Vitamin Oversupplementation - Don't do it!

I once had a dentist tell me that I could flush my multivitamins down the toilet for all the good they were doing me. I smiled and thought he was a bit extreme. I now join him in that advice.

Guess what happens if we oversupplement with folic acid for a long time? Our bodies downregulate (make less of) folic acid receptors in our intestines and other folate-related activity gets altered.

CONCLUSIONS:
Long-term oversupplementation with folate leads to a specific and significant down-regulation in intestinal and renal folate uptake, which is associated with a decrease in message levels of hRFC, PCFT/HCP1, and FR. This regulation appears to be mediated via a transcriptional mechanism, at least for the hRFC system.
PMID:

And what happens if we oversupplement with Vitamin D for a long time? Do the vitamin D receptors in our intestines also get messed up? If so, that would be a very bad thing. The presence of Vitamin D receptors is essential to not getting colitis, per this study:

Abstract The inhibitory effects of vitamin D on colitis have been previously documented. Global vitamin D receptor (VDR) deletion exaggerates colitis, but the relative anticolitic contribution of epithelial and nonepithelial VDR signaling is unknown. Here, we showed that colonic epithelial VDR expression was substantially reduced in patients with Crohn’s disease or ulcerative colitis. Moreover, targeted expression of human VDR (hVDR) in intestinal epithelial cells (IECs) protected mice from developing colitis. In experimental colitis models induced by 2,4,6-trinitrobenzenesulfonic acid, dextran sulfate sodium, or CD4+CD45RBhi T cell transfer, transgenic mice expressing hVDR in IECs were highly resistant to colitis, as manifested by marked reductions in clinical colitis scores, colonic histological damage, and colonic inflammation compared with WT mice. Reconstitution of Vdr-deficient IECs with the hVDR transgene completely rescued Vdr-null mice from severe colitis and death, even though the mice still maintained a hyperresponsive Vdr-deficient immune system. Mechanistically, VDR signaling attenuated PUMA induction in IECs by blocking NF-κB activation, leading to a reduction in IEC apoptosis. Together, these results demonstrate that gut epithelial VDR signaling inhibits colitis by protecting the mucosal epithelial barrier, and this anticolitic activity is independent of nonepithelial immune VDR actions.

What if all that Vitamin D in our milk, in our multivitamins, and Vitamin D drops is decreasing our intestinal Vitamin D receptor activity and depriving us of protection to our intestinal lining? Would that help explain the mysterious rise of leaky guts and gluten intolerances?

Is it too much for me to ask that the government keeps its meddling hands off of my food? I'll eat tuna and eggs and go get some sunlight on my fair skin. I don't need supplements!