November 1, 1999

5 Min Read
Eating Smart Right  from the Start

Eating Smart Right
from the Start
November 1999 -- Nutrition Notes

By: Andrea Platzman, R.D.
Contributing Editor

  Experts agree that breast milk is an optimal source of nutrition for most infants. Human milk contains antibodies and enzymes that protect infants against infections. During the first two or three days of lactation, the breasts produce colostrum, a premilk substance containing antibodies and white cells from the mother's blood.

  Just as any other food product, breast milk is not perfect. According to Robert Lustig, M.D., pediatric neuroendocrinologist at the University of Tennessee, Memphis, vitamin D, iron and fluoride are present only at very low levels in breast milk. However, a complete infant multivitamin will compensate for breast-milk deficiencies.

  If a breast-feeding mother is vitamin-D deficient, the infant will be also. Studies have shown that rickets, or impaired bone mineralization, can develop in breast-fed infants. A vitamin-D supplement of 400 IU is recommended if the infant's exposure to sunlight is limited. Only 0.25 mg of iron is absorbed each day from breast milk; the infant should receive 7.0 mg via a supplement. The concentration of fluoride in breast milk is low also, and it's recommended that breast-fed infants be given 0.25 mg of fluoride per day to prevent dental caries.

Matching formulas

  Before the 1900s, a suitable substitute for breast milk didn't exist, and many infants died if their mothers were unable to nurse or didn't have access to a wet nurse. In 1867, the first milk substitute was developed. It consisted of a mixture of cow's milk, wheat flour, malt flour and potassium bicarbonate. In the early 1900s, formulated milks were developed in an effort to make a product that was nutritionally closer to breast milk.

  "A better-designed formula would have a lower phosphate level in order to absorb calcium," says Lustig. The 2:1 ratio of calcium to phosphorus in breast milk is ideal for the absorption of calcium. These two minerals, along with magnesium, are present in breast milk in amounts that support the growth expected in an infant.

  Docosahexaenoic acid (DHA), a major component of fish oil, is important for proper growth of the infant's brain, and is required for development of the retina and nerve growth. Infants get DHA from breast milk, and there's been controversy over whether this fatty acid should be supplemented in infant formulas. Humans can make DHA from two polyunsaturated fatty acids, linoleic and alpha-linolenic acid, both of which are components of vegetable oils and are now in all infant formulas. But the conversion ability of newborns, especially preterm babies, may be unable to keep up with the demands of the nervous system. Studies are still being conducted on the best source of DHA, if one is used at all, for formulas. The question is whether there might be another element in breast milk that infants need for brain function.

  In the October 1999 American Journal of Clinical Nutrition, James Anderson M.D., professor of medicine and clinical nutrition at the University of Kentucky, Lexington, investigates the possibility that breast feeding is linked to IQ. After Anderson and colleagues looked at 20 studies comparing bottle-fed infants' brain development with that of breast-fed infants, they concluded that babies who are breast fed for at least six months have a slightly higher IQ than those who are bottle-fed. Additionally, they posit that 60% of this increase is related to the nutritional value of milk - the DHA component in particluar, and that 40% is related to the benefits of maternal bonding. However, an accompanying editorial points out that the evaluated studies were not randomized, and that there may be a number of other socio-economic factors involved both in the IQ of infants and in the mother's decision to breast feed.

  Breast milk contains bifidus factors that favor the growth of probiotics such as Lactobacillus bifidus in the digestive tract. Some believe that infant formulas should contain probiotics - live microbial cultures that improve the intestinal balance of healthful microorganisms, as well as prebiotics, which are undigested fibers that promote the growth of these beneficial microorganisms.

First foods

  Breast milk or formula is the only food a baby needs for the first four to six months. "When the baby can sit up; consumes 32 oz. of formula a day, and wants more; or his or her birthweight has doubled; or is six months old, solid foods can be introduced," states Marlene Wust, M.D., Madison East Pediatrics, New York. "Iron deficiency is most prevalent in infants from six months to three years old due to their rapid growth rate and the large amounts of milk they usually drink - which is a poor source of this mineral. Iron-fortified single-grain cereals and formulas are recommended at this stage. An infant's iron requirement increases to 10 mg per day at six months."

  Strained fruits and vegetables and their juices can be introduced one at a time between five and seven months of age. Protein foods such as chicken, meat and egg yolk can be added between six and eight months. New foods should be introduced singly, and at intervals, to allow detection of any allergies.

  At nine to 12 months of age, finger foods such as toast and finely chopped meats can be added to the menu. Breast milk or formula should still be given until one year of age, however, and whole milk until two years of age. Tofu and other soy-based products, seafood, dairy foods and nuts can be included after one year of age, when the infant is better able to digest these foods.

  Many parents make their own baby food, although commercial baby food is a safe, convenient and nutritious alternative to homemade baby food. Some manufacturers, in response to concerned parents and health professionals, have removed or reduced the amount of added salt, sugar and starch in their products.

  "It is important to provide children with nutritious foods and let them choose which ones and how much they eat. Gradually, they will acquire a taste for different foods," says Lustig.

  Andrea D. Platzman, a registered dietitian, is a consultant to the food industry and regularly writes for nutrition publications. She earned a master's degree in nutrition from New York University, and has a culinary and business background.

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