Danielle from BC has been asking about protein and she wants to know what the latest is on plant vs animal proteins.
Thanks for the questions Danielle!
My answer
When I started working in renal, at that point the 2004 KDOQI guidelines recommended that 50% of protein should be high biological value protein (or animal based proteins). The 2020 guidelines now state that there is insufficient evidence to support one protein type over the other.
So, does that mean more plants?
It is recognized that we need more studies investigating the impact of high plant diets on kidney disease function and important clinical outcomes, such as dialysis initiation and quality of life. So for now, we really don’t know. But there is biological plausibility that plant proteins could be good.
If plants are so good, why were animal proteins previously emphasized?
The main advantage of animal proteins is that the evidence that suggests animal proteins do a better job at promoting muscle health/synthesis than plant proteins (Lim, Meng Thiam et al). Furthermore, several protein quality scales, such as biological value, protein digestibility, protein utilization or others have reported that plant proteins have a lower “quality” compared to their animal protein counterparts (Berrazaga, Insaf, et al.)
My own evidence review
As part of my PhD I did a review on the impact of protein source (plant vs animal) on serum phosphate levels and dietary phosphorus intake. In this review I found that observational studies vegetarians tended to consume less phosphorus, however, they also tended to consume less protein and had lower albumin levels. However, many non-vegetarians on dialysis didn’t meet their required protein intake either. Furthermore, the difference in albumin levels between vegetarians and non-vegetarians, while statistically significant, wasn’t always clinically significant.
But, it was still concerning enough for me that I recognize that high plant protein diets are likely to require better planning and potentially more support from me to be nutritionally complete.
How I practice now
With the latest KDOQI guidelines and my own research, my tendency is that I very rarely recommend patients to aim for 50% of their protein intake from animal sources. Instead, I used that 50% threshold as a limit.
Here’s how I calculate it:
For my patient that weighs 80kg and has a BMI within the ideal weight range and we are aiming for a low protein intake (though check out my other blog posts on protein for more about this!):
80kg * 0.6/kg = 48grams protein per day
Limit 50% of this from animal sources = 24 grams maximum from animal sources
Covert to ounces to make more meaningful for patients (divide by 7) = 3.42oz per day
What I say to my patient: “Aim for no more than 3-4 oz of animal protein per day. The rest of your protein should come from plant sources.”
