Review of existing experimental methods for assessing the outcome of plant food supplementation on immune function

Plant food supplements (PFS) have become increasingly popular with respect to their consumption for improving human immune function. Despite this popularity, critical review is lacking regarding the analytical methods used to assess PFS outcome. The suitability of such methods for clinical-based studies remains particularly unclear. We undertook a literature-based review of the methods used to assess PFS outcome in immune function, to identify and assess the relevance of different technologies. Most methods described in this review adequately measured the functions of innate and adaptive immunity, were applicable to both healthy and diseased subjects, and were appropriate for assessing the benefit claims of PFS on immune function. However, the design and reporting quality of studies varied widely across trials, in some cases potentially impacting negatively on the outcomes and interpretations. Several strategies to enhance study robustness and quality were outlined, to improve the validity of the data generated in the field.