I have seen grown men come to their knees with debilitating pain when experiencing kidney stones – almost everyone knows someone who has suffered the incredible pain. I am frequently asked what causes kidney stones, what foods to avoid and what natural supplementation and/or lifestyle changes can assist with both the prevention of stones as well as to assist the body in dissolving them. The following should answer most questions.
According to the National Institute of Diabetes, Digestive and Kidney Diseases, white males over age 50 are most at risk for kidney stones in the U.S. Symptoms range from severe abdominal pain or pain in the side or back, blood in the urine, fever and nausea.
Kidney Biology 101
The kidneys produce the urine that dissolves wastes and excretes them through the urinary tract. Kidney stones form when the urine becomes so saturated with a certain mineral that no more of it can dissolve into the urine (like trying to dissolve too much sugar in your iced tea). The un-dissolved portion of the mineral forms crystals that then clump together and grow into hard stones. Kidney stones usually develop in the kidneys; however they can form anywhere in the urinary tract. This condition is medically known as urolithiasis or nephrolithiasis.When kidney stones are quite tiny, they may pass unnoticed with the urine. Often however, they grow too large to pass easily through the urinary tract, and some stones develop rough or sharp edges. When these stones pass through the urinary tract, it can be quite painful. In some cases, kidney stones cannot pass on their own, and treatment with specialized medical equipment or surgery may be necessary.??For most people, kidney stones are like dandelions in the lawn; they can be eliminated, but they'll be back another year. Therefore, a major part of the treatment for this condition is aimed at preventing recurrences. There are various types of kidney stones. Because treatment for each differs, it is important for the physician to determine the stone's mineral content and to identify any medical conditions that may have contributed to stone formation. Preventive treatment may be with medications and/or changes in the diet. About 80% of all kidney stones are composed of calcium and other minerals, usually a combination of calcium and oxalate, which is the focus of this investigative report. In most cases dietary adjustments are necessary to help prevent recurrence of these types of stones.
Feeling the Pain
The pain of passing kidney stones is typically sharp and cramp-like. As a kidney stone passes from the kidney into the urinary tract, it may block or obstruct urine flow, and pain may shift to the groin and genital areas. Pain associated with kidney stones often comes in waves as the stone moves through the urinary system. Kidney stones are also accompanied by pain, burning or irritation during urination.As a stone passes through the kidney and urinary tract, it may block urination, which can help to promote kidney infection. Symptoms of urinary tract infections related to kidney stones include clamminess, sweating, fever and chill cycles, weakness, loss of appetite and nausea. Kidney stones with associated symptoms of infection are very serious. The National Institute of Diabetes, Digestive and Kidney Diseases advises that a person experiencing these symptoms should immediately contact a medical professional.
Oxalic acid or oxalate is found mostly in foods from plants. Calcium combines with oxalate in the intestines – reducing calcium's ability to be absorbed. Sometimes oxalate or calcium oxalate stones form because there is not enough calcium in the intestines – creating too much oxalate that goes to the kidneys to be excreted. The medical term for too much oxalate in the urine is hyperoxaluria. In certain cases of oxalate or calcium oxalate stones, the physician may recommend reducing oxalate intake along with a slight increase in calcium. It is recommended that these patients have no more than 50 mg of oxalate per day in the diet. To do this, foods with high or moderate amounts of oxalate should be reduced or eliminated from the diet. ??Although there are many foods that contain large amounts of oxalate, eight foods have been shown to be most at fault for raising urine oxalate levels. They are rhubarb, spinach, strawberries, chocolate, wheat bran, nuts, beets, and tea.
In chemical terms, oxalates belong to a group of molecules called organic acids that are naturally-occurring and are routinely made by plants, animals, and humans. Our bodies always contain oxalates, and our cells routinely convert other substances into oxalates. For example, vitamin C is one of the substances that our cells routinely convert into oxalates. In addition to the oxalates that are made inside of our body, oxalates can arrive at our body from the outside, from certain foods that contain them.
There is much confusion about foods that contain oxalates and their correlation with kidney stones. About 80% of kidney stones formed by adults in the U.S. are calcium oxalate stones. Researchers disagree to the extent of benefit from avoiding oxalate foods; they do agree restriction and/or avoidance does reduce the risk of stone formation for those at risk.
For the vast majority of individuals who have not experienced the specific problems described above, oxalate-containing foods should not be a health concern. Under most circumstances, high oxalate foods like spinach can be eaten raw or cooked and incorporated into a weekly or daily meal plan as both baby spinach and mature, large leaf spinach can both make healthy additions to most meal plans. In short, the decision about raw versus cooked or baby versus mature leaf spinach or other oxalate-containing vegetables, for example, should be a matter of personal taste and preference for most individuals.
The following are food sources of oxalates, arranged by food group.
Fruits
blackberries, blueberries, raspberries, strawberries, currants, kiwifruit, concord (purple) grapes, figs, tangerines, and plumsVegetables
spinach, Swiss chard, beet greens, collards, rhubarb, sorrel, okra, parsley, leeks and quinoa are among the most oxalate-dense vegetables, celery, green beans, rutabagas, and summer squash would be considered moderately dense in oxalatesNuts and seeds
almonds, cashews, peanuts, and poppy seedsLegumes
soybeans, tofu and other soy productsGrains
wheat bran, wheat germ, quinoa (a vegetable often used like a grain)Other
cocoa, chocolate, and black tea, ground pepper, lime peelVitamin C
When vitamin C is used by the body, oxalate is produced. Therefore, if the physician has recommended reducing oxalate in the diet, taking vitamin C supplements may not be a good idea, discuss this with your physician.Insoluble fiber
Fiber is the indigestible part of plants. There are two types of fiber: soluble (dissolves in water) and insoluble. Both provide important functions in the body, but it is insoluble fiber (found in wheat, rye, barley, and rice) that may help to reduce calcium in the urine. It combines with calcium in the intestines, so the calcium is excreted with the stool instead of through the kidneys. Insoluble fiber also speeds up movement of substances through the intestine, so there will be less time for calcium to be absorbed.
As always, everyone should consume plenty of clean, pure water, especially those known to form kidney stones. Taking the best fiber supplement without consuming sufficient water to flush the system is of no benefit.
As with any medical condition, seek the guidance of a health professional that can assist you in Health thru Education. There are professional natural supplement complexes that help support kidney function and aid against stone formation, be sure your health professional is nutritionally-aware, naturally.
Resources
- Food chart adapted from the following sources: (1) United States Department of Agriculture, Human Nutrition Information Service, Agriculture Handbook Number 8-11, "Composition of Foods: Vegetables and Vegetable Products." Revised August 1984; (2) data gathered by LithoLink Corporation, a metabolic testing and disease management service for kidney stone patients, founded by Dr. Fredric Coe, a University of Chicago Medical School Professor, and posted on its website at www.litholink.com; (3)data presented by Holmes RP and Kennedy M. (2000). Estimation of the oxalate content of foods and daily oxalate intake. Kidney International(4):1662.
- Assimos, D. G. and Holmes, R. P. Role of diet in the therapy of urolithiasis. Urol Clin North Am. 2000 May; 27(2):255-68.
- Curhan, G. C. Epidemiologic evidence for the role of oxalate in idiopathic nephrolithiasis. J Endourol. 1999 Nov; 13(9):629-31.
- Hanson, C. F.; Frankos, V. H., and Thompson, W. O. Bioavailability of oxalic acid from spinach, sugar beet fibre and a solution of sodium oxalate consumed by female volunteers. Food Chem Toxicol. 1989 Mar; 27(3):181-4.
- Kelsay, J. L. and Prather, E. S. Mineral balances of human subjects consuming spinach in a low-fiber diet and in a diet containing fruits and vegetables. Am J Clin Nutr. 1983 Jul; 38(1):12-9.
- Kikunaga, S.; Arimori, M., and Takahashi, M. The bioavailability of calcium in spinach and calcium-oxalate to calcium-deficient rats. J Nutr Sci Vitaminol(Tokyo). 1988 Apr; 34(2):195-207.
- Mobley (Feb 1999) Hospital Medicine, p. 21-38
- Parivar, F.; Low, R. K., and Stoller, M. L. The influence of diet on urinary stone disease. J Urol. 1996 Feb; 155(2):432-40
- Prakash D, Nath P, and Pal M. (1993). Composition, variation of nutritional contents in leaves, seed protein, fat and fatty acid profile of chenopodium species. Journal of the Science of Food and Agriculture 62(2):203-205.
- Sienera R. (2006). Oxalate contents of species of the Polygonaceae, Amaranthaceae and Chenopodiaceae families. Food Chemistry 98(2):220-224.
