Q: Are baby products with supplements like DHA and probiotics worth buying?
A: Well, it depends on which supplement we're talking about. DHA (docosahexaenoic acid) is a fatty acid that's important for baby brain and eye development (and long-term adult heart health), which is why it's crucial that you both get enough. If you breastfeed -- the best way for infants to get DHA -- and take a supplement yourself (doctors recommend 200 milligrams a day), your baby is most likely getting all she needs. Nursing moms who want to get DHA from food can opt for fish, while women who bottle-feed can use a fortified formula.
As for probiotics, they're healthy bacteria similar to those found in the intestines. Most babies have plenty of the digestion-aiding bugs in their bellies and don't need supplementation. That said, I've had success treating both diarrhea and constipation with probiotics, especially those found in many yogurts (look for "active cultures"). If your baby develops one of these problems, ask your doctor whether using yogurt or probiotic capsules might help.