Effects of a Dietary Supplement on the Incidence of Acute Respiratory Infections in Susceptible Adults

We conducted a randomized, parallel, double-blind, placebo-controlled, 90-day clinical trial from January to April, 2012. All staff who worked at the Omnilife's Entrepreneur Support Department (CREO by its initials in Spanish) were invited to participate. This department within Omnilife has a high incidence of acute respiratory infections (ARI) as reported internally by the company's medical service (accounting for 55% of doctor visits within the department in 2010) and hence, they represent a high number of individuals susceptible to ARI.

We held a preliminary session with the department's entire staff to explain the procedures; we asked subjects interested to participate in the study to sign an informed consent form and fill a clinical history. The latter included an assessment of stress, using the Perceived Stress Scale (in which higher scores indicate higher levels of stress), and physical activity, using the International Physical Activity Questionnaire or IPAQ (in which physical activity is categorized in three levels: light, moderate and vigorous).

In a second session the same week, participants visited the company's medical service for measurements of their weight and height (in accordance with the International Society for the Advancement of Kinanthropometry or ISAK standards), control laboratory tests and a medical examination to rule out the presence of infections. Weight measurements were taken using a Tanita BC553 Ironman Inner Scan Body Fat Scale (capacity of 150 kg, accuracy to 0.1 kg). Height measurements were made using a Seca 206 Stadiometer (accuracy to 0.1 cm, measuring range to 220 cm). Both measurements were performed by a two certified and standardized anthropometrists. Body mass index (BMI) was subsequently calculated using both variables as follows: BMI = weight in kg/(height in m)2.

The medical examination was performed by the attending physician and a nurse. It consisted of an assessment of vital signs following procedures described in the literature and a physical examination of bodily organs and systems. Temperature was measured using a Microlife MT 1931 digital thermometer (measuring range from 32 to 43.9°C, accuracy to 0.1°C). Heart and respiratory rates were measured using a 3M Littmann Classic II S.E. stethoscope. Blood pressure readings were taken using a 3M Littmann Classic II S.E. stethoscope and an Aneroid Sphygmomanometer ce0483 (18-300 mmHg measurement range, accuracy to 2 mmHg).

Laboratory tests were conducted with the support of an external laboratory (Instituto Diagnostico Especializado Arboledas, IDEA by its initials in Spanish). Included were a blood test of six items (fasting glucose, uric acid, creatinine, blood urea nitrogen, cholesterol and triglycerides) analyzed by the spectrophotometric method, a complete blood count with a flow cytometry/microscopy analysis of platelets, and a spectroscopy analysis to assess liver function. Subjects of laboratory analyses were tested after a 12-hour fast. This laboratory has obtained quality control certification from the Quality Assurance for Laboratories Program (PACAL) and the Internal Evaluation Quality Program (PREVECAL). In addition, its staff is certified in clinical diagnosis by the National Association of Clinical Chemists (CONAQUIC).