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Surrogate biomarkers for clinical outcomes afford scientific and economic efficiencies when investigating nutritional interventions in chronic diseases. However, valid scientific results are dependent on the qualification of these disease markers that are intended to be substitutes for a clinical outcome and to accurately predict benefit or harm. In this article, we examine the challenges of evaluating surrogate markers and describe the framework proposed in a 2010 Institute of Medicine report. The components of this framework are presented in the context of nutritional interventions for chronic diseases. We present case studies of 2 well-accepted surrogate markers [blood pressure within sodium intake and cardiovascular disease (CVD) context and low density lipoprotein-cholesterol concentrations within a saturated fat and CVD context]. We also describe additional cases in which the evidence is insufficient to validate their surrogate status. Guidance is offered for future research that evaluates or uses surrogate markers., (© 2017 American Society for Nutrition.)

Dietary Reference Intakes (DRIs) are used in Canada and the United States in planning and assessing diets of apparently healthy individuals and population groups. The approaches used to establish DRIs on the basis of classical nutrient deficiencies and/or toxicities have worked well. However, it has proved to be more challenging to base DRI values on chronic disease endpoints; deviations from the traditional framework were often required, and in some cases, DRI values were not established for intakes that affected chronic disease outcomes despite evidence that supported a relation. The increasing proportions of elderly citizens, the growing prevalence of chronic diseases, and the persistently high prevalence of overweight and obesity, which predispose to chronic disease, highlight the importance of understanding the impact of nutrition on chronic disease prevention and control. A multidisciplinary working group sponsored by the Canadian and US government DRI steering committees met from November 2014 to April 2016 to identify options for addressing key scientific challenges encountered in the use of chronic disease endpoints to establish reference values. The working group focused on 3 key questions: 1) What are the important evidentiary challenges for selecting and using chronic disease endpoints in future DRI reviews, 2) what intake-response models can future DRI committees consider when using chronic disease endpoints, and 3) what are the arguments for and against continuing to include chronic disease endpoints in future DRI reviews? This report outlines the range of options identified by the working group for answering these key questions, as well as the strengths and weaknesses of each option., (© 2017 American Society for Nutrition.)

Secular trends in the relationship of body mass index (BMI) and skinfold thickness to educational and income levels were examined for white and black women aged 18-34 y over the period 1960-80 with data from three successive national surveys: NHES Cycle I, NHANES I, and NHANES II. Statistical models were fitted to assess the variability in mean BMI over time within levels of education or income. Mean BMI and skinfold thickness were negatively associated with both education and income. Over the 20-y period mean BMI increased for both white and black women at all levels of income and education. Because the increase in mean BMI was greater at lower educational levels, the differentiation of BMI by educational level increased over time, yielding a stronger negative association. In contrast differentiation of BMI by income category decreased over time. Black-white differences in mean BMI at comparable educational and income levels persisted over this period.

Secular trends in the relationship of body mass index (BMI) and skinfold thickness to educational and income levels were examined for white and black men aged 18-34 y over the period 1960-80 with data from three successive national surveys: NHES Cycle I, NHANES I, and NHANES II. Statistical models were fitted to assess the variability in mean BMI over time within levels of education or income. There were few secular changes in mean BMI. In both white and black men a secular change from a slight positive association between mean BMI and education to a negative association was characterized chiefly by an increase in mean BMI at the lowest educational level. A slight positive association between income level and mean BMI persisted almost unchanged over this period. Mean BMI was similar for black and white men. These findings are compared and contrasted with those from a similar study for young women.