Protein
What are proteins and amino acids?
Everyone needs protein for growth, normal body function, and the prevention of disease. Protein is especially important during periods of rapid growth and pregnancy. The body uses protein in many different ways: to build new muscles or other tissues, to heal wounds and replace old tissues, to help fight infection, and to transport nutrients and oxygen in the blood. Amino acids are the building blocks of proteins. When amino acids are linked together in a chain, they form proteins. All but 9 or 10 amino acids can be made by the body. These 9 or 10 are called essential amino acids because they must be obtained from the diet.
How much protein is in breast milk as compared to formula?
Breast milk contains about 1 g protein in every 100 mL (3 1/2 ounces). Most baby formulas contain somewhat more protein, about twice the amount as found in breast milk.
How much protein does a newborn baby need?
A full-term baby needs about 2 grams of protein per kg of weight per day initially. Twenty-one ounces of breast milk or 15 ounces of infant formula per day easily provide this amount of protein while also ensuring adequate calorie intake for a baby weighing about 3 kilograms.
Does a premature baby need more protein than a full-term baby?
Yes. A premature baby (born at less than 38 weeks of pregnancy) needs more protein relative to his size, often as much as 3 to 4 grams per kg of weight. To meet this need, the doctors may use a formula with extra protein. When the baby reaches the size of a full-term baby (above 2.5 kg), the protein needs are the same as for a newborn term baby.
Does breast milk provide enough protein for a premature baby?
Frequently not. If a baby is born very prematurely and weighs less than about 3 pounds at birth, breast milk does not have enough protein to support normal growth when fed in an amount that a small baby can digest. However, there are special supplements (or fortifiers) that contain extra protein, minerals, vitamins, and calories that can be added to expressed breast milk. These supplements may be important until the baby reaches 5 pounds or so.
How does one know if a baby is getting enough protein?
In general, if a baby is growing at a normal rate, then the baby is getting enough protein. We measure the baby’s growth in weight and length over time, and compare the growth rate to normal values. If the growth rate is slower than expected, then the doctor will investigate why. One possible cause is that the baby is not receiving enough breast milk or formula.
How much protein is in whole cow’s milk (whole milk bought at the grocery store)?
Whole cow’s milk has three times as much protein as breast milk. It also contains more salt and minerals than found in breast milk. The high protein and mineral content of cow’s milk can stress the kidneys and makes it undesirable for young infants.
Is the protein in cow’s milk the same as in human milk?
No. Cow’s milk protein contains a large amount of casein that forms large curds (or clumps) in the stomach and intestines of babies. These curds may not be digested easily by a baby. Human milk contains a large amount of whey protein that is very easily digested by a baby and does not form large curds. Cow’s milk formulas have been heat treated to improve the digestibility of the casein protein.
Is cow’s milk alright to feed a baby?
Cow’s milk should not be fed to a baby during the first 12 months of life. There is too much protein (which forms curds) and too much salt (which can stress the kidneys). Also, cow’s milk can cause small amounts of blood to be lost in the intestines of babies. This blood loss may cause anemia (or low blood count) and loss of iron stores in a baby.
What are some symptoms of milk allergy?
Symptoms may be very mild or quite severe. Symptoms may include vomiting, diarrhea, stomach cramps, wheezing, runny nose, skin rashes, and poor growth, among others. Your doctor should be notified if such symptoms are present for an extended period (several days) or are particularly severe. Fortunately, the majority of children with milk allergy will tolerate some milk and milk products with no reaction as they get older.
Is the protein in cow’s milk a cause of milk allergy?
Yes. The proteins present in cow’s milk are thought to be the major cause of milk allergy. Cow’s milk protein is thought to be the most common allergy in infants.
How does one avoid cow’s milk allergy?
Breastfeeding is the best way to prevent cow’s milk allergy. However, sometimes substances in the mother’s diet cross into her breast milk in tiny amounts and pass into the baby’s intestines. If the baby is prone to have allergies (which is very uncommon), then this can cause allergy symptoms. The mother may be able to avoid these substances in her diet and prevent the allergy symptoms in her baby.
Is soy formula a better choice than regular baby formulas for a baby with cow’s milk allergies?
Yes. Generally, babies who have allergies to cow’s milk protein will better tolerate soy (vegetable) proteins. Regular baby formulas contain cow’s milk protein that has been specifically treated to make it more digestible. However, regular formulas will still cause allergic reactions in a baby who is allergic to cow’s milk protein. Some infants who are allergic to cow’s milk protein are also allergic to soy protein. For those infants, a hydrolysate formula is a better choice because this formula has been specially treated to reduce allergenicity. Your pediatrician should prescribe infant formulas for your baby in the event of a suspected allergy.
What is a soy formula?
Soy formula contains protein obtained from soy beans (vegetable protein).
Is soy formula different from breast milk and other formulas in any way other than protein?
Yes. Soy formulas have different sugars than those found in breast milk or other formulas. Sometimes babies will do better on soy formula if they do not tolerate the lactose (milk sugar) in breast milk or regular formulas.
My baby is on a soy formula. Is soy protein as good as the protein in regular formula or breast milk?
Yes. Soy infant formulas have been shown to be satisfactory for full-term infants as determined by growth, serum chemical determinations, and balance studies (studies of how much nutrition is retained). Soy protein does not contain all of the essential amino acids; however, the missing amino acids are added to the formula, so soy formulas contain all the essential amino acids. Soy formulas contain slightly higher amounts of protein than do cow’s milk formulas or breast milk because soy protein is only about 80% available to the body, compared to cow’s milk and human milk protein, which are 100% available.
Can soy formulas be used for all babies, including premature babies?
Soy formulas are suitable for most term babies, but are not recommended for premature infants. The soy formulas generally do not meet the special mineral requirements of premature infants.
Does the kind of protein or amount of protein a baby gets cause colic?
Probably not for most infants. Many of the symptoms of colic are similar to those of milk protein allergy. The role of milk protein allergy in baby colic is controversial. Some infants with moderate or severe forms of colic improve with special formulas designed for milk allergies.
Does colic occur in breastfed infants?
Yes. Colic occurs with about the same frequency in bottle-fed and breastfed infants.
Do baby cereals contain protein?
Yes. Cereals differ in the amount and quality of protein they have, but all contain significant quantities of vegetable protein. The vegetable proteins in cereal lack certain amino acids and are a lower quality protein than the protein contained in animal products, such as milk, meat, fish, and eggs. High-protein dry baby cereals contain nearly four times the protein of other dry baby cereals.
Can babies get too much protein?
Yes, if they are fed a diet with too much protein in proportion to other nutrients. For example, whole cow’s milk is not recommended for young infants because it contains three times as much protein and minerals as found in human milk. The higher protein and mineral content can stress the kidneys, making cow’s milk undesirable for young infants.
Does the amount of protein a mother eats affect how much protein is in her breast milk?
No. Although some proteins that a mother eats may get into breast milk in small quantities, almost all of the protein in her milk is made directly in the breast and put into the milk.
Is the protein in human milk helpful in fighting infections?
Yes. Antibodies are proteins that are found in large amounts in human breast milk. Antibodies are passed to the baby from the mother and help to protect the baby from infections, especially those related to the intestines and lungs.
I am breastfeeding my baby, I've heard that breastmilk is lower in protein than formula, how can I be sure that my baby is getting enough protein?
A 6-month-old baby who is beginning to eat solid foods will continue to take breast milk. About two-thirds of the calorie intake usually is from breast milk and about one-third is from solid foods. For example, a 6-month-old infant may get protein from 4 tablespoons per day of dry infant cereal. As the baby grows, protein needs will increase also. Strained meats or egg yolk (1 tablespoon per day), or ground meat, or cheese (1/4 ounce per day) will be enough up to 1 year of age.
My baby dislikes the taste of plain strained meats. What other solid foods are good sources of protein?
Other sources of protein include cottage cheese, yogurt, egg yolks, lean-meat dinners, high-protein cereal, mashed tuna or other mild fish, mashed beans or lentils, and soft milk cheeses. One also can try mixing plain strained meat with another food that the baby likes (eg, with fruits, vegetables, or mashed potatoes).
My baby is allergic to cow’s milk and is on a soy formula. Do I need to avoid other solid-food dairy products, too? How do I do this?
Yes. One should read the ingredient list on food labels carefully and avoid foods that contain milk or milk products such as cream, cheese, yogurt, butter, casein, caseinate, whey, lactalbumin, dry milk solids, or nonfat dry milk.
My baby prefers the combination “dinners” to plain meats. Do these contain adequate amounts of protein? Are the high-meat dinners better?
Plain strained meats contain six times more protein than mixed dinners, which contain meat, vegetables and starches. High- (lean-) meat dinners have intermediate amounts of protein.
Is high-protein baby cereal a good source of protein for my baby?
High-protein baby cereals contain two to four times the amount of protein as regular baby cereals. Four tablespoons of high-protein cereal contain about 5 grams of protein, which is about the same amount of protein contained in one half jar (2.5 ounces) of strained meat for babies. The protein in cereals is a vegetable protein that lacks certain amino acids, and therefore is a lower quality protein than the high quality protein found in animal products (milk, meat, fish, eggs).
Are there any vitamins that contain protein?
No. Vitamin supplements do not contain protein.
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