If you have ever had kidney stones, chances are that you have a vivid memory of the experience. Kidney stones can cause excruciating pain that radiates from the kidney or the flank. This knife-like pain is often accompanied by nausea, vomiting, and abdominal swelling. Infection can make the symptoms of kidney stones even worse, causing fever and chills plus the disconcerting discovery of blood in the urine in between attacks.
Juicing can make the condition better or worse, depending on the choice of juices. Other beverages can also make the condition better or worse, helping stones grow or helping stones dissolve. But before we get into the reasons certain juices and other kinds of drinks make kidney stones better or worse, it is helpful to have a brief review of what kidney stones are.
What Are Kidney Stones?
A kidney stone is usually a crystalline accumulation of calcium with oxalate, uric acid, or cystine. Other chemicals may form crystals with calcium to form stones in rare cases. These chemicals accumulate in urine. The urine may become so concentrated that calcium crystals precipitate out of the urine on their own, or crystals may form around tiny particles called nedi. Some of the microorganisms that cause urinary tract infections, such as Proteus, may also serve as the platform for growing stones.
The more acidic the urine is (from removing acid from the bloodstream after consumption of excess protein), the more chemicals that can cause stones will be dissolved in it. The smaller the volume of urine (due to dehydration or failure to drink enough water), the more readily these chemicals will precipitate out to form stones.
The most common kind of kidney stone, accounting for about 75% of cases, is formed from calcium and oxalate. Calcium oxalate precipitates on calcium phosphate, which accumulates in the purifying loops of the kidney and oozes out into the passageways that channel urine to the bladder. These calcium phosphate plaques interact with oxalates found green leafy vegetables such as Swiss chard (silverbeet), spinach, beet greens, parsley, and lamb’s quarters, and also found in star fruit, poppy seeds, almost all nuts, cocoa and chocolate, many kinds of berries, and the natural sweetener known as palm sugar or jaggery. (There is a guide to the oxalate content of foods later in this article.)
Kidney stones cause excruciating pain as the ureter, which carries urine away from the kidneys, expands and contracts to allow the flow of urine. The lining of the ureter contains pacemakers to regulate the flow or urine into the bladder. These pacemakers force the flow of urine, and stones, into the bladder. Every push against the kidney stone causes a wave a pain that is described as being worse than childbirth, gunshot, or broken bones.
Smaller stones are more painful than larger stones. When a larger stone blocks the flow of urine, nervous reflexes override the pacemakers to change the pressure against the stone, and inflammatory processes expand the ureter. When a smaller stone is just traveling down the ureter, however, it causes pain every time the ureter contracts. Really awful diets cause kidney dysfunction (and sometimes kidney failure) but relatively little kidney pain. Generally healthy diets that contain plant foods and plant juices in the wrong amounts can cause recurring attacks of kidney stones.
Juicing to Stop the Formation of Kidney Stones
There are four different kinds of kidney stones that form through 20 different chemical processes. There are no recommendations for juicing that will work in each and every case. For the 75% of kidney stones that are calcium oxalate stones, however, juicing recommendations are straightforward.
Part of preventing calcium oxalate stones is avoiding juices made with fruits and vegetables that are high in oxalic acid, which combines with calcium phosphate in the lining of the ureter to form calcium oxalate. The one fruit that contains extraordinarily high amounts of oxalic acid that sometimes triggers an attack by itself is starfruit, also known as carambola. The one vegetable that contains enough oxalic acid to trigger an attack is lamb’s quarters. Neither food is often used to make juices and neither food often appears on the table, but both must be avoided.
Which foods cause the most problems for kidney stones? Here’s a list of the oxalate contents of common foods in descending order. There are:
- 800 mg of oxalates in a 3-1/2 oz (100 gram) serving of stewed rhubarb,
- 675 mg of oxalates in a 3-1/2 oz (100 gram) serving of beet roots,
- 645 mg of oxalates in a 3-1/2 oz (100 gram) serving of Swiss chard (silverbeet) or beet greens,
- 600 mg of oxalates in a 3-1/2 oz (100 gram) serving of spinach,
- 269 mg of oxalates in a 3-1/2 oz (100 gram) serving of wheat germ,
- 207 mg of oxalates in a 3-1/2 oz (100 gram) serving of dried soybeans,
- 200 mg of oxalates in a 3-1/2 oz (100 gram) serving of 16 oz/500 ml glass of iced tea,
- 187 mg of oxalates in a 3-1/2 oz (100 gram) serving of roasted peanuts,
- 146 mg of oxalates in a 3-1/2 oz (100 gram) serving of okra,
- 141 mg of oxalates in a 3-1/2 oz (100 gram) serving of fiber cereal,
- 110 mg of oxalates in a 3-1/2 oz (100 gram) serving of lime zest (which would be a problem if lime juice for limeade is made in a macerating juicer instead of a citrus juice extractor),
- 100 mg of oxalates in a 3-1/2 oz (100 gram) serving of parsley,
- 95 mg of oxalates in a 3-1/2 oz (100 gram) serving of peanut butter,
- 90 mg of oxalates in a 3-1/2 oz (100 gram) serving of tomatillos (used in Latin American and Southwestern US cooking),
- 88 mg of oxalates in a 3-1/2 oz (100 gram) serving of green gooseberries,
- 83 mg of oxalates in a 3-1/2 oz (100 gram) serving of lemon zest (which would be a problem if lemon juice for lemonade is made in a macerating juicer instead of a citrus juice extractor),
- 78 mg of oxalates in a 3-1/2 oz (100 gram) serving of tea that has been brewed for 6 minutes (200 mg in a cup of tea brewed 6 minutes),
- 72 mg of oxalates in a 3-1/2 oz (100 gram) serving of tea that has been brewed for 4 minutes (160 mg in a cup of tea brewed 4 minutes),
- 55 mg of oxalates in a 3-1/2 oz (100 gram) serving of tea that has been brewed for 2 minutes (125 mg in a cup of tea brewed 2 minutes),
- 74 mg of oxalates in a 3-1/2 oz (100 gram) serving of collard greens,
- 53 mg of oxalates in a 3-1/2 oz (100 gram) serving of black raspberries,
- 25 mg of oxalates in a 3-1/2 oz (100 gram) serving of dandelion greens,
- 20 mg of oxalates in a 3-1/2 oz (100 gram) serving of celery,
- 15 to 18 mg of oxalates in a 3-1/2 oz (100 gram) serving of in red raspberries, strawberries, blackberries, and blueberries,
- 15 mg of oxalates in a 3-1/2 oz (100 gram) serving of green peppers and hot peppers,
- 15 mg of oxalates in a 3-1/2 oz (100 gram) serving of green beans,
- 14 mg of oxalates in a 3-1/2 oz (100 gram) serving of white bread,
- 10 mg of oxalates in a 3-1/2 oz (100 gram) serving of plums,
- 8 mg of oxalates in a 3-1/2 oz (100 gram) serving of cranberry juice,
- 6 mg of oxalates in a 3-1/2 oz (100 gram) serving of tomato juice, and
- 5 mg of oxalates in a 3-1/2 oz (100 gram) serving of peaches.
Foods not listed here are generally not a problem for people who have kidney stones. Any food that contains more than 50 mg of oxalates in a 100-gram serving will tend to make kidney stones worse. Beets, Swiss chard, parsley, tomatillos, green gooseberries, and both green and black tea are a problem in juice mixes, and wheat germ is a problem in smoothies. These foods are especially problematic when they are eaten by themselves. However, if they are consumed within an hour or two of drinking a high-calcium beverage (such as cow’s milk or calcium-fortified almond or soy milk) or eating a high-calcium food (such as dairy or tofu), they are not as much of a problem because the calcium in other foods binds the oxalate in the berries or vegetables and the calcium oxalate is expelled with feces rather than reassembled in the kidneys.
Since almost all kidney stones contain calcium, it would seem like a good idea to restrict the consumption of calcium-rich foods, but it’s actually not. Calcium in the diet precipitates oxalates in the stomach so that they do not reach the bloodstream. Most doctors , however, advise taking no more than 600 to 800 mg of calcium supplements per day or consuming dairy foods more often than once a day. Some calcium in the diet is essential for bone health and the regulation of the nervous system.
Citrus Juices and Kidney Stones
People who have kidney stones have been traditionally warned to avoid all citrus juices except lemon juice. The reason for this recommendation was survey data collected by the Harvard School of Public Health in the 1980′s. Epidemiologists who asked people who had kidney stones and people who did not have kidney stones what they ate and drank found that people who reported they drank a cup of grapefruit juice or more every day had an 85% higher rate of kidney stones.
The study also found positive associations between kidney stones and consumption of apple juice, tea, wine, and beer, but that both decaf and regular coffee seemed to reduce the risk of kidney stones. Researchers concluded that the acidity of fruit juices, especially orange and grapefruit, released oxalates from plant foods, but that lemon juice had a different chemistry that actually prevented oxalates from entering the bloodstream and protected against kidney stones.
A dozen clinical trials, however, have failed to find that people who drank more fruit juice, even people who drank calcium-fortified fruit juice, suffered higher rates of kidney stones. How is it possible that a juice could be both harmful and helpful?
It turns out that the sugar content of the meal at which citrus juices are consumed makes the difference in how they act in the kidneys. Downing a glass of orange juice with a doughnut, for example, slightly increases the sugar in the urine. This causes calcium to precipitate. Drinking just the orange juice, however, stimulates urination, carrying away the building blocks of kidney stones before they have a chance to precipitate into stones.
The key to successful getting the maximum effect with citrus juicing is the minimize sugar and maximize citric acid. Orange and grapefruit juices have relatively high sugar content, comparable to a sugar-sweetened soda. Consume them in small amounts, no more than 1 cup (240 ml) per day.
Lemon juice has much lower sugar content, about half the sugar in orange or grapefruit juice and only one-third of the sugar content of apple or grape juice. Lemon juice not only increases urination but provides citrates that find their way into the urine. These citrates help keep oxalates dissolved so that they are flushed away before they can form stones. Lemon juice been used in small-scale clinical trials to treat kidney stones successfully.
Lemonade for Treating Kidney Stones
Freshly squeezed lemon juice contains nearly twice as much citrate content as bottled or frozen. Since it’s the citrates in the juice that keep kidney stones in check, you will want to make your lemonade with freshly squeezed juice. No fancy equipment is necessary. Just cut lemons in half at the middle of the fruit (rather than end to end) and squeeze on a lemon juicer or citrus juice extractor.
Most of us find pure lemon juice to be unacceptably puckery. Most recipes for lemonade dilute one part of lemon juice with 3 or 4 parts of water. If you have kidney stones, the additional fluid is beneficial. It helps keep the kidneys flushed so that stones do not form.
Sweetening lemonade with sugar, however, will counteract all the benefits of the juicing. It is essential not to use sugar or sugar syrup or even “natural” sugars like raw cane sugar or jaggery to sweeten your lemonade, and sweetening the mix with other fruit juices defeats the purpose of making a low-sugar fruit drink. You can of course add saccharin (Sweet ‘n Low), sucralose (Splenda), or aspartame (Nutrasweet), but you will actually get a sweeter taste from powdered stevia.
The reason to use powdered stevia (Truvita) rather than stevia extract is after-taste. Powdered stevia is blended with another naturally occurring sugar called erythritol. The sweet taste of erythritol kicks in as the sweet taste of the stevia rebaudiosides is wearing off, so there is no herbal aftertaste. Liquid stevia extract has 300 to 400 times the sweetness of sugar but also has an after-taste of anise or licorice. If you like the Greek alcoholic beverage ouzo, you will like liquid stevia in your lemonade, but if you prefer concentrated lemon flavor, use powdered stevia instead.
Just be sure not to press lemon peel into your lemon juice for lemonade. Lemon peel contains
What About Green Juices for Kidney Stones?
Green leafy vegetables are generally not acceptable for making juices for kidney stones, due to their oxalate content. Green vegetables that are low in oxalates, however, are good candidates for making kidney-friendly green juice drinks. In a macerating juicer, make juices with broccoli sprouts, green peppers, hot peppers, and/or tomatoes. Don’t use black tea, green tea, Swiss chard, spinach, kale, parsley, or beet roots or tops.
If you grow your own veggies for juicing, make sure you do not put out wood ash or lime to alkalize the soil in the beds you use for growing vegetables to make juice. Plants make oxalates to remove excess calcium from their sap, and plants grown on alkaline, high-calcium soils contain more oxalates.
Hibiscus Tea for Kidney Stones
Not to be overlooked in any program for treating kidney stones naturally is a traditional Egyptian herbal tea called kakade, made with dried hibiscus blossoms. In traditional Islamic medicine, this herbal tea is drunk as a “kidney purifier.” Recent scientific investigation, however, has found that it works by reducing the concentration of oxalates in the urine. Regular consumption of this naturally decaffeinated tea also lowers blood pressure and cholesterol.
You can buy hibiscus teas in most larger groceries. It may be labeled as kakade or as sabdariffa (after its botanical name). Hibiscus is also the main ingredient in a tea blend called Red Zinger. Small amounts of liquid stevia extract add an interesting fennel-like taste to the tea; if you don’t want the fennel taste, use powdered stevia instead. Be forewarned that the tea will increase urination and may cause diarrhea if drunk in very large amounts, more than 2 liters (2 quarts) per day.
Lemon juice juice and hibiscus teas are especially helpful in reducing the severity and frequency of calcium oxalate kidney stones. Even more useful, however, is simply making sure to drink enough water to need to to go the bathroom several times a day. Constantly flushing the kidneys prevents the accumulation of minerals that can accumulate and form stones. Drinking water is even more helpful than drinking juice or healthy herbal teas.