Plant-Based Diets to Treat and Prevent Kidney Disease
In this podcast, Shivam Joshi, MD, answers our questions about the benefits of using a plant-based diet to prevent and treat kidney disease, how recommendations differ among patients, and if there are concerns or risks for patients who eat a plant-based diet.
- Joshi S, McMacken M, Kalantar-Zadeh K. Plant-based diets for kidney disease: a guide for clinicians. Am J Kidney Dis. 2021;77(2):287-296. doi: 10.1053/j.ajkd.2020.10.003
Shivam Joshi, MD, is a clinical assistant professor of medicine at NYU School of Medicine and a primary care doctor, nephrologist, and a lifestyle medicine attending at the Bellevue Hospital in New York City. You can reach Dr Joshi on Twitter @SJoshiMD.
Jessica Bard: Hello, everyone, and welcome to another installment of "Podcast360," your go to resource for medical news and clinical updates. I'm your moderator Jessica Bard, with Consultant360 Specialty Network.
According to the National Kidney Foundation, eating plant based foods, such as vegetables and grains, in place of animal based foods, such as red meat may help prevent and treat lifestyle diseases like chronic kidney disease.
Dr. Shivam Joshi, is here to speak with us about that today. Dr. Joshi, is a clinical assistant professor of medicine at NYU School of Medicine, and a primary care doctor, nephrologist, and lifestyle medicine attending at Bellevue Hospital in New York City.
Thank you for joining us today, Dr. Joshi. What led you and your colleagues to study the benefits of plant-based diets and kidney disease?
Dr. Shivam Joshi: I've always been personally vegetarian or semi vegetarian. I've always had this interest in plant based diets.
When I was in fellowship, I wondered if I could combine my personal interests with my professional interests, which was kidney diseases, so I started working into it.
I was surprised because the more I looked into it, the more I found, and I kept going with it. All of a sudden, I became this expert on this topic that no one really wanted to talk about, but everyone wanted to hear about. Almost overnight, I became an expert on this topic and have started to write papers and give talks on the subject, and it's just continued from there.
A lot of the research that we discuss exists in the literature and has been published and people know of, but people just don't know how to apply it, or what it means. What we did in this most recent paper, in the "American Journal of Kidney Disease" is combine all of these into a practical guide for kidney doctors on how to implement and use plant-based diets for patients with kidney disease.
Not only patients with kidney disease, but patients with kidney disease who also have comorbidities like high blood pressure, diabetes, being overweight, and how do you tie all this together. Where's the evidence for these things? What are the pitfalls that our clinicians should look out for? That's how we came about to this.
Our paper was extremely well received. Using the metric scores for papers, it was widely viewed. People loved it on Twitter. It's a very timely topic that could benefit the health of patients.
Jessica: What are the benefits of a plant-based diet regarding prevention or treatment of chronic kidney disease? What are your guidelines for clinicians?
Dr. Joshi: There are several benefits to a plant-based diet for the prevention and treatment of kidney disease. In observational studies¬¬– these studies that look at groups of people for a period of time– what they found is that people who eat a plant based diet or eat less meat or even less red meat, tend to have a lower risk of developing kidney disease. That is eye-opening in itself.
When you start looking at additional data– the small trials that have been done– what we see is that there's a benefit to eating plant-based for people who already have kidney disease.
For example, there are many things that the kidney does. The kidney regulates electrolyte levels, water levels, blood pressure. When you introduce plant-based diets, many of these parameters that are not normal tend to improve.
One of them is metabolic acidosis, which is the amount of acid in the blood. Plant-based diets have also been shown to improve blood pressure in people with kidney disease and without kidney disease, have also been shown to lower serum phosphate levels. There are also observational data suggesting that people who eat plant-based diets have lower mortality.
Sometimes it's not even the whole diet, just eating a few more fruits and vegetables. People who tend to eat more fruits and vegetables tend to have a significantly lower risk of dying compared to those who don't on dialysis.
To answer your second question regarding, what are the guidelines that we give for clinicians? The take home message from the paper is that clinicians may not be using a diet to their benefit.
Actually, the diet that they're recommending may actually be working against it, because on one hand, physicians are prescribing medications to treat things like metabolic acidosis and high phosphate levels, but they're also recommending a diet that emphasizes the consumption of a lot of animal protein, which we know worsens these parameters.
It's as if on one hand, we're doing one thing, and on other hand, we're doing another thing. In many of these cases, both patients and physicians are unaware of the problem that they're creating.
What we are trying to educate to our readers is that they could use our plant based diets to their benefit and reduce, perhaps, number of medications that their patients have to take.
What we suggest is that physicians approach this in a way that patients are comfortable with. It doesn't necessarily mean that patients have to go vegan or totally plant based, but to try and work on aspects of their health where both patients and physicians feel comfortable with.
Towards the end, we give a guideline on the number of servings of foods to aim for, resources that people can use, and some foods to exclude because those foods may cause problems.
Jessica: Are there any concerns or risks for patients who eat a plant based diet? If so, what are they? How should a clinician approach those issues with their patients?
Dr. Joshi: There's always risks and benefits with anything we do in medicine, be it prescribed medication or given diet. In our opinion, we feel that the risks of a standard American diet outweigh its benefits. It would be helpful for patients to eat a diet that's more conducive to their long term health and their comorbidities.
A diet that emphasizes the consumption of foods that are high in fiber, vitamins, minerals, phytonutrients. Those would-be foods like whole grains, beans, lentils, fruits, vegetables, nuts, seeds, things like that. Those are the foods we would recommend.
The big concern historically in consuming these foods in patients who have kidney disease is that patients, one, may not get enough protein, two, that their potassium levels will go high. Now that we're in 2021, we had the benefit of having studies that have looked at this.
The studies that have looked at people who have kidney disease eating a plant based diet, they've shown that patients are able to get enough protein not only if they have non dialysis based CKD, but also if they have CKD that requires dialysis or ESRD. Protein is not a concern that should deter people from implementing these diets.
Obviously, for patients who are on dialysis, their protein requirements are a little bit higher. Protein will always be something to watch out for, but it's no different than any other diet in terms of people can get protein from legumes, lentils, tofu, things like that, so that is attainable.
The other concern or pitfall with these diets historically has been with potassium. Potassium has been a big concern because potassium levels can be lethal. Potassium is what has been used on death row. We certainly don't want to induce hyperkalemia, or elevate potassium levels in our patients and then lead them to a fatal outcome.
However, when you look at the studies, there have actually been very few to almost none, no instances of hyperkalemia in patients eating a plant based diet.
These are observational studies, these are interventional studies. These are studies that have been documented in the literature looking at people eating various components or various proportions of plant based diets, and what they've seen is very few, if not any, instances of hyperkalemia.
The only one instance that was documented was someone who already had a pre existing condition known as a renal tubular acidosis that led to hyperkalemia already. That is reassuring. In our own practice, we haven't had problems with this either.
The question is, why don't people have elevated potassium levels? That is actually an emerging concept. People think that it could be related to a variety of things. It could be related to the fact that there's more fiber in these foods, which then causes an increased amount of potassium to be excreted with more frequent bowel movements. This fiber helps relieve constipation and things like that.
The other aspect of this is that people think that the bioavailability of potassium is less in plant foods compared to animal based foods, similar to how we think about the bioavailability of phosphorous. If less potassium is bioavailable from these foods, then more of it will be excreted when there is a bowel movement.
Then, there's other factors related to it, like improved insulin sensitivity, which drives potassium intracellularly, improved metabolic acidosis, which can also reduce potassium levels, and things like that.
Potassium concern has not been as big in the literature as we've anecdotally have told our patients, but that is not to say that people should totally let their guard down. There are certain foods to watch out for. These are foods that remove these mitigating factors for a rise in potassium and give patients more potassium than they otherwise would consume.
These problematic foods– and we talk about this in the paper– are fruit juices, vegetable sauces, dried fruit, and your potassium additives.
The potassium additives are a no brainer, because if you're giving someone potassium, it's not surprising that their potassium would go up. Potassium additives are 100 percent bioavailable.
The fruit juices, vegetable sauces, and dried fruit take a little bit more explaining. Let's take a glass of orange juice. A glass of orange juice may have two to three oranges worth of OJ, but you don't see someone eating two to three oranges in a sitting at once.
That's the problem. If people eat whole fruits and vegetables, they won't generally get into trouble. It's only when they start doing maneuvers to concentrate the fruit juice or to extract potassium inherently in those foods into a higher concentration that gets into trouble.
Fruit juice is one example. Vegetable sauces are another example. Then, dried fruit is another example, because it removes the water content and allows people to eat more fruit than they otherwise would.
Those are the things to watch out for. Some people may do fine with a little bit in moderation, but in the beginning, I caution my patients to avoid these until we know how they adapt to the diet. Of course, with any dietary change, I do check my labs more frequently and also get in touch with my patients more often to make sure that they're doing OK.
Jessica: Do your findings in your research differ among patients, men or women, different ages, or other patient characteristics?
Dr. Joshi: I would say no. The research that we have in this area isn't a whole lot. Granted, our paper had close to 90 citations, so we had 90 papers to build off of. We haven't noticed those kind of differences as of yet.
As the literature builds, we may start to tease out some more information and be able to identify who this benefits more for and who it doesn't benefit for. We're still in the pretty early stages.
Jessica: You mentioned a take home message earlier, and then you mentioned some things for what's next in the research. If you could sum it up for us, what are your take home messages for this study, and what is next for this research?
Dr. Joshi: That's a great question. We are just at the beginning of learning about the benefits of this diet. We could think of this...It's as if when the Mediterranean diet came onto the scene for cardiology several decades ago, and people were very excited. I feel like this is the same way for nephrology.
We're just at the beginning. Hopefully, in the coming decades, we'll get more research. The research that we need are more observational studies on the long term effects of people eating plant based diets while having kidney disease, especially in regards to progression of their disease.
There's some evidence to suggest that people who do eat, for example, fruits and vegetables have a slower progression of their kidney disease, because it treats their metabolic acidosis compared to people who have untreated metabolic acidosis in kidney disease.
We want to see some more long term observation studies, but also some nice and well done randomized controlled trials that isolate one variable and can prove our point. That would be, I would say, what the future holds and to help get the message out there that these diets could be beneficial for patients.
Jessica: Thank you so much, Dr. Joshi. I appreciate your time on our podcast. I learned a lot, too.
Dr. Joshi: Thanks for having me.