Which type of vitamin D supplement is the safest and most effective?
Novel research published in Journal of Clinical Endocrinology and Metabolism has identified the effectiveness and differences between three forms of vitamin D3 supplements.
A multitude of evidence collected from previous clinical trials continues to support the use of dietary supplements as a safe and effective way to correct vitamin D deficiency, although the types of repletion strategies have shown great inconsistency in their effectiveness. In 2011, the Institute of Medicine published a report which emphasized the importance of evaluating the efficacy of high dose supplementation strategies.
Researchers at Bastyr University in California recently conducted a clinical trial to compare the effectiveness and differences between three different forms of vitamin D supplements in real-life routine practice conditions. The three forms of vitamin D were an emulsified oil drop (DROP), a capsule (CAP), and a chewable tablet (TAB).
They enrolled 55 healthy participants, aged 18-65 years of age, from three clinical health centers in Washington and Hawaii. Each of the three supplements were independently analyzed to measure vitamin D3 content prior to the trial and also at the end for degradation.
The 55 participants were randomized into one of three treatment groups:
- 23 participants received DROP daily at 10,000 IU for 12 weeks.
- 21 participants received CAP daily at 10,000 IU for 12 weeks.
- 22 participants received TAB daily at 10,000 IU for 12 weeks.
The researchers wanted to see if there were changes in vitamin D levels between the three groups, if absorption and overall effectiveness differed between supplements, and if the labeled dosage corresponded with its actual vitamin D content.
Here's what the researchers found:
- All treatments were safe to administer and increased vitamin D levels significantly between baseline and 12 weeks follow up (P< .0001).
- The proportion of people who reached sufficiency was 100% for the CAP and TAB groups and 80% for the DROP group.
- The CAP and TAB supplements both contained double the dose than what was stated on the label. Interestingly, DROP supplements were the most true to the dose claimed on the label, and it was also the most effective supplement evaluated.
The researchers were satisfied with their findings:
"We conclude that the strategy used in this PCT, dosing commercially available vitamin D₃ dietary supplements at 10,000IU/d for 12 weeks, is another safe, effective, and well tolerated strategy for clinical vitamin D₃ repletion in people with suboptimal 25(OH)D."
This study shows that all of the three common forms of vitamin D supplementation are safe and effective at a dose of 10,000 IU/day,
Procedures need to be established and enforced to ensure standardized and independent testing of dietary supplements to make sure that the dose given on the label matches the actual dose contained in the supplement when used in research and clinical practice.