Dietary guidelines provide evidence-based statements on food choices to meet nutritional requirements and reduce the risk of prevailing chronic disea

OBJECTIVE—The aim of this study was to examine the effect of a moderate-fat diet inclusive of walnuts on blood lipid profiles in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS—This was a parallel randomized controlled trial comparing three dietary advice groups each with 30% energy as fat: low fat, modified low fat, and modified low fat inclusive of 30 g of walnuts per day. Fifty-eight men and women, mean age 59.3 ± 8.1 years, started the trial. Dietary advice was given at baseline with monthly follow-up and fortnightly phone calls for support. Body weight, percent body fat, blood lipids, HbA_1c, total antioxidant capacity, and erythrocyte fatty acid levels were measured at 0, 3, and 6 months. Data were assessed by repeated-measures ANOVA with an intention-to-treat model. RESULTS—The walnut group achieved a significantly greater increase in HDL cholesterol–to–total cholesterol ratio (P = 0.049) and HDL (P = 0.046) than the two other treatment groups. A 10% reduction in LDL cholesterol was also achieved in the walnut group, reflecting a significant effect by group (P = 0.032) and time (P = 0.036). There were no significant differences between groups for changes in body weight, percent body fat, total antioxidant capacity, or HbA_1c levels. The higher dietary polyunsaturated fat–to–saturated fat ratio and intakes of ω-3 fatty acids in the walnut group were confirmed by erythrocyte biomarkers of dietary intake. CONCLUSIONS—Structured “whole of diet” advice that included 30 g of walnuts/day delivering substantial amounts of polyunsaturated fatty acid improved the lipid profile of patients with type 2 diabetes.

Decision making in nutrition is based on current available scientific evidence. However, we are currently living in a time of highly accessible information, and with the increase in accessibility has come a concomitant increase in misinformation and pseudoscience relating to nutrition. This presents a challenge to the nutrition research community, practitioners, and consumers, and highlights a need to critically examine the current evidence-based framework in nutrition, and identify strategies for future improvements. This narrative review outlines the current evidence-based framework and approaches to evidence-based practice in the nutrition field, focusing on policy and guideline development. Within the framework, systematic reviews are an important tool for evidence-based practice, underpinning translation guidelines and other implementation documents. Recommendations for consumption of nutrients, foods, and whole diets are required to guide consumers and practitioners; however, these resources must be updated regularly to remain timely and accurate. In turn, clinical practice guidelines guide practitioners in how to implement the evidence base for patients and clients, supporting practitioners to be positioned as a key conduit between scientific evidence and the public. In contrast, health claims may support marketing of food products, but require consideration of the strength and quality of the evidence to support health claims, with external oversight required to ensure claims are appropriate. Collecting, synthesizing, and translating the evidence base in nutrition remains an ongoing challenge, particularly in the current context of increased information availability. To address growing challenges in combating pseudoscience, nutrition researchers, policy makers, and practitioners must work together, and the role of practitioners in translating the evidence base and personalizing it to individual patients must be emphasized. Continuing to address current challenges, including increasing the timeliness and consistency of the approach to the evidence base, is required to ensure informed and robust nutrition policy, research, and practice into the future.