Below is a question we recently received from a Paleo Diet follower:
Dear Mr. Cordain,
I have been trying to follow the Paleo diet as discussed in your wonderful book.
I am 74, diabetes (under good control), some heart disease (no attacks or anything like that) and the scary thing is stage 3 CKD. My question is: Have you had any experience with this diet and a slowing of ckd? My doctor insists that I cut down on protein and eat more carbs.
Thank you for taking time to answer this question.
Dr Loren Cordain’s Response:
Good to hear from you. I believe that a high glycemic load diet (high refined grains, high sugars, high rice, high potatoes, etc.) leads to a condition in the bloodstream (excessive glucose) which predisposes the kidney to failure. In contrast a lifelong diet consisting of low glycemic foods (fresh fruits, fresh veggies, grass produced or free ranging meats and fish) prevents high chronic high blood glucose ( leading to a condition called glycation) which may prevent CKD. Once the kidney begins to fail, it is possible that high protein diets may make matters worse. Clearly, elimination of high glycemic load carbs can be therapeutic for CKD patients.
Loren Cordain, Ph.D., Professor
Department of Health and Exercise Science
Colorado State University
Pedro Carrera Bastos’ Response:
Unfortunately, kidney disease changes things completely and as so, what is generally a very healthy diet may not be the ideal one to kidney patients. As Professor Cordain has mentioned, it is very important to reduce glycation (which is one of the main causes of your kidney disease).
The main causes of glycation are:
1) High blood sugar (following a low glycemic load diet is very important for diabetics, as Prof. Cordain has mentioned) – vegetables are the ideal source of carbohydrate, not grains, who typically present a higher glycemic load. Small amounts of root vegetable and tubers (such as yam and sweet potato) may also be a part of your diet.
IN case you decide to keep the grains in your diet, at least avoid wheat (high glycemic load and contains gluten, which has many adverse effects), corn (high glycemic load), amaranth, white rice, quinoa and millet (all have high glycemic load). Although Legumes are a source of fiber and present low glycemic load, they are a source of various antinutrients and are recent newcomers in the human diet. Nevertheless, in your case, if you feel most include a little more carbs in your diet, pressure cooked legumes will be less adverse than grains, since they present a low glycemic load and pressure cooking reduces the antinutrient load. But instead of increasing the carbohydrate content of the diet, you could increase the fat content, using virgin olive oil, moderate amounts of nuts (such as walnuts, almonds and hazelnuts) and omega-3 fatty acids from fish oil or fatty fish.
2) High fructose diet: in this regard, reduce added sugars and especially HFCS and choose fruits that are low in total fructose – the following table can help you choose:http://thepaleodiet.com/nutritional-tools/fruits-and-sugars/
3) Galactose – together with glucose, it constitutes lactose. Reduce dairy products and to maintain calcium balance, choose vegetable sources of calcium, such as kale and broccoli. Moreover, in kidney insufficiency, high calcium and high phosphorous may lead to arterial calcification, so a low dairy diet is important.
4) Novel food processing procedures, such as extreme heating, irradiation, ionization, pasteurization, and sterilization lead to the non-enzymatic glycation and oxidation of proteins and lipids in common consumed foods. This complex and heterogeneous group of compounds, called advanced glycation and lipid oxidation end products (AGEs and ALEs), once partially absorbed into systemic circulation, may have deleterious health effects. Indeed, in diabetic patients, a high AGE intake was associated with higher levels of C-reactive protein (CRP, a marker of chronic inflammation), TNF-? (also a marker of chronic inflammation) and vascular cell adhesion molecule (VCAM-1, a marker of endothelial dysfunction). In contrast, low AGE diets reduce serum AGE levels, as well as markers of inflammation and vascular dysfunction (CRP, TNF-?, and VCAM-1) in diabetic and renal failure patients. For you, it is important to know that the effects of dietary AGEs and ALEs are much more pronounced in diabetics (who present an enhanced formation of endogenous AGEs due to hyperglycemia), and kidney failure patients (who have an impairment of AGE renal excretion).
AGE and ALE content in food is greatly influenced by processing and cooking conditions, including temperature, time, and moisture. Consequently, avoidance of processed foods and the use of steaming, poaching, boiling, and stewing as the main cooking methods, instead of frying, broiling, and grilling, may be a sensible way to decrease the formation of these compounds. Of interest, tobacco, by being processed in the presence of reducing sugars, represents another source of exogenous AGEs. Indeed, circulating AGE levels have been found to be significantly higher in smokers compared to nonsmokers, so it is highly advisable that kidney patients and diabetics do not smoke.
Regarding Protein, as Prof. Cordain and Maelan Fontes have mentioned, in kidney disease patients, the source of protein is more important than the total amount of protein, and intervention studies appear to show that replacing red meat with boiled fish and boiled poultry while maintaining a moderate amount of protein (such as 1g per kg bodyweight) may be a better strategy than simply reducing protein (attached is a 2008 document Prof. Cordain and myself have written regarding Protein for diabetics).
It is also important to mention that kidney disease patients need to reduce sodium intake (salt) and may have to be careful about potassium and magnesium intake too.
Some supplements that might help are vitamin B1, CoQ10, green tea (which can be used as drink) and omega-3 fatty acids.
In case it is necessary, we can provide the scientific papers that support what we have said.
We hope this helps
Pedro Carrera Bastos
Maelán Fontes Villalba’s Response:
Furthermore, there’s evidence from intervention trials in humans that changing the source of protein could be even better than cutting down the total amount of protein. If I remember well, this trial used 1,35 g/kg/d, when official recommendations is 0,8 g/kg/d for healthy people. This means you have a wide range to increase your protein, or at least you don’t have to cut down as long as you eat more fish and chicken in place of read meat.
So eat a paleodiet with fish and chicken breasts.
I hope this is useful.
Dr Loren Cordain/Pedro Bastos’ detailed response:
Is a Palaeolithic Type Diet safe for the average diabetic (particularly the high levels of protein, since many diabetics have a loss of kidney function)?
One of the most common misperceptions about high protein diets is that they can damage the kidneys of healthy normal individuals. This concept is known as the “Brenner Hypothesis” (1) and suggests that increased dietary protein elevates the kidney’s filtration rate (GFR) which in turn alters the kidney’s structure (glomerulosclerosis) which then causes albumin to appear in the urine (microalbuminuria).
Although these series of steps represent the hypothesis Brenner and colleagues proffered (1), their experiments actually showed an entirely different series of events.
In reality, they demonstrated that patients with pre-existing kidney disease had an elevated GFR, glomerulosclerosis and microalbuminuria and that by reducing dietary protein the GFR and microalbuminuria could be lowered (1).
They further suggested that because elevated dietary protein increased the GFR in short term studies (< 2 weeks) of healthy normal subjects, protein was responsible for kidney damage.
The Achilles heel of this hypothesis is that elevated GFR from increased dietary protein had only been shown under short-term conditions (1-4 wks). At the time in 1982, no one had bothered to examine kidney function with chronic high protein diets in healthy normals.
Arne Astrup’s group finally got around to doing this experiment in 1999 in a randomized dietary intervention over a 6-month period comparing a high protein diet (25% energy) vs. a low protein diet (12% energy) (2) upon kidney function in 65 overweight male and female subjects without pre-existing kidney disease. They found that the high protein diet did not cause urinary albumin to increase.
Additionally, the specific GFR, which is an expression of the filtration rate per unit kidney volume, did not change during the high protein diet, indicating that renal (kidney) adaptation occurred to the higher protein load. The authors summarized:
“We therefore conclude that a high dietary protein intake does not appear to have adverse effects on renal function in individuals without renal impairment.”
One year later, Belgium researchers investigated body-builders and other well-trained athletes with high- and medium protein intake. The athletes underwent a 7-day nutrition record analysis and their blood and urine samples were analysed, and the conclusion was:
“It appears that protein intake under 2. 8 g.kg does not impair renal function in well- trained athletes as indicated by the measures of renal function used in this study.” (3)Further, in the National Health and Nutrition Education Survey (NHANES III) of more than 12,000 subjects, dietary protein intake was unrelated to the incidence of microalbuminuria in normal, healthy subjects (4).
Similar results were found by Knight and colleagues, who analysed 1624 women without pre-existing kidney disease, enrolled in the Nurses’Health Study, and concluded that high protein intake does not seem to be associated with renal function decline in women with normal kidney function (5).
Thus, there is no evidence that chronic high protein diets will cause renal injury, as more recent reviews of the scientific literature also conclude (6-8).
And it should be mentioned that the incidence of diabetic end stage kidney disease has increased steadily over the past three decades (9, 10). If dietary protein were responsible for causing kidney damage, then one might expect that dietary protein would have steadily increased during this same time interval. In fact, dietary protein significantly declined during this same period (11).
Also, various studies have shown that high protein diets are effective strategies in Dislipidemia, Obesity, Hypertension, and Type 2 Diabetes (12-26), which are known risk factor for developing kidney disease (27, 28).
Nevertheless, reducing dietary protein may retard the progression of renal failure or delay the need for dialysis therapy in patients with advanced Chronic Kidney Disease (CKD), which is why the National Kidney Foundation (NKF) recommends (28), for patients with advanced CKD not undergoing dialysis, a diet of 0.6 g protein/kg/day, allowing it to be increased to 0.75 g protein/kg/d (this is still beyond the RDA, which is 0.8 g protein/kg/d).
As for patients with mild to moderate kidney disease (such as some Diabetics), the NKF states that Dietary protein restriction is an inconclusive strategy (28). Moreover, in a comprehensive review of all randomized controlled trials evaluating the effectiveness of low protein diets upon GFR and kidney function, 11 studies (total n = 1223) showed no therapeutic effect, while only three investigations (total n = 235) demonstrated a significant benefit of dietary protein restriction on kidney failure progression (29).
As so and to avoid risk of malnutrition, a better strategy for diabetics with kidney damage, which has been shown to be nearly as effective as protein restriction in people with kidney disease (30-33), could be to substitute red meat with fish and chicken, maintaining a normal protein intake (between 0,8 grs/kg and 1,3 grs/kg).
It is also advisable that Diabetics avoid foods that contain high amounts of AGEs (Advanced Glycation End Products), which are suspected to cause kidney damage even in healthy people (34). AGE content in food is greatly influenced by cooking conditions, including temperature, time, and moisture (34). As so, steaming, poaching, boiling, and stewing, instead of frying, broiling, and grilling, are the advised culinary methods (34).
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