Is there a role or target value for nutritional vitamin D in chronic kidney disease?

Native vitamin D in CKD and renal transplantation: meaning and rationale for its supplementation

Chronic kidney disease (CKD) poses a significant epidemiological challenge, necessitating effective patient management strategies. Nutritional intervention, particularly vitamin D supplementation, has garnered attention for its potential therapeutic utility in CKD. Despite widespread acknowledgment of the importance of vitamin D, particularly in bone and mineral metabolism, its supplementation in CKD patients for non-skeletal purposes remains contentious due to limited evidence. Hypovitaminosis D linked with CKD substantially contributes to disturbances in mineral and bone metabolism, increasing the risks of cardiovascular complications and skeletal disorders. Notably, CKD patients experience progressive vitamin D deficiency, exacerbating as the disease progresses. Guidelines recommend monitoring 25-hydroxyvitamin D (25 (OH)-D) levels due to their correlation with mineral metabolism parameters, although robust evidence for recommending supplementation is lacking. The primary aim of this paper is to focus on the main open questions regarding vitamin D supplementation in CKD, reporting the current evidence concerning the role of vitamin D supplementation in CKD and in renal transplant recipients.

The Benefit of Anti-Inflammatory and Renal-Protective Dietary Ingredients on the Biological Processes of Aging in the Kidney

One of the significant organ systems which decline in aging is the kidney. While the causes of age-associated decline in renal function are likely multifactorial, oxidative stress and inflammation are hypothesized to play important roles in the structural and functional changes of the kidney. During aging there is a general decline in the glomerular filtration rate (GFR), a primary measurement used to assess kidney function. Inflammation and oxidative stress have been hypothesized to have a significant detrimental effect on renal function in aging and this may be attenuated by renal protective dietary ingredients. These dietary ingredients may affect renal function directly or through a microbiome-mediated secondary product. Likewise, structural changes including renal tubular atrophy, interstitial fibrosis, and glomerulosclerosis have all been described in aging. Such detrimental changes may benefit from dietary ingredients that may delay or attenuate the occurrence of such changes. This review will describe the physiology and pathophysiology of aging in renal function with an emphasis on dogs and cats that develop a decline in kidney function naturally. In addition, the varying biomarkers of health and renal dysfunction will be discussed. Finally, we will evaluate the aid in the management of this normal decline through dietary intervention in animal models.