Interesting you should post this, Resi! I just got back from a work conference, and we listened to a speaker who I have seen multiple times before, who is an expert in vitamin D studies. She gave a really interesting speech about how pretty much EVERYONE should supplement with vitamin D and the RDI (recommended daily intake) is FAR below what it should be, but that it takes forever for the feds to change the recommendation. She said 10,000 IUs would be considered the upper limit for vit D intake (and that's not even dangerous at that level, it's just borderline), and that most adults should be getting closer to 2,000 IUs per day - I believe the RDI is 800 IUs for adults? Or maybe even as low as 400?
People in the northern climates are quite often vit D deficient, because not only do we not get outside as much (especially during the winter), but the sun is just at the wrong angle for our bodies to be able to produce vit D. And we'd have to drink like 10 glasses of milk a day to even get the minimum vit D requirement.
She also recommended that babies get vit D supplements, because vit D deficiency is linked to a whole HOST of medical conditions and newer studies are showing that having adequate vit D stores may help prevent some diseases (I can't think of which ones at the moment, but I will link you to some of her articles, she's really fascinating!). She talked about how breastfed babies especially should get vit D supplements because breastmilk doesn't have D. She explained that breastmilk IS the perfect food for babies, but because of the way our society has evolved, we have developed a need for supplementation, because (in her words) our babies aren't crawling around in the buff on the equator. (Basically, breastmilk is perfect when babies are able to be in sunlight a lot and at the right angle of sunlight to have their bodies produce vit D.)
Sorry, this is super long, but basically, I do plan on supplementing Ben with a multivitamin. I'd just rather KNOW he is getting the vitamins he needs, and anything he gets from his solid foods and breastmilk is just icing on the cake!
Here's some articles from the lady I was talking about...she's really on the cutting edge of nutrition research!
Handouts from Cathy Breedon | MeritCare Health System