Vitamin D Update
In November of 2010, the Institute of Medicine released a report, Dietary Reference Intakes for Calcium and Vitamin D. This was a long-awaited report given that in the time since their previous report from 1997, many researchers have been arguing that:
- In addition to causing rickets and osteomalacia, vitamin D deficiency can lead to many other diseases including cancer and autoimmune diseases.
- Optimal amounts of vitamin D in the blood are between 80 to 100 nmol/l (32 to 40 ng/ml), which was much higher than previously thought.
- Many more people than ever before are deficient in vitamin D, especially given the higher levels thought to be optimal.
I also promoted the higher levels for vitamin D, especially given that studies published in the late 2000s on vitamin D listed categories of “insufficiency” and “deficiency” that were in line with the more recent, higher recommendations by some researchers.
But when the Institute of Medicine released their report last November, they did not agree, for the most part, with the three points above. Their Report Brief summarizes their findings (on both calcium and vitamin D):
The committee assessed more than one thousand studies and reports and listened to testimony from scientists and stakeholders before making its conclusions. It reviewed a range of health outcomes, including but not limited to cancer, cardiovascular disease and hypertension, diabetes and metabolic syndrome, falls, immune response, neuropsychological functioning, physical performance, preeclampsia, and reproductive outcomes. This thorough review found that information about the health benefits beyond bone health—benefits often reported in the media— were from studies that provided often mixed and inconclusive results and could not be considered reliable. However, a strong body of evidence from rigorous testing substantiates the importance of vitamin D and calcium in promoting bone growth and maintenance.
The IOM did increase the RDA for vitamin D from 400 IU to 600 IU for adults. But they continue to recommend ideal levels of vitamin D to be between 40 – 50 nmol/l (16 – 20 ng/ml).
I recently finished going back through many of the study summaries on the Bones, Vitamin D, and Calcium page of VeganHealth.org and adjusted them to reflect the IOM’s findings. I also added some information from other vitamin D studies, such as one on tanning beds, another on vitamin D2 vs. D3, and a 2011 report from EPIC-Oxford on vitamin D levels in vegetarians.
The good news is that many vegans who were struggling to raise their vitamin D levels to 80 nmol/l no longer need to worry about that, as 40 – 50 nmol/l is apparently fine and is the recommendation I will be promoting unless the IOM changes its recommendations in the future or there is other overwhelming evidence to do so.
This does not negate the importance of vegans making sure they get a reliable source of vitamin D. As I’ve pointed out many times, I have been contacted by many vegans whose vitamin D levels dropped well below 40 nmol/l and developed symptoms of deficiency. And even without overt symptoms (such as fatigue, or muscle or bone pain), you should not allow your bones to be harmed because you are neglecting vitamin D. My recommendations have stayed pretty much the same – if you are not getting enough sun to produce plenty of vitamin D, you should take about 1,000 IU of vitamin D per day.