Redman LM, Ravussin E Caloric restriction in humans: impact on physiological, psychological, and behavioral outcomes. Antioxid Redox Signal. 2011 Jan 15;14(2):275-87. doi: 10.1089/ars.2010.3253. Epub 2010 Aug 28. Review.
Rink SM, Mendola P, Mumford SL, Poudrier JK, Browne RW, Wactawski-Wende J, Perkins NJ, Schisterman EF Self-report of fruit and vegetable intake that meets the 5 a day recommendation is associated with reduced levels of oxidative stress biomarkers and increased levels of antioxidant defense in premenopausal women. J Acad Nutr Diet. 2013 Jun;113(6):776-85. doi: 10.1016/j.jand.2013.01.019. Epub 2013 Mar 19.
Zheng J, Zhou Y, Li S, Zhang P, Zhou T, Xu DP, Li HB Effects and Mechanisms of Fruit and Vegetable Juices on Cardiovascular Diseases. Int J Mol Sci. 2017 Mar 4;18(3). pii: E555. doi: 10.3390/ijms18030555. Review.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
