Background

Propolis is a natural resinous mixture produced by honeybees using substances collected from different parts of plants. Because propolis has exhibited antioxidant and anti-inflammatory properties and based on evidence from limited in vitro (cell studies), in vivo (animal studies) and clinical research, it is thought that propolis may improve cognitive function in the elderly. However, more clinical research is needed to examine this possibility.

The study

In this 24-week randomized controlled trial, 68 Japanese adults ages 60–79 years with normal cognition (according to the Mini-Mental State Exam) and living with forgetfulness (subjective or as pointed out by others) took capsules containing either 543 mg of propolis extract (standardized to include 58 mg of artepillin C, the main bioactive component of propolis) or a placebo.

The researchers assessed cognitive function using Cognitrax, a test that evaluates various cognitive function domains such as processing speed, verbal memory, visual memory, reaction time, and executive function. They also assessed several blood and urine markers, including blood lipids, TNF-α (an inflammatory and immune marker), creatinine, and urea nitrogen (markers of kidney and liver function).

The results

Propolis extract improved verbal memory (+17%) more than placebo (10%). Total and LDL cholesterols worsened in both groups but to a smaller degree in the propolis extract group. Propolis resulted in clinically irrelevant improvements in urea nitrogen, creatinine, and uric acid relative to placebo.

In subgroup analyses including only participants with >100 on the standardized score of the neurocognitive index (i.e., the participants with the highest cognitive function), propolis extract improved verbal memory and processing speed more than placebo.

Note

The researchers did not specify a primary outcome. Moreover, they tested a large number of outcomes without making adjustments for multiple comparisons, which increases the risk of false positive results. It’s also worth pointing out that one of the study authors received a medical advisory fee from Yamada Bee Company, the manufacturer of the propolis supplement used.

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This Study Summary was published on April 4, 2021.