Many parents are eager for their babies to move beyond the breast or bottle and take that first messy bite of food. Years ago, some doctors even advised parents to feed new babies solids so they'd sleep better.

Not anymore. Today, research shows that babies fare better on a breast-milk or formula diet until their digestive systems are ready to handle solids. But when is that? Dr. Lewis First, head of pediatrics at Vermont Children's Hospital at Fletcher Allen Health Care, helps parents digest the latest research on what babies should eat, and when.

KIDS VT: How do parents know when their baby is ready for solid food?

LEWIS FIRST: Some parenting books say your baby is developmentally ready for solid foods between 4 and 6 months of age. Rather than look at a particular age, parents should consider whether their baby has lost those primitive reflexes that make it difficult for them to take a solid food on the tongue and move it backward to be chewed and swallowed.

Basically, babies are ready when the tongue-thrust reflex, which helps the baby latch onto the breast nipple, has disappeared. You can measure that by your baby's head and neck control. If you pull your baby up from lying on his or her back to a sitting position and the head remains on the same plane as the back, that's a good sign your baby is getting ready to process solid food without risk of choking or difficulty swallowing.

KVT: Do infants get much nutrition from solids?

LF: As exciting as it is to start babies on solid foods, parents need to realize that most of those solids fill your baby up but don't fill your baby out — meaning they have very few calories to help your baby grow. Typically, a four-ounce jar of vegetables has only 20 to 40 calories. Four ounces of breast milk or formula have 80 calories.

If you load your baby's stomach with a lot of cooked carrots and then try to breast-feed, he or she may not take milk. Solid foods can provide some nutrients and iron, but, for the most part, babies' weight gain, growth and development in the first year of life are dependent upon breast milk — or, secondarily, formula.

KVT: What are the other benefits of delaying solids?

LF: When parents wait six months to start solids, even if their baby shows developmental readiness earlier, studies show they reduce their baby's risk of ear and respiratory infections. Other studies suggest that babies who exclusively breast-feed to 6 months will also be less apt to become obese, get diabetes, have allergic skin diseases such as eczema or develop celiac disease. Six months of exclusive breast-feeding also reduces your baby's likelihood of sudden infant death syndrome.

KVT: Which foods should babies eat first?

LF: Breast milk has very little iron. As soon as your baby reaches six months, he or she will need more. Most parents start with an iron-fortified rice cereal.

Between 6 and 9 months, you can introduce finger foods. Good ones include soft pieces of fruit, scrambled eggs, cut-up pasta, soft squash, peas and Cheerios.

But parents should introduce new foods no more frequently than once every two to three days. If your baby develops an allergy, you want to be able to figure out the culprit. Once your child has tried a new food and you haven't seen vomiting, diarrhea, fussiness or a skin rash, that food is probably good to go and you can add another.

KVT: When should parents introduce animal proteins?

LF: Meat contains a lot of zinc and iron, so if your baby has been exclusively breast- or formula-fed, there's no problem getting the meats going as soon as your baby has started on cereals, fruits and vegetables.

KVT: Any advice for parents who make their own baby food?

LF: Avoid beets, spinach, turnips and collard greens, all of which contain high levels of nitrates. Too much can cause serious anemia. Steaming or baking fruits and vegetables is preferable to boiling, which destroys many of the nutrients and vitamins. And, once you open any jar of baby food, homemade or store-bought, you shouldn't keep it longer than one to two days, because it spoils quickly.

KVT: Are there other foods that should be avoided within the first year?

LF: You don't want to give babies whole milk before one year, because that can lead to an iron deficiency. You don't want to give your baby honey because of the risk of botulism. Foods that are choking hazards — such as whole grapes, hard fruits, hard candies, hard cheeses, popcorn and raisins — should be avoided until your child has molars, which is usually not until 2 years of age.

KVT: Any other new recommendations?

LF: Worried your baby is going to be allergic to eggs or peanuts? Studies now show that if you wait beyond the window of six to eight months, and don't introduce them until one year, you may actually increase the risk that your child will become allergic to those foods.