Dietary Supplement Use Is High Among Individuals With Parkinson Disease

Christine C. Ferguson, MS, RD; Linda L. Knol, PhD, RD; Anne Halli-Tierney, MD; Amy C. Ellis, PhD, RD


South Med J. 2019;112(12):621-625. 

In This Article



A questionnaire was distributed to online PD support groups across the United States to assess dietary supplement use. Anyone age 18 years and older with a diagnosis of PD was eligible to take this survey via convenience sampling. Those with PD residing outside the United States were excluded because of differences in dietary supplement classification and regulation. Those with severe motor symptoms that may impair the ability to complete an online survey could receive assistance. The University of Alabama institutional review board approved the protocol, and informed consent was obtained from study participants.


Qualtrics software (Provo, UT) was used to administer the questionnaire to participants. The National Health and Nutrition Examination Survey and the Nutrition Data System for Research are two validated tools for the assessment of dietary supplement intake, and the verbiage and formatting from these tools served as the framework in the development of this questionnaire.[6,7] Respondents were asked about sociodemographic information, dietary supplement use or nonuse, and information about individual supplements taken. The sociodemographic information included age, sex, date of onset of PD, ZIP code, government financial aid assistance as a proxy of economic status, and a question about current medications. Internet protocol addresses were collected to assess for duplicity.

Respondents were asked about dietary supplement use in the past 30 days. Skip algorithms were used to reduce participant burden. If respondents reported taking at least one dietary supplement, then they were asked if they were taking a multivitamin or 12 other individual dietary supplements, including vitamin D, calcium, Mucuna pruriens, coenzyme Q10 (CoQ10), vitamin B6, vitamin B12, folic acid, melatonin, vitamin E, iron, fish oil, and N-acetylcysteine (NAC). These dietary supplements were selected based on the previous literature, showing evidence of common use or potential benefits or harms to those with PD.[2,5,8] For each dietary supplement taken, respondents were prompted to answer two additional questions about the reason for use and start of use with respect to PD diagnosis. Moreover, a free-text box question was included for respondents to report any additional dietary supplements taken. Dietary supplement users were asked whether they had spoken to a healthcare professional about their supplement use.

Statistical Analysis

The primary outcome measures of the study included dietary supplement use or nonuse and the types of dietary supplements being taken. Secondary measures included the reason for dietary supplement use, whether the participant started taking the supplements before or after PD diagnosis, and whether a healthcare professional was consulted at any point about their use.

Frequencies were calculated to describe dietary supplement use or nonuse, discussion of use with a healthcare professional, assistance used to complete the survey, and types of individual dietary supplements taken. Mann-Whitney U, Fisher exact, and χ2 tests were used to detect sociodemographic differences between users and nonusers of dietary supplements in addition to comparing dietary supplement use with previous reports among the general population and those with PD.[3] Analyses were performed using SPSS version 25 (IBM SPSS Statistics, Armonk, NY). All of the tests were two-tailed, and P < 0.05 was considered statistically significant.