How much D3 is too much?
Posted: Fri Feb 14, 2014 2:52 pm
According to these guys 10,000 IU per day is safe
http://www.vitamindcouncil.org/blog/hel ... h-project/
http://www.vitamindcouncil.org/blog/hel ... h-project/
Welcome to This is MS, the leading forum for Multiple Sclerosis research and support. Join our friendly community of patients, caregivers, and researchers celebrating over 20 years of delivering hope through knowledge.
https://www.thisisms.com/forum/
http://www.huffingtonpost.com/carolyn-d ... 40931.htmlIt turns out that all the enzymes metabolizing vitamin D require magnesium as a necessary co-factor.[2],[3] When you take high doses of Vitamin D and if you are already low in magnesium, the increased amount of metabolic work drains magnesium from its muscle storage sites. That's probably why muscles are the first to suffer magnesium deficiency symptoms -- twitching, leg cramps, restless legs and charlie horses. Angina and even heart attacks affecting the heart muscle are all magnesium deficiency symptoms.
http://www.ncbi.nlm.nih.gov/pubmed/20170394The underestimated problem of using serum magnesium measurements to exclude magnesium deficiency in adults; a health warning is needed for "normal" results.
I agree on the 10,000 IU per day of Vit d3. See the below abstract ...marcopolo wrote:According to these guys 10,000 IU per day is safe
http://www.vitamindcouncil.org/blog/hel ... h-project/
J Bone Miner Res. 2007 Dec;22 Suppl 2:V64-8. doi: 10.1359/jbmr.07s221.
Vitamin D toxicity, policy, and science.
Vieth R.
Abstract
The serum 25-hydroxyvitamin D [25(OH)D] concentration that is the threshold for vitamin D toxicity has not been established. Hypercalcemia is the hazard criterion for vitamin D. Past policy of the Institute of Medicine has set the tolerable upper intake level (UL) for vitamin D at 50 mug (2000 IU)/d, defining this as "the highest level of daily nutrient intake that is likely to pose no risks of adverse health effects to almost all individuals in the general population." However, because sunshine can provide an adult with vitamin D in an amount equivalent to daily oral consumption of 250 mug (10,000 IU)/d, this is intuitively a safe dose.
The incremental consumption of 1 mug (40 IU)/day of vitamin D(3) raises serum 25(OH)D by approximately 1 nM (0.4 ng/ml). Therefore, if sun-deprived adults are to maintain serum 25(OH)D concentrations >75 nM (30 ng/ml), they will require an intake of more than the UL for vitamin D. The mechanisms that limit vitamin D safety are the capacity of circulating vitamin D-binding protein and the ability to suppress 25(OH)D-1-alpha-hydroxylase.
Vitamin D causes hypercalcemia when the "free" concentration of 1,25-dihydroxyvitamin D is inappropriately high. This displacement of 1,25(OH)(2)D becomes excessive as plasma 25(OH)D concentrations become higher than at least 600 nM (240 ng/ml). Plasma concentrations of unmetabolized vitamin D during the first days after an acute, large dose of vitamin D can reach the micromolar range and cause acute symptoms.
The clinical trial evidence shows that a prolonged intake of 250 mug (10,000 IU)/d of vitamin D(3) is likely to pose no risk of adverse effects in almost all individuals in the general population; this meets the criteria for a tolerable upper intake level.
PMID: 18290725 [PubMed - indexed for MEDLINE]
I am not so sure the Vitamin D Council recommends 10,000 IU:marcopolo wrote:According to these guys 10,000 IU per day is safe
http://www.vitamindcouncil.org/blog/hel ... h-project/
http://www.vitamindcouncil.org/blog/why ... mment-4002Where did the Vitamin D Council get its recommendation that adults take 5,000 IU/day of vitamin D3 for the rest of their life? The Institute of Medicine’s Food and Nutrition Board say 600 IU/day is enough for adults and the Endocrine Society says 2,000 IU/day is enough for most adults.
A better authority for the same info.jimmylegs wrote:re safety, intuition doesn't quite do it for me. I use that vieth study to guide how much d3 i'll take in one dose, but i'll never again take high dose vit d3 without ensuring balanced magnesium status. I wish there were more studies that looked specifically at magnesium response to long term high dose vit d3.
Am J Clin Nutr. 2007 Jan;85(1):6-18.
Risk assessment for vitamin D.
Hathcock JN, Shao A, Vieth R, Heaney R.
Abstract
The objective of this review was to apply the risk assessment methodology used by the Food and Nutrition Board (FNB) to derive a revised safe Tolerable Upper Intake Level (UL) for vitamin D. New data continue to emerge regarding the health benefits of vitamin D beyond its role in bone. The intakes associated with those benefits suggest a need for levels of supplementation, food fortification, or both that are higher than current levels. A prevailing concern exists, however, regarding the potential for toxicity related to excessive vitamin D intakes. The UL established by the FNB for vitamin D (50 microg, or 2000 IU) is not based on current evidence and is viewed by many as being too restrictive, thus curtailing research, commercial development, and optimization of nutritional policy. Human clinical trial data published subsequent to the establishment of the FNB vitamin D UL published in 1997 support a significantly higher UL. We present a risk assessment based on relevant, well-designed human clinical trials of vitamin D.
Collectively, the absence of toxicity in trials conducted in healthy adults that used vitamin D dose > or = 250 microg/d (10,000 IU vitamin D3) supports the confident selection of this value as the UL.
PMID: 17209171 [PubMed - indexed for MEDLINE] Free full text