Kidney Diets: Less Fear, More Food

The For Kidneys Sake podcast series is brought to you by Imperial College Healthcare NHS Trust and North West London Integrated Care Board (NWL NHS)

What should you actually eat if you’ve just been told you have chronic kidney disease?

It’s one of the first questions patients ask and unfortunately, the internet often makes the answer far more confusing than it needs to be. In this episode of For Kidneys Sake, Dr Andrew Frankel and Prof Jeremy Levy are joined by renal dietitian Lina Johansson to cut through the noise and explain what people with early CKD (stages 2–3) really need to know about diet.

Rather than restrictive lists of forbidden foods, Lina explains why the focus should be on a cardio-renal-metabolic friendly diet: more fruits, vegetables, and whole grains, fewer ultra-processed foods, and sensible salt reduction. The conversation tackles common myths from unnecessary potassium restrictions to the modern obsession with high-protein diets and offers practical advice clinicians can confidently share with patients. 

Top 5 Takeaways

1. Most online “renal diet” advice is for advanced CKD — Much of the information patients find online is designed for people with late-stage kidney disease or dialysis, not those with early CKD.

2. Early CKD diets should focus on heart-healthy eating — A cardio-renal-metabolic friendly diet emphasises fruits, vegetables, whole grains, and healthier protein choices.

3. Potassium restriction is usually unnecessary — Patients with CKD stages 2–3 typically do not need to restrict potassium unless blood levels rise or certain medications require monitoring.

4. Ultra-processed foods are the real dietary villain — Reducing foods with additives, preservatives, and high salt content can improve blood pressure, metabolic health, and kidney outcomes.

5. Avoid high-protein trends — Extra protein shakes, bars, and supplements may accelerate kidney decline; moderation and more plant-based protein sources are preferable.

Resources Mentioned in This Episode:

KidneyWise
https://kidneywise.co.uk

Kidney Care UK – Kidney Kitchen 
https://www.kidneycareuk.org/kidney-kitchen/

Kidney Research UK
https://www.kidneyresearchuk.org

NHS Website
https://www.nhs.uk

Resource Links:
NICE GUIDELINES [NG203] chronic kidney disease: assessment and management Overview | Chronic kidney disease: assessment and management | Guidance | NICE

Northwest London CKD guidelines for primary care Chronic kidney disease (nwlondonicb.nhs.uk)

The purpose of this podcast is to inform and educate health care professionals working in the primary care and community setting. The content is evidence based and consistent with NICE guidelines and North West Guidelines available at the time of publication.

The content of this podcast does not constitute medical advice and it is not intended to function as a substitute for a healthcare practitioner’s judgement.

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Transcript

Joana Teles 

For Kidney's Sake makes kidney disease management easy. For Kidneys Sake is for primary care clinicians. For Kidney's Sake is nice, consistent, short and sweet. Welcome to For Kidneys Sake brought to you by Northwest London NHS Kidney Care Team.

Andrew Frankel 

Hello there, I'm Andrew Frankel, Consultant Kidney Doctor here at Imperial College Healthcare NHS Trust.

Jeremy Levy 

And hello, I'm Jeremy Levy, also a consultant nephrologist at Imperial, and I'm really delighted that today we're to be joined by a good friend of ours, Lina Johansson, who's also one of our colleagues here at Imperial, who's a fabulous kidney dietician. And the aim is to answer all the commonest questions that patients ask us about diet and chronic kidney disease, because they do ask us as well.

Lina Johansson 

Hi, ⁓ thank you for inviting me on this. I'm very excited to be here.

Jeremy Levy 

We're really excited as well, Lina and this is really really important because for all of us as clinicians doctors, nurses, pharmacists, actually patients always ask us what they can eat and actually what they shouldn't eat and people now are flooded and overwhelmed with information from social media, from advertising, friends and I certainly feel, I really hope Lina's not going to disagree with me on this occasion, I feel that we all doctors, nurses, pharmacists, we should be able to start this conversation. We should be able to start to answer those questions and we shouldn't, in my view, be saying, let's find you a dietician, but I hope Lina's not gonna disagree with me.

Lina Johansson 

No, not at all.

Andrew Frankel 

I completely agree with you that we do get so many questions from patients. One that I frequently get, particularly with people with early CKD, is how can I change my diet to improve my kidney function? So Lina. we need you to tell us from your experience what is the first thing people should do from a dietary perspective when told they have CKD.

Lina Johansson 

Well, Andrew.

I think it's really important to understand how people feel when they first get diagnosed in order to answer that question. So when people first get told that they have CKD, they feel really shocked and usually quite scared. And the first question that you probably get asked is, well, what can I eat to help my kidneys? And that's really because they want to feel some sense of control about what's happening. And what they usually get told is, well, go away and just try and eat less salt. So they go home, they Google, what can I eat with CKD? And then they get even more confused because they get faced with this barrage of information and they get more anxious. And then usually what happens is they start cutting out lots of foods that they normally eat because they're too scared and people won't have access to renal dietitian. So they really need the next best thing, which is information from trusted sources and also from trusted clinicians such as our colleagues in primary care. So I think that's what we can focus on over the next 10 minutes, 10-15 minutes of this podcast.

Andrew Frankel 

So you would start by helping people, pointing them in the right direction, take us through those first steps.

Lina Johansson 

So firstly...I think I tell them that the information that they're reading online is very unlikely to apply to them. The information online is confusing, conflicting, but mainly it's aimed at people with far more advanced CKD than stage two or stage three. Sometimes it's even aimed for people on dialysis. So it really talks about restricting a whole host of foods, which can be really counterproductive if you're applying it to stages two and ⁓ potentially cutting out lots of healthy foods like fruits and vegetables or cutting out all of your protein which is completely not necessary.

Jeremy Levy 

Lina, that's great. And you've been a bit modest here because, of there is a really, really good source of information on the web, which is actually Lina's own website, which is all about kidney diets and eating properly with early CKD, amongst other things called KidneyWise, which is a very good resource. But just I think to reinforce what Lina said, ⁓ I just Googled renal diet and kidney diet separately before this podcast. ⁓ And luckily, a very sensible page, in my opinion, appeared early, which was from Kidney Research UK.

But the second hit actually came from the Mayo Clinic and I thought it was really poor because it said, and I'll quote here, a renal diet is designed to support kidney health by limiting certain nutrients, particularly sodium, potassium, phosphorus and protein. So it straightaway started talking about limiting things, which is really depressing. And then I used a bit of AI. We're all doing it now, aren't we? And actually, Copilot actually was very good when I said early CKD.

So there is lots of confusion out there, Lina. So what is gonna be your summary? First line of best advice when we start this conversation.

Lina Johansson 

In summary, people need to eat a cardio renal metabolic friendly diet that protects the kidneys by really targeting their blood pressure, supporting their blood sugar control if they have diabetes and dyslipidemia. Now, this sounds really complex, but in essence, it's healthy eating, just with an eye on protein, which we'll talk about a bit later. So what does this look like? It's basically a diet with plenty of fruits and vegetables, plenty of whole grains, such oats, switching up your red meat and putting in more chicken or fish, including things like vegetarian sources of beans and pulses and reducing ultra-processed foods to cut down on sugar, salt, additives. So I hope people understand what we mean by ultra-processed foods.

Jeremy Levy 

Well, I'm worried about Andrew, Lina and I'm always worried about Andrew. I know all about it, but go on, remind us.

Andrew Frankel 

Yeah, I definitely need a bit of advice here because people talk about this all the time and I think we've to be really clear about what we mean by it.

Lina Johansson 

You. Yeah. So a good place to start is to explain what processed foods are as opposed to ultra processed foods. So processed foods are ones that have basic changes to them, such as foods that are frozen canned or that have just a few additions to them like sugar or a bit of salt or a bit of oil. So that's processed foods. Now, ultra processed foods will have ingredients in them that you wouldn't normally find in your kitchen such as things like preservatives, flavour and colour enhancers, texture modifiers, sweeteners and the list goes on. So some examples of these sorts of foods are soft drinks, ready-made or shop-bought cakes, shop-bought biscuits, some ready-made meals, ⁓ yeah, so those sorts of foods. So reducing ultra-processed foods is a way of really improving your health, cutting down on your unhealthy fats, reducing salt and sugar, and it's just sensible advice for all of us really to follow.

Andrew Frankel 

Does this, because this is what often concerns people, do patients have to punish themselves by having bland tasteless meals? Is that what will happen if you follow this advice?

Lina Johansson 

No, not at all, Andrew.

When people first reduce salt, can taste a little bit more bland compared to what they're to, but you do get used to that. But it's adding in all the other flavours that you can. And those are completely not restricted on a diet that's kidney friendly. So things like garlic, ginger, all your herbs, lemon, all your spices like cumin, chilli, all the masalas, turmeric, those are absolutely fine.

⁓ But on the topic of salt, the guidance is to keep salt intake to roughly less than six grams a day, which is about a teaspoon. And in the UK, people tend to eat about nine grams of salt a day. So...

If you are using processed or ultra-processed foods, and in some cases people do, a good tip is to use the traffic light system, which can be helpful to work out if food is low, medium or high in salt. But cooking from fresh is also good because you can use small amounts of condiments, even if they do contain a bit of salt, to help with flavour. So in all, reducing salt, try to eat more from fresh, reduce the amount of processed foods and look at traffic light labels. Those are all good places to start.

Jeremy Levy (08:53)

Okay, so we've got slightly lower salt intake, cooking mostly from fresh ingredients, minimising ultra processed foods. Bread actually doesn't it? Contains quite a lot of salt, so if you're eating toast for breakfast, bread with soup for lunch and then more in the evening, you're actually getting quite a lot of salt in your bread. Okay, so we've done salt and we've done ultra processed food and Andrew's learnt one thing already. What comes next?

Lina Johansson (09:17)

Well, potassium comes up all the time.

Jeremy Levy (09:19)

⁓ our favourite friend, potassium. I'm glad you said that. Patients get obsessed with potassium, don't they? And stopping eating everything with potassium. And that goes back to what you said at the beginning about people on dialysis where potassium is a wicked brother. But actually, at this stage, it's not really. And most of it's rubbish advice, isn't it?

Lina Johansson 

Yes, is really unnecessary to limit potassium. So for most people with stage 2 or 3 CKD, they do not need to restrict potassium or indeed phosphate, which might be another thing that they've read about. ⁓ But restricting potassium happens when people have zero guidance on what to eat. So they Google and they read about these high potassium foods and then start trying to follow it. And potassium is in healthy foods like fruit, some vegetables and it brings all sorts of health benefits like reducing the risk of cancers and it's good for bowel health so we need people to keep on eating good sources of potassium for as long as possible.

Andrew Frankel 

So when do people with CKD actually need to become aware of potassium rich foods?

Lina Johansson 

I think there are only two situations really when they need to start becoming aware. So if their blood potassium is starting to reach around 5.3 or above, or if they're on medications such as ACE's ARBs or Finerenone and it's only then that they should really be careful. But even then they should be eating plenty of fruits and veg, just minimising those that are high in potassium or boiling them.

⁓ And also ultra-processed foods tend to have a lot of additives which have potassium, so that's another reason to avoid them.

Jeremy Levy 

That was really clear Lina, Thank you very much. And it comes back to things we've talked about in earlier episodes. Patients knowing their numbers could be really, really useful. As you just mentioned, if people's potassiums are running at 4.2, there's absolutely no problem here whatsoever. They really don't need to worry about it. So knowing their numbers is a really good piece of advice for patients as well. You briefly mentioned phosphate. us a little bit about phosphate and when it's relevant.

Lina Johansson 

So for early CKD, phosphate is not an issue. There's no reason to follow a diet, so they can simply just ignore this.

Andrew Frankel 

Okay, another diet reconstituent that I'm so often asked about is protein. Because there's so much on social media about increasing protein intake in older people, people using GLP-1 receptor agonists for weight loss, and also of course all the bodybuilders, male and female, who are obsessed with protein. It seems to be everywhere.

Lina Johansson 

Absolutely, Andrew. It is all over social media.

But however, there is some evidence that a high protein diet can lead to a faster deterioration in kidney function. So we generally say, don't eat extra protein. So don't have those high protein bars, the high protein yogurts, the high protein shakes and powders. And if you are eating quite a bit of animal protein, just try and think about switching it up and being more flexitarian. Having more vegetarian sources of protein like lentils, chickpeas, legumes, soy products and dairy. So it's just moving the dial a little bit more away from high protein animal-based sources.

Jeremy Levy 

And protein clearly is still important, isn't it? So we don't want them to stop eating protein. And you went past vegetarianism. Can people stay vegetarian if they've got chronic kidney disease? And is it a better diet?

Lina Johansson 

Yes, absolutely.

Absolutely people can stay vegetarian if they have CKD and as Lina we have quite a high population of Asian vegetarians in North West London. Is it better? Well, I think we could probably all benefit from having a more plant-based diet.

And on that note, I just want to explain probably what a plant-based diet is because that often confuses people. So a plant-based diet doesn't mean being vegan or being 100 % vegetarian. You can still have some lean meat or fish as part of a plant-based diet. So it's eating more plants, eating from fresh, it's part of a healthy diet, whether you have CKD or not, and you can still include some animal-based protein in there.

Andrew Frankel 

So useful advice irrespective of whether you have CKD. in summary, how do you approach patients when starting to talk about diet if they've got CKD stage two or three?

Lina Johansson 

I think the first thing I start saying is you do not need a potassium restriction unless indicated. You likely they would benefit from having more fruits and veg and more whole grains as most people don't eat enough of those anyway. Then about reducing ultra processed foods as we talked about and thinking about having a more plant based diet in relation to protein sources and last but not least, producing salt.

Andrew Frankel 

And have you got any tips? I know this is really where dieticians who support patients really are so useful and helpful. How do you make this stick with patients? Many people are not initially eating a healthy diet currently. How do you actually make this change and then this stick?

Lina Johansson 

So, Andrew, you're absolutely right. This is the key, really. And I think it's really important to understand where your patient is at and suggesting a change, maybe even one change, that they can understand the reason for and that is manageable and achievable for them to undertake. So one easier way, instead of describing it as a kidney diet, which often brings a lot of confusion with it, describing it as a heart health diet can make it feel much more implementable, much more accessible. And not talking about what you can't eat, but what you can eat. Because just saying, eat less salt, will send people straight to Dr. Google.

Jeremy Levy 

So that's been really, really helpful. Talking about heart with kidneys, heart friendly diets, heart healthy diets seems to be really important. And we know here on this podcast, everything about kidney health, helps heart health and cardiovascular disease all together. And we haven't touched on hypertension, but everything we've talked about helps prevent hypertension or make it better on all aspects of cardiovascular disease. So actually everything we've talked about covers sort of the whole range of cardiorenal, metabolic hypertensive disorders doesn't it?

Lina Johansson 

Yeah, absolutely. That's why it's so important that diet features in CKD stages two and three, because it gives you the baseline for your future health.

Jeremy Levy 

This has been really, really brilliant, Lina. I'm going to ask you in a moment to give you all three top tips, but you never answered my question at very beginning, which I'm going to get back to. Are you happy when people like me and Andrew and our GP colleagues out there and practice nurses start this conversation?

Lina Johansson 

Absolutely, we need you because they will not have access to renal dietitians. So I'm really hoping that this podcast can give you the first tips in terms of starting that conversation and to give some really useful, sensible advice to people with CKD.

Jeremy Levy 

I'm really relieved you said that, because otherwise I'm going to be in deep trouble. I agree with you completely as well, because otherwise, if our colleagues out there simply say, go and Google it, as we said at the beginning, they'll just get terrible advice.

Andrew Frankel 

Well, it's...And Jeremy, of course, this podcast goes out to all the healthcare workers, particularly in primary care. Most of these people are sitting in primary care and we really need to give this sensible advice to them so that they feel confident in actually liberating people from these Google-defined diets.

Lina Johansson 

Absolutely.

Jeremy Levy 

Andrew, we're at exactly the same place you and I and luckily, Lina your top three takeaways from this conversation about Dias and CKD.

Lina Johansson 

Right, so I think firstly we need to direct people to really trusted sources of information online. So Kidney Care UK is excellent and they have a section called Kidney Kitchen which has loads of recipes, loads of good advice and it's been endorsed by kidney dietitians and it's a really good, good source for people. NHS badge websites are also good and Kidney Research UK also has good information. So that's my top tip. With early CKD most people do not need potassium restrictions and that's important to reinforce.

The diet that is cardio-renal metabolic friendly has more fruits, more veg, more whole grains, a more flexitarian approach with more pulses, less ultra-processed foods. so cooking from fresh, even if it's only one or two meals a week, every little counts. Those will be my top tips.

Jeremy Levy 

Lina, that's been absolutely brilliant. And I am going to remind everybody because actually Lina's website, https://kidneywise.co.uk, is just brilliant. I look at it actually every week because there's a great newsletter and that's got great resources out there as well.

Andrew Frankel 

And I agree completely. Been fantastic speaking to you, Lina. Thank you so much.

Lina Johansson 

Thank you both. I've really enjoyed being here today and I must also say that I listen to your podcasts every time it comes out and they're fantastic. Thank you so much.

Jeremy Levy 

That's great. And Andrew, you didn't remind listeners that the whole set of our podcast is available online. We've got a menu and a library. People can go back and listen to all the previous episodes and they can subscribe to a newsletter to remind them about CKD issues and what future episodes are going to be coming. But that was what you were meant to say, but you'd forgotten. So I've said it.

Andrew Frankel 

I forgot, yes

I know, and of course you forgot, perhaps it would useful to tell people that these podcasts are entitled for kidneys sake.

Jeremy Levy 

Bye everybody.

Lina Johansson 

Bye.

Joana Teles
Thank for listening. We hope you enjoyed this episode. All information is fully consistent with NICE and Northwest London guidelines. You can find out more in the show notes and contact us with any suggestions or questions. Send us a text using the text function at the top of your show notes. Thank you for listening to For Kidneys' Sake podcast and we see you at the next episode.