Know Your Stones...Protect Your Kidneys (cont.)
Too much of a good thing: When it comes to vitamins, more is not always better. For this reason, tolerable upper limits (UL) have been set to let people know what level they need to stay below to avoid any harmful health consequences. There is some evidence to suggest that ascorbic acid (vitamin C) taken in high doses can increase stone formation in people who are at risk. In order to avoid this increased risk, you will need to stay below the UL of 2,000 mg/day that has been set for ascorbic acid. An 8-ounce cup of orange juice contains only about 130 mg of vitamin C, so the most likely way to exceed the safety limit would be through supplements. If you do take a vitamin supplement, be sure to read the labels carefully and speak with your physician if you have any questions.
The oxalate & calcium connection: It was once believed that dietary calcium and oxalate needed to be reduced in order to prevent the formation of calcium oxalate stones. Research has now shown that calcium is actually needed when ingesting oxalate-rich foods in order to assist with decreasing the absorption of the oxalates. The other necessary intervention is to limit your overall intake of oxalate-rich foods. These foods include beets, chocolate, coffee, cola, nuts, rhubarb, spinach, black tea, and wheat bran.
Weight it out: One of the numerous health benefits of weight loss could be lowering your risk of kidney stones. In a recent study of over 200,000 people, being obese and gaining the most weight over the 46 year follow-up period put people at the greatest risk for kidney stones. The risk was solely based on weight and not the diet or fluid intake. If you are overweight, cutting your calories and following a well balanced diet may be the key to kidney-stone prevention.
How can your diet decrease the risk for calcium stones?
Calcium connection: It was once believed that dietary calcium was responsible for calcium stones, and the recommendation was to avoid calcium rich dairy products. Numerous studies have now refuted this advice. In fact, foods high in calcium, including dairy products, are believed to help prevent stone formation. One study of over 45,000 men found that those who consumed fewer than 850 mg of calcium per day were at an increased risk for kidney stones. The goal is to meet the guidelines for an adequate intake of calcium through your diet. The Recommended Adequate Intakes set for calcium are:
7 to 12 months-270 mg
1 to 3 years-500 mg
4 to 8 years-800 mg
9 to 13 years-1300 mg
14 to 18 years-1300 mg
19 to 50 years-1000 mg
51+ years-1200 mg
Fluid fix: Drinking enough fluid will reduce the concentration of stone-forming minerals in the urine by diluting it. The goal is to drink at least 10 full glasses of fluid each day (at least half should be water) in order to produce over 2 quarts of urine on a daily basis. The average daily output of urine is about 1½ quarts, so this is somewhat higher. Some ways to reach your fluid goals are: