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Do you have a love-hate relationship with coffee? Sometimes, misinformation and/or lack of information often leads people to believe some of the bad rep towards coffee. I have heard people saying that coffee makes you acidic, others say that it can cause dehydration, and some believe that it is bad for the heart. What negative feedback about coffee have you heard, recently?

I know there are also some people that think coffee can cause kidney stones. Coffee lovers will say that it’s not true. I love coffee and I would confirm that it will not cause kidney stones. I have been drinking coffee for more than two decades and I’ve never had a problem with it.

Well, some of you who are reading this may argue that this is only a personal bias and experience. While you have a point, I think it will also be beneficial if we look at established clinical studies and medical research confirming that coffee does not cause kidney stones.

What are kidney stones?

Kidneys work as a filter, cleaning the waste from the blood and creating urine. Sometimes, salt and other minerals that are dissolved in the urine form a crystal and get stuck in our kidney. These formations are called kidney stones. Sizes of stones can range from small as a sugar crystal to as big as a ping pong ball. We rarely notice the presence of a kidney stone until they cause a blockage. When this happens, one can feel an intense pain. It means that kidney stones have traveled into the ureters, the narrow tubes leading to the bladder.

When you have kidney stones, you can feel any of the following symptoms:

  • Severe pain in the back, belly, or groin
  • Frequent or painful urination
  • Blood in the urine
  • Nausea and vomiting

According to National Health Services UK, kidney stones often form when concentrations of minerals in the body become too much and start to build up. The kidney cannot filter all of the waste and some of these minerals stay in the kidney. Kidney stones can be made up of any of the following minerals:

  • calcium
  • ammonia
  • uric acid – a waste product produced when the body breaks down food to use as energy
  • cysteine – an amino acid that helps to build protein

You and I are prone to developing kidney stones, but the following conditions increase the risk:

  • eat a high-protein, low-fibre diet
  • are inactive or bed-bound
  • have a family history of kidney stones
  • have had several kidney or urinary infections
  • have had a kidney stone before, particularly if it was before you were 25
  • have only one fully working kidney
  • have had an intestinal bypass (surgery on your digestive system), or a condition affecting the small intestine, such as Crohn’s disease

It is important to understand the nature and causes of kidney stones. This gives us a clear picture of how kidney stones are developed and whether or not drinking coffee can cause them.

If food and drinks can cause kidney stones, you should note that calcium, ammonia, uric acid, and cysteine are the most common minerals that cause kidney stones. If you eat foods or drink liquids that are rich in these minerals, over-consumption of such can lead to kidney stones. However, it is important to note that coffee does not contain any of the former minerals. Coffee, essentially, contains caffeine and other antioxidants. As a matter of fact, antioxidants are typically beneficial compounds that help avoid cell damage.

Due to its high antioxidant content, coffee is known to help decrease the risk of some cancers and liver diseases. You can also lose weight if you drink coffee in moderation.

Let’s now focus on medical evidence that coffee does not cause kidney stones.

Coffee and kidney stones: research findings

Researchers at the Harvard School of Public Health, Department of Nutrition, developed a study to assess the effects of certain beverages on kidney stone formation. Published in the American Journal of Epidemiology, the researchers determined the relationship between 21 different types of beverages and the risk of kidney stone formation in more than 45,000 men. They found that caffeinated coffee reduced the risk of kidney stone formation by 10 percent.

Another significant finding, the research team found that whether the coffee is decaf or not, the same effect is achieved. Those who drink decaf coffee also had 10 percent reduction in kidney stone formation.

In another useful study published by PubMed, two large groups of nurses and one group of physicians were followed for many years to determine what habits and diets are considered healthy or unhealthy. For the duration of the study, some people in the group developed kidney stones and some did not. The interesting part of the study was the questionnaire used determined the specific food and beverage intake of the participants, as well as the amount taken.

The amounts are important to keep in mind. For coffee and tea, it was 8 oz servings. For juices, a small glass. For carbonated drinks and beer, a glass, bottle or can. For wine, a 5 oz glass. Servings were graded over the range of less than 1, 1, 2-4, and 5-6, weekly, as well as more than 1 serving a day. A significant effect meant that as the amounts increased, the risk of new stones increased or decreased in rough proportion. The researchers called it the ‘dose’ effect.

According to the researchers, colas and non-cola drinks sweetened with sugar were associated with the development of kidney stones. Punch was also associated with more stones, but not all drinks with sugar in them were bad. Apple juice, grapefruit juice, and tomato juice did not raise or lower risk of stones.

How about coffee? It turns out that men who drank coffee had a lower risk of developing kidney stones.

In a report published by the American Study for Nutrition, the researchers analyzed 217,883 participants over an eight-year period and they found that coffee can lower the risk of kidney stone incident.

How to prevent kidney stones?

However, drinking coffee is not the only solution to reduce the risk of developing kidney stones. Dr. Melanie Hoenig, an assistant professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center, shared the top ways to prevent kidney stones. Here are her recommendations:

Drink plenty of water.

Water helps dissolve the substances in the urine. Try to drink at least 8 glasses of water a day. Also, try other liquids like fresh fruit juices, particularly lemon and orange juice. The citrate in these drinks can dissolve stones easily.

Get the calcium you need.

Know your daily calcium requirement. Lack of calcium or over-consumption can lead to kidney stone formation. Men 50 and older should get 1,000 milligrams (mg) of calcium per day, along with 800 to 1,000 international units (IU) of vitamin D to help the body absorb the calcium. Preferably, get calcium from natural sources so the body can use it easily.

Reduce sodium.

Eat less table salt. This is especially true if you are prone to developing kidney stones. Current guidelines suggest limiting total daily sodium intake to 2,300 mg. If sodium has contributed to kidney stones in the past, try to reduce your daily intake to 1,500 mg. This will also be good for your blood pressure and heart.

Limit animal protein.

Eat less red meat. Limit your chicken and eggs. Instead, get plant-based proteins, because they don’t reduce citrate levels as much. Plus, it is good for your heart.

Avoid stone-forming foods.

Beets, chocolate, spinach, rhubarb, tea, and most nuts are rich in oxalate, and colas are rich in phosphate, both of which can contribute to kidney stones.

Strive for a well-balanced diet. Anything in excess is bad for the health. The same thing is true with coffee. It can help reduce kidney stone formation, but drink coffee in moderation. At most, three cups a day are good enough to let you enjoy coffee and get its health benefits.