Ng JY, Garber A, Luong M, Cooley K, Busse JW. No improvement in disclosure of natural health product use to primary care medical doctors in the last 15 years: A survey of naturopathic patients. Complementary Therapies in Clinical Practice 2020;19:101-106 

The original article abstract can be found on the Science Direct website

Why was this study conducted?

Natural health products (NHPs), such as vitamins, herbs, medical cannabis, and various supplements, have the potential to produce toxic effects or interact with pharmaceuticals; as a result, it’s important medical doctors know if their patients are using them. To determine whether there has been any shift in the usage and disclosure of NHPs in Ontario, a group of researchers from McMaster University and the Canadian College of Naturopathic Medicine repeated a survey administered in 2003 to patients of a naturopathic teaching clinic in Toronto.

What does this study add?

One of the most common NHP patients used was cannabis, which was reported by 9% of respondents. As was the case 15 years ago, less than half (42%) of naturopathic patients reported the use of NHPs to their primary care medical doctor.  In an adjusted model, the only factor associated with disclosure of NHP use was whether their medical doctor asked about it (Odds Ratio=5.27, 95% Confidence Interval 2.57-10.78).  But three-quarters of respondents stated their medical doctor did not ask about their use of NHPs. The results suggest that no progress has been made in encouraging dialogue between patients and medical doctors on the topic of NHPs.

Is there anything else I should know?

Only 25% of clinic patients approached by the researchers completed the questionnaire, of which 54% used only NHPs and 46% used them concurrently with prescription drugs.  The characteristics of the survey population did not differ greatly from the 2003 sample and the rate of nondisclosure of natural health products remained consistent.  

Author Details

The latest scientific evidence on this topic was reviewed by the Centre's leadership team. This research summary is written by Corinne Hodgson, DHealth, assessed for accuracy by Dr. Jason Busse, DC, PhD. There are no conflicts of interest. Questions regarding this piece should be directed to Dr. Jason Busse (

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