Vitamin D Safety

April 27, 2017

Director's Letter

Carole Baggerly

Director, GrassrootsHealth

After feedback from many of you, we are continuing to give you scientific information to help you address negative vitamin D stories in the press by giving you new evaluation tools and information. Many of you know that vitamin D levels above 40 ng/ml have helped you, but it is hard to deal with some of the professional's reactions when a new person asks for a vitamin D test, or tells them they want to supplement with 5,000 IU/day.

We are getting ready to launch a new project - D*action Omega-3! We let you know about this in January, and the pieces are coming together. The new project will be an option for all participants - new and old. We are testing this new project with people who were interested and will launch to the general public around June. Until then, you can continue to take or read up on omega-3s and look for information about their health benefits.

Similar to vitamin D, we are looking to move the research of Omega-3 for health benefits into practice.

Onwards!

Carole Baggerly

Director, GrassrootsHealth

A Public Health Promotion & Research Organization

Moving Research into Practice NOW!

Response to Vitamin D in the News

There has been a lot of press recently stating the RDA of vitamin D should be lowered, not increased because of a presentation made at the annual meeting of the Endocrine Society, April 1-4, Orlando, Florida.

The research comes from a team at Creighton University, Omaha, Nebraska, including lead author Lynette Smith, and Christopher Gallagher who made the presentation at the Endocrine Society meeting.

The study, done in 2007-2008, looked at post-menopausal women aged 57-90 with the aim to determine vitamin D levels (called 25(OH)D) and blood levels of another marker that is closely associated with vitamin D sufficiency - parathyroid hormone (PTH). PTH and vitamin D levels both show how calcium is absorbed by the body, typically as vitamin D levels rise to sufficiency, PTH lowers.

The conference abstract states, "Based on the DiaSorin assay system the estimated RDA to exceed 20 ng/ml was 800 IU daily whereas LC-MS/MS estimated that 400 IU daily would meet the RDA."

This study was not intended to show that 20 ng/ml is the optimal level of 25(OH)D, but rather that if that level is your goal, as it is the level currently recommended by the Institute of Medicine, then the specific test method used to measure that concentration will make a difference in the outcome.

When using the current gold standard LC-MS/MS method rather than the DiaSorin, the test results from the same samples came out higher, suggesting that a lower level of supplementation (less than 600-800 IU/day) was needed to reach the same endpoint of 20 ng/ml.

The real target is 40-60 ng/ml

While some news reports jumped on the idea that a lower intake of vitamin D may be needed to meet the requirement of 20 ng/ml, let's not lose sight of the fact that many organizations, including GrassrootsHealth, will assert that 20 ng/ml is NOT enough for bone health, or immune function or many other conditions.

Our focus needs to be on the optimal levels needed for health--with a range, of course, that is both safe and effective. Our panel of 48 vitamin D researchers reached a consensus that the range of 40-60 ng/ml (100-150 nmol/L) does exactly that. That was the range they agreed upon in 2007, it is the range that is still recommended today based on current research.

How Much is Too Much Vitamin D

How to evaluate articles stating "too much vitamin D" causes health problems

Evaluation of vitamin D3 intakes up to 15,000 international units/day and serum 25-hydroxyvitamin D concentrations up to 300 nmol/L on calcium metabolism in a community setting
S.M. Kimball, N. Mirhosseini & M.F. Holick
Dermato-Endocrinology
April 13, 2017
Read Paper

This recently published paper seems to have been released at just the right time, when many news outlets are purporting the misuses of "over testing" and too much vitamin D "popping."

Is 15,000 IU/day too much?

According to the 2010 standards set by the Institute of Medicine, the safe tolerable upper intake level (UL) is 4,000 IU/day. In 2011 the Endocrine Society recommended 10,000 IU/day as the tolerable upper limit. In the introduction to this study it says that an adult in a bathing suit exposed to sunlight for a length of time to cause a slight pinkness in the skin 24 hours later is equivalent to 15,000 IU. Having this amount of sun exposure would be similar to our ancestral level, or the amount of vitamin D nature intended us to get on a daily basis.

This study set out to determine the effect(s) of supplementation with vitamin D at doses between 1,000 - 15,000 IU/day; to see not only what vitamin D levels were achieved, but more importantly, whether there were any adverse effects, any overdose symptoms, in people taking up to 15,000 IU/day.

Who participated in the study?

3,882 people who enrolled in a wellness program between 2012 and 2015 were included in the study. The mean age was 59, with 60% women. The distribution of Body Mass Index (BMI) of participants was 36% in the normal range, 37% overweight, and 28% obese. At the time of enrollment, participants reported taking an average of just over 2100 IU vitamin D / day and their average serum level was 87 nmol/L (35 ng/ml).

A goal of this program was to achieve a minimum 25(OH)D concentration of 100 nmol/L (40 ng/ml).

How did the study work?

Researchers used anonymized data from a wellness program in Canada. The program focuses on disease prevention and gives advice on lifestyle, nutrition, and supplements, and encourages achieving a 25(OH)D level of at least 100 nmol/L (40 ng/ml). They start with a blood test for each individual and create an individualized treatment plan including supplements based on the outcome of that initial blood test.
What did the researchers find?

None of the participants showed any signs of toxicity. Hypercalcemia and hypercalciuria were not related to higher vitamin D levels or higher vitamin D doses. Hypercalcemia was present in 1.2% of participants upon entry and 1.3% at follow-up. Each new case of elevated calcium, 20 in all, was investigated for cause and is described in detail in the paper. They took measurements for calcium, PTH, 25(OH)D, and biochemical markers for both kidney and liver function for many of the participants so they could best explore adverse conditions.

The most reliable marker for problems with calcium is serum PTH. This study found that there was no significant reduction in PTH levels in participants with the highest intakes of vitamin D or the highest vitamin D levels. It would be wise, instead of cautioning all doctors about the dangers of hypercalcemia, to instead train doctors on the value of PTH measurement and what it means to calcium homeostasis.
The researchers found that it required, on average, 6000 IU/day to achieve a vitamin D level of 100 nmol/L (40 ng/ml) for someone with a normal BMI, 7000 IU/day if overweight and 8000 IU/day if obese. At the end of the study the average serum level for all participants was 126 nmol/L (51 ng/ml).

This study did not assess disease or other factors, it was about safety. With almost 4000 participants it did show that vitamin D levels up to 300 nmol/L (120 ng/ml), as well as vitamin D intakes of up to 15,000 IU/day, are safe.

What can you do now with this information?

This is one study demonstrating that vitamin D is indeed safe over a wide range of dosages. There are others, but if you search pubmed for papers on vitamin D overdose cases you will find very few.

Stick to recommending that people start by testing their current vitamin D level, and then using supplements or sun to achieve a minimum of 40 ng/ml (100 nmol/L). This paper presents that person with some data - that they will most likely need between 6,000 - 8,000 IU / day to get there. It also presents them with information for their doctor, when their doctor tells them to reduce their vitamin D intake, or that too much vitamin D could be dangerous.