Soy-Based Infant Formula Parent Information Revised November 2005

Soy-Based Infant Formula - Parent Information
Revised November 2005

Breastmilk is the best food for babies. Dairy-based infant formula is the next best choice. Under the advice of a health practitioner, soy-based infant formula may be recommended as a substitute for a dairy-based infant formula for infants with cows’ milk allergy or intolerance, or lactose intolerance. However,up to 40 percent of infants who are allergic to cows’ milk will also be allergic to soy.

Over the past decade there has been some concern among health practitioners and policy makers about the safety of soy-based infant formula, mainly about the high levels of phytoestrogens in soy-based infant formula. Phytoestrogens are like a weak form of the female hormone, oestrogen (phyto = plant, oestrogen = female hormone). Many plants, including soybeans, contain phytoestrogens, and these are present in the infant formula made from soybeans.

The long-term effects of phytoestrogens on an infant’s development are not known, although as yet there is no conclusive evidence of harm. However,
international research has indicated that phytoestrogens can cause changes to sexual development in animals. The research suggests that, in rare circumstances, the phytoestrogens in soy-based infant formula may affect the function of the thyroid gland.

The Ministry of Health has taken a precautionary approach and recommends that soy-based infant formula be used only where it is medically indicated, even though there is no conclusive evidence that phytoestrogens in soy-based infant formula harm human infants.

If your baby is under a year old and your doctor or health practitioner has specifically recommended that you use soy-based infant formula, you should continue to do so. If you have any concerns, you should ask your doctor or health practitioner about alternatives to soy-based infant formula. If your baby is over one year of age, and you have been using a soy-based infant formula, you could ask your doctor or health practitioner about giving your baby cows’ milk to drink. Infants often grow out of cows’ milk allergy and intolerance.

Weaning foods for infants may contain small amounts of soy, which would usually be only a small part of a young child’s total food intake. Unless your child has a diagnosed soy allergy or intolerance, soy-based products may be a useful and nutritious part of their diet.

For more nutritional information:

Talk to your:

Plunket, Public Health, or Practice nurse
Hospital Community dietitian or Public Health dietitian
General Practitioner
Midwife
Specialist Pediatrician

or contact your local public health service resource provider for leaflets e.g., Eating for Healthy Babies and Toddlers, Code 1521, Eating for Healthy Breastfeeding Women, Code 6003.

UK Scientific Advisory Committee on Nutrition (SACN) document on soy infant formula is available at www.sacn.gov.uk/pdfs/smcn_03_10.pdf

Breastfeeding
It is recommended that you breastfeed your baby for the first 4–6 months of life. Breast milk is specially made for your baby:

it changes with your baby’s needs
it helps protect your baby against infection
it lowers the risk of allergies
it is cheap, safe, environmentally friendly and ready to use!

Professional advice should be followed before using an infant formula. It is possible to go back to breastfeeding after stopping, but it’s difficult. Part bottle/part breastfeeding can slow or stop the production of breast milk. Infant formula should be used only as directed, as proper use is important for baby’s health. Social and financial implications should be considered when choosing a method of feeding. Good nutrition is important for a mother who is breastfeeding.

Related information

Breastfeeding
Food
HealthEd resource - Feeding Your Baby Infant Formula
Nutrition