Background/Objectives: Microgreens are rich in nutrients and phytochemicals that can support healthy aging, including attenuation of cardiovascular disease risk. The nutrient and phytochemical contents of red beet (i.e., bull’s blood’ beet, Beta vulgaris) and red cabbage (Brassica oleracea var capitate) microgreens, as well as existing preclinical evidence suggest their cardioprotective effects, but the feasibility, gastrointestinal tolerability, and human health effects of daily microgreen consumption are unknown. This study aimed to evaluate the feasibility and gastrointestinal tolerability of 2 weeks of daily microgreen consumption in healthy middle-aged/older (MA/O) adults. A secondary aim was to characterize potential health effects. Methods: Healthy MA/O adults (initial n = 26) were randomized to consume either 2 cups of ‘bull’s blood’ beet or red cabbage microgreens daily for 2 weeks in a crossover design, with each treatment period separated by 2 weeks. Feasibility was determined through participant retention and intervention compliance (i.e., total doses consumed divided by 14 days), while gastrointestinal tolerability was determined by a gastrointestinal health questionnaire and bowel movement log. Impacts of microgreen consumption on brachial and aortic hemodynamic parameters, and gut microbiota composition were evaluated. Results: Daily consumption for 2 weeks of ‘bull’s blood’ beet and red cabbage microgreens was found to be feasible as indicated by high participant retention (final n = 24) and overall treatment compliance of 95.6%. Gastrointestinal symptom severity was not impacted overall, though an improvement in gastrointestinal inflammation-associated symptom severity scores following the red cabbage microgreen intervention (p = 0.047) was observed. There were no changes in bowel movement quality, hemodynamic parameters, or on alpha or beta diversity of the gut microbiota. Conclusions: Daily consumption of ‘bull’s blood’ beet and red cabbage microgreens is feasible and tolerable in healthy MA/O adults. Future studies designed to evaluate their health impacts are needed.

Aging is a major non-modifiable risk factor for cardiovascular disease (CVD), in part due to its detrimental effects on vascular endothelial function. Dietary interventions, including those rich in plant-based components or following dietary patterns such as the Mediterranean Diet, have been shown to improve endothelial function in older adults, assessed via brachial artery flow-mediated dilation (FMD). However, it is well recognized that FMD responses to dietary interventions often show considerable variability among individuals. This variability presents a major challenge to translating findings into effective, population-level guidance highlighting the need for more tailored approaches for CVD risk prevention. Thus, to advance these precision nutrition approaches, research must move beyond the overall group mean effects and begin to investigate the factors driving this variability. This narrative review summarizes current evidence on nutritional interventions that improve endothelial function with aging, highlights potential contributors to individual response variability, and outlines future research directions to reduce this variability to enhance clinical relevance and advance precision nutrition for the aging population.