● Food Intelligence · Vegetable
Lettuce is the most glucose-neutral food in the atlas — published GI=0, GL=0. Across 90,287 logged meals containing lettuce, the cohort averaged +30.8 mg/dL, but that number reflects the croutons, sandwich bread, wraps, and dressings on the plate alongside the leaves, not the lettuce itself. A plain salad averages just +27.9 mg/dL; a sandwich with lettuce averages +40.3 mg/dL.
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No — lettuce is GI=0, GL=0, the most glucose-neutral food in the atlas. The +30.8 mg/dL cohort average across 90,287 meals reflects what's on the plate alongside the leaves, not the lettuce itself. Across 90,287 logged meals containing lettuce, the average glucose peak was +30.8 mg/dL. But every form of lettuce — romaine, iceberg, butter/Bibb, leaf, spring mix — anchors at 0 mg/dL in our calculator because published GI=0 and GL=0. The signal we measure comes from the carb container around the lettuce: a plain-salad meal averages +27.9 mg/dL, a sandwich with lettuce jumps to +40.3 mg/dL (+12 mg/dL), and a wrap or tortilla lands at +36.8 mg/dL (+9 mg/dL). Swap a tortilla for a lettuce wrap and the cohort drops to +31.5 mg/dL — a near-baseline reading driven by the protein and fat inside, not the leaves outside.
Some members spike +27 mg/dL. Others spike +47.2. The only way to know how you'll spike is to measure with a Signos CGM.
Lettuce is a near-pure-water food — a cup of romaine contains roughly 1g of net carbs, almost all of it fiber, and the published glycemic index and glycemic load are both 0. Any post-meal glucose response measured in a cohort of 90,287 lettuce-containing meals is therefore almost entirely attributable to other ingredients: the bread of a sandwich, the tortilla of a wrap, the croutons of a Caesar, the sweetener in a dressing. The carb-bucket analysis makes this concrete — light-carb meals with lettuce averaged +27.0 mg/dL while very-heavy-carb meals averaged +47.2 mg/dL, a 75% escalation across the same headline ingredient. The carb-pair slot tells the same story at the meal level: a plain salad anchors at +27.9 mg/dL, a sandwich pushes to +40.3 mg/dL (+12 mg/dL), and a lettuce wrap — which substitutes leaves for the bread itself — settles back to +31.5 mg/dL. The mechanism is observational, but it is also the cleanest in the atlas: lettuce is a control variable, and pairings are the intervention.
This page draws on 90,287 lettuce-containing meals from 15,383 unique Signos members, collected through the Signos production CGM platform. Data were filtered to postprandial glucose responses (PPGR) between 0 and 100 mg/dL to exclude sensor artifacts and implausible readings. The food was identified using a regex matching "lettuce" as a primary ingredient. Because published glycemic index and glycemic load for lettuce are both 0, the calculator applies a zero-GI override: all five form anchors (romaine, iceberg, butter/Bibb, leaf, spring mix) ship at 0 mg/dL by design. The cohort-derived form means (which clustered between +25.4 and +28.9 mg/dL) are preserved in `option_mean_full_cohort` for transparency but not surfaced as the calculator anchor — they reflect the dressing, croutons, sandwich bread, or wrap underneath the leaves rather than the leaves themselves. Carb-pair modifier effects were estimated using Welch's t-test on matched pairs against the plain-salad baseline (+27.9 mg/dL, n=43,687). All reported effects carry p<0.001 unless noted. Any carb-pair slot requires at least 100 matched meals before it appears in the recipe builder.