Dr. Holub attends the DRI Workshop

November 6, 2007

Reference:

Dr. Holub attends the DRI Workshop (Sept. 18-20, 2007)

Summary:

The Institute of Medicine (IOM) and the Food and Nutrition Board convened the recent workshop (September 18-20, 2007) in Washington, D.C. entitled ‘The Development of DRIs 1994-2004: Lessons Learned and New Challenges’. The workshop was aimed at fostering discussion about the process for developing the DRIs (Dietary Reference Intakes) for the various nutrients and includes AI (Adequate Intake), RDA (Recommended Dietary Allowance), EAR (Estimated Average Requirement), AMDR (Acceptable Macronutrient Distribution Range), and UL (Tolerable Upper Intake Level). The workshop was not intended to provide consensus recommendations on issues but rather focus on describing the range of stakeholder inputs and opportunities for such. The workshop was held at the National Academy of Sciences auditorium on Constitution Ave., Washington. The workshop was jointly sponsored by the U.S. Department of Health and Human Services, U.S. Department of Agriculture, the Canadian Institutes for Health Research, with additional support from Health Canada. Health Canada now cooperates fully with the Food and Nutrition Board in the U.S. on the DRI process and recommendations.

The workshop was structured to foster discussions among expert research and government scientists and nutrition practitioners, as well as others from academia, government, health care/nutrition practice, and industry. Following introductory remarks from Dr. John Suttie (Chair, University of Wisconsin) and Dr. Christine Taylor (Institute of Medicine) who provided an overview of the current DRI framework and issues, various presentations from committee members of the Food and Nutrition Board along with other invited speakers were given over the next two and a half days ranging from sessions entitled ‘Conceptual framework for DRI development’, ‘Criteria for scientific decision-making’, ‘General guidance for users on DRIs’, and ‘Looking to the future process for DRI development’.

The topic of nutritional requirements and recommendations surrounding omega-3 fatty acids occurred on a couple of occasions during the discussions. Reference was made from the speakers on evidence-based literature supporting the potential role for omega-3 fatty acids and particularly fish/fish oils containing DHA/EPA with respect to a reduction in coronary heart disease-related mortality. A question was posed from the audience (yours truly) as to whether or not evidence for a potential beneficial role of omega-3 fatty acids in reducing cardiac-related mortality should be considered in the DRI process in studying future recommendations. A committee member responded by suggesting that such would not be appropriate. Death from chronic disease appeared not to have been a parameter to date for setting DRIs. The general discussions over the two and a half days focused on emphasizing the DRIs for enhancing health while some significant inconsistency in opinion developed when the question of setting recommendations for the attenuation of risk factors related to chronic disease was raised. It was also pointed out to the committee members that recommended intakes for nutrients would be higher if the reduction in risk factors for current disease were considered as opposed to focusing exclusively on the enhancement of human health. I also made reference to the recent recommended intakes for omega-3 fatty acids from Australia and New Zealand as α-LNA plus long-chain n-3 (EPA/DPA/DHA) where AI values were given as well as suggested dietary target values for reducing chronic disease risk (see www.dhaomega3.org).

For me personally, I was somewhat discouraged by the apparent lack of enthusiasm amongst the committee members in considering disease and death therefrom (eg., cardiovascular-related) as a key parameter in considering DRIs since, in the case of omega-3 fatty acids as α-LNA and as DHA/EPA, some of the benefits with respect to reduced mortality in risk individuals have often become apparent without any significant modification of conventional risk factors for cardiovascular disease. It is well known that the conventional risk factors as measured in our health care system for cardiovascular disease/mortality risk (including lipid/lipoprotein profiles, blood pressure, others) represent only a small fraction of the total risk factors for cardiovascular events which often include inflammatory, arrhythmic, thrombotic, blood flow, plaque stability and other factors which are not currently measured in our health care system. Several of these latter risk factors can be favourably attenuated with fish/fish oils (and in some case with plant-based omega-3 fatty acid as α-LNA). Many of the delegates advised that more transparency in the DRI process and opportunities for evidence-based input from experts is needed.

Health Canada gave official nutrient status to α-linolenic acid (LNA) with a RNI (Recommended Nutrient Intake) at 0.5% of energy in 1990. AI values for α-linolenic acid (α-LNA) were established in 2002 by the IOM. For example, the AI for men and women was established at 1.6 and 1.1 gms of α-LNA per day, respectively. For children aged 1-18 years, an AMDR range (% of energy) of 0.6-1.2 % was established as α-LNA with no specific requirement for the longer-chain omega-3 fatty acids as DHA and/or EPA. The IOM did indicate that approximately 10% of the total omega-3 fatty acid intake as α-LNA can come from longer-chain n-3 fatty acids (DHA + EPA) with no specification to ensure minimal amounts of DHA. Following the presentation from a committee member on options for criteria to determine when to update/review existing DRIs, I questioned the speaker on my concern regarding the fact that DHA (docosahexaenoic acid) is considered to be a ‘physiologically-essential’ omega-3 fatty acid in the brain and retina yet the IOM established α-LNA as the only official omega-3 fatty acid for nutrient essentiality in 2002. I also pointed out the very limited conversion efficiencies of α-LNA to DHA in humans and referred to recent cross-country measurements of DHA in breast milk indicating that North American breast milk has one of the lowest levels of DHA in contrast to other countries. I closed my commentary and questioning by asking when consideration may come forth on granting official nutrient status to DHA for pregnancy, lactation, infancy, young children and others. The possibility for a ‘DHA equivalency’ with respect to α-LNA intakes was suggested also as historically done for ‘niacin equivalents’. In other words, there could be a recommended intake based on the ‘DHA equivalency’ which could be: DHA intake (mg) + (α-LNA intake in mg)*(portion converted to DHA). Consideration to other DHA precursors such as stearidonic acid, EPA, and DPA needs resolution as well as potential beneficial effects of each omega-3 fatty acid (independent of or in addition to DHA). The inclusion of expert advisors on an ‘ah hoc’ basis to assist in revising the DRIs for omega-3 fatty acids would enhance the current process and recommendations in this nutrient category.

I would suggest to those who have a concern about the current DRIs from the Institute of Medicine and Food and Nutrition Board that an understanding of the processes and individuals involved in establishing DRIs may serve in our collective efforts to have recommended intakes of omega-3 fatty acids (all evidence-based) which best serve the enhancement of human health globally as well as the prevention/management of chronic disorders. Recommendations from the Institute of Medicine have a very strong impact on recommendations offered by various health professionals both in North America and globally.

The audience was informed that a summary publication would be forthcoming which reflects both the presentations and discussions raised from the audience at this workshop for public information.

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