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Green Tea And CKD: What Patients Need To Know

Three green-hued bags of Bigelow decaffeinated green tea with lemon
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Green tea has long been revered for its potential health benefits. If you have CKD, you might be wondering if those potential benefits extend to the kidneys. So, what's the deal with green tea and CKD?

Table of Contents

As a renal dietitian, I was inspired to write this article about green tea and CKD after reading a comment in a Facebook group. A patient stated their doctor had told them to avoid green tea for kidney health.

Admittedly, this is a recommendation I had never heard before! So I thought I’d dive into the evidence on my own and share my findings with you.

If you have CKD, I know it can be tough to get a straight answer on many things when it comes to nutrition & the kidneys! So here I’ll do my best to break down the facts on green tea – once and for all. Let’s take a look at some potential benefits, as well as potential concerns.

What Is Green Tea?

Hand holding a green box of Bigelow Green Tea. This article investigates the link between green tea and CKD
A box of Bigelow Green Tea at my local grocery store – this is my personal go-to brand of green tea!

Green tea is a popular drink that comes from the plant Camellia Sinensis. You can purchase it as a loose leaf tea, as bagged tea, or in a powdered form known as matcha. You can also find green tea in the form of a dietary supplement, generally called “green tea extract”.

Green tea contains a small amount of caffeine, approximately 28 mg per 8 oz cup (unless it’s decaffeinated, of course). 28 mg is about 1/3 of what you’d get in an 8 oz cup of coffee.

Additionally, green tea has long been studied for its health benefits. Let’s take a closer look at how it might benefit kidney health.

Potential Benefits of Green Tea for Kidney Health

Hand holding a green box of Twinings Pure Green Tea
Twinings Green Tea is also a popular choice.

Currently there are no clinical trials demonstrating direct kidney protective benefits of green tea. However, several attributes of green tea have sparked interest in its potential impact on kidney health:

Antioxidants

Green tea is rich in polyphenols – compounds in plants with antioxidant properties.

In particular, green tea contains a type of polyphenol called catechins. These antioxidants combat harmful free radicals (unstable molecules in the body that can contribute to cellular damage and inflammation), potentially benefitting the cells of the kidneys.

Reduced Inflammation

What is inflammation, anyway? When your body senses an injury or invader, your immune system releases inflammatory cells to start the healing process. For example, when you get a cut or when you get sick, the inflammatory response kicks off. This is called acute inflammation.

However, inflammation can also occur on a longterm, chronic basis.

According to the Cleveland Clinic, chronic inflammation happens when your body sends out inflammatory cells, even when there is no danger present. Chronic low-grade inflammation is a component of various disease processes, including kidney disease.

Compounds in green tea – primarly a polyphenol called epigallocatechin-3-gallate (EGCG) – have been studied for their impact on diseases associated with chronic inflammation, ranging from heart disease to diabetes to cancer. Current research indicates these findings may extend to people with kidney disease as well (1).

Blood Pressure Management

High blood pressure is a major risk factor for kidney disease progression. Along with diabetes, high blood pressure is one of the top two causes of chronic kidney disease.

Numerous studies suggest an association between green tea and improvements in blood pressure (2). This could be beneficial for people hoping to prevent kidney disease, or, among patients looking to better manage their hypertensive kidney disease.

That said, we need further research on the direct impact of green tea use on patients with CKD.

Diabetic Nephropathy

As noted before, diabetes is a major cause for chronic kidney disease. CKD caused by diabetes is also called diabetic nephropathy.

One 2012 study using mice as subjects showed green tea may offer preventative benefits for diabetic nephropathy, preventing hyperfiltration as well as preventing protein loss in the kidneys (3). High protein losses in the urine – also called proteinuria – is a known risk factor for the progression of CKD.

Studies among humans also appear to show a reduced risk for diabetes among regular green tea drinkers (4).

Limitations of Current Research on Green Tea and CKD

Despite some promising evidence regarding green tea and CKD, I have to acknowledge some limitations in the research.

Limited Clinical Evidence About Green Tea and CKD

First of all, most studies investigating the link between green tea and kidney disease in humans are observational. This means they can only establish correlations, not cause-and-effect relationships.

More clinical trials are necessary to show the direct impact of green tea on kidney health in humans. In particular, we want to see randomized controlled trials (RCTs) that study green tea and CKD, as RCTs are the gold standard for evidence.

Conflicting Findings About Green Tea and CKD

Some studies have shown the potential benefits of green tea on kidney function markers, while others haven’t replicated those findings. This inconsistency highlights the need for further research – especially among human subjects.

Varying Preparations of Green Tea in Research

Green tea has been studied in various forms, including brewed tea preparations, as well as dietary supplements containing green tea extract. Green tea supplements may contain only specific polyphenol compounds, as opposed to the full range of compounds offered by brewed green tea.

Therefore, it’s important to think which form of green tea is being used in any studies you encounter. Research on brewed tea may not directly translate to the effects of green tea supplements, and vice versa.

Potential Concerns Related to Green Tea and CKD

Many green tea beverages such as this Yogi green tea make health claims such as “supports vitality” which is pretty vague in my opinion. This particular green tea is likely similar to any other one you’d find at the store.

While there seem to be plenty of potential benefits to consider, we do need to discuss a few potential concerns. Remember, just because something is “natural” it doesn’t mean it’s safe.

Kidney Stone Formation

Certain components in green tea, particularly oxalate, could theoretically increase the risk of kidney stone formation in susceptible individuals when consumed in large quantities. However, existing research on this association is inconclusive.

NOTE: if you are a kidney stone former or think you may be susceptible, staying well hydrated is THE number one most important thing you can do – rather than obsessing about oxalates. Just like CKD, there’s not one “right” diet for kidney stones.

Interaction With Medications

Green tea may interact with certain medications, including blood thinners, chemotherapy drugs, and statin medications, as noted in this excellent article from the Memorial Sloan Kettering Cancer Center.

In general, I think it’s a good practice to run any new dietary supplements past your doctor before starting to use them. Yes, even with “natural” supplements like green tea.

Your doctor uses their expertise to prescribe specific therapeutic doses of medication to you – and a supplement that either heightens or dampens the effect of a medication could be very harmful.

Toxicity at High Doses

The same article from MSKCC also notes that high doses of green tea and its primary catechin EGCG have been associated with liver toxicity as well as nausea and abdominal pain. However, it’s worth noting these side effects seem more likely when using using green tea extract as a dietary supplement, as opposed to brewed green tea.

Potassium Content

Some varieties, especially loose-leaf teas, may have higher potassium content. If you have dietary restrictions related to potassium you may be been advised to monitor how much green tea you drink. That said – potassium in foods may not matter as much as you think.

Reduced Elimination of Kidney Toxins?

Finally – the study that kicked off this whole blog post! One study from 2015 (5) found that the catechins in green tea seemed to block elimination of kidney toxic compounds from the body. However, there are a few things that made me take this study’s findings with a grain of salt.

  1. This study involved providing very high doses of green tea to rats – likely more than a human would consume.
  2. Additionally, the green tea preparation given to the rats was brewed for 30 minutes. This long brew time increases the potency of the compounds in the tea (6). Any tea drinker knows you shouldn’t brew your tea for anywhere near that long! Green tea for enjoyment at home requires a brew time of 2-3 minutes on average.
  3. One single study isn’t enough for us to conclusively say “people with CKD should avoid green tea” – especially when the findings of the study haven’t been replicated elsewhere. In fact, there seems to be a greater body of evidence that green tea is protective against various types of kidney diseases (7).

In looking at many, many research and review articles about green tea, my takeaway is that current evidence tends to favor using green tea for kidney health, rather than avoiding it.

Another important factor to consider is how you choose to consume green tea: brewed tea or green tea extract supplements. Let’s look at the differences.

Brewed Green Tea Versus Green Tea Supplements

Left: hand holding a canister of matcha tea powder. Right: a hand holding multicolored pills.
Drinking brewed green tea isn’t exactly the same as taking green tea extract as a dietary supplement.

Both brewed green tea and green tea supplements can offer potential health benefits, but they differ in their delivery of these benefits.

Brewed Green Tea and CKD

Brewing green tea from the whole tea leaf means you get the full spectrum of potentially beneficial compounds in the tea leaves. Additionally, it delivers hydration and is a source of flavor and enjoyment.

Green Tea Supplements and CKD

Green tea supplements – typically marketed as green tea extract – can provide concentrated doses of specific compounds like polyphenols and catechins. When searching Amazon for supplements containing EGCG (the primary catechin in green tea), I found options ranging from 100mg to 1000mg per capsule. In contrast, one cup of brewed tea contains 200-300mg EGCG (8).

However, one downside of supplements is they may not contain the full range of beneficial compounds present in the whole leaf. Taking a pill also bypasses the hydrating and flavor aspects of brewed tea.

Lastly, it’s important to point out that most studies where green tea use had negative side effects involved green tea supplements, rather than brewed tea. A higher dose of green tea (as found in many supplements) does NOT necessarily equate to being a better choice for your health.

As a dietitian, I always encourage my patients to be cautious with dietary supplements. The industry as a whole is not very well regulated.

Additional Recommendations for Kidney Health

Improving kidney health isn’t as simple as adding a few cups of green tea to your day and hoping that does the trick.

The best approach for healthy kidneys is 1) managing the root cause of kidney damage and 2) taking steps to decrease the workload on the kidneys. My top tips for healthy kidneys include:

  • Control your blood sugar and blood pressure (diabetes and hypertension are the top two causes of CKD!)
  • Follow a kidney-friendly diet that prioritizes more plant protein than animal protein
  • Stay well hydrated, mostly with water
  • Incorporate regular exercise
  • Avoid smoking

If you need guidance in any of these areas, speak with your care team. I know that making changes and forming new habits is tough. This is why, as a dietitian, I help patients like you by offering specific action steps to help you form new, kidney-healthy habits.

Conclusion

Hand holding a beige and green box of green tea
Another example of a bagged green tea at my local grocery store. If you enjoy drinking green tea, it’s likely safe to do so in reasonable amounts.

Overall, my findings bode well for those who enjoy drinking green tea!

It appears to be safe, and possibly beneficial for kidney health to incorporate brewed green tea in varying amounts (9). However, I suggest caution with green tea extracts and supplements in high doses.

If you aren’t sure whether drinking green tea is a good option for you, talk with your renal dietitian and consult your doctor.

And remember – consuming any one single food or beverage is NEVER the key to managing kidney disease. There is no such thing as a magic bullet for kidney health.

Prioritizing an overall healthy lifestyle — including a balanced diet, regular physical activity, and managing other health conditions — remains the cornerstone of managing kidney disease effectively.

For personalized help and guidance on what to eat for optimal kidney health, consult with a Board Certified Renal Dietitian (like me!). You can also find me on Instagram and TikTok for additional tips every week – let’s connect! Until next time, be well. — Kate, Your Kidney Dietitian

Picture of Kate Zalewski, RDN, CSR, LDN

Kate Zalewski, RDN, CSR, LDN

Kate Zalewski is a Registered Dietitian and Board Certified Specialist in Renal Nutrition based in Chicago, Illinois. She helps people with kidney disease and other kidney health concerns navigate the complex and confusing world of nutrition. With a gentle yet realistic approach, Kate guides you in making changes that can improve your labs and slow disease progression, while still allowing you to enjoy the foods you eat. Book an appointment with Kate.

2 thoughts on “Green Tea And CKD: What Patients Need To Know”

  1. Susan L Creighton

    Kate. I want to thank you so much for this information about green tea and kidney health. I have been a big green tea drinker for years. I was diagnosed with Kidney Disease stage 3b last year. I have not given up having my green tea. After reading this information I do see I need to make an adjustment. Water is my friend a green once in a while I guess will be ok. Susan Creighton

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