A Classification System for Defining and Estimating Dietary Intake of Live Microbes in US Adults and Children

Consuming live microbes in foods may benefit human health. Live microbe estimates have not previously been associated with individual foods in dietary databases. We aimed to estimate intake of live microbes in US children (aged 2–18 y) and adults (≥19 y) (n = 74,466; 51.2% female). Using cross-sectional data from the NHANES (2001–2018), experts assigned foods an estimated level of live microbes per gram [low (Lo), <104 CFU/g; medium (Med), 104–107 CFU/g; or high (Hi), >107 CFU/g]. Probiotic dietary supplements were also assessed. The mean intake of each live microbe category and the percentages of subjects who ate from each live microbe category were determined. Nutrients from foods with live microbes were also determined using the population ratio method. Because the Hi category comprised primarily fermented dairy foods, we also looked at aggregated data for Med or Hi (MedHi), which included an expanded range of live microbe–containing foods, including fruits and vegetables. Our analysis showed that 52%, 20%, and 59% of children/adolescents, and 61%, 26%, and 67% of adults, consumed Med, Hi, or MedHi foods, respectively. Per capita intake of Med, Hi, and MedHi foods was 69, 16, and 85 g/d for children/adolescents, and 106, 21, and 127 g/d for adults, respectively. The proportion of subjects who consumed live microbes and overall per capita intake increased significantly over the 9 cycles/18-y study period (0.9–3.1 g/d per cycle in children across categories and 1.4 g/d per cycle in adults for the Med category). This study indicated that children, adolescents, and adults in the United States steadily increased their consumption of foods with live microbes between the earliest (2001–2002) and latest (2017–2018) survey cycles. Additional research is needed to determine the relations between exposure to live microbes in foods and specific health outcomes or biomarkers.