I was recently asked whether collagen supplements are safe for people with chronic kidney disease (CKD). While I’ve seen collagen-based protein supplements at conferences, I hadn’t looked closely at them until now—so this was the perfect opportunity to dig in.
What Is Collagen?
Collagen is one of the most abundant proteins in the body. It provides structural support and strength to tissues, acting like scaffolding.
Dietary Sources of Collagen
Collagen is available as a supplement, but it also occurs naturally in:
- Meats containing connective tissue
- Gelatin
As the Knox Gelatin website explains, when you simmer bones to make broth, collagen is released. Once cooled, the broth gels because of collagen. According to Knox nutrition info, gelatin is 100% protein: a 1.8 g serving contains =2 g protein (I am assuming this difference is a result of nutrition label rounding rules).
Why Might Collagen Be a Concern in CKD?
After collagen ingestion, hydroxyproline levels in the blood increase sharply. Hydroxyproline is a precursor for oxalate metabolism. High oxalates have been linked to CKD progression and complications (read more here).
Hydroxyproline and Oxalates: What’s Known?
A cross-over study of 10 healthy adults tested the effect of hydroxyproline intake on oxalates. Participants consumed either:
- 30 g of Knox Gelatin Powder (high in hydroxyproline), or
- 30 g whey protein
Both groups followed the same oxalate-controlled diet. Results showed:
- Higher circulating hydroxyproline with gelatin
- Urinary oxalate excretion increased by 43% compared to whey protein
Have Collagen Protein Supplements Been Studied in CKD?
I was able to find two studies that included a collagen-based protein supplement, Liquacel, as part of their protocols. However, the problem with both of these studies is that participants were given a variety of nutrition supplements to chose from and neither study reported how often participants chose LiquaCel or a different product.
- Hemodialysis study – Participants were offered LiquaCel or NovaSource Renal (study link). Survival benefits were reported, but the authors did not specify which product participants chose. Albumin levels did not improve.
- Oral nutrition supplement study – LiquaCel was again offered as one of several options (study link). Use of oral nutrition supplements was linked to fewer hospital readmissions, but product-specific results were not reported.
Is Collagen Safe for People With CKD?
It depends on disease stage and goals of care:
- End-stage kidney disease (dialysis): At this stage, kidneys have no function left. Concerns about CKD progression no longer apply. Protein supplementation (including collagen) may be more appropriate if it helps reduce malnutrition risk.
- Earlier-stage CKD (pre-dialysis): Here, the goal is to preserve kidney function. Since collagen is known to increase hydroxyproline and oxalate levels, it could potentially contribute to CKD progression and may not be advisable (read more on oxalates and CKD).
Key Takeaways
- Collagen is widely available in supplements and gelatin, but its metabolism raises hydroxyproline and oxalates.
- Evidence suggests collagen intake increases both serum oxalates and urinary oxalate excretion.
- No studies have directly examined collagen intake and CKD progression.
- In people with earlier CKD, avoiding collagen may help reduce oxalate load.
- In dialysis patients with malnutrition, collagen may still have a role if whey or other protein sources are not tolerated.
Frequently Asked Questions About Collagen and CKD
1. Do collagen supplements increase oxalates?
Yes. Collagen is rich in hydroxyproline, which the body converts into oxalates. Studies show collagen intake can significantly increase urinary oxalate excretion compared to whey protein.
3. Is collagen safer than whey protein for CKD?
Not necessarily. Whey protein does not increase oxalates the way collagen does. For people with CKD and inadequate protein intake, who are trying to delay disease progression, whey or other protein sources may be safer options.
4. Can dialysis patients safely use collagen protein?
Possibly. In dialysis, kidney function is already lost, so concerns about disease progression are less relevant. Collagen based supplements have been studied as part of a nutrition supplement formulary among people receiving hemodialysis. These studies have reported that nutrition supplements may be useful in preventing malnutrition.
5. Should people with early-stage CKD avoid collagen?
Yes, at least for now. While no direct studies have examined collagen and CKD progression, the evidence suggests that collagen raises oxalates, which could worsen kidney health (low-oxalate diet in CKD).
