Soy Formula Flashcards
What are phytoestrogens?
Plant derived substances with estrogenic activity.
Present in soy based infant formulas (isoflavone class) - genistein, denistein, glycitein.
40ug/ml
Why are there concerns about phytoestrogens?
There is concern that they may mimic the actions of extradition or alter estradiol metabolism and consequently modify the processes influenced by estradiol. This is more of a theoretical risk than an evidence based risk.
What is the metabolism of phytoestrogens?
Consumed in inactivated form: beta-glycosylated isoflavones
In gut: activated by removal of glycoside by bacteria
Absorbed
Inactivated by the liver through the formation of gluconidated or sulfated isoflavanes
So only 0-3% of consumed phytoestrogens are in their active form
Do infants consuming soy based formula accumulate phytoestrogens?
No
What are the thyroid concerns regarding soy based formula? What should you do?
There was a study that demonstrated that in infants with congenital hypothyroidism, there were abnormal thyroid function tests
WHY: phytoestrogens can inhibit thyroid peroxidase, potentially lowering free thyroxine concentrations.
If parents are insistent on using soy based formulas in a kid with congenital hypothyroidism, you should periodically test their thyroid levels.
What have the animal studies shown regarding the effect of soy based formulas?
Is there evidence that these effects are relevant for humans?
infertility and abnormal sex organ development
Brain maturation abnormalities
Alternations in immune system
RELEVANCE: we have seen no evidence of their relevance in humans (no evidence of overt harm).
Human trials have shown that some women have higher incidence of regularly using asthma and allergy meds and longer duration of menstruation.
Do soy based formulas support growth and nutrition?
Yes - for normal children. No for preterm infants
Why would some parents choose soy formula for their infant with CMPA?
Cheaper and better tasting than hydrolysed formula
NB CMPA is not the most common reason people are using soy based formula. Mothers often choose it because of personal preference. Doctors sometimes recommend it for colic and diarrhoea.
Is soy based formula recommended in CMPA?
It is contraindicated in non-IgE mediated CMPA - high rate of coincident soy allergies in these kids
It can be used in IgE mediated CMPA because there are much lower rates of allergy (7-14%), after a clinical challenge.
However most societies do not recommend it for CMPA.
How can you tell the difference between IgE and non-IgE mediated CMPA?
IgE: urticaria, angioedema, resp sx and GI sx. Often appear fairly quickly. 60%
Non-IgE: GI symptoms. Most common symptom is bloody stool. 40%
Skin prick testing can also help
What is the gold standard for diagnosis of CMPA?
Double blind, placebo controlled food challenge
Why do all of the societies no recommend any soy based treatment for CMPA?
Because it is difficult to distinguish between IgE and non-IgE mediated CMPA. So it is safer if ppl just give hydrolysed formula.
Which infants should use soy-based formula
Those with galactosemia or those who have religious/cultural reasons not to consume dairy products.
