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ConsumerLab.com Answers

Too Much Vitamin D

Question:
Is it possible to get too much vitamin D?

Answer:
Raising low levels of vitamin D has many benefits. Among them is that levels of C-reactive protein (CRP), a marker of inflammation, decrease as vitamin D levels increase. However, increasing vitamin D levels beyond sufficient levels has a slight inflammatory action, as shown in a recent study. And even higher levels of vitamin D can result in hypercalcemia (too much calcium in the blood) with symptoms including constipation, confusion, weakness, loss of appetite and painful calcium deposits. For details about this and extensive information about vitamin D uses and dosage, see the Vitamin D Supplements Review, which includes our latest product tests.

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Danielle11099   July 24, 2016
After reading Consumer Labs original report on the recommended levels, I backed off taking Vitamin D supplements/fish oil other than in a multi, since my last tested levels were quite high. I now eat a small can of locally sourced sockeye salmon, with skin and bones, no salt, about three times a week. Will check my labs when I see my doc next month. I live in Washington state where strong sun shines only a few months a year.

John6869   July 17, 2015
Your report states that one can get adequate vitamin D from 15 minutes of sun exposure twice a week.In the summer most people likely get considerably more than that-does one need to be concerned that more than 30 minutes /week in the sun will cause vitamin D blood levels to be too high to be healthy?

John14032   May 14, 2017
Skin cancer is a bigger worry from too much sun. Vitamin D overdose is impossible from UV exposure; the skin reaches an equilibrium where the vitamin degrades as fast as it is created.

https://en.wikipedia.org/wiki/Vitamin_D#Synthesis_in_the_skin

Robert5768   June 10, 2015
It is not terribly helpful to the average person to read a correct dose expressed as ng/ml. How is one supposed to translate that into a form that a non-scientist can use? As with other supplements, Vitamin D in the bottle is described in terms of "IU" or in milligrams. It would be helpful if ConsumerLab would provide its recommendations for all supplements in terms familiar to the consumer not as ng/ml.

ConsumerLab.com   June 11, 2015
Hi Robert - The ng/mL numbers you refer to have to do with levels of vitamin D in the blood, not dosage. We express all dosage information in IU, as that is what you will see on supplements.

Arthur5764   June 10, 2015
Check with Vitamin D Council.org - optimal levels of vit d3 have been shown in multiple studies to be over 40 ng/ml. I have been prescribing 2-5k IU vitamin d3 gel caps/day for over 10 years now to 100's of patients. I have only had 1 patient have side effects (high calcium and general malaise) in all this time.

A C Sands MD

Meri16839   May 13, 2018
You are overprescribing Vitamin D based on the latest research. I was seeing a functional medicine provider who had me taking 6,000 IU of Vitamin D, and I started experiencing frequent falls, one causing a broken elbow. I didn't put it together until I read the ConsumerLab report. At that time I had been taking 6,000 IU of Vitamin D for a year and had been experiencing frequent falls for about six months (at least 1 or 2 times a month, often in Zumba classes). I backed off to 2,000 IU of Vitamin D a years and a half ago and haven't fallen once since then. My level is about 35 now and I think that's perfect.

Pamela16843   May 15, 2018
Thanks for this valuable post Meri. I spend countless hours reading and reviewing and changing my supplements since my integrative dr moved away from Columbus. This is very helpful. Thank you.

Susan16848   May 16, 2018
After increasing my dosage of Vitamin D to 5000 IU I too began falling. When I read consumer labs report on falling being a side effect of too much D I cut back to 2000 IU and after a few months of not falling and my appetite increasing some. I feel better. Thank you consumer labs.

ConsumerLab.com   June 10, 2015
Dear Dr. Sands - Studies do not show optimal levels to be over 40 ng/mL, as you suggest. We recommend that you review the information in the section of our Vitamin D Review entitled "Deficiency vs. Insufficiency and How Much Is Too Much?" (https://www.consumerlab.com/reviews//Vitamin_D/#howmuch).

You may not see immediate adverse effects with high levels, but several studies now show higher mortality rates (i.e., more deaths) among people with levels above 40 ng/mL. The range we suggest of 25 to 35 ng/mL should provide the benefits of vitamin D without risk. We also suggest that you check the unbiased and authoritative opinion of the Institute of Medicine of the National Academies, which considers 20 ng/mL adequate for bone and overall health in healthy individuals.

Virginia5789   June 14, 2015
The lab my MD uses says the normal blood level for D, 25- Hydroxy, is 30-100 ng/ml.

I also understand that some neurologists are using higher doses in their patients to help prevent /treat dementia and other problems.
A couple of references: C. Annweiler, et al, "Higher Vitamin D Dietary Intake is Associated with Lower Risk of Alzheimers's Disease: A 7-year Follow-up," Journals of Gerontology Series A: Biological Sciences and Medical Sciences 67, no.11 ( Nov 2012): 1205-11.

D.J Llewellyn, et al, "Vitamin D and Risk of Cognitive Decline in Elderly Persons,"Archies of Internal Medicine 170, no. 13 (July 12, 2012): 1135-41.

ConsumerLab.com   July 31, 2015
Hi Virginia - The "standard range" or "reference range" which appear on blood test reports are not based on the expert recommendations of the Institute of Medicine of the National Academies, but reflect levels which the lab has found in 95% of a "healthy" population. However, increasing evidence suggests harmful effects with levels above 40 or 50 ng/mL as discussed in several sections of our Vitamin D Supplements Review (https://www.consumerlab.com/reviews//Vitamin_D/).

Also, keep in mind that vitamin D ranges are sometimes expressed as "nmol/L" rather than "ng/mL" - and so the numbers may need to be converted in order to make an accurate comparison. For example, in the second study you cite, deficient levels associated with cognitive decline were expressed as less than "25 nmol/L" which would be less than "10 ng/mL."

Mat8246   January 3, 2016
My lab (LabCorp) as well references vitamin D ranges between "ng/mL" 30-100 as healthy. Based on this my naturopath thought my lab result of 35.6 as needing increased supplementation.
After reading the studies ConsumerLab cites, I plan to back off my supplementation. It would seem the labs need to adjust their healthy range references based on the latest studies.

This CL Answer initially posted on 1/20/2012. Last updated 8/8/2017.

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