By Joy Blakeslee, RD

Soybeans are native to Northern China and have been an important food crop in Asia for more than 3,000 years. Today, soy is a mainstream ingredient with 37 percent of Americans consuming soy foods or beverages once a month or more. Soy has become more popular for many reasons, including people’s desire to eat more healthfully and the wider availability and variety of delicious soy foods.

Soy protein is an excellent source of protein. It contains all nine essential amino acids, making it a complete protein. Amino acids are the building blocks of protein and recent research shows soy protein contains a good balance of amino acids required by the human body making it an excellent way to meet some of your protein needs.1 Soy protein is naturally cholesterol-free, low in saturated fat and provides zero grams of trans-fats per serving. Soy is also beneficial to heart health and can improve blood cholesterol levels.2 Soybeans are also naturally rich in
isoflavones, a beneficial antioxidant that recent research indicates may have positive effects in kidney disease including a reduction of
inflammation.3,4

Good Soy Foods for People Living with Chronic Kidney Disease (CKD)
In general, soy foods are safe; however for people with CKD, some soy foods are better than others. People with CKD can safely enjoy tofu, soymilk and soy yogurt.5 Soy protein fortified breakfast cereals can also be an additional source of protein and nutrients for people with CKD.

Soy nuts, whole soybeans, soy flour and fermented soy products, and pastes are high in potassium and phosphorus, minerals people with CKD should limit in their diets. Soy-based sausages and burgers, packaged marinated tofu and many Asian dishes are typically high in sodium.5 People with CKD should eat these soy foods in moderation.

Remember, when making any diet modification, or if you have any questions or concerns, always check with your doctor or renal dietitian before making these changes. Here are some practical ways to include soy foods into your diet.

Good Soy Choices: Benefits and Usage Tips
Tofu
Tofu is made from curdled soymilk and can be processed with calcium sulfate, making it a good source of calcium. One serving (1/4-1/2 cup) of tofu contains seven grams of protein, the same as one ounce of meat or one egg.

Tofu comes in different textures including firm, soft and silken, making it very versatile. Tofu has a bland taste that easily absorbs the flavors of other ingredients. Look for tofu in the produce section of the grocery store. Tofu is sold in 12 to 14 ounce blocks packaged in water-filled vacuum-packed tubs or aseptic packages. Once the tofu package is open, rinse leftover tofu daily and cover with fresh water for storage. Change the water daily to keep it fresh, and use the tofu within a week. Here are some quick tips for using tofu.
• Add cubes of firm tofu to soups, stews and casseroles
• Blend silken tofu into dips and salad dressings
• Grill firm tofu and use as a filling for sandwiches
• Stir-fry tofu with ginger, garlic and vegetables

Soymilk and Soy Yogurt
Soymilk and soy yogurt are terrific alternatives to dairy products. Fresh soybeans are ground, cooked and strained and made into soymilk. Look for soymilk fortified with calcium and vitamin D to get the comparable nutritional benefits of dairy milk. Soymilk naturally contains almost half the phosphorus of regular milk making it a good choice for people with CKD.

Soymilk comes in a variety of flavors including plain, vanilla and chocolate. Soymilk has become so popular that flavors such as coffee, chai tea and eggnog are now available. Soy yogurt comes plain and in a variety of fruit flavors. No longer just considered a “health food,” soymilk and soy yogurt are commonly available in the refrigerated dairy case. Many grocery stores now offer their own in-store brand of soymilk. Here are some simple ideas for using soymilk and soy yogurt.
• Cook whole grain hot cereal with soymilk
• Use soymilk in your cereal and coffee beverages
• Blend soymilk with berries to make nutritious smoothies
• Use soymilk when making casseroles, soups and sauces
• Create low-fat dips and dressings with plain soy yogurt
• Make breakfast parfaits by layering soy yogurt and granola or cereal
• Blend soy yogurt and berries to create creamy frozen treats

Soy Fortified Cereals
Some cereals companies now fortify grain-based breakfast cereals with soy protein. The fact that these cereals contain soy protein may not be obvious. Look for these clues: If the box says “high in protein” or “isoflavones,” it very likely contains soy ingredients – just check the ingredients label to be sure. Soy protein ingredients are listed on food labels as soy protein, soy protein concentrate, soy protein isolate, soy grits, soy flakes or soy bits. Three widely available types of cereal containing soy protein include Kashi® Golean Crunch, Kashi® Golean and Kellogg’s® Special K® Protein Plus.

For more details regarding soy as a protein choice for people with CKD, please refer to Soy-A Protein Option, written by Joan Brookhyser, RD, CSR, CD. Published in the March/April 2005 issue of Kidney Beginnings: The Magazine, Vol. 4, and is available online at http://www.aakp.org/aakp-library/Soy-Option/.

References
1. Pellett, Peter, Protein Requirements in Humans, Amer J Clin Nutr, 51:723-37, vol 339:1990;1131-1134
2. Bhathena, SJ, Velasquez, MT, Protective effect of dietary phytoestrogens in chronic renal disease. Journal of Renal Nutrition, 2001 Oct; 11(4):183-09
3. Fanti. P. Asmis. R. Stephenson T.J. Sawaya. B.P. Franke. A.A. positive effect of dietary soy in ESRD patients with systemic inflammation- correlation between blood levels of the soy isoflavones and the acute-phase reactants. Nephrology Dialysis Transplant, 2006 July: 21: 2239-2246
4. Food and Drug Administration. Food labeling, health claims, soy protein, and coronary heart disease. Fed Reg 1999;57:699-733
5. Brookhyser, J. Soy-a protein option. Kidney Beginnings: The Magazine, 2005 March/April: Vol. 4, No. 1

Joy Blakeslee is a Registered Dietitian and manager of the Publicis Culinary and Nutrition Center. Joy develops recipes and food products prototypes for organizations including the United States Soybean Board.

This article originally appeared in the March 2008 issue of aakpRENALIFE.

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