression, but overdosing can actually reverse said gene expression.

It's something to keep in mind -- not only can (random example) 6000IU not be better for you than 3000IU, it can actually be worse, even if you're nowhere near the toxicity threshold. It might not be "toxic," but it could undo the beneficial effects of a lower dosage.

Sadly, I'm too much of a newbie to post links, but a Google search of the terms "vitamins and gene expression" will give you links to several scholarly papers on vitamin C, A, and D in relation to gene expression, all on the first page of the search.

Again…this is a fairly new field of study, and might turn out to be flawed, but for the time being it's worth learning about.