Gut & Microbiome
Does blood sugar after a meal differ person to person?
The claim, precisely: postprandial glucose varies with individual and microbiome
Yes, predicted by gut bacteria more than genes — which is why it's best measured individually.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: Population patterns (Observational)
How the studies fall
What the evidence shows
The same meal produces highly variable glucose/lipid responses across people, and microbiome + phenotype predict it better than carb counting — while GENETICS explains little (twin design). You cannot infer an individual's bread response from GI tables or their genome; you must measure them. The core justification for our n-of-1 CGM method.
The evidence (6)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Mendes-Soares H, et al. 2019 · Am J Clin Nutr | observational | supports | moderate | US n=327 CGM microbiome model predicts PPG R=0.60 vs carb 0.40 ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction |
| Mendes-Soares H, et al. 2019 · Am J Clin Nutr | observational | supports | moderate | Israeli model generalized to US cohort (r~0.62) >> carb counting (r~0.34) ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction |
| Berry SE, et al. (PREDICT/Spector) 2020 · Nat Med | observational | supports | high | PREDICT n=1002 twins: glucose CV 68%, TG CV 103%; microbiome>macros; genetics ~0.2-9.5% variance ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction |
| Zeevi D, et al. (Segal) 2015 · Cell | observational | supports | high | n=800 + RCT: personalized model predicts iAUC; algorithm-diet lowered response |
| Zeevi D, et al. (Segal) 2015 · Cell | observational | supports | high | n=800 46898 meals high variability to identical meals; ML+microbiome predicts PPG; RCT validation lowered responses |
| Berry SE, et al. (PREDICT/Spector) 2020 · Nat Med | observational | supports | high | PREDICT1 n=1002 twins CV glucose 68% TG 103% to identical meals; microbiome>macros; genetics modest 9.5% ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction |
Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.