Nutrition-Related N-of-1 Studies Warrant Further Research to Provide Evidence for Dietitians to Practice Personalized (Precision) Medical Nutrition Therapy: A Systematic Review

Abstract

N-of-1 trials provide a higher level of evidence than randomized controlled trials for determining which treatment works best for an individual, and the design readily accommodates testing of personalized nutrition. The aim of this systematic review was to synthesize nutrition-related studies using an N-of-1 design. The inclusion criterion was adult participants; the intervention/exposure was any nutrient, food, beverage, or dietary pattern; the comparators were baseline values, a control condition untreated or placebo, or an alternate treatment, alongside any outcomes such as changes in diet, body weight, biochemical outcomes, symptoms, quality of life, or a disease outcome resulting from differences in nutritional conditions. The information sources used were Medline, Embase, Scopus, Cochrane Central, and PsychInfo. The quality of study reporting was assessed using the Consort Extension for N-of-1 trials (CENT) statement or the STrengthening Reporting of OBservational Studies in Epidemiology (STROBE) guidelines, as appropriate. From 211 articles screened, a total of 7 studies were included and were conducted in 5 countries with a total of 83 participants. The conditions studied included prediabetes, diabetes, irritable bowel syndrome, weight management, and investigation of the effect of diet in healthy people. The quality of reporting was mostly adequate, and dietary assessment quality varied from poor to good. The evidence base is small, but served to illustrate the main characteristics of N-of-1 study designs and considerations for moving research forward in the era of personalized medical nutrition therapy.

The Potential of Fasting-Mimicking Diet as a Preventive and Curative Strategy for Alzheimer’s Disease

“…Genetic, environmental, and lifestyle factors strongly impact on human lifespan. Among them, nutrition is considered an essential component not only affecting health status but also with the potential to increase lifespan [18]. Nutrients are substances the body requires to perform its basic functions and are contained in the foods introduced with diet.…”

“…Nutrients are substances the body requires to perform its basic functions and are contained in the foods introduced with diet. They have three essential actions: provide energy, contribute to body structure, and regulate chemical processes [18][19][20]. These basic functions allow us to live, grow, reproduce, move, and respond to environmental insults.…”