Diet and Kidney Stones: The Ideal Questionnaire.

Diet frequently contributes to patients' urinary stone disease. It is important to determine when this is the case and when it is not, as failure to do so may delay the implementation of other, more appropriate therapies. When diet is thought to be involved, one of two approaches may be taken: (1) provide a general list of all possible dietary factors that influence the risk for all types of stones and let the patient decide which dietary change(s) are needed; or (2) prescribe specific modifications that address each patient's need for change and their personal characteristics (i.e., urinary risk factors, type(s) of stones they have formed, dietary preferences, nutrient needs, etc.). The latter of these approaches is "minimally invasive" and is thus consistent with the goal of other therapies. However, this approach requires a rigorous appraisement of each patient's diet and linkage, when possible, to urinary and other stone risk factors. When the collaboration of a registered dietitian nutritionist or other nutrition professional experienced in dietary assessment is not available, screeners or questionnaires may be useful. Unfortunately, there is no such tool that is validated for identifying dietary stone risk factors. The development of a brief, 40-item, stone-specific food screener is described. While further validation is needed, it may provide the basis for a standardized instrument that could be used more broadly; desired features of such an instrument are described. Patient Summary: Personalized nutrition therapy is useful in mitigating the effects or recurrence risk of many chronic diseases. It is also useful in stone disease, a condition with highly variable risk expression, even among patients who form the same types of stones. A standardized and validated stone-specific dietary assessment tool would be valuable in clinical management and in research studies involving the description of patients' diets and dietary intervention.

The Efficacy of Polyunsaturated Fatty Acids as Protectors against Calcium Oxalate Renal Stone Formation: A Review.

In the pathogenesis of hypercalciuria and hyperoxaluria, n-6 polyunsaturated fatty acids (PUFAs) have been implicated by virtue of their metabolic links with arachidonic acid (AA) and prostaglandin PGE2. Studies have also shown that n-3 PUFAs, particularly those in fish oil-eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)-can serve as competitive substrates for AA in the n-6 series and can be incorporated into cell membrane phospholipids in the latter's place, thereby reducing urinary excretions of calcium and oxalate. The present review interrogates several different types of study which address the question of the potential roles played by dietary PUFAs in modulating stone formation. Included among these are human trials that have investigated the effects of dietary PUFA interventions. We identified 16 such trials. Besides fish oil (EPA+DHA), other supplements such as evening primrose oil containing n-6 FAs linoleic acid (LA) and γ-linolenic acid (GLA) were tested. Urinary excretion of calcium or oxalate or both decreased in most trials. However, these decreases were most prominent in the fish oil trials. We recommend the administration of fish oil containing EPA and DHA in the management of calcium oxalate urolithiasis.

[Role of drinking and dietary factors in effective dissolution therapy and recurrence prevention of uric acid kidney stones].

The use of alkaline mineral waters leads to alkalization of urine and an increase in level of urinary citrate, which represent important factor inhibiting the formation of urinary stones. Combination of alkaline mineral waters with citrates facilitates the achievement of target urine pH level not only during dissolution therapy, but also during recurrence prevention. Alkalization of urine and reducing of the influence of alimentary factor dont preclude drug therapy. Patients should be counselled about complex strategies aimed to modifiable risk factors for urinary stone disease.

Hydroxycitrate: a potential new therapy for calcium urolithiasis.

Alkali supplements are used to treat calcium kidney stones owing to their ability to increase urine citrate excretion which lowers stone risk by inhibiting crystallization and complexing calcium. However, alkali increases urine pH, which may reduce effectiveness for patients with calcium phosphate stones and alkaline urine. Hydroxycitrate is a structural analog of citrate, widely available as an over-the-counter supplement for weight reduction. In vitro studies show hydroxycitrate has the capacity to complex calcium equivalent to that of citrate and that it is an effective inhibitor of calcium oxalate monohydrate crystallization. In fact, hydroxycitrate was shown to dissolve calcium oxalate crystals in supersaturated solution in vitro. Hydroxycitrate is not known to be metabolized by humans, so it would not be expected to alter urine pH, as opposed to citrate therapy. Preliminary studies have shown orally ingested hydroxycitrate is excreted in urine, making it an excellent candidate as a stone therapeutic. In this article, we detail the crystal inhibition activity of hydroxycitrate, review the current knowledge of hydroxycitrate use in humans, and identify gaps in knowledge that require appropriate research studies before hydroxycitrate can be recommended as a therapy for kidney stones.

Pears and renal stones: possible weapon for prevention? A comprehensive narrative review.

Urinary stones have been recognized as a human disease since dawn of history and treatment of this condition is reported by Egyptian medical writings. Also, pears have a very long history, being one of the earliest cultivated fruit trees and also known for medicinal use. Urinary tract stone formation represents a common condition and also a significant burden for health care service, due also to possible frequent relapses. Furthermore, urinary stones have been reported to have relationship with different metabolic derangements, and appropriate diet could contribute to avoid or reduce urinary stone formation. Citrate is an inhibitor of crystal growth in the urinary system, and hypocitraturia represents a main therapeutical target in stone formers. Pears contain a significant amount of malic acid, a precursor of citrate, and have antioxidant activity as well. A diet supplemented with pears, and associated with low consumption of meat and salt could impact positively cardiometabolic risk and urinary tract stone formation. However, very few studies evaluated the impact of pears utilization on health, and none on urinary tract stone formation in particular. High content in malate could warrant protection against stone formation, avoiding patients at high risk to be compelled to assume a considerable and expensive amount of pills.

Dietary treatment of urinary risk factors for renal stone formation. A review of CLU Working Group.

OBJECTIVE: Diet interventions may reduce the risk of urinary stone formation and its recurrence, but there is no conclusive consensus in the literature regarding the effectiveness of dietary interventions and recommendations about specific diets for patients with urinary calculi. The aim of this study was to review the studies reporting the effects of different dietary interventions for the modification of urinary risk factors in patients with urinary stone disease. MATERIALS AND METHODS: A systematic search of the Pubmed database literature up to July 1, 2014 for studies on dietary treatment of urinary risk factors for urinary stone formation was conducted according to a methodology developed a priori. Studies were screened by titles and abstracts for eligibility. Data were extracted using a standardized form and the quality of evidence was assessed. RESULTS: Evidence from the selected studies were used to form evidence-based guideline statements. In the absence of sufficient evidence, additional statements were developed as expert opinions. CONCLUSIONS: General measures: Each patient with nephrolithiasis should undertake appropriate evaluation according to the knowledge of the calculus composition. Regardless of the underlying cause of the stone disease, a mainstay of conservative management is the forced increase in fluid intake to achieve a daily urine output of 2 liters. HYPERCALCIURIA: Dietary calcium restriction is not recommended for stone formers with nephrolithiasis. Diets with a calcium content ≥ 1 g/day (and low protein-low sodium) could be protective against the risk of stone formation in hypercalciuric stone forming adults. Moderate dietary salt restriction is useful in limiting urinary calcium excretion and thus may be helpful for primary and secondary prevention of nephrolithiasis. A low-normal protein intake decrease calciuria and could be useful in stone prevention and preservation of bone mass. Omega-3 fatty acids and bran of different origin decreases calciuria, but their impact on the urinary stone risk profile is uncertain. Sports beverage do not affect the urinary stone risk profile. HYPEROXALURIA: A diet low in oxalate and/or a calcium intake normal to high (800-1200 mg/day for adults) reduce the urinary excretion of oxalate, conversely a diet rich in oxalates and/or a diet low in calcium increase urinary oxalate. A restriction in protein intake may reduce the urinary excretion of oxalate although a vegetarian diet may lead to an increase in urinary oxalate. Adding bran to a diet low in oxalate cancels its effect of reducing urinary oxalate. Conversely, the addition of supplements of fruit and vegetables to a mixed diet does not involve an increased excretion of oxalate in the urine. The intake of pyridoxine reduces the excretion of oxalate. HYPERURICOSURIA: In patients with renal calcium stones the decrease of the urinary excretion of uric acid after restriction of dietary protein and purine is suggested although not clearly demonstrated. HYPOCITRATURIA: The administration of alkaline-citrates salts is recommended for the medical treatment of renal stone-formers with hypocitraturia, although compliance to this treatment is limited by gastrointestinal side effects and costs. Increased intake of fruit and vegetables (excluding those with high oxalate content) increases citrate excretion and involves a significant protection against the risk of stone formation. Citrus (lemons, oranges, grapefruit, and lime) and non citrus fruits (melon) are natural sources of dietary citrate, and several studies have shown the potential of these fruits and/or their juices in raising urine citrate levels. CHILDREN: There are enought basis to advice an adequate fluid intake also in children. Moderate dietary salt restriction and implementation of potassium intake are useful in limiting urinary calcium excretion whereas dietary calcium restriction is not recommended for children with nephrolithiasis. It seems reasonable to advice a balanced consumption of fruit and vegetables and a low consumption of chocolate and cola according to general nutritional guidelines, although no studies have assessed in pediatric stone formers the effect of fruit and vegetables supplementation on urinary citrate and the effects of chocolate and cola restriction on urinary oxalate in pediatric stone formers. Despite the low level of scientific evidence, a low-protein (< 20 g/day) low-salt (< 2 g/day) diet with high hydration (> 3 liters/day) is strongly advised in children with cystinuria. ELDERLY: In older patients dietary counseling for renal stone prevention has to consider some particular aspects of aging. A restriction of sodium intake in association with a higher intake of potassium, magnesium and citrate is advisable in order to reduce urinary risk factors for stone formation but also to prevent the loss of bone mass and the incidence of hypertension, although more hemodynamic sensitivity to sodium intake and decreased renal function of the elderly have to be considered. A diet rich in calcium (1200 mg/day) is useful to maintain skeletal wellness and to prevent kidney stones although an higher supplementation could involve an increase of risk for both the formation of kidney stones and cardiovascular diseases. A lower content of animal protein in association to an higher intake of plant products decrease the acid load and the excretion of uric acid has no particular contraindications in the elderly patients, although overall nutritional status has to be preserved.

Can obese stone formers follow dietary recommendations?

INTRODUCTION: Obese patients have an increased risk of kidney stones, and several studies have identified specific urinary derangements on 24-hour collections. The objective of this study was to assess obese and super-obese stone formers, and their compliance with dietary modifications over time, based on 24-hour urine outcomes. PATIENTS AND METHODS: A retrospective review was performed searching for all stone formers who completed a 24-hour urine collection before and after dietary counseling for stone prevention. Patients were excluded if placed on medical therapy in addition to dietary therapy. Patients were divided in three main groups according to their body mass index (BMI): 30, 30-40, and >40 kg/m(2). Demographic data and 24-hour urine stone risk parameters (volume, sodium, uric acid, citrate, and oxalate) were assessed. Initial 24-hour urine results were compared to follow-up results after dietary counseling. Then, the outcomes from each group were compared to each other. RESULTS: Two hundred and fourteen stone formers (67% male) were identified with a mean age of 49.5±15.0 years. One hundred twenty-eight (59.8%) patients had BMI <30 kg/m(2), 61 (28.5%) between 30-40 kg/m(2), and 25 (11.7%) >40 kg/m(2). Among patients with BMI <30 kg/m(2), there were significant improvements in all urinary parameters (p<0.001) as well as in the group with BMI between 30 to 40 kg/m(2) (p=0.02 for oxalate, p<0.001 for other parameters). Among super-obese patients, there were significant improvements in the urinary volume (p=0.03), sodium (p<0.001), uric acid (p=0.001), and oxalate (p<0.001). There were no significant differences in the improvements observed in the urinary volume (p=0.69), sodium (p=0.08), uric acid (p=0.17), and citrate levels (p=0.97) between the groups. CONCLUSION: Dietary recommendations can be an equally effective strategy in decreasing the risk or stone recurrence in obese and super-obese kidney stone formers as it is in those who are not obese.

Noncitrus alkaline fruit: a dietary alternative for the treatment of hypocitraturic stone formers.

BACKGROUND AND PURPOSE: Fruits and vegetables are natural suppliers of potassium, bicarbonate, or bicarbonate precursors such as citrate, malate and others-hence, possessing potential effects on citraturia. We aimed to compare the acute effects of a noncitrus (melon) fruit vs citric ones (orange and lime) on citraturia and other lithogenic parameters. PATIENTS AND METHODS: Two-hour urine samples were collected from 30 hypocitraturic stone-forming patients after an overnight fast and 2, 4, and 6 hours after the consumption of 385 mL (13 oz) of either freshly squeezed orange juice (n=10), freshly blended melon juice (n=10), or freshly squeezed lime juice (n=10). Urinary citrate, potassium, pH, and other lithogenic parameters were determined and net gastrointestinal alkali absorption (NGIA) was calculated. Potential renal acid load (PRAL) and pH from juices were determined. RESULTS: Significant and comparable increases of mean urinary citrate were observed in all groups, whereas mean urinary potassium, pH, and NGIA were significantly increased only after consumption of melon and orange juices. The pH of melon juice was higher and the PRAL value was more negative compared with orange juice, indicating a higher alkalinity. CONCLUSIONS: These findings suggested that melon, a noncitrus source of potassium, citrate, and malate, yielded an increase in urinary citrate excretion equivalent to that provided by orange, and hence represents another dietary alternative for the treatment of hypocitraturic stone-formers. Despite its low potassium content, lime also produced comparable increases in citraturia possibly because of its high citric acid content.

Effect of vitamin A supplemented diet on calcium oxalate renal stone formation in rats.

OBJECTIVES: To study the effect of a vitamin A supplemented diet on calcium-oxalate stone formation in rats and to test its expected action in the dissolution of renal calculi. MATERIAL AND METHODS: Twenty-four male Wistar rats were randomly divided into three groups of eight rats each. The first group (group A) received a normal diet for six weeks. The second group (group B) was fed a lithogenic diet by the addition of ethylene glycol 0.5% to drinking water for three weeks then a normal diet for three weeks. The third group (group C) received the same lithogenic diet for three weeks then a vitamin A supplemented diet 20 times the normal amount (5.1mg/100g of diet) at the three last weeks. One day before the end of treatment, each animal was placed for 24h in metabolic cage in order to collect urine samples and determine the urinary parameters. RESULTS: The glomerular filtration rate and the urinary excretion of citric acid which fell in group B have been restored in group C. CONCLUSIONS: This study shows that a vitamin A supplemented diet at the rate of 20 times standard ration could improve the renal function by restoring the glomerular filtration rate and by increasing the urinary pH and excretion of citric acid.

Tea and coffee as the main sources of oxalate in diets of patients with kidney oxalate stones.

We analyzed nutritional habits of 22 stone formers with special regard to oxalate content as one of the main nutritional lithogenic factors associated with kidney stones. Daily dietary oxalate intake was 354 +/- 261 mg and 406 +/- 265 mg in men and women respectively. These values were much higher than those found by other researches. The main sources of oxalate in diets were regular tea and coffee (80-85%). Only 15-20% of oxalate was derived from other plant foods. Patients did not adhere to high fluid diet and, what is more, as common beverage they chose rich-oxalate black tea. Patients' daily intake of calcium was low and didn't exceed 520 mg. Vitamin C consumption was higher than Polish Dietary Reference Intake (DRI) and vitamin B6 lower than DRI. In the management of stone patients, to lower the risk of recurrence, appropriate diet (according to the type of stone) should be provided by dietitian.

Food oxalate: factors affecting measurement, biological variation, and bioavailability.

Food and nutrition professionals provide medical nutrition therapy for patients with kidney stones. If the stones contain oxalate or the patient has been diagnosed with hyperoxaluria, reduction of dietary oxalate may be appropriate. Differences in oxalate values for a single food may be due to analytical methods, and/or biological variation from several sources, including cultivar, time of harvest, and growing conditions. Bioavailability of food oxalate and, thus, urine oxalate, will also be affected by salt forms of oxalate, food processing and cooking methods, meal composition, and the presence of Oxalabacter formigenes in the patient's gut. Dietary advice for reducing urinary oxalate should include both reduction of dietary oxalate and simultaneous consumption of calcium-rich food or supplement to reduce oxalate absorption.

Comparison between lemonade and potassium citrate and impact on urine pH and 24-hour urine parameters in patients with kidney stone formation.

OBJECTIVES: The past few decades have been notable for advances in minimally invasive techniques to treat kidney stones. Despite successful surgical management of calculi, the impact of diet on stone disease prevention remains an important factor. Dietary modifications can be applied to prevent stone recurrence in an economical manner that is acceptable to patients. Lemonade has been studied in the past and found to increase urinary citrate levels in small groups of patients. The present study examined the effect of lemonade intake on a change in urinary pH and improvement of urinary stone risk factors compared with potassium citrate treatment. METHODS: A total of 21 stone-forming patients were treated with lemonade therapy and potassium citrate supplementation in a prospective cross-over trial. we performed 24-hour urine collections at baseline and with each treatment arm. the results between the two groups were examined to determine whether differences existed in the urinary stone risk factors. RESULTS: Potassium citrate, but not lemonade, improved citrate levels and urinary ph to a significant degree. patients taking potassium citrate had a significantly decreased urine volume compared with their urine volume drinking lemonade. neither lemonade nor potassium citrate affected the uric acid levels to a significant degree. CONCLUSIONS: The results of our study have shown that lemonade did not provide improvements in urinary citrate or pH levels but did assist patients in maintaining urine output compared with potassium citrate therapy.

Dietary and holistic treatment of recurrent calcium oxalate kidney stones: review of literature to guide patient education.

Urolithiasis is a condition that can cause significant morbidity among patients. Dietary manipulations traditionally advised include fluid, protein, oxalate, calcium, citrate, and sodium changes in the diet. Evidence-based practice guidelines suggest that there is not ample evidence to confidently recommend dietary changes, since inadequate studies have been done to quantify the risks of diet in stone formation. While fluid intake patterns have the weightiest evidence in the literature, not even fluid intake meets the guidelines for evidence-based practice. Health care providers should recognize that current patient education is largely based on intuition. It behooves us as clinicians to look critically at all our practices, review the available literature, and question what we believe we know. A summary of available literature is provided to guide the clinician in educating patients in reducing their risk of recurrent calcium oxalate stone disease.

The probiotic approach: an alternative treatment option in urology.

OBJECTIVE: The prophylactic and therapeutic use of probiotic microorganisms is a wide and still controversial field. The review paper is aimed to summarize recent findings on the health-benefiting effects of probiotics in urological diseases. The use of certain beneficial strains against urogenital infections, bladder cancer recurrence and renal stone formation is discussed. METHODS: Literature search of PubMed documented publications and abstracts from meetings. RESULTS: Various clinical trials have now been performed which substantiate the beneficial effects of the probiotic strains L. rhamnosus GR-1, L. fermentum RC-14 and L. crispatus CTV-05 against urogenital infections, such as urinary tract infections and bacterial vaginosis. The potential of L. casei Shirota to reduce the recurrence rate of bladder cancer is one of the most intriguing examples for the use of probiotics in medical practice. The use of O. formigenes in the prevention of calcium oxalate stone disease was only recently suggested and needs to be further investigated. CONCLUSION: Clinical trials increasingly provide a profound scientific basis for the use of probiotics in medicinal practice including urology. Efforts to make probiotic products available which are validated according to the guidelines recommended by the WHO and FAO and produced according to Good Manufacturing Practice will contribute to the acceptance of probiotic therapy by both the physicians and the patients.

Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up.

Diet plays an important role in the pathogenesis of kidney stones. Because the metabolism of many dietary factors, such as calcium, may change with age, the relation between diet and kidney stones may be different in older adults. Uncertainty also remains about the association between many dietary factors, such as vitamin C, magnesium, and animal protein, and the risk of kidney stone formation. To examine the association between dietary factors and the risk of incident, symptomatic kidney stones in men and to determine whether these associations vary with age, a prospective cohort study was conducted of 45,619 men without a history of nephrolithiasis. Self-administered food frequency questionnaires were used to assess diet every 4 yr. A total of 1473 incident symptomatic kidney stones were documented during 477,700 person-years of follow-up. For men aged <60 yr, the multivariate relative risk (RR) for stone formation in the highest quintile of dietary calcium as compared with the lowest quintile was 0.69 (95% confidence interval [CI], 0.56 to 0.87; P = 0.01 for trend). By contrast, there was no association between dietary calcium and stone formation in men aged 60 yr or older. The multivariate RR for men who consumed 1000 mg or greater of vitamin C per day compared with those who consumed less than the recommended dietary allowance of 90 mg/d was 1.41 (95% CI, 1.11 to 1.80; P = 0.01 for trend). Other dietary factors showed the following multivariate RR among men in the highest quintile of intake compared with those in the lowest: magnesium, 0.71 (95% CI, 0.56 to 0.89; P = 0.01 for trend); potassium, 0.54 (95% CI, 0.42 to 0.68; P < 0.001 for trend); and fluid, 0.71 (95% CI, 0.59 to 0.85; P < 0.001 for trend). Animal protein was associated with risk only in men with a body mass index <25 kg/m(2) (RR, 1.38; 95% CI, 1.05 to 1.81; P = 0.03 for trend). Sodium, phosphorus, sucrose, phytate, vitamin B(6), vitamin D, and supplemental calcium were not independently associated with risk. In conclusion, the association between calcium intake and kidney stone formation varies with age. Magnesium intake decreases and total vitamin C intake seems to increase the risk of symptomatic nephrolithiasis. Because age and body size affect the relation between diet and kidney stones, dietary recommendations for stone prevention should be tailored to the individual patient.

Nephrolithiasis with unusual initial symptoms.

OBJECTIVE: To describe a less common initial symptom of nephrolithiasis, its diagnostic pitfalls, risk factors, and mimicry of other conditions. Intervention and long-term management of nephrolithiasis is also discussed. CLINICAL FEATURES: A Caucasian man aged 25 years had sudden bilateral inguinal and occasional periumbilical pain. The initial symptom suggested an abdominal pathologic condition; however, costovertebral angle pain followed 1 hour later with no radiation between the 2 anatomic sites. The initial urine dipstick result was negative for hematuria, but a kidney, ureter, and bladder radiograph revealed a smooth 2-mm x 3-mm stone lodged at the left: vesico-ureteral junction. INTERVENTION AND OUTCOME: The patient was referred to a regional university medical center to receive extracorporeal shockwave lithotripsy several days after his initial visit. He was given pain medicine for the waiting period and received daily lumbar spine adjustments with a mild reduction in pain. He eventually received ureteroscopic laser lithotripsy because the shock-wave unit had malfunctioned before his appointment. The fragment analysis showed a calcium oxalate composition, and the patient was advised to lower his intake of oxalates. The patient had become a vegetarian approximately 3 months before this first stone episode. CONCLUSION: Nephrolithiasis is a condition commonly seen in chiropractic practice. Although it is usually easy to recognize, the diagnosis can be elusive if the typical historic factors and diagnostic results are absent or altered. The short-term management of nephrolithiasis is pain management, stone elimination, and the collection of a specimen to identify the composition and underlying metabolic abnormality. Long-term management is to prevent the recurrence of stones. Conservative comanagement by the chiropractic physician can be implemented through nutritional means.

[Kidney calculi--is nutrition a trigger or treatment?]. / Nierensteine--ist die Ernährung Trigger oder Therapeutikum?

Kidney stones occur in up to 15% of the population. The incidence of stone disease is 0.1-0.4%, i.e. 100 to 400 out of 100,000 people form a kidney stone every year. The recurrence rate is high, reaching 52% within 10 years and 75% within 20 years, respectively. Since urinary supersaturation, the driving force for crystallisation and stone formation, directly depends on nutritional habits, dietary recommendations are an important part of stone treatment. The benefit of urine dilution by means of a high fluid intake (urine volume at least 2.5 L/d) has been established by several studies. On the other hand, incorrect dietary recommendations, such as the restriction of calcium as advocated for decades, can even promote stone formation! Indeed, large prospective trials have clearly demonstrated that the risk for stone formation decreases with increasing daily calcium intake. It is therefore mandatory that low-calcium diet is finally abandoned in patients with calcium kidney stones and replaced by a sufficient calcium consumption, i.e. 1200 mg per day. Furthermore, epidemiological studies confirm that a diet rich in meat protein carries an increased risk for forming upper urinary tract stones; thus, daily protein intake should not exceed 1 g/kg body weight, which corresponds with general recommendations for a healthy diet. Last but not least, more recent studies have shown that the consumption of high quantities of fruits and vegetables may protect against kidney stone formation, since it raises urinary excretion of citrate, an important inhibitor of crystallization. The present review emphasizes on the relations between nutrition and stone formation in the urinary tract and offers convenient and inexpensive measures for the prevention of recurrence of nephrolithiasis.