Knowledge, Attitudes, and Clinical Practices Regarding Food-Drug, Herb-Drug, and Supplement-Drug Interactions: A Pilot Cross-Sectional Study Among Healthcare Professionals in Portugal.
A discrepancy exists between perceived clinical relevance and actual practice among healthcare professionals in Portugal, with important gaps in technical knowledge regarding food-drug, herb-drug, and supplement-drug interactions.
Key Findings
Results
The majority of healthcare professionals recognised the clinical relevance of herb-drug interactions, but far fewer reported routinely asking patients about relevant product use.
90.6% of participants recognised the clinical relevance of herb-drug interactions
Only 57.6% reported routinely asking patients about food supplements or herbal product use
Only 46.0% reported routinely asking patients about teas or infusions
This gap highlights a discrepancy between perceived importance and actual clinical practice
The knowledge instrument consisted of 22 items with a score range of 0-22
The median knowledge score was 9.00 with an interquartile range of 9.00
The mean knowledge score was 9.34 ± 5.91
These scores suggest that on average, professionals answered fewer than half of knowledge items correctly
Results
Significant differences in knowledge scores were observed between healthcare professions, with pharmacists achieving the highest scores and nurses the lowest.
Differences between professions were statistically significant (p < 0.001)
Pharmacists achieved the highest knowledge scores among the professional groups studied
Nurses achieved the lowest knowledge scores among the professional groups studied
Non-parametric tests were used for group comparisons given the study's cross-sectional design
Results
In exploratory analyses, academic training and continuing education were associated with higher knowledge scores, whereas professional experience was not.
Academic training was positively associated with higher knowledge in exploratory analyses
Continuing education was positively associated with higher knowledge in exploratory analyses
Professional experience was not associated with higher knowledge scores
These findings suggest that formal and ongoing education, rather than time in practice, drives knowledge in this domain
Methods
The study was a cross-sectional pilot conducted among 311 healthcare professionals in Portugal using convenience and snowball sampling.
311 healthcare professionals participated in the study
An online questionnaire was used as the data collection instrument
Recruitment relied on convenience and snowball sampling, which limits generalisability
Descriptive statistics and non-parametric tests were used for analysis
The authors note the findings should be interpreted 'within the limits of this sample'
What This Means
This research suggests that while most healthcare professionals in Portugal—including doctors, pharmacists, and nurses—recognize that interactions between medicines and natural products like herbal supplements, teas, and food supplements can be clinically important, far fewer actually ask their patients about these products during consultations. In a survey of 311 healthcare professionals, only about half reported routinely inquiring about herbal product or supplement use, and fewer still asked about teas or infusions. When tested on their actual knowledge of these interactions, participants scored on average less than half of the possible points, indicating substantial gaps in technical understanding.
The study also found that not all healthcare professions are equally prepared: pharmacists scored highest on the knowledge test, while nurses scored lowest. Importantly, having more years of professional experience did not lead to better knowledge—instead, formal academic training and participation in continuing education were the factors linked to higher scores. This suggests that simply working longer in a clinical setting does not automatically build knowledge in this area; structured education is needed.
This research matters because the use of natural products alongside conventional medicines is increasingly common, and interactions between them can sometimes cause serious harm to patients. The findings point to a need for better education on this topic during professional training and throughout healthcare careers, as well as more structured approaches in clinical settings—such as routinely asking patients about all products they use—to improve patient safety.
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Silva W, Campos M, Pena A. (2026). Knowledge, Attitudes, and Clinical Practices Regarding Food-Drug, Herb-Drug, and Supplement-Drug Interactions: A Pilot Cross-Sectional Study Among Healthcare Professionals in Portugal.. Nutrients. https://doi.org/10.3390/nu18162600