Part 1C: In vivo & Ex vivo Laboratory Trials

ex vivo studiesIn order to evaluate the studies about pharmaceuticals and nutritional supplements, including antioxidants, it is useful to understand “scientific” studies and the games that can be played with statistics, variables and factors involved. In Part 1B of “The Devil’s Advocate on Antioxidants,” I laid out a simplified version of the progression of scientific studies, along with the pros and cons of each stage:

1) Research-- thousands of lead compounds are narrowed down to hundreds for a targeted issue
2) Pre-Clinical Trials-- laboratory and animal testing
    • Laboratory Studies
      • In vitro-- test tube experiments that may or may not correspond to human testing
Now we will look at the other types of laboratory studies:

Outside of a lab, Human Studies are another form of in vivo studies. This is typically the final phase which incorporates several stages, including three primary phases, that typically span a period of 6-7 years in total. The difference between phases within Human Studies has to do with the size of the group sampled as well as the pre-existing health of study participants. Each phase also has a specific goal in mind such as determining general or statistical data related to the safety, effectiveness, optimal dosage and benefit-risk ratio of the compound or pharmaceutical being studied. In the case of pharmaceuticals, each new product must complete all of the phases before being submitted to the FDA for review.

The cons of studies on humans may include factors such as the volunteers not being consistent with lifestyle choices, for instance consumption of fats may change based on education and perception of what is healthy to the participant. (4) Ethics is definitely involved in human studies as well, such as the tested compound having an unanticipated negative or dangerous effect upon the health of the participants-- antioxidant clinical trials fall into this category. Ethically they could not continue with several studies because of the increased incidence of cancers with the use of antioxidants. (5, 6, 7)

Next time, we will discuss the two main types of Human Studies along with the pros and cons of the different types. As you can see there are many factors that need to be considered when evaluating these studies in order to make healthy choices for you and your family. Hopefully this blog series has helped to remove some of the confusion!

L'chaim-- To Life!


2 Ibid.
3 Ibid.
4 In Defense of Food, Michael Pollan
5 JAMA, February 28, 2007—Vol 297, No. 8, at University of Wisconsin -Madison.
6 The Journal of American Society of Nutrition, 2007, “Antioxidant Supplementation Increases the Risk of Skin Cancers in Women but Not in Men.”
7 Arch Intern Med. 2004; 164: 2335-2342.