Concerns for the use of soy-based formulas in infant nutrition

Question 1

What are phytoestrogens?

Answer 1

Plant derived substances with estrogenic activity

Question 2

What type of estrogen are contained in soy-based infant formulas?

Answer 2

Isoflavone class, which includes genistein, daidzein, glycitein

Question 3

What is the potency of isoflavones?

Answer 3

Relatively weak estrogens. ~1/1000-1/10 0000 of potency of estradiol.

Question 4

What is the daily intake of phytoestrogens consumed by infants on soy-based formula?

Answer 4

4-11mg/kg body weight

13 000-22 000 times greater than [plasma estradiol]

Question 5

What percentage of phytoestrogens in soy-based infant formulas are present in biologically inactive form?

Answer 5

94%

Question 6

What are contraindications to the use of soy based formula

Answer 6

1. Congenital hypothyroidism - as inhibits thyroid peroxidase lowering free thyroxine
2. Premature infants - as provides inadequate nutrition and growth

Question 7

What are some concerns noted with isoflavones from soy based formulas in animal studies?

Answer 7

1. sex organ development
2. brain maturation
3. immune system function
4. stimulate cancer development
5. infertility

Question 8

Why should soy based formula not be used in CMPA?

Answer 8

Coincident soy protein allergy

7-14% in IgE mediated, higher in non-IgE mediated

Question 9

What are indications for soy based formulas?

Answer 9

1. Galactosemia

2. Cannot consume dairy based products for cultural or religious reasons