アミロースが消化･吸収されずに大腸まで達すると、いわゆる「善玉菌」のエサになり、腸内環境を望ましい方向に導く､､､という現象は、わりと良好な実験結果が得られているようである。ただし、ブタを対象とした実験では、という条件付きではあるが〈笑〉。
発想としては面白いと思ったのだが、根が怠惰なもので、あいにく、人間を対象とした同様の介入研究でどのような結果が出ているのかはフォローしていない(⇦おい！)
そういえば、そそっかしい医者だが学者だかが、ブタの実験結果が出揃った時点で、「快腸デンプン」なるキャッチフレーズで、テレビに出たり本を出したりしていたことを朧気ながら記憶している。いや、気持ちはわかるけどさあ〈笑〉。
これは、腸内細菌の問題とは違う目的の研究だが、ちょっとやそっとの工夫では、アミロースを未消化のまま大腸へと送り届けるのは難しそうだということがわかって、その点で興味深い(⇩)。
Neither low salivary amylase activity, cooling cooked white rice, nor single nucleotide polymorphisms in starch-digesting enzymes reduce glycemic index or starch digestibility: a randomized, crossover trial in healthy adults
The American Journal of Clinical Nutrition, Volume 114, Issue 5, November 2021, Pages 1633–1645, https://doi.org/10.1093/ajcn/nqab228
ABSTRACT
Background
It was suggested that low salivary-amylase activity (SAA) and cooling or stir-frying cooked starch decreases its digestibility and glycemic index.
Objective
We determined the effects of SAA, cooling, and single-nucleotide polymorphisms (SNPs) in the salivary amylase (AMY1), pancreatic amylase (AMY2A, AMY2B), maltase-glucoamylase (MGAM), and sucrase-isomaltase (SI) genes on starch digestibility and glycemic index of cooked polished rice.
Methods
Healthy subjects [pilot, n = 12; main, n = 20 with low-SAA (<50 U/mL), and n = 20 with high-SAA (>105 U/mL)] consumed test meals containing 25 g (pilot) or 50 g (main) available carbohydrate at a contract research organization using open-label (pilot) or assessor-blinded (main), randomized, crossover, Latin-square designs (trial registration: NCT03667963). Pilot-trial test meals were dextrose, freshly cooked polished rice, cooked rice cooled overnight, stir-fried hot rice, or stir-fried cold rice. Main-trial test meals were dextrose, dextrose plus 10 g lactulose, plain hot rice, or plain cold rice. In both trials, blood glucose was measured fasting and at intervals over 2 h. In the main trial, breath hydrogen was measured fasting and hourly for 6 h to estimate in vivo starch digestibility. Data were analyzed by repeated-measures ANOVA for the main effects of temperature and stir-frying (pilot trial) or the main effects of SAA and temperature (main trial) and their interactions. Effects of 24 single nucleotide polymorphisms (SNPs) were assessed separately. Means were considered to be equivalent if the 95% CI of the differences were within ±20% of the comparator mean for glucose response/glycemic index or ±7% for digestibility.
Results
Pilot: neither temperature nor stir-frying significantly affected glucose incremental AUC (primary endpoint, n = 12). Main: mean ± SEM glycemic index (primary endpoint, n = 40) was equivalent for low-SAA compared with high-SAA (73 ± 3 vs. 75 ± 4) and cold rice compared with hot rice (75 ± 3 vs. 70 ± 3). Estimated starch digestibility (n = 39) was equivalent for low-SAA compared with high-SAA (95% ± 1% vs. 92% ± 1%) and hot rice compared with cold rice (94% ± 1% vs. 93% ± 1%). No meaningful associations were observed between genotypes and starch digestibility or glycemic index for any of the SNPs.
Conclusions
The results do not support the hypotheses that low-SAA, cooling, and common genetic variations in starch-digesting enzymes affect the glycemic index or in vivo carbohydrate digestibility of cooked polished rice. This trial was registered at clinicaltrials.gov as NCT03667963.
結局､､､腸内菌叢を良好な状態に保つためには、食物繊維の豊富な食事を摂ること、オリゴ糖を含む食材を上手く取り入れること、などという、ごく常識的な知識に基づいた食生活が「王道」なのだろうね。
奇手として「糞便移植」なる介入方法がある。まだデータも充分とは言い難いし、そんなのアリかよ、と言いたくなるが、パイロット･スタディの結果は一貫して良好で侮りがたい。
私は、御免被りたいが〈笑〉。
