A nurse is teaching a client about foods to avoid before having an occult blood test of the stool. Which of the following foods should the nurse instruct the client to avoid?

Choice A reason: Potatoes do not contain substances that cause false-positive occult blood tests. They are low in heme and do not mimic blood in stool, making them safe to consume before testing. Choice B reason: Red meat contains heme, which can cause false-positive results in occult blood tests by mimicking blood. Avoiding red meat for 48–72 hours ensures test accuracy, making this the correct choice. Choice C reason: Yogurt lacks heme or oxidizing agents that interfere with occult blood tests. It is a safe food choice before testing, as it does not affect results, making this incorrect. Choice D reason: Apples do not typically cause false positives, though some fruits with peroxidase (e.g., turnips) might. Apples are generally safe, making this less critical to avoid than red meat.