What Your Kidney Disease Diet Actually Needs (And What the Internet Got Wrong)

A Conversation with Jen Hernandez RDN, CSR, LDN

When I was deep in my Lyme disease diagnosis, I came across everything. Hyperbaric chambers. Bee venom therapy. A woman online who swore cutting out oxalates changed her life. And every single time I stumbled onto one of these rabbit holes, part of me wanted to believe it, because that's what you do when you're sick and the medical system isn't giving you answers. You look for something certain.

I've talked about this pattern a lot on the podcast, and this week's conversation with Jen Hernandez takes another look at it through the topic of kidney disease nutrition.

Jen is a registered dietitian, board-certified specialist in renal nutrition, and the founder of Plant Powered Kidneys. She also wrote the book on it — literally. Plant Powered Kidney Nutrition came out at the end of last year, and it's already making waves with people who have spent years being told what they can't eat as a kidney disease patient.

This conversation is for anyone who has ever Googled "kidney disease diet" and walked away more confused and scared than when they started. And even if kidneys aren't your thing, the patterns Jen describes will feel familiar across a wide range of medical conditions.

The Deer in Headlights Moment

Jen started her career working with the National Kidney Foundation and in dialysis clinics. What she kept seeing was two very different groups of new patients walking through the door.

The first group had no idea. Total shock. The second group had essentially grown up expecting it — aunties on one side of the room, cousins on the other. Already in dialysis. No sense that anything could have been different.

Both of those groups broke her heart, but for different reasons.

What she knew, and what patients often didn't, was that chronic kidney disease is not an automatic sentence to dialysis and kidney failure. It's a lifelong condition, yes, and there's no cure. But the trajectory is something that can actually be influenced. She's seen it happen with her own students and patients again and again.

And yet, people are still being told to wait until dialysis to see a dietitian. Or being handed nutrition guidelines that were written in 1992 and never updated. It's one of those things that's not malicious — it's just a broken system that hasn't caught up.

The Foods We're Unnecessarily Afraid Of

Here's where I think a lot of you are going to feel very seen.

Oxalates

You might’ve seen this one online. Oxalates are an "anti-nutrient" in foods like spinach, nuts, seeds, and beans — and somewhere along the way, the internet decided that meant you should cut them out.

Jen explains that for most people with kidney disease, oxalates are not a significant concern. They become relevant for people who have kidney stones (specifically the oxalate kind, which affects about 10% of the population). And even then, cutting out oxalate-rich foods is not the first intervention.

What actually helps:

  • Getting enough calcium, which binds to oxalate and prevents stones from forming in the first place

  • Reducing sodium, which many of us are eating way too much of anyway

  • Staying well-hydrated — people prone to kidney stones should aim for two to three liters of fluid per day

So before you say goodbye to your spinach, get a 24-hour urinalysis and talk to a dietitian who will actually look at your full picture.

Potassium

Jen explained that for years — including when she worked in dialysis — the guidance was clear: potassium is bad. Don't eat bananas. Don't eat potatoes. Stay away from avocado.

And then the 2020 guidelines came out and basically said: that's not really how it works.

Here's the problem. Someone newly diagnosed with stage three kidney disease goes online looking for answers. They find all this content telling them to cut potassium. They're already getting about half of the daily recommended amount. And then they cut it further. They end up unknowingly restricting a nutrient that supports heart health, blood pressure, and kidney function itself.

Only about 10 to 20% of people with CKD actually need to limit potassium, and even that number is more nuanced than "you have kidney disease, so no." If a provider is telling you to avoid potassium without looking at your specific labs and situation, Jen says that's a red flag worth paying attention to.

Phosphorus

Same story, different nutrient. There are two types: organic phosphorus (the kind naturally occurring in foods like oats, beans, and whole grains) and inorganic phosphorus (the kind added to processed foods as a preservative). The body doesn't absorb organic phosphorus the same way — and in some cases, the phytates in foods like oatmeal actually prevent phosphorus absorption, which is a benefit for people with kidney disease.

The handout telling you to avoid oatmeal? Check the copyright date. Jen says if it's anything before 2020, it's likely outdated.

The Avoidance Trap

Jen and I talked about possibly the most important concept in all of the nutrition space: people almost always ask what they need to cut out, not what they can add in.

What do I need to eliminate? What can't I have? What should I avoid?

And I get it. When you're navigating a chronic illness and the medical system hasn't given you much to work with, restriction feels like control and action. It feels like you're doing something.

But Jen's entire approach with Plant Powered Kidneys is built around the opposite idea: kidneys thrive with more plants. More fiber, whole foods, and variety. Not a vegan diet necessarily — you can include animal protein, just in appropriate amounts. It's called plant powered, not plant exclusive.

The hardest part is that the advice that actually works sounds too boring to be real. Drink more water. Eat more fruits and vegetables. Include beans and whole grains. People hear that and think, there has to be a catch. But there isn't. The catch is that we've spent so long being told everything is dangerous that the straightforward stuff doesn't feel trustworthy anymore.

When Two Conditions Clash

I asked Jen about something that comes up a lot in my world: what happens when two conditions have contradictory treatment needs? POTS, for example, often requires extra sodium. But kidney disease generally calls for sodium restriction.

Her answer was exactly what I expected from someone who's been in this field for a while: there's no such thing as one kidney diet.

The guidelines are starting points, not prescriptions. And the person who can help you figure out which guidelines actually apply to you is a dietitian who has time to look at your food journal, your labs, and make the connection between what you ate on Tuesday and what showed up in your blood work on Thursday.

Physicians are not that person — not because they aren't capable, but because the system doesn't give them the time. A one-sentence directive to "watch your sodium" doesn't tell you anything. A dietitian can actually explain what that means for your specific body and situation.

What to Do With All of This

If you have chronic kidney disease, or you love someone who does, here's what I'd take from this conversation:

  • Find out your actual numbers before restricting anything. Ask about a 24-hour urinalysis, look at your potassium levels, and get a baseline before cutting out foods based on internet advice.

  • Check the date on any educational material you've been given. Renal nutrition guidelines have changed significantly in the last five years. Old handouts are still circulating.

  • Work with a renal dietitian, not just a general one. The CKD population metabolizes nutrients differently, and you need someone who understands that specific population.

  • Shift the question from "what do I cut out?" to "what can I add?" More water. More plants. More fiber. It's not glamorous, but it's what the evidence actually supports.

Jen's book, Plant Powered Kidney Nutrition, is on Amazon and is a great starting point — especially if you're in the mild to moderate stages of CKD and want to understand what you're actually working with. She also has a free private Facebook group (Plant-Powered Kidneys) with over 13,000 members where she does weekly Q&As.

Disclaimer: Everything we discuss here is just meant to be general education and information. It's not intended as personal mental health or medical advice. If you have any questions related to your unique circumstances, please contact a licensed therapist or medical professional in your state of residence.

Destiny Davis, LPC CRC, is solely responsible for the content of this article. The views expressed herein may or may not necessarily reflect the opinions of the guest.

The content in this blog post comes directly from a real, human interview between Destiny and her guest on The Chronic Illness Therapist Podcast. This written version was formatted using AI. Listen to the full episode to hear the actual conversation.

Listen to my full conversation with Jen Hernandez on Ep 121: What Your Kidney Disease Diet Actually Needs (And What the Internet Got Wrong)

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Podcast cover art for "The Chronic Illness Therapist Podcast with Destiny Davis, LPC CRC

Listen to Jen’s interview with me, Destiny Davis, on Ep 121: What Your Kidney Disease Diet Actually Needs (And What the Internet Got Wrong)

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Jen Hernandez, registered dietitian, board-certified specialist in renal nutrition, and author, in a light blue top against a vibrant orange background

Jen Hernandez is a nationally-recognized registered dietitian, board-certified specialist in renal nutrition, and author of Plant-Powered Kidney Nutrition. In 2018, Jen founded Plant-Powered Kidneys, a virtual private practice and educational hub for people with chronic kidney disease. Jen helps people in all stages of kidney disease, focusing on evidence-based nutrition and lifestyle guidelines. The clients and students of Plant-Powered Kidneys learn how to preserve their kidney function so that they can delay or even prevent kidney failure and dialysis.

Connet with Jen:
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Destiny Davis, LPC CRC, smiling in a pink sweater standing outdoors with crossed arms

Meet Destiny - The host of The Chronic Illness Therapist Podcast and a licensed mental health therapist in the states of Georgia and Florida. Destiny offers traditional 50-minute therapy sessions as well as therapy intensives and monthly online workshops for the chronic illness community.

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