Dr. Bill Sears discusses how a baby’s first foods can play a key role in their long-term development.

During the first year after giving birth, you will spend more time feeding your baby than any other interaction. This natural act is something you’ll both want to enjoy!

Fortunately, new insights into infant feeding have downgraded old customs and upgraded the new art and science of early infant feeding. If you’re coming into my office for your baby’s five- or six-month checkup and talking about her first foods, these are the top tips for a child’s nutrition I recommend every parent know.

Serve up real foods.

When you serve your baby only real foods during the first couple of years, you program your baby for lifelong, healthy eating habits. Conversely, if you make a habit of feeding your children highly processed and fast foods, they begin to crave these types of food and conclude that their taste and intestinal feel is the norm. Teaching your child to appreciate the flavor of fresh foods will program him to crave freshly prepared, unsalted, unsweetened foods, while canned and processed items will taste foreign.

In my pediatric practice, I have worked with a group of mothers I dubbed “pure moms”-those who fed their babies real foods and store-bought foods that were organic and nutritionally chosen. I noticed that these “pure kids” of “pure moms” were not sick as often. They didn’t have as many illnesses in infancy because the real foods better matured their immune system. When they encountered junk food in preschools and at birthday parties, they would come home and complain of an upset tummy. As soon as I hear a mother tell me a similar story, I celebrate by telling her, “Good, that means that you have programmed your child’s gut brain to feel good when she eats good and feel bad when she eats bad.” Parents should enjoy that window of opportunity to shape their child’s tastes for long-term healthy eating habits.

Choose brain food.

For better or worse, the organ most affected by nutrition is your baby’s brain. During the first two years, a baby’s brain triples in size. Your baby’s brain is 60 percent fat, so smart infant feeding requires a healthy-fat diet. This is a natural accompaniment to mother’s milk, which is 40 to 50 percent fat. I also recommend discarding high-carb, rice-based cereals in favor of avocados. Delicious, nutritious and smooth, this taste-shaping fruit is rich in healthy fats, in addition to essential minerals and antioxidants. Plan to add traditional carrots, squash, sweet potatoes, pears, applesauce and bananas between 6 and 7 months.

When a mother is pregnant and lactating, I recommend supplementing her diet with nutrients that boost the brain, including fish and flax oil that are rich in omega-3 fatty acids. This standard should carry over to the nutritional choices that are essential to infant or child development. Coldwater fish such as salmon and tuna with essential fatty acids that are high in EPA and DHA from fish oils can help shape tastes for seafood a taste that most children and many adults have never acquired.

The longer you wait, the better for baby.

New insights into infant feeding have shown that a baby is not mature enough to accept many solid foods until around 6 months. The tongue-thrust mechanism causes the tongue to protrude outward when any foreign food is placed on it, protecting a baby against choking. This safety mechanism diminishes between 4 and 6 months, after which babies develop better coordination of swallowing movements for solid foods. Moving down the digestive tract, many digestive enzymes seem to kick in around 6 months, and the lining of the intestines matures into a protective mechanism called “closure.” This means the smart intestinal police, which act like checkpoints for foreign invaders, are more likely to screen out potential food chemicals and allergens that don’t belong in the body. Intestines also mature more at around 6 months by secreting immunoglobulin IGA, a protective paint that coats the intestines and protects against the entry of allergens.

Remember a baby’s tummy is the size of her fist. Start with a fingerful before thinking of a fistful of food.

Watch your baby, not the calendar.

Babies will often tell us when they’re ready and willing to eat solids-we just have to look for the signs. Watch for “mooching,” as a baby starts grabbing your spoon, reaching for food on your plate, looking at you hungrily and mimicking feeding behaviors, such as when you open your mouth to eat. Use your finger for baby’s first spoon; they’re used to its soft, familiar feel. Also, your finger tells you if the food is too hot.

Start slow, go slow.

Remember, a baby’s tummy is the size of her fist, so it’s very unlikely you’re going to get down more than a fistful of food at any one time, even by 9 months. Start with a fingerful before you even think of a fistful. Place a small amount of food in the middle of baby’s tongue. If she smiles approvingly at the feel and taste of the first test dose, gradually increase the amount and the thickness. In feeding our eight babies, we chose a time of the day when the baby seemed the hungriest. For formula-fed babies, this is usually in the morning; for breastfed babies, offer solids when your milk supply is often lowest, usually toward the end of the day. Start with a new food each week while you keep a food diary recording their likes.

Avocados are taste-shaping fruits rich in healthy fats, essential minerals and antioxidants.

Remember, learning to eat is like learning to speak.

You want your child to eat and speak comfortably before doing it correctly. Enjoy a bit of glorious mess as you learn the art and the science of feeding your baby.

Bill Sears, M.D., is a father of eight and the author of 42 books on family health, including The Healthiest Kid in the Neighborhood. A practicing pediatrician for over 40 years, he is an Associate Clinical Professor of Pediatrics at the University of California, Irvine, School of Medicine. Dr. Sears is a fellow of the American Academy of Pediatrics (AAP) and a fellow of the Royal College of Pediatricians (RCP).