| 英文摘要 |
Foods contain a variety of essential and non-essential components. Emerging evidence suggests that both the traditional essential and some non-essential portions of foods provide health benefits. For example, vitamin A and C must be provided in the diet to prevent deficiency diseases, but what about non-vitamin A producing carotenoids, polyphenols, isothiocyanates, allyl sulfides, etc.? The weight of experimental evidence suggests that these and other dietary bioactives contribute to healthfulness. Most countries have “quantitative” Recommended Dietary Allowances (RDAs) to help guide health professionals to avoid deficiency diseases in their populations. The United States has the Dietary Reference Intakes that includes RDAs, Adequate Intakes and Upper Levels. In addition, many countries provide “qualitative” advice, such as the Dietary Guidelines for Americans, which focus more on recommendations for food pattern consumption. The amount of clinical evidence necessary for establishing an RDA is substantial. While it is possible to conduct a randomized placebo-controlled trial to establish an RDA for vitamin C, there are inherent difficulties in constructing human trials for food extracts or for dietary bioactives. Thus, the amount of evidence that can be collected for non-essential food components may be less than what is expected for the essentials. Some suggest that the “totality of the evidence” should be sufficient to drive public health messages about non-essentials. Here we address potential mechanisms for “accreditation” of bioactive food components and will address issues regarding design of studies, lack of biomarkers, challenges in funding needed research, and the consequences in inaction. |
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