The connection between kidney disease, vitamin D deficiency, and depression

Patients with chronic kidney disease (CKD) have an increased risk of both vitamin D deficiency and developing depression. According to a population study published in Frontiers in Nutrition, maintaining optimal vitamin D levels in the blood may reduce the risk of severe depression in these patients.

Chronic kidney disease affects approximately 10% of the global population and is characterized by a gradual decline in kidney function over time. The high prevalence of CKD is mainly due to an aging population and the increasing incidence of type 2 diabetes, obesity, high blood pressure, and cardiovascular disease. Environmental toxins, such as mercury, can also put a strain on the kidneys.
As CKD progresses, it increases the risk of anemia, metabolic bone diseases, and cardiovascular diseases. Additionally, around 34% of CKD patients suffer from severe depression. Besides reducing quality of life, severe depression also increases the risk of complications, hospitalizations, and premature death. It is also believed that depression may be linked to chronic inflammation and unhealthy lifestyle habits, which further deteriorate kidney function. Therefore, more attention should be given to preventing depression in CKD patients.

• Mild chronic kidney disease often has no symptoms
• CKD can eventually progress to chronic kidney failure
• Common symptoms of chronic kidney failure include fatigue, loss of appetite, nausea, vomiting, weight loss, and persistent itching. Many also suffer from depression
• Advanced stages of chronic kidney failure are treated with dialysis or kidney transplantation.

The greater the vitamin D deficiency, the stronger the link to severe depression

Most cells in the body have vitamin D receptors, which regulate numerous genes and metabolic processes. Since vitamin D plays a role in the nervous system and inflammation regulation, researchers sought to investigate its connection to CKD and depression. It was already known that vitamin D deficiency is widespread among kidney patients, but the relationship between deficiency and depression risk remained unclear.
To study this, researchers collected data from TriNetX, a global platform aggregating data from 133 healthcare institutions. The study included nearly 18,000 patients aged 50 and older, all diagnosed with CKD. These patients were divided into two groups: one with vitamin D deficiency and one with sufficient vitamin D levels. Measurements were taken at least three months after diagnosis, and the patients were then monitored for three years to track the development of severe depression.
The researchers found vitamin D deficiency in 42% of patients in stage 3 CKD, 62% in stage 4, and 86% in stage 5, showing a direct correlation between declining kidney function and vitamin D depletion. There was also a clear link between increasing vitamin D deficiency and a higher risk of severe depression, particularly in men.
The study's findings emphasize the crucial role of vitamin D in mood regulation for CKD patients. This may be due to the fact that most brain cells have vitamin D receptors and that vitamin D helps counteract chronic brain inflammation, a common cause of depression. A better understanding of vitamin D’s role in preventing depression could have significant implications for new treatment strategies for CKD. Additionally, kidney patients may require higher doses of vitamin D, as their kidneys struggle to activate it effectively.
The sun is the primary source of vitamin D, which the body synthesizes from a cholesterol precursor in the skin. However, during winter at northern latitudes, the sun’s angle is too low for this process to occur. As a result, health authorities recommend vitamin D supplements for everyone during the winter months and year-round for at-risk groups. However, there is no guarantee that these supplements will sufficiently raise blood levels, which should ideally be above 75 nmol/L.
Vitamin D is also found in fatty fish, cod liver, cod roe, eggs, and full-fat dairy products, but the typical diet provides only modest amounts.

References:

I-Wen Chen et al. Association between vitamin D deficiency and major depression in patients with chronic kidney disease: a cohort study. Frontiers in Nutrition 2025

Tuomas Mikola, et al. The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta‐analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition, 2022.