Household Trials in Food and Nutrition: Rethinking Methodologies beyond Individual RCTs

Nutrition is crucial for growth and development across the lifespan, influencing population health. Governments establish dietary guidelines and policies to maintain nutritional status, often relying on evidence from randomized controlled trials (RCTs), considered the gold standard for evaluating interventions. However, most nutrition RCTs focus on individuals, with relatively few conducted at the household/family level. Household-level interventions offer a broader perspective, reflecting family dynamics and food choices within the home environment. This case study systematically reviewed household-level dietary interventions to provide methodological recommendations for future research. A search across eight databases identified 15,926 articles, with 362 undergoing full-text screening and 25 meeting inclusion criteria. Majority of studies were published in the northern hemisphere (n = 21, 84%) with few published in the southern hemisphere (n = 4, 16%). Of these, 13 papers were fortification studies, nine focused on whole foods or dietary patterns, and three examined family meal interventions. Most studies collected biological samples and anthropometric data, with compliance assessed through dietary questionnaires or food records. Most studies measured effects at the individual level rather than the household level. This demonstrates that household trials are not being used to their full potential and future research is needed to better understand what household analysis would display.