Nutrition plays a fundamental role in sustaining health and preventing disease. Poor diet is linked to diseases that are the most frequent causes of death and major health care costs in the United States. These include many of the chronic diseases and associated health disparities within the NIDDK’s research mission, such as type 2 diabetes, obesity, chronic kidney disease, and nonalcoholic fatty liver disease, as well as inherited nutritional disorders. Nutrition research provides the evidence base to understand and address these diet-related diseases. The NIDDK supports an extensive and collaborative portfolio in nutrition research, which is the largest within the agency, sponsoring basic, clinical, and translational research on diet and nutrition, metabolism, and related diseases and disorders, and also helps to inform other Federal efforts, such as the Dietary Guidelines for Americans. NIDDK-supported research over the years has yielded important knowledge about human nutrition and improved the lives of people with many forms of diet-related disease.
- Over the past several decades in the U.S., disease burdens have been shifting towards more diet-related chronic diseases, which can also make individuals more vulnerable to infectious diseases.
- For many years, micronutrient deficiencies and undernutrition were prevalent in the U.S. population. Food fortification programs, such as for folate and iodine, have addressed some micronutrient deficiencies. Yet, undernutrition and specific nutritional deficiencies remain, and obesity has emerged in recent decades as a major challenge.
- The NIDDK has supported many clinical studies of diet-related diseases:
- The landmark Diabetes Prevention Program (DPP) clinical trial showed that people at risk for type 2 diabetes could prevent or delay disease onset and improve blood sugar levels through a lifestyle intervention consisting of modest improvements in diet and exercise. Translation of this research led to the CDC’s National Diabetes Prevention Program.
- NIDDK’s Look AHEAD (Action for Health in Diabetes) study found that people with obesity and type 2 diabetes in an intensive lifestyle intervention program of healthy eating and physical activity could achieve and maintain weight loss, resulting in the health benefits of lower diabetes medication needs, maintained physical mobility, and better quality of life.
- Clinical trials by the NIDDK’s Nonalcoholic Steatohepatitis (NASH) Clinical Research Network demonstrated that vitamin E could improve NASH, in adult study participants overall and in some children with severe disease.
- NIDDK-supported studies of chronic kidney disease in adults and children, such as the Chronic Renal Insufficiency Cohort and Chronic Kidney Disease in Children study, assessed impacts of dietary components and patterns on disease progression and risk of cardiovascular disease, to optimize health outcomes.
- The NIDDK has also supported pioneering studies on how gut microbes in the “microbiome” influence host nutrient absorption, metabolism, and health outcomes.
- However, a major challenge in clinical studies of diet and nutrition has been accurately measuring diet, due to the limitations of existing methodology relying on self-reported dietary intake data.
Today and Tomorrow
Clinical Studies of Diet and Nutrition
- An NIDDK intramural study found that people consumed more calories per day and gained weight on a diet of ultra-processed foods, while losing weight on an unprocessed food diet. Controlled feeding studies such as this, where participants are provided with all their meals and snacks, avoid the pitfalls of self-reported dietary assessment tools.
- NIDDK-funded researchers showed benefits of time-restricted feeding in individuals with metabolic syndrome consuming all of their usual daily diet within 10 hours. Participants experienced moderate weight loss, and, in some cases, lower blood pressure, lower blood glucose levels, and other improved outcomes.
- The DPP Outcomes Study, currently in its third phase, shows the enduring impact of the lifestyle modification intervention using diet and exercise on the incidence and course of type 2 diabetes and its complications. Another long-term study with NIDDK support, of thousands of women in the Nurses’ Health Study II, found that supplemental folate intake before pregnancy was associated with a lower risk of developing gestational, or pregnancy-related, diabetes.
- NIDDK-supported studies relating to vitamin D and calcium have found that a diabetes drug reduces vitamin D levels and calcium uptake, possibly explaining the drug-related risk of bone fractures, and shown that vitamin D supplements do not alter type 2 diabetes development in people at high risk.
- Ongoing efforts by the NIDDK and others at NIH are underway to improve research methods for accurately measuring dietary intake and nutrition in clinical studies, such as those using new tools and technologies, including biomarkers and wearable sensors.
Understanding Microbiome-Host Nutritional Interactions
- NIDDK-sponsored studies have shown the microbiome’s dramatic role in dietary response related to health conditions such as obesity, or in childhood undernutrition and the design of more effective therapeutic foods.
- NIDDK intramural investigators and their collaborators recently utilized a controlled feeding study of underfeeding and a clinical trial with an antibiotic to provide the first evidence in humans, based on directly measured calories, that changes in the gut microbiome have a measurable effect on the body’s ability to metabolize nutrients.
- The NIDDK will continue to support innovative work on microbial-host interactions in dietary response, nutrient metabolism, and health impacts. Research opportunities include standardizing designs of diet and microbiome-related studies so that results are easier to evaluate and compare.
Precision Approaches to Dietary Recommendations
- Dietary recommendations based on population-wide data offer a one-size-fits-all guide to healthy eating. However, scientific evidence supports a growing recognition that dietary responses vary greatly among individuals, limiting the usefulness of such guidelines.
Nutrition science is moving toward more holistic, food-based, and personalized or “precision nutrition” approaches, as outlined in the 2020-2030 Strategic Plan for NIH Research developed by the NIH Nutrition Research Task Force, with leadership from the NIDDK and others at NIH. These approaches consider the interplay of many factors contributing to individual variability in dietary response. The NIDDK, in collaboration with other NIH and Federal partners, is moving forward with research to pursue these new and emerging research directions.
- The NIDDK, through its role in the Task Force and other activities, will continue to coordinate across the Institute and with partners across the NIH, Federal government, and with other stakeholders to advance research aligned with this vision for the future of nutrition science—one that is precision nutrition-focused, innovative, collaborative, and health-promoting for all.