Written by Cherilyn Davis, MD | Reviewed by Katie E. Golden, MD
Updated on June 3, 2024

Key takeaways:

If you have kidney disease, what you drink and how much you drink can affect your kidney function.

There’s research to show that some drinks and juices can slow the decline of kidney function. Drinks like water, low-fat milk, and coffee can help protect the kidneys.

When it comes to kidney health, moderation is really important. To function at their best, your kidneys need the right balance of fluid and specific nutrients.

Hirurg/E+ via Getty ImagesThe kidneys are constantly filtering the fluids in your body to get rid of toxins and waste. So, it probably comes as no surprise that what you drink can affect your kidney function. And if you have any type of kidney disease — whether it’s from a chronic condition or a temporary illness — paying attention to your fluid intake is particularly important. We’ll go through five drinks and juices that can help your kidneys function at their best.

Water
About 60% to 70% of your body is water. And your kidneys rely on water to make urine, which is how they remove waste from your body. Water also helps to keep your blood vessels open so that blood can reach your organs, including your kidneys.

You help protect your kidneys when you drink enough water each day. One study showed that people who drank almost 2 L of water daily were less likely to develop kidney problems. This was especially true for older adults and men.

But what about people who already have declined kidney function? Some studies have looked at whether drinking water can increase your GFR. GFR stands for glomerular filtration rate, which is a way to measure kidney function. The higher your GFR, the better your kidneys function. One study found that when people with kidney disease drank more water, their GFR didn’t increase. But another study showed that people who drank more water were more likely to have a higher GFR, and vice versa. People who drank less water were more likely to have a lower GFR.

So, at the end of the day, it’s unclear if drinking water can improve kidney function in people with kidney disease. But if you have low kidney function, staying hydrated can help keep your kidneys working better. Severe dehydration can actually lead to kidney damage, making kidney disease worse. And even mild dehydration, if it happens too often, can cause kidney damage. Dehydration ultimately leads to the buildup of waste in your body, making your kidneys work harder to remove it.

Some people with chronic kidney disease may need to monitor their fluid intake more than others. If you have late-stage kidney failure or require dialysis, too much fluid can overwhelm your kidneys and cause other health issues. Your healthcare professional can help figure out the right amount of fluid for you based on your kidney function and overall health.

Low-fat milk
One long-term study found that people with chronic kidney disease who drank low-fat milk had a slower decline of their kidney disease. In other words, their kidneys worked better for longer.

Scientists think that certain nutrients in dairy — like calcium, potassium, vitamin D, and magnesium — may help lower blood pressure and protect the kidneys. Of note, the researchers didn’t see that same benefit in people who drank high-fat milk. So it’s possible that too much fat content may decrease the potential benefits of milk, or it may even be harmful.

Coffee
Many people wonder if coffee is bad for the kidneys. But experts actually believe that coffee may help protect your kidneys. Research shows that coffee consumption is associated with a lower risk of developing kidney disease. This may be because it improves blood sugar and lowers inflammation in the kidneys. But it’s not clear if it can slow how quickly kidney disease worsens.

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In one study, participants who drank 1 or more cups of coffee daily had a lower risk of death from kidney disease compared to people who never drank coffee. Another study found that people who drank 3 cups of coffee a day had an even lower risk of disease. But these studies didn’t find a similar benefit in people who already had poor kidney function. So, coffee may not have the same protective effects for people with kidney disease.

If you have kidney disease and like drinking coffee, keep these things in mind:

Drink coffee in moderation. Aim for fewer than 3 cups a day. That’s because large amounts of coffee can be high in potassium, which can lead to high potassium levels in someone with bad kidneys.

Drink plain, black coffee. Added ingredients can be harmful. For example, syrups can be high in potassium and phosphorus. They may also contain a lot of sugar.

Consider drinking decaf if regular coffee increases your blood pressure. More research is needed to know whether caffeine adds to the health benefits of coffee. But experts do know that a spike in blood pressure is hard on the kidneys.

Green tea
Green tea contains catechins, which are antioxidants. Antioxidants help decrease inflammation in the body, which can be helpful for your kidneys. Green tea has also been shown to decrease the risk of kidney stones.

In particular, green tea contains the catechin epigallocatechin-3-gallate (EGCG), which may be helpful for people with kidney disease. Several studies have shown that it can slow the decline of chronic kidney disease. But it’s important to note that these studies were done in the lab in “disease models,” not in actual humans.

So, just like coffee, it’s best to drink green tea in moderation if you have kidney disease.

Unsweetened cranberry juice
You may have heard that cranberry juice is good for kidneys. Cranberries are rich in flavonoids, another type of antioxidant. You may have heard that cranberry juice can help prevent UTIs (urinary tract infections). That’s because cranberry juice may help prevent bacteria from sticking to the urinary tract.

People with kidney disease need to be extra careful about preventing UTIs. Some UTIs can lead to pyelonephritis — an infection in the kidneys. Scientists think that cranberries also interfere with bacteria sticking to the kidneys, just like they prevent it from sticking to the urinary tract.

Look for low-sugar or unsweetened options. Extra sugar can increase both blood sugar and blood pressure, which are both harmful to your kidneys.

Is beet juice bad for your kidneys?
Beet juice has become a popular health topic given that it’s packed with antioxidants. But how does it affect the kidneys?

Research suggests that drinking beet juice can help lower your blood pressure. And keeping your blood pressure within a normal range is one of the best things you can do to protect your kidney health. And one small study of people with chronic kidney disease suggests that drinking beetroot juice may help slow down the progression of heart and kidney disease. But this is early research, so it’s too early to draw any conclusions.

It’s also important to note that beet juice contains oxalates. This can be a problem for people who are prone to a certain type of kidney stone (calcium oxalate stones). But for most people, oxalate foods don’t pose any significant health risks.

What drinks should people with kidney disease avoid?
A person with kidney disease should avoid drinking:

Cola beverages: Studies show that drinking two or more cola drinks a day may be harmful for people with kidney disease. Experts believe the phosphoric acid in cola drinks can strip calcium from bones, increasing the risk of kidney stones and kidney failure.

Alcohol: Drinking alcohol makes your kidneys less able to filter your blood and increases blood pressure, which can lead to kidney damage.

Sugary beverages: Sweetened drinks can harm the kidneys in different ways. They increase blood sugar, blood pressure, and inflammation in your body. Sugary drinks can also contribute to weight gain, which further increases the risk for these harms for your kidneys.

There’s some evidence that drinking two or more diet colas a day may also worsen kidney function. But the study was done only in white females, so more research is needed to be certain.

The bottom line
When it comes to keeping your kidneys healthy, what you drink can make a difference. To help protect your kidneys, drink beverages like plain water, coffee with low-fat milk, and unsweetened cranberry juice. But like most diet and nutrition advice, the research in these areas is constantly evolving. The safest approach is to drink your beverage of choice in moderation.

Written by:
Cherilyn Davis, MD
Cherilyn Davis, MD, is a board-certified pediatrician in New York City. She has held local and national roles at the American Medical Women’s Association including board member of the physician division and physician chair of social media.

Edited by:
Katie E. Golden, MD
Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.
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References
Amin, R., et al. (2022). Therapeutic potential of cranberry for kidney health and diseases. eFood.

Bao, H., et al. (2016). The Green Tea Polyphenol(—)-epigallocatechin-3-gallate and its beneficial roles in chronic kidney disease. Journal of Translational Internal Medicine.

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