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July 25, 2002
Mr. Chairman and Members of the Committee,
Thank you for the opportunity to appear before you today representing the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH). This document describes in some detail the activities of ODS, and it highlights both the opportunities and the challenges associated with developing good science in the field of dietary supplements. At the end of this testimony, I also provide some comments requested by the Committee on the role of diet and lifestyle intervention in the prevention of (or contribution to) chronic diseases.
Health Effects of Dietary Supplement Ingredients
Dietary supplements are widely used by American consumers, often in combination with other lifestyle measures such as diet and physical activity, for their potential benefits in health promotion and disease prevention. Surveys show that 40% or more of American adults use supplements, primarily vitamins and minerals, but herbal and other supplements as well. There are many hopes pinned on dietary supplements to improve health and prevent disease, hopes that have been realized when some of them have been put to a true scientific test. Some examples of these include:
By contrast, the positive effects of other products have not yet been proven and need further exploration. A prime example of this is the finding that, instead of reducing cancer risk, beta-carotene may actually increase lung cancer incidence and mortality in a sub-population of cigarette smokers. Furthermore, a recently completed NIH-funded study showed that St. John's wort was no better than a placebo in improving symptoms in patients with major depression of moderate severity.
Many ingredients have yet to be tested in a rigorous, scientifically sound manner. Some are under active investigation at the NIH, including:
The Emerging Role of ODS in Dietary Supplement Research
ODS was authorized by the Dietary Supplement Health and Education Act of 1994 (DSHEA) and was formally installed in the Office of the NIH Director in 1995. Its mission, based on a comprehensive strategic planning process, is to "identify and foster research on the health benefits and risks of these substances based on the merit of the underlying scientific evidence, regardless of how they might be currently incorporated into the different categories of commercial products or their regulatory status in the commercial marketplace."
This strategic planning process helped considerably in guiding ODS activities by identifying the research and education goals that ODS would meet. ODS has been able to embark on a number of important activities, including:
I became Director of ODS towards the end of 1999. By that time, ODS started the development of a program of comprehensive Dietary Supplement Research Centers around the country. By the end of 2000, the program had four of these multidisciplinary Centers. The Centers are jointly funded with the National Center for Complementary and Alternative Medicine (NCCAM) and are administered by NCCAM. The National Institute of General Medical Sciences (NIGMS) and the Office of Research on Women's Health (ORWH) also participate in funding these Centers. The National Institute of Environmental Health Sciences (NIEHS) supports the activities of another related Center.
Let me pause for a moment to stress a theme that runs through all of the activities that I have just mentioned. All of them have been developed in collaboration with other agencies, both within and outside the NIH. They could not have been accomplished otherwise. To me, this is the strength of forging partnerships and exploring common research goals. Our position in the Office of the Director, NIH, has permitted us to do just that.
More recently, the budget for ODS has grown, from approximately $3.5 million in FY 1999 to $17 million in FY 2002. This has permitted expansion of our research agenda into new and important areas:
In partnership with other Institutes and Centers at NIH, ODS funds research grants in areas such as:
The development of other new areas of investigation relies on forging strategic partnerships with other agencies as well. A few current examples include Interagency Agreements with:
We have worked with partners in the private sector in a number of areas:
In my view, these collaborations – within and outside the NIH – are crucial to the advancement of science in the area of dietary supplements. Further details of these and other interactions can be found on the ODS website ods.od.nih.gov.
Development of a Research Agenda for Ephedra
I noted earlier that ODS and NCCAM jointly funded an evidence report on the efficacy and safety of ephedra-containing dietary supplement products for weight loss and for athletic performance. This report, still in draft form and under review by content experts, has been developed by the RAND/Southern California Evidence-Based Practice Center, one of a network of such Centers supported by AHRQ. This is the first step for us in determining whether – and what – further research is necessary to understand the potential health benefits and risks of ephedra.
Among the studies to be included in the RAND report is a recently published clinical trial (Boozer CN et al, International Journal of Obesity 26:593-604, 2002) of a product containing ephedra and kola (a source of caffeine). The authors concluded that it was both effective and safe for weight loss over a 6-month period in a population of well-characterized, carefully monitored subjects. This is important information, but it must be remembered that this is a single study conducted under careful medical supervision and it is not yet clear whether a similar profile of benefit and safety would be seen in more typical settings with more prolonged use.
CANTOX Health Sciences International conducted a risk assessment study of ephedra under contract to the Council for Responsible Nutrition ("Safety Assessment and Determination of a Tolerable Upper Limit for Ephedra"). Its approach and conclusions will be considered in the RAND report as well. We will await the results of the full evidence report before determining what future clinical research strategies are necessary.
In the meantime, ODS has begun to develop other components of a research agenda for ephedra. We have funded the validation of several methods for the analysis of ephedra and the development of standard reference materials for ephedra. We initiated an evaluation of potential ephedra toxicity by the National Toxicology Program of the NIEHS.
Dietary Interventions to Prevent Chronic Disease
You have asked me to address some issues related to the role of dietary interventions that may be involved in the prevention of, or contribution to, chronic diseases. While this is somewhat outside the purview of ODS, I did have the benefit of comments from colleagues in some of the NIH ICs, which I present below.
The Dietary Guidelines for Americans issued by the Departments of Agriculture and Health and Human Services in 2000 recommend a diet low in saturated fat and cholesterol and moderate in total fat as part of an overall healthy eating pattern. There is strong evidence that saturated fat raises blood cholesterol levels and increases the risk of heart disease. Clinical trials have shown that blood cholesterol lowering reduces the risk of heart disease, and the composite results of the diet trials are entirely consistent with drug trials that have shown comparable blood cholesterol reductions. The critical importance of maintaining a healthy weight and a physically active lifestyle is emphasized in the 2000 Guidelines. Balancing dietary intake with energy expenditure to maintain a healthy weight and avoid weight gain during adult life was given increased attention because of the concern for the rising epidemic of obesity and the increase in sedentary lifestyles in the US. The 2000 Guidelines emphasize that a healthy eating pattern consists of a variety of foods, with several recommendations related to eating a variety of grains, fruits and vegetable, including whole grain foods and eating at least 5 servings of fruits and vegetables a day. Other aspects of a healthy eating pattern consist of eating a variety of other foods including lean meat, fish, poultry, low-fat dairy products, and foods rich in unsaturated fats (such as olive oil and canola oil). Fresh fruits and vegetables, which are low in saturated fat and rich in folic acid and other vitamins, antioxidants, and fiber, are encouraged because in population studies their consumption is associated with a reduction in heart disease and its risk factors.
A large body of evidence on the adverse effect of overweight, obesity and adult weight gain and physical inactivity has been recently summarized in a February 2002 International Agency for Research on Cancer (IARC) report on Weight Control and Physical Activity. This research indicates that avoiding overweight, obesity and adult weight gain is linked with reduced risk of colon, postmenopausal breast, endometrial cancer, adenocarcinoma of the esophagus, and renal cell cancer. In addition, increasing physical activity is linked with reduced risk for colon and breast cancer. The evidence is also strong to support weight control by increasing physical activity and decreasing caloric intake for reducing the risk for heart disease, hypertension, and type 2 diabetes mellitus.
There is limited research on the specific effect of weight control diets, including plant-based diets, on cancer outcomes. Recent meta-analyses of cohort studies and randomized controlled trials on the effect of fruits and vegetables on selected cancers, such as colon cancer, have not found strong protective effects of such diets on colon cancer incidence. Therefore, these new data are inconsistent with prior research on the protective effect of high intakes of fruits and vegetables on colon cancer incidence. Extensive research is ongoing on the effects of specific dietary components, including individual nutrients such as calcium, folate, and various carotenoids, as well on types of fatty acids and how these are influenced by the genetic characteristics of the individual. In addition, research is ongoing on the effect of specific food groups and dietary patterns on cancer outcomes.
At the present time, there are not major clinical trials directly investigating the specific comparative effects of plant-based versus animal-based or high protein diets in the prevention of chronic diseases, such as cancer, diabetes, and heart disease. With careful attention and good diet design, either of these approaches can contribute to the prevention of chronic disease, but in general, a variety of food choices are suggested. Advantages of plant-based foods include their low levels of saturated fat and lack of cholesterol and their high content of folic acid and other vitamins, beneficial antioxidants, and fiber. As has been described in the literature and lay media, a vegetarian diet can be considered healthful; however, individuals choosing a vegetarian diet must be careful of their selections in order to obtain adequate amounts of all nutrients (i.e., vitamin B-12 and iron). Animal-based diets, comprising most high-protein diets, tend to be high in saturated fat and cholesterol; on the other hand, they are excellent sources of many micronutrients and trace elements.
Currently, the Department of Health and Human Services and the US Department of Agriculture, along with the Canadian government, have contracted with the Food and Nutrition Board of the Institute of Medicine to prepare a report on Dietary Reference Intakes with a focus on macronutrients (carbohydrates, proteins, and fats). This report is being prepared by a committee of experts and, after undertaking a review of all available scientific studies in this area, is to make recommendations related to various macronutrient intakes to the health of the public. It is anticipated that recommendations will be made related to adequate levels of intake, levels that may exert positive health benefit, and levels that may be associated with adverse health events. The committee has also been requested to identify research needs and opportunities related to this topic. The report is due to be released within the next several weeks.
Mr. Chairman and Members of the Committee, I thank you again for inviting me to review the accomplishments of the Office of Dietary Supplements at NIH, and to highlight some of its ongoing research opportunities and challenges. I would be happy to answer questions from the Committee.
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Last revised: July 25, 2002