There is some controversy on whether the ketogenic diet raises the possibility of kidney stones. Since it is problem that can potentially cause a LOT of pain and there are some people who have done the ketogenic diet for extended periods of time, I thought I would gather some of the info about it and what can be done in order to stay on the safe side. The problem could potentially arise in some people who are predisposed to develop kidney stones due to structural differences (congenital issues).
According to Lyle McDonald in "The Ketogenic Diet: A Complete Guide for the Dieter and Practitioner":
"In epileptic children, there is a low incidence (5%) of small kidney stones. This may be related to the dehydrated state the children are deliberately kept in rather than the state of ketosis itself. [...]
Individuals who are predisposed to kidney stones (or have preexisting kidney problems) should consider seriously whether a ketogenic diet is appropriate for them.
Some data that suggests that 1 in 20 children will develop kidney stones on the ketogenic diet:
J Child Neurol. 2007 Apr;22(4):375-8.
Kidney stones and the ketogenic diet: risk factors and prevention.
Sampath A, Kossoff EH, Furth SL, Pyzik PL, Vining EP.
_http://www.ncbi.nlm.nih.gov/pubmed/17621514
A cohort study was performed of children started on the ketogenic diet for intractable epilepsy from 2000 to 2005 (n = 195). Children who developed kidney stones were compared with those without in terms of demographics, urine laboratory markers, and intervention with urine alkalinization (potassium citrate). Thirteen children (6.7%) developed kidney stones. The use of oral potassium citrate significantly decreased the prevalence of stones. (3.2% vs 10.0%, P = .049) and increased the mean time on the ketogenic diet before a stone was first noted (260 vs 149 patient-months, P = .29). The prevalence of kidney stones did not correlate with younger age or use of carbonic anhydrate inhibitors (eg, topiramate or zonisamide) but trended toward higher correlation with the presence of hypercalciuria (92% vs 71%, P = .08). No child stopped the diet due to stones; in fact, the total diet duration was longer (median 26 vs 12 months, P < .001). Kidney stones continue to occur in approximately 1 in 20 children on the ketogenic diet, and no statistically significant risk factors were identified in this cohort. As oral potassium citrate was preventative, prospective studies using this medication empirically are warranted.
Drinking enough water and alkalinizing the urine with citrate seems to make the difference:
Epilepsia. 2002 Oct;43(10):1168-71.
_http://www.ncbi.nlm.nih.gov/pubmed/12366731
Kidney stones, carbonic anhydrase inhibitors, and the ketogenic diet.
Kossoff EH, Pyzik PL, Furth SL, Hladky HD, Freeman JM, Vining EP.
Because carbonic anhydrase inhibitors and the ketogenic diet are each known risk factors for kidney stones, simultaneous use of these therapies has been discouraged. The objective of this study was to establish the prevalence of nephrolithiasis in children in this combination-therapy population.
[...]CONCLUSIONS:
The combined use of carbonic anhydrase inhibitors and the ketogenic diet does not increase the risk of kidney stones. We recommend that all patients treated with combination therapy should be treated with increased hydration. Urine alkalinization should be considered for children with previous renal abnormalities, family histories of kidney stones, hematuria, or elevated urine calcium-to-creatinine ratios. If renal stones are found, we advocate discontinuation of the carbonic anhydrase inhibitor.
A summary of a study:
Oral Potassium Citrate May Help Prevent Kidney Stones in Children on the Ketogenic Diet
_http://www.medscape.com/viewarticle/706503
July 27, 2009 — Oral potassium citrate supplementation may help prevent kidney stones in children who receive the ketogenic diet, according to the results of a study reported online July 13 in Pediatrics.
"Kidney stones occur in 6% of children who receive the KD," write Melanie A. McNally, BS, from the School of Medicine, Johns Hopkins University in Baltimore, Maryland, and colleagues. "Potassium citrate (Polycitra K [Cypress Pharmaceuticals]) is a daily oral supplement that alkalinizes the urine and solubilizes urine calcium, theoretically reducing the risk for kidney stones."
The full study quoted is available here. _http://pediatrics.aappublications.org/content/124/2/e300
The reasons why there might be an increased incidence in kidney stones are described in this case study:
Renal Stone Associated with the Ketogenic Diet in a 5-Year Old Girl with Intractable Epilepsy
_http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852806/
There have been several reports about renal calculi developing in children on the ketogenic diet since the first report more than 30 years ago.9-11 The prevalence of renal caculi in people on the ketogenic diet is 3-10%, compared with 1 in several thousand in the general population.12 Chronic acidosis, dehydration, low urine pH, and fat malabsorption all contribute to the formation of uric acid and calcium oxalate stones.9,10 In this paper, we describe the case of a 5-year-old girl who developed a renal stone after beginning a ketogenic diet to control refractory complex partial seizures.
One last study:
_http://www.ncbi.nlm.nih.gov/pubmed/10893623
J Urol. 2000 Aug;164(2):464-6.
Nephrolithiasis associated with the ketogenic diet.
The ketogenic diet has been used for treating seizure disorders for more than 70 years. Nephrolithiasis is a known complication of this diet with a reported stone rate as high as 10% but there is sparse literature detailing the nature and treatment of these stones. We report on 4 children with nephrolithiasis on this diet.
[...] CONCLUSIONS:
The ketogenic diet induces several metabolic abnormalities that increase the propensity for stone formation. Urologists should be aware of this potential complication. Fluid liberalization and bicitrate are recommended as prophylaxis.
In short, there is a chance that some individuals might develop kidney stones on the ketogenic diet, especially if there is a predisposition. There are a lot of discussions on paleo blogs and forums. It seems that the tips of
drinking enough water, taking citrate supplements in the form of magnesium citrate or potassium citrate and making sure you are absorbing your fats will likely take care of any potential problem.
Some folk do have a predisposition to form kidney stones. It doesn't mean they can't benefit from the ketogenic diet. But in case of doubt, do keep well hydrated and take citrate supplements. :)
