Q: Is there any risk in not feeding beef or pork to our nearly 8-month-old son as he gets older? He is still on vegetables, fruits and oatmeal, but one of these days, we need to introduce proteins. — Via e-mail

A: You started proteins almost eight months ago! Breast milk and formula, mainstays of a baby’s first-year diet, both contain lots of protein. Fish, dairy products and eggs will eventually also be good sources. Egg whites should not be given to children under age 1 since they may cause allergies.

Proteins come from plants, too. Important sources include soy foods (for example, tofu and tempeh, staples of many Asian diets), soy milk, legumes (peas, beans, lentils, peanuts), nuts and seeds.

Cooked and strained peas and beans are early solids with protein. They can be mixed with blander-tasting foods like soupy corn or rice cereals for children who initially resist the taste.

To reduce allergy risk and to prevent choking, children under age 2 should not be given peanut butter. In children or families with lots of allergies, it’s better to wait until 3. Whole peanuts, which can block small airways, should not be fed to children under 3.

As children grow, their nutritional needs change, varying with gender and activity level. Children also absorb, digest and metabolize nutrients differently.

All of us need certain amino acids — the building blocks of proteins — to survive and thrive. Essential amino acids are those that we can’t make on our own and that our diet must provide. Two additional amino acids — cysteine and tyrosine — are essential for young babies, whose ability to make them doesn’t mature until later in the first year.

Breast milk contains the amino acids required in the first year. But when babies start eating solids and drinking less milk, the balance can be tricky.

Dairy products, eggs, fish, poultry and meat contain a wide range of essential amino acids, as do legumes and soy foods and milks. Other sources are foods made from quinoa, an ancient South American grainlike food, or from hemp seeds (hemp milk and even ice cream are now available).

Corn, rice, wheat and other grains also contain proteins but with fewer of the necessary amino acids. If animal protein is not part of a child’s diet, a variety of plant-derived foods is important. With all these options, omitting red meat needn’t interfere with adequate protein intake.

The daily protein requirement should be spread out in feedings over the course of the day since babies’ bodies can’t store extra protein. They break down the proteins into amino acids that stimulate tissue growth. Spreading out protein across the day will stimulate growth several times daily.

Nutrients other than protein need special attention, too: iron and vitamin D and, for babies and children who are not given any milk or animal-based foods, vitamin B12.

Vitamin D supplements are recommended for all infants who are breast-fed (baby formula is fortified with vitamin D). Iron is found in plant foods as well as in meats, but is not as readily absorbed, so the daily requirements are higher for children and adults who eat no meat.

Check with your pediatrician about iron supplementation, since too much iron is not healthy. Vitamin B12 is found only in animal-based foods and foods contaminated with B12-producing microorganisms. Poultry, fish and eggs contain plenty of B12 — so, again, red meat isn’t essential.

Questions or comments should be addressed to Dr. T. Berry Brazelton and Dr. Joshua Sparrow, care of The New York Times Syndicate, 620 Eighth Ave., 5th Floor, New York, N.Y. 10018. Questions may also be sent by e-mail to:

nytsyn-families@nytimes.com