Despite the research showing the benefits of higher amounts of vitamin D, many doctors continue suggesting 400 IU daily. The common fear is that higher amounts will result in toxicity.
However, a new study conducted by the Mayo clinic may just put these fears to rest. The study found that vitamin D toxicity is, in fact, quite rare.
The results were published in the journal, Mayo Clinic Proceedings.
Previous research shows higher amounts of vitamin D protect against age-related diseases including heart disease, cancer, and osteoporosis. Based on these studies, between 5000 to 7000 IU are suggested daily. This dosage generally provides blood levels in the 50–70 ng/ml range.
For the current study, the authors took a total of 20,308 vitamin D measurements from the participating individuals. The majority of participants were white and lived in areas that received little sunlight during the winter. Information was collected about vitamin D and calcium supplementation.
The Mayo researchers were screening participants for signs of vitamin D toxicity. The primary sign, hypercalcemia, is high blood calcium levels.
According to the results of the study, about 8% of participants had vitamin D blood levels above 50 ng/ml. A total of 37 participants (0.2%) had blood levels above 100 ng/ml. Only 4 participants with vitamin D levels over 50 ng/ml had high blood calcium levels.
The key finding was that blood levels above 50 ng/ml were not associated with high blood calcium levels or toxicity.1
Traditional doctors suggest that blood levels not reach above 30 ng/ml. Around 5000 IU of Vitamin D daily corresponds to a blood level of 50 ng/ml.
Previous fears about vitamin D toxicity are unfounded. The concern is that vitamin D will accumulate to harmful levels in the body, which rarely happens.
Nevertheless, there are some individuals that need to be cautious in taking higher amounts of vitamin D. This includes individuals with existing kidney disease.