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Dietary Causes of Kidney Stones and Kidney Failure Information
Introduction
There are many conditions in Western industrialised societies today that were unheard of, or at least very rare, just a century ago. The same conditions are still unheard of in primitive peoples who do not have the 'benefits' of our knowledge. There is a very good reason for this: They eat what Nature intended; we don't. The diseases caused by our incorrect and unnatural diets are those featured on these pages.
Dietary causes:
Kidney stones:
Oxalate-rich foods such as spinach, rhubarb, beets, strawberries, wheat bran, nuts and nut butters.Kidney failure:
High-carb, low-fat 'healthy' diet. Cereals.Kidney stones
It is a common belief that both uric acid and calcium oxalate stones are more likely to form in the kidneys on a high-protein, low-carb diet than on a higher-carbohydrate diet with more fruit and vegetables. That belief is not borne out by the evidence.
Nearly thirty years ago, kidney stones were shown to be associated with high intake of refined carbohydrates.[1] So one has to wonder why the National Institute of Diabetes and Digestive and Kidney Diseases at the United States National Institutes of Health, is surprised that: 'the number of people in the United States with kidney stones has been increasing over the past 20 years.'[2] What is really worrying is that they begin that quote with 'For unknown reasons'. They also note that kidney stones occur more frequently in men; Europeans are more prone to develop kidney stones than Africans; kidney stones strike most typically between the ages of 20 and 40; and once a person gets more than one stone, others are likely to develop.
And what change has been made to peoples' eating habits in the past twenty years? 'Healthy eating' was introduced. And who are most likely to follow this message? The 20-40s.
They continue, 'People who form calcium stones used to be told to avoid dairy products and other foods with high calcium content. But recent studies have shown that foods high in calcium, including dairy foods, help prevent calcium stones. Taking calcium in pill form, however, may increase the risk of developing stones. . . . You may be told to avoid food with added vitamin D and certain types of antacids that have a calcium base. If you have very acidic urine, you may need to eat less meat, fish, and poultry. These foods increase the amount of acid in the urine'.
So, if you have kidney stones, and if you form calcium stones and if you have very acidic urine you may need to eat less meat. But drinking lots of water will reduce the acidity, this diet is known to reduce the need for antacids, and we don't need calcium supplements as we are eating enough.
So where does the problem lie?
You may be interested to know that the National Kidney Foundation, discussing oxalate stones, says 'The foods with a high content of oxalate are spinach, rhubarb, beets, strawberries, wheat bran, nuts and nut butter'.[3] They don't mention meat at all.
The evidence all suggests that the way to avoid kidney and gall bladder diseases is to eat a diet composed mainly of animal protein and fat.
Kidney failure
Technically termed Renal Nephropathy, kidney disease is an inevitable result of the chronically uncontrolled blood glucose and chronic high insulin levels found with Type-2 diabetes. Yet it is one of the most frequently-repeated criticisms of low-carbohydrate, higher protein diets is that they will allegedly lead to kidney failure, despite many studies which have shown such a claim to be completely false.[4] [5] [6] [7]
The long-running Nurses' Health Study, for example, showed that a high protein intake was not associated with renal function decline in women whose kidneys were healthy at the start of the study. However, high total protein intake, particularly high intake of non-dairy animal protein, did show a borderline significant relationship with declining kidney function in women whose kidneys were not healthy at the beginning of the study.[8]
Protein metabolism results in the production of urea, a waste product which must be filtered through the kidneys. While such increases pose no threat to healthy kidneys, damaged kidneys may not be able to safely process increased amounts of urea. Critics of low carbohydrate diets, however, seek to convince those ignorant of the above facts that high protein intakes will damage healthy kidneys.
There is actually no reason for people with impaired kidney function to resign themselves to a life of low protein, high carbohydrate fare, and the consequent fatigue, muscle loss, and immune impairment. Californian researchers hypothesized that a diet with unrestricted protein intake, but low in carbohydrates and iron might reduce free radical and glycative damage in compromised kidneys.[9] It's no secret that carbohydrates elevate blood sugar levels, which in turn increases glycative activity in the body; and that excess iron has been implicated as a potent free-radical promoter. So the researchers placed patients with diabetic kidney damage on a diet in which chicken and fish, which are low in iron, were substituted for red meat, intakes of iron-binding foods, such as dairy and eggs, were increased and total carbohydrate intake was halved. The composition of the trial diet was 25-30% protein, 30% fat, 35% carbohydrate, and 5-10% alcohol. A control group of similarly kidney-impaired diabetics consumed the low-protein diet recommended for kidney patients consisting of 10% protein, 25% fat, and 65% carbohydrate, which is also the ratio recommended for the general population. The results of the trial were impressive: 39% of the low-protein, high-carb control group patients either died or deteriorated to a point necessitating kidney transplant; in the unrestricted protein group, the corresponding figure was 20%.
Evidence suggests that people with signs of kidney dysfunction should opt for iron-poor sources of protein such as poultry, fish, pork, eggs, and cultured dairy products together with a low carbohydrate intake, but not so low as to cause ketosis.
There is little doubt that a 'healthy' high-carb diet and subsequent high blood insulin can contribute to diabetic patients' deteriorating kidney function; and that insulin treatment in type-2 diabetes patients may cause further injury to the kidney. A low-carb, high-fat diet, with a moderate protein intake may actually prevent renal failure in type-2 diabetics.[10]
References
[1]. Thom JA, et al. The Influence of Refined Carbohydrate on Urinary Calcium Excretion. Br J Urol 1978; 50:7, 459-464.
[2]. http://www.niddk.nih.gov/health/kidney/pubs/stonadul/stonadul.htm, accessed 21 August 2003.
[3]. http://www.kidney.org/general/atoz/content/kstones.html, accessed 21 August 2003.
[4]. Poortmans JR, Dellalieux O. Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sport Nutr Exercise Metab 2000; 10: 28-38.
[5]. Blum M, et al. Protein Intake and Kidney Function in Humans: Its Effect on Normal Aging. Arch Int Med 1989; 149: 211-212.
[6]. Skov AR, et al. Changes in renal function during weight loss induced by high vs low-protein low-fat diets in overweight subjects. Int J Obes 1999; 23: 1170-1177.
[7]. Wrone EM, et al. Association of dietary protein intake and microalbuminuria in healthy adults: Third National Health and Nutrition Examination Survey. Am J Kidney Dis 2003; 41: 580-587
[8]. Knight EL, et al. The Impact of Protein Intake on Renal Function Decline in Women with Normal Renal Function or Mild Renal Insufficiency. Ann Int Med 2003; 138: 460-467.
[9]. Facchini FS, Saylor KL. A Low-Iron-Available, Polyphenol-Enriched, Carbohydrate-Restricted Diet to Slow Progression of Diabetic Nephropathy. Diabetes 2003; 52: 1204-1209.
[10]. Nielsen JV, Westerlund P, Bygren PG. A low-carbohydrate diet may prevent end-stage renal failure in type 2 diabetes. A case report. Nutr Metab 2006; 3: 23
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