Supplements Have a Role in Treating Kidney Disease

The global dietary supplement industry generates more than $400 billion a year. Supplements are alleged to treat many health concerns, from immune conditions and cognition to sexual dysfunction and premature wrinkles. Although some supplements have been proven to be helpful, others have no scientific basis.
I can preach all day that a healthy diet rarely needs supplementation. But even as a dietitian, I find it difficult to consistently eat a diet that is both sufficiently varied and adequate to provide for all my nutrition needs. Our patients with kidney disease, surely, are not immune to this plight. They may even be more inclined to nutrient deficiencies, as poor diet is linked to increased incidence and progression of chronic kidney disease (CKD).
I find that patients with kidney disease often have an interest in dietary supplementation, even those with a well-rounded diet. Though we can discourage the use of supplements, or at the very least encourage patient transparency regarding supplement use, many will continue dietary supplementation at the suggestion of their friends, family, or even their preferred daytime talk show host. 
What these patients truly require is education on using supplements that are most beneficial to them. By recommending supplements that address patients’ pain points like inflammation, dyslipidemia, cardiovascular health, and reduced progression to end-stage renal disease (ESRD), we can improve patient health and, hopefully, decrease use of questionable supplements.
Although probiotics have been used in the treatment of digestive issues for many years, the gut-kidney axis is only recently being explored. Studies show that the microbiota of patients with CKD is altered, even in the early stages of disease, producing additional inflammation and metabolic dysfunction. This can be remedied, or at least alleviated, by introducing a probiotic supplement.
Some probiotics have been shown to: 
Decrease inflammation
Decrease fasting blood glucose
Decrease low-density lipoprotein cholesterol, triglycerides, and total cholesterol
Increase estimated glomerular filtration rate (eGFR)
Decrease blood urea nitrogen and urea
Decrease uric acid
Probiotic-rich foods like kimchi or fermented pickles may not be appropriate because of excessive sodium content or simply due to patient preference — kombucha isn’t for everyone. However, adding a probiotic supplement can improve gut microbiota without undermining dietary concerns. 
When recommending probiotics, patients should be educated to ensure that their probiotic has strains that have been proven to be beneficial for kidney health. Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium species, and Streptococcus thermophilus have been shown to have a positive effect on kidney health and decreasing progression of CKD at a dosage of 109 colony-forming units per day.
Though nephrology and cardiology are separate fields, it cannot be overstated that kidney patients are also heart patients. 
Patients with CKD and an eGFR < 60 mL/min/1.73 m2 are most likely to die from cardiovascular causes, and this likelihood increases as eGFR decreases. CKD-associated dyslipidemia results in elevated triglycerides and reduced high-density lipoprotein cholesterol often accompanied by proteinuria, and has been linked to an increase in atherosclerosis.
A simple fish oil supplement can work to decrease oxidative stress, relieve inflammation, and improve serum lipids, leading to improved kidney and cardiovascular health. One meta-analysis found that high-dose fish oil supplementation, though it had no effect on serum creatinine or eGFR, was associated with a lower risk for proteinuria and progression to ESRD. 
Fish oil’s popularity in recent years bodes well for the kidney patient. It is now easily obtained over the counter in high doses to meet the recommended adequate intake of omega-3s, which is 1100 mg/d for women and 1600 mg/d for men. There are also more burpless varieties of these supplements to increase compliance. 
Patients with renal disease are prone to vitamin D deficiency through inadequate intake and limited sunlight, which is exacerbated by the diseased kidney’s inability to effectively convert calcidiol to calcitriol. Vitamin D deficiency is linked to poor bone health, fatigue, muscle pain, impaired wound healing, and depression. Low vitamin D status has also been linked to poor outcomes in cancer, multiple sclerosis, cardiovascular disease, type 2 diabetes, and weight loss.
A meta-analysis of over 6000 patients with CKD found that high levels of 25-hydroxy vitamin D (25(OH)D) are associated with significantly improved survival rates regardless of CKD or ESRD status. 
Kidney Disease: Improving Global Outcomes guidelines recommend supplementing with ergocalciferol or cholecalciferol to correct (OH)D deficiency. This ensures adequate supply for conversion to calcitriol, but it cannot affect bone and mineral metabolism without further intervention in the form of calcitriol supplementation. By supplementing with ergocalciferol or cholecalciferol to meet the recommended daily allowance of 15 µg (600 IU) for adults under 70 years and 20 µg (800 IU) for adults over 70 years, the primary care team can ensure that the body has all the building blocks required for the nephrology team to then address mineral and bone disorder in CKD without the fear of promoting hypercalcemia. 
Patients should be reminded to purchase dietary supplements from reputable dealers, especially when purchasing online. Retailers like Amazon are increasing the barriers required to sell supplements to improve the quality of products sold on the site. But other online retailers may sell products from outside of the United States that fall outside of the US Food and Drug Administration’s jurisdiction. 
Patients should also be reminded that “more is not always better” and counseled on appropriate dosages for individual needs. 
Patients will probably continue to lean on dietary supplements, regardless of our approval. Transparency and education are important when working with patients with CKD, especially in regard to dietary supplements. 
When recommended appropriately, however, the supplements discussed can lead to better outcomes with improvements in kidney health by addressing inflammation, serum lipids, glycemic control, and cardiovascular health.