Coffee's Effect on the Kidneys

Research has explored whether coffee is bad for the kidneys as well as other health effects of coffee, such as its impact on our immune system and risks of heart disease and cancer. Based on the current body of research, coffee doesn't appear to increase the risk of kidney disease, but coffee may affect blood pressure in certain people as well as those with kidney stones.

This article discusses coffee's effect on overall kidney health, as well as kidney disease and kidney cancer.

Is Coffee Bad for the Kidneys?

Numerous studies have concluded that coffee is unlikely to harm the kidneys or cause chronic kidney disease (CKD).

In fact, research has identified several benefits to consuming a moderate amount of coffee. The caffeine in coffee can improve energy levels and metabolism to aid in fat burning. Coffee is also high in polyphenols (a type of antioxidant) that are associated with a lower risk of health conditions such as cancer, heart disease, and diabetes.

However, certain precautions are recommended, such as drinking moderate amounts of coffee and limiting coffee if you have high blood pressure or kidney stones.

Studies on Coffee and Kidney Disease

Population-based epidemiological studies have tended to show an association between consumption of coffee and possibly a protective effect on kidney function.

A 2022 study concluded people who drank any quantity of coffee every day had a 15% lower risk of kidney injury and people who drank 2 to 3 cups of coffee daily had a 22%–23% lower risk.

A meta-analysis published in 2016 showed no association between coffee consumption and increased risk of kidney disease in male participants.

However, one study evaluating overweight/obese elderly people with metabolic syndrome found consuming more than 2 cups of caffeinated coffee daily resulted in a decline in kidney function compared to people drinking less than 1 cup daily. However, decaffeinated coffee did not cause a decline in kidney function.

It is important to note that eating too many high-potassium foods—like bananas, sweet potatoes, spinach, tomatoes, avocados, and oranges to name a few—can be hard on the kidneys if you have CKD. The good news is that coffee is in the low-potassium group, making it a safe choice in moderation.

Coffee and Genetic Kidney Disease

In the past, basic science studies have indicated that caffeine could increase the risk of growth of kidney cysts in patients with autosomal dominant polycystic kidney disease (PKD).

However, in more current clinical studies, consumption of coffee was not noted to be a risk factor for PKD progression.

Does Coffee Increase the Risk of Kidney Stones?

Beyond medical diseases of the kidney, there are still special situations where the intake of coffee might need to be moderated. One such case is people who form kidney stones.

Oxalate stones are one of the most common varieties of kidney stones, and it just so happens that one of the main sources of oxalate in our diet is regular coffee (black tea being the other culprit).

Therefore, patients with kidney stones, especially those with calcium oxalate stones, should still regard coffee as a possible risk factor.

Does Coffee Increase the Risk of Kidney Cancer?

The evidence regarding this is quite mixed. Studies have typically indicated a reduced risk of renal cell carcinoma with coffee consumption. However, for an unknown reason, this association seems to be true for caffeinated coffee only.

Decaffeinated coffee consumption seemingly increases the risk of clear cell renal cell carcinoma subtype, a particular kind of kidney cancer, but more studies need to be done to better understand this potential link.

The Relationship Between Coffee, Hypertension, and Kidney Disease

High blood pressure (after diabetes) is the biggest cause of kidney disease. 

There is some evidence that drinking caffeinated coffee could cause a short-lasting increase in blood pressure, with the effects seemingly exaggerated in older patients and people who are not regular drinkers of coffee.

Given this possible link between coffee intake and elevated blood pressure, the concern is often raised about coffee's ability to cause damage to the kidneys. Despite this plausibility, there is evidence to the contrary.

Data shows that as long as daily consumption of coffee does not exceed 3 to 4 cups (with each 8-ounce cup having anywhere from 100-200 mg of caffeine), there is no increase in the risk of kidney disease in healthy young subjects.

If you have high blood pressure or are at risk for high blood pressure, ask your healthcare provider if it’s safe for you to have caffeine and how much coffee is acceptable.

Decaf and Hypertension

Coffee has been found to increase nervous system activity as well as blood pressure, independent of its caffeine content. 

Therefore, the effect of an increase in blood pressure is even seen with decaffeinated coffee, making it appear that there might be something other than caffeine in coffee that could be responsible for this blood pressure elevation.

How to Safely Enjoy Coffee With Kidney Disease

Living with kidney disease does not mean that you have to cut out coffee entirely. There are ways to safely enjoy coffee:

• Limit the amount of coffee. Studies indicate consuming less than 3 to 4 cups of coffee daily doesn't affect kidney health.
• Skip the cream, creamers and milk. Black coffee is best because cream, non-dairy creamers, and milk contain phosphorus and potassium. When living with kidney disease, the kidneys aren't able to filter phosphorus and potassium from your blood as well, which can lead to heart complications. 
• Count coffee in your fluid allowance. When living with kidney disease, your kidneys may not be able to filter as much extra fluid from your body. You may need to limit or avoid drinking coffee if it’s causing excess fluid buildup.
• Choose alternative beverages. If caffeine affects your blood pressure, consider switching to decaf coffee, black tea, and green tea. Teas are lower in caffeine and potassium compared to coffee. And remember that water is the best thing to drink for your kidneys.

Summary

Current research indicates coffee is unlikely to harm the kidneys or cause chronic kidney disease and several potential health benefits have been identified based on the caffeine and antioxidant content of coffee.

However, people with high blood pressure or calcium oxalate kidney stones may need to limit their coffee intake. If you are unsure whether coffee is safe for you to drink, talk to your healthcare provider about how much coffee is acceptable for you.