Saturday, February 6, 2010

Supplemental alpha-tocopherol: A Perspective on Approaching an Evidence-based Project


As part of a Continuing Professional Development project with ARAMARK Canada Ltd. at the Toronto Rehabilitation Institute (Toronto Rehab), I reviewed the literature on supplemental α-tocopherol. My objectives were to weigh the potential risks versus benefits of supplemental α-tocopherol in primary and secondary prevention of cardiovascular disease (CVD) to determine specific practice considerations for supplemental α-tocopherol including the type of supplement, dose and duration. This was an opportunity for me to hone my skills using evidence-based methods. As expected, a plethora of literature on this topic existed, so I focused on randomized controlled trials (RCTs).

Reading, critiquing, and comparing the many papers that exist on the topic was time consuming, but necessary. Some studies looked at α-tocopherol alone, while others looked at α-tocopherol in combination with other antioxidant supplements. Studies were inconsistent in terms of dose, unit of measure (mg versus IU) and source (natural versus synthetic). I discovered there are specific conversion factors to use depending on the unit of measure, as well as the source (natural or synthetic). Taking the Dietary Reference Intake (DRI) course in the past proved helpful as I was able to easily retrieve required information on α-tocopherol.

Working on such a large project really put my organizational abilities to the test. Initially feeling overwhelmed, I decided to arrange the stack of papers. Primary prevention papers were filed in one binder and secondary prevention in another. Within the secondary prevention group, where I devoted most of my time, I compartmentalized further. For example, the outcomes of short term trials (under five years) were examined separately from studies longer than five years. Within these groups, I looked at the dose and type of supplement (natural versus synthetic) and made the necessary conversions.

I highly recommend reading Deborah (Boyko) Wildish’s chapter on micronutrient supplementation (Wildish, 2008), a resource that helped me immensely in my critique.

Factors considered for each article:

  • Population being studied
  • Type of chronic disease(s) or conditions the participants experienced
  • Form of supplemental E
  • Dose and timing (i.e., when was it administered)
  • Study duration
  • Inclusion of other antioxidants e.g., vitamin C, β-carotene
  • Outcome measures

The checklist (p. 190) details factors impacting the strength of study design and quality of evidence.

Keeping to a schedule was paramount for completing such a large project. When I was away from the task for an extended period, I found I wasted valuable time simply reviewing what I had done. The next time I take on such a project, I plan to consistently devote a few hours each week to keep the project alive and the momentum flowing.

I highly encourage involving members of the interprofessional team. I liaised with our program physician, pharmacist and other RDs on issues related to α-tocopherol. Our staff librarian was most helpful in assisting me with the literature search and in obtaining journal articles. This was a huge time saver!

Project Conclusions

For Primary Prevention: No benefits or risks reported with 20-660 IU/d for three to 10 years. Thus, not enough evidence to support recommending supplemental α-tocopherol for primary prevention of CVD.

Secondary Prevention: Equivalent evidence reporting both risk and benefit associated with 22.5 to 800 IU/d for 1.4 to 9.4 years, and increased risk of mortality observed with α-tocopherol supplementation >150 IU/day. It was questionable whether lower doses offered any benefit. More research is required. Therefore, supplementation with vitamin E is NOT recommended for secondary prevention of CVD.

The experience of completing this project left me with several salient points of learning. Firstly, studies generally are not designed to measure treatment risk because inflicting potential harm on humans is unethical. Thus, whenever risk emerges in a study, even if small, it may be more serious than reported because the researchers focused on treatment benefits. Secondly, I learned that you must have a keen interest in your topic to sustain your interest. Finally, there must be practical application of your findings to your daily practice with clients and colleagues. Sharing the results of project work communicates our expertise to colleagues. Not only is this self-empowering, but it helps raise the profile of RDs, and fosters interprofessional relationships.


REFERENCES

Wildish DE. (2008). Addressing clinical queries for micronutrient supplementation in the management of diseases and medical conditions: What can I tell my patient? In: Yoshida T, Ed. Micronutrients and Health Research. Publishers, Inc.: 181-205.

Other references available upon request.


CONTACT:
Maria Ricupero, RD, CDE
ARAMARK at Toronto Rehab
T: (416) 597-3422 (5239)
E: ricupero.maria@torontorehab.on.ca