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1.  The challenges of nutrition policymaking 
Nutrition Journal  2015;14:15.
In my over three decades of work in the field of food and nutrition, I have participated in many efforts that seek new policy initiatives in the hopes that these programs can curb rates of obesity and chronic disease and help consumers make healthier dietary choices. Because of the profound effect that many of these policies have on consumers, the food environment, federal nutrition assistance programs and subsequent policy and regulatory recommendations, it is imperative that only the strongest, best available evidence is used to set policy. This review evaluates methods by which current nutrition policies use scientific research as well as provides recommendations for how best to ensure future nutrition policies are truly science-based and likely to have a meaningful impact on public health. Specifically, this review will:Describe the current food and nutrition policy environment in the USExamine how science is used in federal food and nutrition policymaking efforts, using the Dietary Guidelines for Americans (DGA) as an exampleDescribe strong versus weak science as well as what types of studies are most appropriate for use in policymakingDiscuss the potential effects and consequences of making policy recommendations in the absence of scientific consensus or agreementMake recommendations to support the present and ongoing development of science-based policy likely to positively impact public health
doi:10.1186/s12937-015-0001-8
PMCID: PMC4322557
Dietary guidance; Nutrition policy; Evidence based review; Sodium; Added sugars
2.  Limitations of Observational Evidence: Implications for Evidence-Based Dietary Recommendations12 
Advances in Nutrition  2014;5(1):7-15.
Data from randomized controlled trials (RCTs) provide the strongest evidence for establishing relations between exposures, including dietary exposures, and health outcomes. However, not all diet and health outcome relations can be practically or ethically evaluated by using RCTs; therefore, many dietary recommendations are supported by evidence primarily from observational data, particularly those from prospective cohort studies. Although such evidence is of critical importance, limitations are often underappreciated by nutrition scientists and policymakers. This editorial review is intended to 1) highlight some of these limitations of observational evidence for diet-disease relations, including imprecise exposure quantification, collinearity among dietary exposures, displacement/substitution effects, healthy/unhealthy consumer bias, residual confounding, and effect modification; and 2) advocate for greater caution in the communication of dietary recommendations for which RCT evidence of clinical event reduction after dietary intervention is not available.
doi:10.3945/an.113.004929
PMCID: PMC3884102  PMID: 24425715
3.  Evaluation of the Effect of Four Fibers on Laxation, Gastrointestinal Tolerance and Serum Markers in Healthy Humans 
Background
Average dietary fiber intake in the United States is roughly half of the recommended amount. As new dietary fiber products are introduced to increase fiber intake, it is critical to evaluate the physiological effects of such fibers. Aims: This study examined the effect of 4 fibers derived from maize or tapioca on fecal chemistry, gastrointestinal (GI) symptoms and serum markers of chronic disease.
Methods
Twenty healthy subjects completed the single-blind crossover study in which 12 g/day of fiber (pullulan, Promitor™ Resistant Starch, soluble fiber dextrin or Promitor Soluble Corn Fiber) or placebo (maltodextrin) were consumed for 14 days followed by a 21-day washout. GI symptom surveys were completed (days 3 and 14), stools were collected (days 11–14), diet was recorded (days 12–14) and fasting blood samples were obtained (day 15).
Results
The 4 test fibers were well tolerated, with mild to moderate GI symptoms. Total short-chain fatty acid (SCFA) concentrations did not differ among the treatments. Fecal pH and individual SCFAs were affected by some treatments. Stool weight and serum markers of chronic disease did not change with these treatments.
Conclusion
Increasing fiber intake by 12 g/day was well tolerated and may have a positive impact on colon health due to fermentation.
doi:10.1159/000275962
PMCID: PMC2853587  PMID: 20090313
Pullulan; Resistant starch; Short-chain fatty acids; Gas production; Cholesterol; Ghrelin
4.  Increasing doses of fiber do not influence short-term satiety or food intake and are inconsistently linked to gut hormone levels 
Food & Nutrition Research  2010;54:10.3402/fnr.v54i0.5135.
Background
People who eat more fiber often have a lower body weight than people who eat less fiber. The mechanism for this relationship has been explained, in part, by increased satiety, which may occur as a result of changes in appetite-suppressing gut hormone levels, and decreases in food intake at subsequent meals.
Objective
We hypothesized that increasing doses of mixed fiber, consumed in muffins for breakfast, would proportionally influence satiety, gut hormone levels, and subsequent food intake.
Design
This was a randomized, double-blind, crossover study. Healthy men (n=10) and women (n=10) with a BMI of 24±2 (mean±SEM) participated in this study. Fasting subjects consumed a muffin with 0, 4, 8, or 12 g of mixed fibers and approximately 500 kcal. Visual analog scales rated hunger and satiety for 3 h; blood was drawn to measure ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY3–36 (PYY3–36) at various intervals; and food intake was measured at an ad libitum lunch.
Results
Responses to satiety-related questions did not differ among treatments. However, despite lack of differences in satiety, gut hormone levels differed among treatments. Ghrelin was higher after the 12 g fiber dose than after the 4 and 8 g fiber doses. GLP-1 was higher after the 0 g fiber dose than after the 12 and 4 g fiber doses, and PYY3–36 did not differ among fiber doses. Food intake was also indistinguishable among doses.
Conclusion
Satiety, gut hormone response, and food intake did not change in a dose-dependent manner after subjects consumed 0, 4, 8, and 12 g of mixed fiber in muffins for breakfast.
doi:10.3402/fnr.v54i0.5135
PMCID: PMC2895513  PMID: 20596303
fiber dose; fiber; ghrelin; GLP-1; PYY; appetite; hunger; visual analog scales
5.  Carbohydrates, Dietary Fiber, and Resistant Starch in White Vegetables: Links to Health Outcomes12 
Advances in Nutrition  2013;4(3):351S-355S.
Vegetables are universally promoted as healthy. Dietary Guidelines for Americans 2010 recommend that you make half of your plate fruits and vegetables. Vegetables are diverse plants that vary greatly in energy content and nutrients. Vegetables supply carbohydrates, dietary fiber, and resistant starch in the diet, all of which have been linked to positive health outcomes. Fiber lowers the incidence of cardiovascular disease and obesity. In this paper, the important role of white vegetables in the human diet is described, with a focus on the dietary fiber and resistant starch content of white vegetables. Misguided efforts to reduce consumption of white vegetables will lower intakes of dietary fiber and resistant starch, nutrients already in short supply in our diets.
doi:10.3945/an.112.003491
PMCID: PMC3650507  PMID: 23674804
6.  White Potatoes, Human Health, and Dietary Guidance12 
Advances in Nutrition  2013;4(3):393S-401S.
The white potato is a concentrated source of carbohydrate, dietary fiber, and resistant starch and continues to be the staple food of choice for many cultures. The white potato is also a concentrated source of vitamin C and potassium. Two of the nutrients in white potatoes, dietary fiber and potassium, have been designated as nutrients of concern in the 2010 Dietary Guidelines for Americans. Potatoes are often maligned in nutrition circles because of their suspected link to obesity, and popular potato foods often contain more fat calories than carbohydrate calories. Some food guides do not include potatoes in the vegetable group because of their association with high-fat diets. However, potatoes should be included in the vegetable group because they contribute critical nutrients. All white vegetables, including white potatoes, provide nutrients needed in the diet and deserve a prominent position in food guides.
doi:10.3945/an.112.003525
PMCID: PMC3650512  PMID: 23674809
7.  Health Benefits of Fruits and Vegetables1 
Advances in Nutrition  2012;3(4):506-516.
Fruits and vegetables are universally promoted as healthy. The Dietary Guidelines for Americans 2010 recommend you make one-half of your plate fruits and vegetables. Myplate.gov also supports that one-half the plate should be fruits and vegetables. Fruits and vegetables include a diverse group of plant foods that vary greatly in content of energy and nutrients. Additionally, fruits and vegetables supply dietary fiber, and fiber intake is linked to lower incidence of cardiovascular disease and obesity. Fruits and vegetables also supply vitamins and minerals to the diet and are sources of phytochemicals that function as antioxidants, phytoestrogens, and antiinflammatory agents and through other protective mechanisms. In this review, we describe the existing dietary guidance on intake of fruits and vegetables. We also review attempts to characterize fruits and vegetables into groups based on similar chemical structures and functions. Differences among fruits and vegetables in nutrient composition are detailed. We summarize the epidemiological and clinical studies on the health benefits of fruits and vegetables. Finally, we discuss the role of fiber in fruits and vegetables in disease prevention.
doi:10.3945/an.112.002154
PMCID: PMC3649719  PMID: 22797986
8.  Concentrated oat β-glucan, a fermentable fiber, lowers serum cholesterol in hypercholesterolemic adults in a randomized controlled trial 
Nutrition Journal  2007;6:6.
Background
Soluble fibers lower serum lipids, but are difficult to incorporate into products acceptable to consumers. We investigated the physiological effects of a concentrated oat β-glucan on cardiovascular disease (CVD) endpoints in human subjects. We also compared the fermentability of concentrated oat β-glucan with inulin and guar gum in a model intestinal fermentation system.
Methods
Seventy-five hypercholesterolemic men and women were randomly assigned to one of two treatments: 6 grams/day concentrated oat β-glucan or 6 grams/day dextrose (control). Fasting blood samples were collected at baseline, week 3, and week 6 and analyzed for total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, insulin, homocysteine and C-reactive protein (CRP). To estimate colonic fermentability, 0.5 g concentrated oat β-glucan was incubated in a batch model intestinal fermentation system, using human fecal inoculum to provide representative microflora. Fecal donors were not involved with the β-glucan feeding trial. Inulin and guar gum were also incubated in separate serum bottles for comparison.
Results
Oat β-glucan produced significant reduction from baseline in total cholesterol (-0.3 ± 0.1 mmol/L) and LDL cholesterol (-0.3 ± 0.1 mmol/L), and the reduction in LDL cholesterol were significantly greater than in the control group (p = 0.03). Concentrated oat β-glucan was a fermentable fiber and produced total SCFA and acetate concentrations similar to inulin and guar gum. Concentrated oat β-glucan produced the highest concentrations of butyrate at 4, 8, and 12 hours.
Conclusion
Six grams concentrated oat β-glucan per day for six weeks significantly reduced total and LDL cholesterol in subjects with elevated cholesterol, and the LDL cholesterol reduction was greater than the change in the control group. Based on a model intestinal fermentation, this oat β-glucan was fermentable, producing higher amounts of butyrate than other fibers. Thus, a practical dose of β-glucan can significantly lower serum lipids in a high-risk population and may improve colon health.
doi:10.1186/1475-2891-6-6
PMCID: PMC1847683  PMID: 17386092

Results 1-8 (8)