The Dietary Guidelines for Americans 2015-2020 were released in January 2016 and have made significant updates for the consumer based on good science. However, the translation of the scientific basis of the recommendations to the Dietary Guidelines did not include some key scientific insights important to healthy lifestyles. Based on our ongoing commitment to creating safe, trusted, and effective medical nutrition solutions to prevent and manage chronic diseases, we conducted a detailed review in collaboration with our research partners at the Joslin Diabetes Center and the Harvard T.H. Chan School of Public Health. We have identified a few gaps in the Guidelines that should be considered in the context of the latest findings in clinical research. We believe that providers should be prepared to discuss the following points with their patients.
We are encouraged by many of the items that the USDA has identified as important components of a healthy lifestyle, such as new eating patterns and behaviors, and food variety and nutrient density, each of which is enormously important. Three items we would like to see the USDA proceed on further, with greater clarification and rigor, include (1) guiding consumers to limit intake of sugar to less than five percent of total calories; (2) encouraging them to consume healthy fats; (3) and reducing consumption of grains. Further, we believe additional emphasis should be placed on consumers achieving and maintaining a healthy weight.
1. Healthy fats – The Dietary Guidelines recommend reducing fat consumption by consuming fat-free and low-fat dairy products and limiting saturated and trans fats. They also indicated that healthy diets include oils.
We are pleased that the USDA indicated that healthy fats like vegetable oils should be included in a healthy diet. We would also like the USDA to indicate to consumers the importance of healthy fats used appropriately, such as the correct fat to use for various cooking activities, as well as noting that saturated fat is not necessarily unhealthy. Find out more here.
A 2015 meta-analysis found that low-fat diets do not necessarily perform better for weight loss or for maintaining health, compared to low-carbohydrate diets or higher fat dietary interventions. Dr. Walter Willett of the Harvard T.H. Chan School of Public Health has indicated that fats in the diet can be healthy:
“Fats from plant oils […]; nuts, such as almonds, peanuts, walnuts, and pistachios; avocados; and fish, especially oily fish such as salmon and canned tuna, are excellent sources of unsaturated fat. Eating unsaturated fat in place of refined grains and sugar can improve blood cholesterol profiles and lower triglycerides, and in turn, lower the risk of heart disease.”
New medical foods that provide natural sources of plant-based proteins with optimal levels of essential amino acids can provide a good source of higher quality protein and help facilitate transitions to more healthy diet plans. For consumers and patients with nutrient insufficiency and deficiency, healthy fats play an important role in addressing chronic health issues. If the diet does not provide adequate amounts of healthy fats, then providers may consider recommending use of specialized medical foods with healthy lipids and/or use of specialized healthy oil nutrients like omega-3 and specialized resolving mediators (SPMs).
2. Added sugar – The Dietary Guidelines recommend limiting added sugar in the diet so that it does not comprise more than 10% of calories.
According to Dr. David Ludwig, “excess intake of refined sugar plays a significant role in the epidemics of obesity and related diseases.” We know that even if a person is not overweight, obese, or suffering from chronic disease like diabetes, long-term intake of added sugars like fructose lead to the development of metabolic syndrome, cardiovascular disease, and type 2 diabetes. Free form added sugars have also been shown by clinicians at the University of Louisville Medical School to contribute to metabolic overload, the development of non-alcoholic fatty liver disease, insulin resistance, diabetes, and obesity. When coupled with other poor quality carbohydrates (i.e. selected forms of maltodextrins), investigators at the Cleveland Clinic have seen negative influence on gut microbiota, negatively impacting the gut-liver immune axes and metabolic pathways. Complete epidemiological evidence suggests that the percentage of added sugars in the diet should be below 5% of total calories to significantly reduce health risk factors. At intake of the current recommendation of 10% of calories from added sugars, it is still likely that consumers’ intake may be more than is optimal for a healthy lifestyle.
When discussing sugar intake with patients, clinicians should remember that less sugar is preferable. When selecting nutrition solutions like medical foods, a combination of high quality carbohydrates with added sugar at or less than 5% of calories is preferable.
We are pleased that sugar has been identified as a major influence of chronic disease and that the USDA recommends reducing added sugars. For future guidelines, we would like to see the USDA go further and indicate to consumers that their diets should include little to no added sugar, with levels of sugar consumption never exceeding five percent of total calories.
3. Grains and Carbohydrates – The Dietary Guidelines recommend that 50% of grains consumed should be whole grains.
While we agree that whole grains can be an important component of a healthy diet, we believe that the USDA’s recommendations are too supportive of grains and carbohydrates in the diet. There is very limited nutritional value to processed grains like white bread and, further, highly processed carbohydrates are disease causing. Indeed, in a 2013 editorial, Dr. David Ludwig and Dr. Walter Willett explain “many starchy foods, particularly highly processed grains and potato products, have a high glycemic index, raising blood glucose and insulin more rapidly than an equivalent amount of sucrose.”
Quality carbohydrates should comprise less than 45% of total calories. This amount has been shown by investigators at Brandeis University to support optimal metabolic handling and load, as well as more balanced and controlled glucose responses. Quality sources of carbohydrates, including amylopectin, can help manage glycemic load and glycemic index, resulting in reduced risk of chronic health problems. High quality carbohydrates, including whole grains that have high nutrient quality and density can be an important part of a healthy dietary pattern.
4. Maintain a healthy weight.
Almost seventy percent of American adults are overweight or obese. We believe that the preponderance of overweight and obesity in the United States warrants increased attention to achieving and maintaining a healthy weight. Clinicians should help increase awareness of the importance of healthy weight, while being sensitive to the nutritional and behavioral needs of patients.
Metagenics Institute is committed to ensuring that practitioners have access to the most complete and relevant information that will help patient management and outcomes though our clinical research and provider education programs. We are pleased to see important progress in guidelines from the USDA, and believe their 2015 Dietary Guidelines represent progress toward more healthful eating for Americans. We encourage providers to review all available clinical evidence for optimal patient management and health outcomes and look forward to continuing to contribute to this important need.
References
Bolsinger J; Pronczuk A; Hayes KC. Dietary Carbohydrate Dictates Development of Type 2 Diabetes in the Nile Rat. Journal of Nutritional Biochemistry. 2013 Nov; 24(11):1945-1952.
Cespedes EM; Hu F. Dietary patterns: from nutritional epidemiologic analysis to national guidelines. Am J Clin Nutr. 2015 May; 101(5):899-900.
Gross LS; Li L; Ford ES; Liu S. Increased Consumption of Refined Carbohydrates and the Epidemic of type 2 diabetes in the United States: an ecologic assessment. AM J Clin Nutr. 2004 May; 79(5):774-779.
Ludwig, DS. Examining Health Effects of Fructose. JAMA. 2013 Jul; 310(1):33-34.
Nickerson KP; Chanin R; McDonald C. Deregulation of intestinal anti-microbial defense by the dietary additive, maltodextrin. Gut Microbes. 2015;6(1):78-83.
Song, M., Schuschke, D. A., Zhou, Z., Chen, T., Shi, X., Zhang, J., Zhang, X., Pierce, W. M., Johnson, W. T., Vos, M. B. and McClain, C. J. Modest fructose beverage intake causes liver injury and fat accumulation in marginal copper deficient rats. Obesity, 2013; 21:1669–1675.
Stanhope KL; Schwartz J; Havel P. Adverse Metabolic Effects of Dietary Fructose: Results from Recent Epidemiological, Clinical, and Mechanistic Studies. Curr Opin Lipidol. 2013 Jun; 24(3):198-206.
Willett WC; Ludwig DS. Science Souring on Sugar. BMJ. 2013 Jan; 346:e8077.
