By Hrefna Palsdottir

Kidney stones are a common health problem for many people.

Passing these stones can be incredibly painful. And, unfortunately, people who have experienced kidney stones are more likely to get them again (1).

However, there are a few things you can do to reduce this risk. This article explains what kidney stones are and outlines eight dietary ways to fight them.

What Are Kidney Stones?

Also known as renal stones or nephrolithiasis, kidney stones are composed of hard, solid waste materials that build up in the kidneys and form crystals.

Four main types exist, but about 80 percent of all stones are calcium oxalate stones. Less common forms include struvite, uric acid and cysteine (2, 3).

While smaller stones are usually not a problem, larger stones may cause a blockage in part of the urinary system as they leave the body.

This can lead to severe pain, vomiting and bleeding.

Kidney stones are a common health problem. In fact, about 12 percent of U.S. men and 5 percent of U.S. women will develop a kidney stone during their lifetime (3).

What's more, if you get a kidney stone once, studies suggest you are up to 50 percent more likely to form another stone within 5–10 years (4, 5, 6).

Below are 8 natural ways you can reduce the risk of forming another kidney stone.

Bottom Line: Kidney stones are firm lumps formed from crystallized waste products in the kidneys. They are a common health problem and passing large stones can be very painful.

1. Stay Hydrated

When it comes to kidney stone prevention, drinking plenty of fluids is generally recommended.

Fluids increase the volume and dilute the stone-forming substances in urine, which makes them less likely to crystallize (3).

However, not all fluids are equal for this purpose. For example, a high intake of water is linked to a lower risk of kidney stone formation (7, 8).

Beverages like coffee, tea, beer, wine and orange juice have also been associated with a lower risk (9, 10, 11).

On the other hand, consuming a lot of soda may contribute to kidney stone formation. This is true for both sugar-sweetened and artificially sweetened sodas (9).

Sugar-sweetened soft drinks contain fructose, which is known to increase the excretion of calcium, oxalate and uric acid. These are important factors for kidney stone risk (12, 13).

Some studies have also linked a high intake of sugar-sweetened and artificially sweetened cola to an increased risk of kidney stones, due to the phosphoric acid content (14, 15).

Bottom Line: Staying hydrated is important for preventing kidney stones. Yet some beverages may decrease the risk, while others may increase it.

2. Increase Your Citric Acid Intake

Citric acid is an organic acid found in many fruits and vegetables, particularly citrus fruits. Lemons and limes are especially rich in this plant compound (16).

Citric acid may help prevent calcium oxalate kidney stones in two ways (17):

1. Prevents stone formation: It can bind with calcium in the urine, thus reducing the risk of new stone formation (18, 19).

2. Prevents stone enlargement: It binds with existing calcium oxalate crystals, preventing them from getting larger. It can help you pass these crystals before they turn into larger stones (16, 19).

An easy way to consume more citric acid is to eat more citrus fruits, such as grapefruit, oranges, lemons or limes.

You can also try adding some lime or lemon juice to your water.

Bottom Line: Citric acid is a plant compound that may help prevent kidney stones from forming. Citrus fruits are great dietary sources.

3. Limit Foods High in Oxalates

Oxalate (oxalic acid) is an anti-nutrient found in many plant foods, including leafy greens, fruits, vegetables and cocoa (20).

However, your body also produces it in considerable amounts.

A high oxalate intake may increase oxalate excretion in urine, which can be problematic for people who tend to form calcium oxalate stones (21).

Oxalate can bind calcium and other minerals and form crystals, which can lead to stone formation (21).

However, foods high in oxalate also tend to be very healthy, so a strict low-oxalate diet is no longer recommended for all stone-forming individuals.

Nowadays, a low-oxalate diet is only suggested for patients who have hyperoxaluria, a condition characterized by high levels of oxalate in the urine (17).

Before changing your diet, consult your doctor or dietitian and get tested to find out whether you will benefit from limiting high-oxalate foods.

Bottom Line: Foods high in oxalate can be problematic for some people. However, seek advice from a health professional before limiting these foods, as it's not necessary for all stone-forming people.

4. Don't Take High Doses of Vitamin C

Studies indicate that vitamin C (ascorbic acid) supplements are associated with a higher risk of getting kidney stones (22, 23, 24).

A high intake of supplemental vitamin C may increase the excretion of oxalate in the urine, as some vitamin C can be converted into oxalate within the body (25, 26).

One study among middle-aged and older Swedish men found that vitamin C supplement takers may be twice as likely to develop kidney stones as those who don't take supplements (23)

However, note that vitamin C from food sources, such as lemons, is not associated with an increased stone risk (27).

Bottom Line: There is some evidence that taking high doses of vitamin C supplements may increase the risk of calcium oxalate kidney stones in men.

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