The estimated quantities of live microbes (per gram) for 9388 food codes contained in 48 subgroups in the NHANES database were determined by 4 experts in the field (MLM, MES, RH , and CH). Because of the expected variation in the numbers of living microorganisms in each food type, the foods were assigned to categories with ranges defined as low (Lo; <104 CFU/g), medium (Med; 104–107 CFU/g), or high (Hi; >107 CFU/g) levels of live microbes. These levels of Lo, Med, and Hi were chosen to reflect the approximate numbers of viable microbes expected to be present in pasteurized foods (<10 4 CFU/g), fresh fruits and vegetables eaten unpeeled (104–107 CFU/g), and unpasteurized fermented foods and probiotic supplements (>107 CFU/g).
As a first step, food subgroups estimated to contain only food codes having <104 CFU/g were identified by 3 individuals (MLM, MES, and RH) (Supplemental Table 1 Supplemental Table 1 . Assignments were based on professional knowledge of the field and by reviewing primary publications that assessed the indicated foods. Disagreement between the 2 experts occurred for ∼150 food codes (Team 1) and ∼250 food codes (Team 2). For Team 1, most disagreements were for cheese and formulated foods such as salads, sandwiches, or dips containing cheese or cultured dairy foods. These were resolved by consulting the literature (34 ), the relative expected weight of the live microbe–containing food compared with the other ingredients (for example, bread), and the use of preservation methods (for example, pasteurization). For example, a sandwich containing processed American cheese was categorized in the Lo category. Sandwiches containing cheese and other major components (for example, steak) were similarly categorized in the Lo category. Cheddar cheese and general cheese sandwiches were labeled as Med, to take into account the weight of the bread and other potential condiments (for example, mayonnaise). For Team 2, 24 of these food codes were described as “pickled” fruits or vegetables. Reviewers subsequently reconciled these differences by consultation within and between the teams (MLM, MES, RH, and CH) and by external consultation with Fred Breidt, USDA Agricultural Research Service Microbiologist, Food Science and Market Quality and Handling Research Unit, Raleigh, NC.
Although “pickled” fruits or vegetables could be acidified and not fermented, the food descriptions were inadequate to distinguish between these 2 possibilities. The experts agreed to assume these were fermented or partially fermented in the case of refrigerated and non-heat-treated products and assigned all such pickled foods to Med. For the last step, intakes of Med and Hi categories were determined by linking microbe definitions to food codes. A fourth category was also developed, MedHi, consisting of an aggregate of consumers of foods from Med, Hi, or both Med and Hi categories.
As a first step, food subgroups estimated to contain only food codes having <104 CFU/g were identified by 3 individuals (MLM, MES, and RH) (
Although “pickled” fruits or vegetables could be acidified and not fermented, the food descriptions were inadequate to distinguish between these 2 possibilities. The experts agreed to assume these were fermented or partially fermented in the case of refrigerated and non-heat-treated products and assigned all such pickled foods to Med. For the last step, intakes of Med and Hi categories were determined by linking microbe definitions to food codes. A fourth category was also developed, MedHi, consisting of an aggregate of consumers of foods from Med, Hi, or both Med and Hi categories.
