Journal Club: low protein diet

Effect of a very low protein diet on outcome: long-term follow-up.

This is the long-term follow-up of the B group from the original MDRD study.
Enrollment criteria:
  • Age: 18-70
  • Abnormal Cr 1.2-7 women 1.4-7 in men.
  • MAP of 125 or less (160/100)
  • Proteinuria less than 10g per day
  • No diabetics
GFR 13-24 mL/min for the B study (low protein versus very low protein diet). Higher GFR were enrolled in the A study (normal protein versus low protein diet).
Protein was restricted for 3 years.
9 months after the study every nutritional parameter was the same between the two groups.

The primary end-point was a composite of death or dialysis and just about every patient in both groups (95.7%) reached this end-point preventing a separation between the groups (p=0.5). Likewise there was no separation with regards to time to dialysis (p=0.4).

The surprising finding occurs when they looked at death after the initiation of dialysis. There were 34 deaths in the very low-protein group and 19 deaths in the low-protein group (p=0.01).

The separation begins around 15 months and grows over time. This difference was statistically significant and grew to a 2-fold increased risk of death after 6 years.

My take is this fits well with what I tell my patients when they ask me about protein restriction. I have always counseled patients against protein restriction. The two largest RCT were both negative trials (The Modification of Diet in Renal Disease and the Northern Italian Cooperative Study Group). Additionally my patients do not have the benefit of dedicated and repeated nutritional couseling that the patients in these trials receive. My fear is that with little therapeutic upside there is signifigent risk of malnutrition from overzealous protein restriction.

This study probably does not apply to my worry as I doubt patients would adhere to a very low-protein diet.

My other concearn regarding low-protein diets is patients need to get calories from somewhere. Calories can only come from protein, carbohydrates or fat. Considering that the vast majority of CKD patients are destined to die before dialysis I worry that my advice for protein restriction will result in increased carbohydrates (bad for diabetes and possibly CV disease, see Richard Johnson’s fructose hypertension research) and/or increased fats (bad for CV disease) and enhance the risk of death from the more likely outcome.

5 Replies to “Journal Club: low protein diet”

  1. "This study probably does not apply to my worry as I doubt patients would adhere to a very low-protein diet"

    I wouldn't be so sure – faced with dialysis one can do a lot. I had FSGS and to stave off dialysis did the very low protein diet for many months. I ate <12 grams of protein a day from memory and weighed every bit of zucchini etc that I ate to make sure I stayed below the cut off. There was not a signle day when I breached my 'allowed' protein.

    I would say it made just about zero difference in my time to dialysis though.

    But don't doubt that patients can do it, and will. Esp if they have a 'control' kind of coping mechanism (as I do).

  2. It was said "This study probably does not apply to my worry as I doubt patients would adhere to a very low-protein diet".

    As a stege 3-4 CKD patient probably due to high BP, and I have kept to a very low protein diet as per "Coping With Kidney Disease" by Mackenzie Walser. As a kidney researcher at Johns Hopkins for 45 years, Dr. Walser must have done something right. I have recorded my lab numbers carefully every few months for over 3 years now on the diet. In my case my eGFR loss was very quick until I got on the diet and it slowed. As Dr. Walser said you MUST take Essential Amino Acids (EAA) from a trustworthy source during the diet, which I have done. I have no obvious signs of distress from the diet, and I can live with what doesn't seem to bother me.
    I notice that many doctors don't seem to look at the dialysis mortality numbers the same way that I do. My research shows that 1 out of 4 die in dialysis in the first year. I know that statistic has helped me to stay true to the diet in question.

    After looking at the conclusions of the MDRD study, I suspect something is rotten in Denmark. I don't know who funded or ran the study, but my results are different. I'll stay with my Walser diet for a while yet.
    Chris

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