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Low Carb Kidney Damage?

June 4, 2012 Written by JP    [Font too small?]

The term “low carbohydrate diet” conjures up certain stereotypes in the minds of many patients and physicians alike. A common misconception about this controversial way of eating is that it is inevitably rich in dairy and meat, and severely lacking in fruits and vegetables. Another myth about low carbing is that it raises various cardiovascular risk factors. But, perhaps the most prevalent mistaken notion about carbohydrate restriction is that it is damaging to the kidneys. All of these assertions have been summarily rebutted in the scientific literature in recent years. Still, not everyone is aware.

It’s universally agreed upon that reducing carbohydrate intake lowers blood sugar and insulin output in non-diabetics and type 2 diabetics. Ironically, most mainstream nutritionists are hesitant to recommend low carbohydrate diets in those with high blood sugar. This is in part due to concerns about the effects of such a diet on the cardiovascular and renal system. This is a worry because diabetics are documented as exhibiting a higher risk of heart disease, kidney failure and stroke than the general population.

A new study in the Clinical Journal of the American Society of Nephrology should, at long last, put the issue of low carb induced kidney damage to rest. In the 2 year trial, two diets were compared in a group of 307 obese adults: a conventional low fat diet vs. a high protein, low carbohydrate diet. The results, in as much as kidney function and health were concerned, determined that the low carbohydrate diet actually improved various measures of kidney health including a decline in serum creatinine (-4.2%) and cystatin C (-8.4%). In addition, there were no signs of kidney stone formation or reduced bone density in the carbohydrate restricted volunteers. It might surprise you to know that several other, peer-reviewed investigations confirm these current findings. The bottom line is that low carbohydrate diets tend to affect kidney function, in those without preexisting kidney disease, better or comparably to lower fat, lower protein diets.

There is a minor, albeit notable, exception to the rule stated in the previous paragraph. Ketogenic diets, which are very low in carbohydrates, are known to contribute to kidney stone formation in approximately 6% of those maintaining this diet over the long term. While this is a legitimate concern, this small risk can be effectively and safely managed using potassium citrate, an inexpensive and all-natural “drug”. Furthermore, those on highly restrictive, ketogenic diets are typically doing so to manage serious health concerns such as Alzheimer’s disease, cancer or epilepsy. In these instances, the small possibility of kidney stones isn’t a primary consideration.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

Study 1 – ASN: Do Low-Carb Diets Damage the Kidneys? (link)

Study 2 – Comparative Effects of Low-Carbohydrate High-Protein Versus (link)

Study 3 – Randomized Clinical Trial of Standard Dietary Treatment Versus a (link)

Study 4 – Renal Function Following Long-Term Weight Loss in Individuals(link)

Study 5 – Further Decrease in Glycated Hemoglobin Following Ingestion of (link)

Study 6 – A Low-Carbohydrate Diet May Prevent End-Stage Renal Failure (link)

Study 7 – A Low-Iron-Available, Polyphenol-Enriched, Carbohydrate (link)

Study 8 – Effects of a Ketogenic Diet on the Quality of Life in 16 Patients (link)

Study 9 – Empiric Use of Potassium Citrate Reduces Kidney-Stone (link)

Study 10 – The Ketogenic Diet as a Treatment Paradigm for Diverse (link)

Carbohydrate Restriction May Improve Diabetic Kidney Function

Source: Nutr Metab (Lond). 2006 Jun 14;3:23. (link)

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Posted in Diet and Weight Loss, Food and Drink, Nutrition

11 Comments & Updates to “Low Carb Kidney Damage?”

  1. LeonRover Says:

    Interesting re K Citrate.

    When checking the referenced study I noted the supplement was called PolyCitra. In addition, Na Citrate was substituted when a child refused PolyCitra.

    I concluded that the acidifying was Citrate.

    If this is so, I speculate that Mg Citrate might fulfill a similar purpose.

  2. kristi Says:

    Great post! One of the reasons I love this blog is that you used evidence based sources!

  3. JP Says:

    Hi Leon,

    Some research supports the use of magnesium citrate (combined with potassium citrate) for kidney stones:




    Be well!


  4. JP Says:

    Thank you, Kristi! That’s always been one of my objectives: to provide an evidence-based foundation for the information I share in my columns.

    Be well!


  5. rob Says:

    Good to read another study that reinforces that carbs, outside of most fruits and veggies, are just not needed to live a uber health life

  6. JP Says:

    Indeed, Rob. 🙂

    Be well!


  7. JP Says:

    Update: The role that calcium and hydration play in kidney stone formation …


    J Am Coll Nutr. 2015 Apr 9:1-7.

    Effects of Hydration and Calcium Supplementation on Urine Calcium Concentration in Healthy Postmenopausal Women.

    OBJECTIVE: The aim of this study was to determine whether calcium supplementation, compared with placebo, increases urine calcium concentrations to levels indicative of increased renal stone risk, and the role that fluid intake, as indicated by urine volume, may play in mitigating this risk.

    METHODS: This is a secondary analysis of data from a randomized placebo-controlled trial of 500 mg/d calcium supplementation to prevent bone loss. Subjects were 240 white postmenopausal women age 40 to 70 years in good general health. Effects of supplementation on 1-year changes in 24h urine calcium concentration and urine volume were examined.

    RESULTS: Both treatment group and urine volume were strong independent predictors of urine calcium concentration (p < 0.001). Among subjects with urine volume under 2 L/24 h, more than half of placebo subjects were at lowest risk for renal stones compared with less than 35% of calcium-supplemented subjects. Among those with higher urine volumes, all placebo subjects and more than 80% of calcium supplemented subjects were at lowest risk. CONCLUSIONS: The increased risk of renal stones with calcium supplement use may be largely eliminated with adequate fluid intake, but older adults may not spontaneously consume adequate fluids to minimize this risk and should be counseled to do so. Be well! JP

  8. JP Says:

    Update 04/17/15:


    Exp Clin Endocrinol Diabetes 14 April 2015

    Curcumin Attenuates Urinary Excretion of Albumin in Type II Diabetic Patients with Enhancing Nuclear Factor Erythroid-Derived 2-Like 2 (Nrf2) System and Repressing Inflammatory Signaling Efficacies

    Curcumin has a therapeutic potential in treating diabetic kidney disease (DKD) while potential mechanisms underlining this beneficial effect remain to be elucidated. In the present study, curcumin intervention was performed in patients with Type II diabetes mellitus (T2DM) by oral intake of curcumin at the dose of 500 mg/day for a period of 15–30 days. Nephritic excretion of urinary micro-albumin (U-mAlb) and blood metabolic indexes were assessed before and after this intervention. In addition, the lipid oxidation index, malondialdehyde (MDA) in plasma and the status of anti-oxidative Nrf2 system in blood lymphocytes were measured. The effect of curcumin on inflammation was assessed by measuring plasma lipopolysaccharide (LPS) content and inflammatory signaling protein in blood lymphocytes. A self-comparison method was used for assessing statistical significances of these measurements. Here we show that curcumin intervention markedly attenuated U-mAlb excretion without affecting metabolic control of participated patients. In addition, curcumin reduced plasma MDA level with enhanced the Nrf2 system specifically regulated protein, NAD(P)H quinone oxidoreductase 1 (NQO-1) together with other anti-oxidative enzymes in patients’ blood lymphocytes. Furthermore, we observed reduced plasma LPS content and increased IκB, an inhibitory protein on inflammatory signaling in patient’s lymphocytes after curcumin administration. Finally, several gut bacterials important for maintaining gut barrier integrity and function were upregulated by curcumin.

    In conclusion, short-term curcumin intervention ablates DKD progress with activating Nrf2 anti-oxidative system and anti-inflammatory efficacies in patients with T2DM.

    Be well!


  9. JP Says:

    Updated 12/16/16:


    Eur J Clin Nutr. 2016 Dec 14.

    DASH dietary pattern and chronic kidney disease in elderly Korean adults.

    BACKGROUND/OBJECTIVES: Dietary patterns are linked to risk and outcomes in chronic kidney disease (CKD). Dietary intake varies by race, region and age. The relationship between a Dietary Approaches to Stop Hypertension (DASH) diet and CKD in elderly Koreans is unclear.

    SUBJECTS/METHODS: We conducted cross-sectional analyses of 2408 community-dwelling elderly participants from the Korean National Health and Nutrition Examination Survey (2011-2012). DASH dietary patterns for six nutrients (protein, fiber, calcium, potassium, total fat and sodium) were collected by 24 h recall. DASH-US (based on the US recommendations) and DASH-KQ (Korean quartile) scores were generated by summing the scores for the six nutrients. Multivariate logistic regression analysis was used to calculate odds ratio (OR) for the association between a DASH diet and CKD.

    RESULTS: Mean subject age was 72.4±5.1 years, 13.9% had CKD and 23.8% had diabetes. Protein, fiber, calcium and potassium intake was lower in CKD than non-CKD participants. In multivariate logistic regression analysis adjusted for age, sex, body mass index, comorbid conditions and other factors, a high DASH score was associated with a low odds for CKD based on DASH-US (OR=0.78, 95% confidence interval (CI), 0.65-0.94, P=0.009) and DASH-KQ (OR=0.95, 95% CI, 0.91-0.99, P=0.022). In six nutrients of DASH diet, high fiber intake showed a low odds for CKD in the DASH-KQ model (P for trend=0.010).

    CONCLUSIONS: Our findings suggest that higher adherence to a DASH diet and higher fiber intake are associated with lower odds of CKD in elderly Koreans. These results should be corroborated through longitudinal studies of the association between a DASH diet and high-fiber diet on the risk of developing CKD.

    Be well!


  10. JP Says:

    Updated 05/07/17:


    EXCLI J. 2016 Jun 27;15:424-433. eCollection 2016.

    Grape seed powder improves renal failure of chronic kidney disease patients.

    Chronic kidney disease (CKD) is a syndrome characterized by progressive and irreversible deterioration of renal function linked to slow destruction of renal parenchyma, eventually terminating in death when sufficient number of nephrons are damaged. Oxidative stress is commonly observed in CKD patients resulting from an imbalance between overproduction of reactive oxygen species (ROS) and impairment of defence mechanisms. Grape seed extract (GSE) is a polyphenolic mixture exhibiting antioxidant and anti-inflammatory properties. We conducted an interventional pilot study of supplementation with GSE capsules (GSE group, n = 23) or placebo (control group, n = 10) on CKD patients. Blood and urine samples were collected at baseline and after a six-month-long supplementation period to determine some renal function biomarkers, as well as antioxidant, anti-inflammatory and haematological parameters. GSE improved glomerular filtration rate (GFR) and proteinuria, increased the anti-oxidant status as assessed by high plasma catalase and superoxide dismutase and also lowered lipoperoxidation and carbonylation. GSE ameliorated inflammation by decreasing CRP, triglyceridemia and counteracted anemia and thrombocytopenia. Supplementation with 2 g GSE/day for six months improved some kidney function parameters of CKD patients and this beneficial effect of GSE seems to be mediated at least partly by its antioxidant and anti-inflammatory properties.

    Be well!


  11. JP Says:

    Updated 03/25/18:


    Am J Kidney Dis. 2018 Mar 12.

    Coffee Consumption and Incident Kidney Disease: Results From the Atherosclerosis Risk in Communities (ARIC) Study.

    BACKGROUND: Moderate coffee consumption has been suggested to be associated with lower risk for chronic conditions such as diabetes, a major precursor to chronic kidney disease (CKD). However, the association between coffee and CKD has not been fully established.

    STUDY DESIGN: Prospective cohort study.

    SETTING & PARTICIPANTS: 14,209 participants aged 45 to 64 years from the Atherosclerosis Risk in Communities (ARIC) Study.

    PREDICTORS: Coffee consumption (cups per day) was assessed at visits 1 (1987-1989) and 3 (1993-1995) using food frequency questionnaires.

    OUTCOMES: Incident CKD defined as estimated glomerular filtration rate < 60mL/min/1.73m2 accompanied by ≥25% estimated glomerular filtration rate decline, CKD-related hospitalization or death, or end-stage renal disease. RESULTS: There were 3,845 cases of incident CKD over a median of 24 years of follow-up. Men, whites, current smokers, and participants without comorbid conditions were more likely to consume higher amounts of coffee per day. After adjustment for demographic, clinical, and dietary factors, higher categories of coffee consumption were associated with lower risk for incident CKD compared with those who never consumed coffee (HR for <1 cup per day, 0.90 [95% CI, 0.82-0.99]; 1-<2 cups per day, 0.90 [95% CI, 0.82-0.99]; 2-<3 cups per day, 0.87 [95% CI, 0.77-0.97]; and ≥3 cups per day, 0.84 [95% CI, 0.75-0.94]). In continuous analysis, for each additional cup of coffee consumed per day, risk for incident CKD was lower by 3% (HR, 0.97; 95% CI, 0.95-0.99; P<0.001). LIMITATIONS: Self-reported coffee consumption and observational design. CONCLUSIONS: Participants who drank higher amounts of coffee had lower risk for incident CKD after adjusting for covariates. Coffee consumers may not be at adverse risk for kidney disease. Be well! JP

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