2019-20 TOW #6: Formula feeding

As a companion topic to last week’s review on breastfeeding, we are taking some time to learn about formula feeding. While breastfeeding is recommended as the optimal nutrition for babies, there are families for whom this is not an option (see commentary below from a pediatrician who was not able to breastfeed her baby); parents rely on us to have expertise on formula feeding as well.

Teaching materials for this week:

Take-home points about formula feeding:

  1. How much formula to provide? after the first few weeks of life, for every 1 kg (or 2 pounds) babies drink ~1 ounce of formula, up to about 7-8 ounces (I usually say closer to 6 ounces is optimal), every 3-4 hours. This amount approximates the baby’s stomach capacity and will meet metabolic needs of an otherwise healthy infant (which is ~100kcal/kg/day in babies <10 kg). Babies should be gaining 25-30g/day through 3 months, then 15-20g/day from 3-6 months (see helpful table in case discussion). Total intake in the day should be no more than 32oz. There is some evidence that using larger bottles (>=6 oz) at 2 months may be associated with feeding too much at one time, and with more rapid weight gain/overweight at 6 months.
  2. Parents often ask about how to choose a formula-what should we say?: Although claiming unique properties, all of the major standard formulas commercially available are essentially similar and contain enough vitamins and minerals to meet babies’ needs. If fully formula-fed, vitamin D should be adequate to meet 400 IU daily. There should never be an indication to use “low-iron” formulations. There is mixed evidence on whether adding long-chain fatty acids DHA and ARA to formulas has benefit for vision and cognition; nonetheless, these are now routinely added to most formulas in the US. Check out info for parents on choosing a formula from the AAP healthychildren website on choosing a formula
  3. What are recommendations for preparing formula? This is important to know and families should follow labels carefully. (I will always remember a baby brought to us at clinic seizing and hypoxic from hyponatremia due to inproperly mixed formula.) For powdered formula, it is typically 1 scoop for every 2 ounces. Fill the water first, then add the powder. In places with safe drinking water, standard tap water can be used without boiling (heavy boiling may increase concentrations of lead, in fact). Be cautious about well water – this should be tested for lead and other heavy metals. There is some concern about mild fluorosis if formula is mixed with fluoride-containing water – in which case you can sometimes mix with bottled water. At room temperature, discard formula not used within 2 hours. Refrigerated formula should be discarded after 24 hours.
  4. When should we consider switching formulas? Most infants tolerate standard formulas and do not require switching. Parents often ask about switching formulas when babies have irritability and colic, which are unlikely to improve because of a formula change. Infants with specific GI symptoms, such as diarrhea, constipation, blood in the stool, and excessive gas are more likely to benefit from a formula switch.
  5. When should infants have special formulas? Soy-based formulas can treat some cow-milk formula intolerance, whether from lactose intolerance or cow milk protein allergy. Infants that have an IgE-mediated cow milk allergy may switch to soy-based formula, though up to half of infants allergic to cow’s milk may also not tolerate soy. In these cases, hydrolyzed formulas are required (such as Alimentum, Nutramigen, Pregestamil, and Neocate). These formulas are 3-4 times more expensive and may require prescriptions to be covered by insurance/WIC, though most are available over the counter. (See the helpful table to review these in the article above).

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