Q: Are there blood tests that can determine which nutrients my body may be lacking? —Sharon La Macchia Saukville, Wisconsin
A: Such blood tests are commonly used in alternative medicine circles. Some of the analyses look for nutritional deficiencies, but those are rare in our country, so your results are likely to be normal. Other tests supposedly tell you whether you fall short on "ideal" nutrient levels, but they have not been well validated and may be misleading since we don't even know what ideal blood levels are or how they fluctuate. I would recommend the standard tests any internist would order, including measuring blood cell counts, glucose, cholesterol, major electrolytes, and both liver and kidney function. If everything is normal, you'll probably gain little by further testing. Instead, focus on a balanced, healthful diet, and as an insurance policy, take a multivitamin. I also suggest fish oil capsules, which contain omega-3 fatty acids. Of note, while most of us are relatively deficient in omega-3s, this is not likely to show up on a blood test—the very point I'm making.