A nurse is providing dietary teaching to a client who has frequent kidney stones. Which of the following instructions should the nurse include in the teaching?

A. "Take a vitamin C supplement twice daily.” High doses of Vitamin C can be metabolized into oxalate by the body. Since calcium oxalate stones are the most common type of kidney stone, increasing oxalate production increases the risk of stone formation. B. "Avoid eating tree nuts, such as almonds.” The majority of kidney stones are made of calcium oxalate. Clients prone to these stones should limit foods high in oxalates to reduce the amount of oxalate filtered by the kidneys. High-oxalate foods include tree nuts (almonds, cashews), spinach, rhubarb, beets, and chocolate. C. "Increase the amount of protein in your diet.” High intake of animal protein increases the excretion of calcium and uric acid while decreasing urinary citrate (which helps prevent stones). This creates an environment conducive to stone formation. D. "Limit your intake of dairy products.” Calcium in the digestive tract binds to oxalate, preventing the oxalate from being absorbed into the bloodstream. If a client restricts calcium, more unbound oxalate is absorbed and excreted by the kidneys, increasing the risk of stones. Normal calcium intake is recommended.