Meta-analysisindependent cross-checkabstract checked★ key study I-SRC-103 in-depth review
Very low protein diets can delay dialysis in advanced kidney disease
Low protein diets for non-diabetic adults with chronic kidney disease.
Overview
Hahn D et al.. Cochrane Database Syst Rev 2020 · PMID 33118160 · DOI 10.1002/14651858.CD001892.pub5
Under supervision, very low protein diets reduced the number reaching kidney failure over 1-4 years; ordinary low protein diets made little difference.
Does the study support the specific claim? Partly · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Test protein restriction in chronic kidney disease
- How was the study done?
Cochrane review of trials
- How many people, animals or samples were studied?
17 trials, 2996 adults
- What was actually found?
Very low protein diets delayed kidney failure; low protein diets did not clearly
- How large was the observed effect?
ESKD RR 0.65 (0.49-0.85)
- What do the results mean in everyday life?
Diet can slow kidney disease, but slowly and under medical care
- What are the study's limitations?
Open-label trials; adherence difficult
- What does it say about Elawady's specific claim?
Contradicts reversal within two months
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Whether kidney failure can be reversed (it was not studied and did not occur)
Scientific in-depth review
1. Full reference
- Authors
- Hahn D et al.
- Journal
- Cochrane Database Syst Rev
- Year
- 2020
- Identifier
- PMID 33118160 DOI 10.1002/14651858.CD001892.pub5
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works record checked
- Retracted
- no
- Corrections
Update of earlier version: Cochrane Database Syst Rev. 2018 Oct 04;10:CD001892. doi: 10.1002/14651858.CD001892.pub4.
- Extent checked
- abstract only
- Conflicts of interest and funding
One author received lecture fees on nutrition in renal disease.
2. Research question
Do low or very low protein diets slow progression to end-stage kidney disease in non-diabetic adults with CKD?
3. Study design and population
- Study design
- Meta-analysis – Cochrane systematic review and meta-analysis of RCTs (GRADE)
- Population
Adults with non-diabetic CKD stages 3-5, not on dialysis
- Country
International
- Period
Searches to 7 September 2020
- Sample size
17 studies, 2996 participants
- Inclusion and exclusion criteria
RCTs/quasi-RCTs of protein restriction for at least 12 months
4. Methods and endpoints
- Exposure / intervention
Very low protein (0.3-0.4 g/kg/day) or low protein (0.5-0.6 g/kg/day) diet
- Comparator
Low or normal protein intake (>=0.8 g/kg/day)
- Endpoints
Death, ESKD (need for dialysis), GFR, weight, malnutrition
- Statistical methods
Random-effects meta-analysis; RR/SMD; GRADE
5. Actual results
- Results
Low vs normal protein: ESKD RR 1.05 (0.73-1.53; low certainty); death RR 0.77 (0.51-1.18; moderate). Very low vs low protein: ESKD RR 0.65 (0.49-0.85; 165 per 1000 fewer; moderate certainty); death RR 1.26 (0.62-2.54). Follow-up 12-50 months.
- Absolute risks
Very low vs low protein: 165 fewer per 1000 reached ESKD (reported).
- Authors' conclusion
Very low protein diets probably reduce progression to ESKD in CKD stages 4-5; low protein diets may make little difference; adverse effects and quality of life are poorly studied.
6. Strengths
- Cochrane, GRADE
- Long follow-up trials
7. Weaknesses
- Open-label trials
- Adherence and malnutrition data limited
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Well-conducted review; trials at high risk of performance bias.
9. Assessment of the statistical interpretation
RR 0.65 with 165 fewer per 1000 implies a control risk of about 47% and an NNT of about 6 over 1-4 years (stats/C-SRC-47_lowprotein.py).
10. Relevance to the specific claim
Shows that diet can delay (not reverse) kidney failure in advanced CKD under supervision, over years. This is the honest 'supporting' side: diet matters for CKD. It contradicts the idea that kidney failure and dialysis can be ended in two months.
11. Independent contrary findings
KDIGO 2024 (I-SRC-134) suggests 0.8 g/kg/day and supervised very-low-protein diets only for selected patients.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Moderate-certainty evidence that strict supervised protein restriction delays ESKD; no evidence of reversal.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | moderate |
| Directness | indirect |
| Reproducibility | replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Safety (malnutrition) and quality of life.
15. Linked fact checks
- He could stop kidney failure and dialysis in all of Egypt within two months and prevent seasonal influenza within three weeks. – Studies with mixed or unclear results