New research published in the Journal of Renal Nutrition has found that use of vitamin D supplements in patients with chronic kidney disease has increased four-fold in recent years.
Twenty six million American adults have chronic kidney disease, while millions more are at risk for developing it. Chronic kidney disease (CKD) is loss of kidney function, and it progresses over time. As the disease progresses, waste can build to high levels in your blood to make you feel sick. The disease is associated with cardiovascular, metabolic, and infectious complications.
Some studies suggest vitamin D deficiency may contribute to these complications, making it an important modifiable risk factor. Despite this, researchers have yet to explore the use of vitamin D supplements in this group. If there’s okay to good evidence for the use of vitamin D supplements, are CKD patients using them?
Recently, researchers examined the trends in vitamin D supplement use in people with chronic kidney disease and the relationship of supplementation to vitamin D levels.
They examined rates of vitamin D supplementation among the participants from the Chronic Renal Insufficiency Cohort (CRIC). The CRIC is an ongoing observational study created in 2001 to continually examine risk factors for cardiovascular disease and CKD progression. All participants recruited for the cohort were diagnosed with mild to moderate chronic kidney disease.
The researchers in this study assessed the data on vitamin D supplement use from all 3,939 participants of the CRIC each year from 2003 to 2010.
The researchers were interested in whether vitamin D supplementation increased, decreased, or remained unchanged over the seven-year period.
They found the following:
- Overall, use of vitamin D supplements increased from 10% to 44% over the 7 year study period. The increase in supplement use was mainly through patients using supplements containing only vitamin D3 or D2 more so than multivitamins containing vitamin D.
- The predominant form of vitamin D supplement used switched from vitamin D2 (69.3% in 2003) to vitamin D3 (77.2% in 2010).
In a subgroup analysis, the researchers looked at 1,155 participants from the same cohort to compare the vitamin D levels of those using vitamin D supplements with those not using supplements. Here’s what the researchers found:
- The vitamin D levels of those taking a supplement containing more than 400 IU/day was significantly higher with an average level of 42 ng/ml among non-Black participants and 40.5 ng/ml among Black participants.
- Only 3.8% of non-Black and 16.5% of Black participants taking a supplement had levels lower than 20 ng/mL, compared to 22.7% of non-Black and 62.4% of Black participants not taking a supplement.
The researchers concluded,
“This study revealed an increasing use of cholecalciferol [vitamin D3] supplementation among participants in the CRIC study and that supplementation was associated with greater 25(OH)D levels.”
Although the results had significant findings, there were still some limitations. The biggest limitation of the study is the use of self-reporting, which may lead to inaccurate data on supplement use.
Furthermore, these findings suggest there will be limitations for future trials that are evaluating the effects of vitamin D supplementation on CKD. Since more and more CKD patients are supplementing with vitamin D, it will be more difficult to control patients’ use of supplements. However, these trials are needed in order to help determine how effective vitamin D supplementation is on the health of people with CKD.