The mean vitamin D content from 10 OTC brands was only 33% of what the label claimed, with the actual content ranging from less than 1% to 82% of the advertised level. The study was presented at the meeting of the Joint Consortium of Multiple Sclerosis Centers and America's Committee on Treatment and Research in Multiple Sclerosis.
Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Vitamin D Content is Low or Unpredictable. according to an article on Medical News. Dr. Calebresi collected 10 bottles of OTC supplements from local and on-line retail pharmacies. Vitamin D3 was extracted by standard techniques and samples were analyzed by liquid chromatography and mass spectrometry. Liquid chromatography and mass spectrometry are tests that show the chemical content of specimens.
The unpredictability of the samples varied widely. Unfortunately, national in-store retail brands nor online brands proved to be reliable.
Also, Vitamin D2 has been shown to be unreliable in the past.
Supplements, including vitamins, are not regulated by the FDA. A lot of them are coming from China these days, so quality is an issue. Apparently, people fleeing from Big Pharma are falling into the arms of Big Supplement.
If you are wondering about whether your supplement is working, you can check this website: https://www.consumerlab.com/. Consumer Labs is a certified drug testing facility so, unlike the authors of the study, it can name the companies it studies.
However, in the discussion about the Vitamin D article, one poster noted:
While ConsumerLab provides a valuable service, it is important to understand that many of the products are evaluated under what they call the Voluntary Certification Program (VCP). Under that program a manufacturer pays an upfront fee to be included in the test for a particular supplement, while other brands are selected randomly. Results for a VCP are omitted from the online reports if the product fails; in such a case no mention is made of the fact that the product was even tested. So, CL has knowledge of deficient products which is being withheld from report subscribers. This is of concern for something like Vitamin D content-claim testing, but even more so for something like chromium supplement testing, where CL reported a rather alarming incidence of contamination with hexavalent (potentially carcinogenic) chromium in non-VC products -- but left subscribers in the dark with regard to any VC products in which they uncovered similar (or even greater) risk. Despite the valuable ratings CL provides, it's important to understand this shortcoming when using their reports. The VC program is described on the CL website.
Another poster noted:
The United States Pharmacopeia (USP) has a voluntary testing and auditing program for dietary supplements. USP-verified vitamin D is readily available at many supermarkets and drugstores. It can be identified by the USP mark on the label. A number of other USP-verified supplements are also available, including other vitamins, minerals, fish oil, glucosamine/chondroitin, and CoQ10. For information about the USP dietary supplement verification program, go to http://www.usp.org/USPVerified/dietarySupplements/. To see lists of USP-verified products, and stores where they can be bought, go to http://www.usp.org/USPVerified/dietarySupplements/supplements.html. Some of the listed brand-name products may also come in non-USP-verified versions -- so before buying, it's important to check for the USP mark on the label.
So, who to trust these days.... Even non-profits, are not completely transparent. Let the FDA or another government agency test it? So, what happens when administrations change? You get a pro-business administration in charge, they eviscerate the regulations. You get a pro-regulatory administration in charge, and everyone howls about the paper work and added expense.
You would think we learned something from Katrina or the Gulf spill about a good role for regulating business should be... but apparently, we haven't.