"When I typed vitamin D into your search report window, I was re-directed to a page of advertizements for various vitamin D companies. I am sure that is an error, very disappointing. I really want information on the efficacy, dosage and recommended brands."
We do not intermingle our information or search results with advertising. We consider such routine practices as unethical, dishonest, and it is one of the things that separates us from our peers. The advertisements that you saw were from Google. We have no control over the advertising shown by Google searches.
As for vitamin D efficacy, it is well documented (even in the mainstream medical literature) that natural vitamin D from sunlight and seafood is a powerful, health-maintaining nutrient. However, supplemental vitamin D is less beneficial, and some people get absolutely no benefit from it. It is important to know that vitamin D is virtually useless if the person is deficient in either magnesium or calcium, because they are interdependent. Likewise, the body will not properly utilize the optimal vitamin D (D3) if the liver is sufficiently dysfunctional. Be advised that too much vitamin D from supplementation will prevent a body from properly coping with cholesterol, which can lead to major problems, so less can sometimes be more.
There are good reasons why you did not see any recommended brands from us. As part of our ethical policies, we rarely recommend particular brands. There are two important reasons for this policy. Firstly, we want to stay journalistically clean by not having any perceived or real conflicts of interest. Secondly, we cannot recommend specific brands in good faith because supplement ingredients change so regularly that any such advice might eventually get lots of people hurt. We operate under the old principle of "First do no harm". Thus, the main advice that we give concerning brands is that everyone should strive to be an educated consumer in knowing exactly what the ingredients are and where they originated. For instance, you would be shocked to know how many companies are getting unmonitored ingredients from China, and then relabeling their resultant products as being "American Made", using the trickery of it being "produced" in America, since it is where they mixed the foreign ingredients together. In case this helps, we get most of our own supplement products from vitacost.com, and we currently give the most trust to supplements that are made by Nature's Way. Nevertheless, check each product for yourself, for we cannot make blanket endorsements for any company, nor can we predict future behaviors. Our overall statement about vitamin D is that it is indeed very important to health, but it is over-hyped amongst the writers of alternative therapies. You may find our article about supplement gotchas interesting: The Supplementation Problem and Our Supplement Recommendations. You may also wish to read: Sunscreen Lies and Cosmetic Trade Secrets for some fascinating information about vitamin D.