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This article is part of our special May 2021 issue. Download the full issue here.
Relation
Esposito C, Garzarella EU, Bocchino B, et al. A standardized polyphenol blend extracted from poplar-type propolis for the relief of symptoms of uncomplicated upper respiratory tract infection (URTI): a single-center, randomized, double-blind, placebo-controlled clinical trial.Phytomedicine. 2021;(80):153368.
Study objective
Evaluation of the Effects of a Standardized Oral Spray of Poplar Propolis Extract (MED-Propolis) on the Symptoms of Mild Upper Respiratory Tract Infections (URTIs)
Draft
A single-center, placebo-controlled, double-blind clinical trial conducted in an outpatient setting
Participant
122 subjects took part in this study (58 in the propolis group and 64 in the placebo group). The age range was 18 to 77 years; 54 subjects were male and 68 female. All subjects had signs and/or symptoms of URTI. Subjects were examined by a physician and were eligible for inclusion in the study if they experienced one or more of the following common URTI symptoms: sore throat, dull dysphonia, and swelling and redness of the throat, which began on the same day as the baseline visit (t=0).
intervention
Subjects were randomly assigned to receive either an oral propolis spray or a placebo spray from t1 to t3 (5 days). The dose was 2 to 4 sprays 3 times daily. Researchers assessed each participant at 4 time points: baseline = t0, after 3 days = t1, after 5 days = t2, and after 15 days = t3.
The propolis spray was standardized to contain 15 mg/ml polyphenols. The spray had a reproducible composition of the 6 main flavonoids found in this type of propolis (i.e. galangin, chrysin, pinocembrin, apigenin, pinobanksin, quercetin). Each participant used 2 to 4 sprays 3 times daily for 5 days. The placebo spray had an identical appearance and taste to the propolis spray.
Study parameters assessed
Aside from the primary outcome measure, researchers assessed the persistence of positive bacterial throat cultures at t3. They performed throat swabs on all subjects at t0 and then again at t2 and t3 on those subjects who had an initially positive throat culture. At time t0, 8 people in the treatment group and 7 people in the placebo group were positive for bacterial URTI. At t3, no positive bacterial throat culture was found in any of the subjects in the treatment or placebo groups.
Primary outcome measures
The primary endpoint was resolution of URTI symptoms. The researchers assessed these symptoms at baseline (t0), 3 days (t1), after 5 days (t2) and at the final time point (t3) of the study, 15 days.
At t1, 17% of participants in the treatment group still had 1 symptom of URTI. In contrast, approximately 72% of people in the placebo group still experienced 1 symptom (RR: 2.93, CI: 1.95-4.42).
The results of a univariate analysis showed that only treatment with oral propolis spray was associated with the disappearance of symptoms (resolution of all symptoms in the treatment group vs. the placebo group: X2=35.57, df=1,P<0.001; Resolution of sore throat in the propolis vs. placebo group: X2 = 28.38, df = 1,P<0.001; Resolution of muted dysphonia in the propolis vs. placebo group: X2=4.38, df=1,P=0.036; and resolution of swelling and redness of the throat in the propolis vs. placebo group: X2 = 16.85, df = 1,P<0.001).
Clinicians using natural medicine should not be afraid to include propolis in treatment plans for many types of infections.
All logistic models of the data were also significant and showed that the propolis spray was the only variable that correlated with resolution of all symptoms and individual symptoms (all symptoms: X2 = 46.51, df = 7,P<0.001; Sore throat: X2=34.21, df=6,P<0.001; Swelling and redness of the throat: X2=23.19, df=6,P<0.001; Subdued dysphonia: X2=7.87, df=3,P=0.048).
No association was found between the resolution of symptoms after 3 days and the type of infection (bacterial or viral) or the age or gender of the subjects.
Key insights
The disappearance of all URTI symptoms occurred 2 days earlier in the propolis group compared to the placebo group. Symptoms disappeared within 5 days in the placebo group and within 3 days in the treatment group. This finding applied to both viral and bacterial URTIs. Because so few bacterial URTIs were detected in this study, the authors could not draw any conclusions regarding the effect of propolis on antibiotic-resistant bacteria.
Practice implications
Propolis has always interested me, and it has defied my attempts to categorize it. Is it a herbal medicine? Well, not exactly. It is certainly a “natural medicine”. Propolis is a very complex mixture of polyphenols, wax, resins, pollen, essential oils, minerals, vitamins and other components. It occurs when bees collect plant excreta and mix it with their saliva.1The bees use propolis to seal their hives and it has an antimicrobial effect on the hive. The composition of propolis varies depending on the type of bees, the time of year, the plants the bees visit, and other variables.2
Dietrich Klinghardt, MD, recommends including Brazilian green propolis in treatment plans for people with Lyme disease accompanied by bartonellosis. Bartonella is a gram-negative, intraerythrocytic bacterium that can be transmitted to humans by ticks and other vectors.3In my experience, concomitant bartonellosis can make treatment for Lyme disease more complex. People with chronic tick-borne illnesses need treatment options, and it's good to know that propolis can be on the menu.
The bad thing about propolis for the pharmacist is that it is such a complex and variable mixture, making it difficult to identify the “active compounds”. The good thing about propolis for those who study and respect natural medicine is that it is such a complex and variable mixture, with supposed synergies in medicinal compounds. A 2019 review by Przybylek and Karpinski notes that "this diversity of chemical composition gives propolis an additional advantage as an antibacterial agent. The combination of many active ingredients and their presence in different proportions prevents the emergence of bacterial resistance."4Due to the worrying increase in nosocomial infections caused by antibiotic-resistant bacteria (particularly of the gram-negative variety), there has been a recent focus on the development of “antibiotic hybrids”. These new drugs combine different classes of antibiotics to overcome bacterial resistance.5Perhaps the many ingredients in propolis make it the ultimate “antibiotic hybrid”?
Clinicians using natural medicine should not be afraid to include propolis in treatment plans for many types of infections. Like many natural medicines, propolis contains nutrients that can boost immunity and anti-inflammatory compounds to deal with the inflammatory nature of infections.6It has the versatile ability to be directly antimicrobial, nourishing and immune-boosting at the same time.7This is a high bar that would be difficult for a synthetic drug to achieve.
As I continue to review studies on botanical/natural medicine, it seems to be less common to see a well-designed study on these topics in the United States. This study is no exception. The current study was a collaboration between scientists in Italy and China. There are countless variables that go into the U.S. healthcare system equation. But one thing is certain: we spend more on health care and have worse outcomes than other developed nations.8I can't help but wonder how much it would benefit us if even a tiny fraction of the money we invest in pharmaceutical research were put into research into natural medicines and there was a serious attempt to integrate them into our primary healthcare system. This appears to be particularly true in the era of increasing microbial resistance to conventional antibiotics.
On a trip to Japan, I remember being impressed that prescription “Kampo” herbal formulas were available in pharmacies. Every pharmacist we visited was familiar with Kampo herbal formulas and had a handy Kampo reference book to help us describe the composition and effects of these common recipes. In Japan, 90% of doctors prescribe Kampo herbal formulas, and the government insurance plan covers them.9
URTIs are the most common reason for doctor visits worldwide. They cost $22 billion and cause more than 20 million missed school/work days annually.10Imagine the suffering that could be averted and the money that could be saved by including propolis in the average URTI primary care visit. This could help patients avoid more complicated URTIs and reduce the need for prescriptions such as steroids and codeine, which have significant side effects. Patients can also receive better nutrition to ward off the next immunological attack.