I never supplemented with Iron as DD took to solids with gusto at 6 months and we offered foods high in iron as her first foods. We aren't fully vegetarian, but kosher and do not eat much meat. DD LOVES to self feed all kinds of beans, spinach, etc.
We do however supplement with D. We started when she was 9 months (summer was just ending). We live in New England and DD's holistic health care provider is currently doing a study of her patients testing D levels in parents and children. What they are finding that the level of D mom takes and is exposed with does not mean mom's levels are high and therefore does not directly correlate with it's availability in breastmilk and baby's levels. Something to do with how your body processes the D it receives .... They are finding that most children in the practice have low levels- not necessary critical, but lower than it should be. Also considerably lower than kids in southern states/countries nearer to the equator. I am sure there is info online that you could dig up, I just don't have my finger on the resources our HCP gave us.
I take a vitamin with extra D and haven't had my levels checked. I think that if you live in a colder, cloudier, northern region it is definitely worth really looking into. If someone is living in Miami or southern california they are more likely getting a ton of direct sunlight exposure, but living in Washington, Canada, Maine you are not getting as much natural exposure and your infant isn't likely spending that much time outside with skin exposed when most of your calendar year it is long sleeved, hat wearing weather.
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