I got this e-mail today from BabyWeekly. I never knew this. I just bought carrots and was going to make them for DS tomorrow:"Once your baby is eating some solid foods, remember fresh is usually best. However, according to the American Academy of Pediatrics, beets, carrots, collard greens, and turnips contain large amounts of nitrates in some parts of the country. Nitrates can cause a type of anemia in your baby.
Even though you can't personally test the vegetables in your area, rest assured that baby-food companies take precautions to avoid using vegetables high in nitrates. So if you want to feed these vegetables to your baby, it is safest to buy commercially prepared jarred foods"