Hiele M, Ghoos Y, Rutgeerts P, Vantrappen G
Department of Internal Medicine, University Hospital Gasthuisberg, Leuven, Belgium.
Biomed Environ Mass Spectrom. 1988 Oct;16(1-12):133-5. doi: 10.1002/bms.1200160123.
13CO2 breath tests were developed to study the digestion and absorption of (13C)lactose, (13C)sucrose, (13C)starch and (13C)glucose using naturally enriched substrates. Measurements of 13CO2 breath excretion were done in steady state conditions in order to study the assimilation rate of these carbohydrates as reflected by their oxidation rate. The reproducibility of the tests in the same individual was excellent. The excretion rate of 13CO2 after administration of (13C)glucose and (13C)sucrose was identical, while the excretion rate of 13CO2 after lactose was somewhat slower, although not significantly. In contrast, the excretion of 13CO2 after 50 g (13C)starch was significantly slower than the 13CO2 excretion after 50 g (13C)glucose or 50 g (13C)disaccharides. As the monosaccharide constituents used in this study have comparable absorption rates, the delayed excretion of 13CO2 after a (13C)starch load must be due to a slower digestion. It is concluded that (i) digestion and not monosaccharide transport is the rate-limiting step in the assimilation of polysaccharides and (ii) that the present breath tests are suitable to study the digestibility of naturally labelled carbohydrates.
13CO2呼气试验用于研究使用天然富集底物的（13C）乳糖、（13C）蔗糖、（13C）淀粉和（13C）葡萄糖的消化和吸收情况。在稳态条件下进行13CO2呼气排泄测量，以研究这些碳水化合物的同化率，该同化率由它们的氧化率反映。这些试验在同一个体中的可重复性极佳。给予（13C）葡萄糖和（13C）蔗糖后13CO2的排泄率相同，而给予乳糖后13CO2的排泄率稍慢，尽管不显著。相比之下，50克（13C）淀粉后13CO2的排泄明显慢于50克（13C）葡萄糖或50克（13C）二糖后13CO2的排泄。由于本研究中使用的单糖成分具有可比的吸收率，（13C）淀粉负荷后13CO2排泄延迟必定是由于消化较慢。得出的结论是：（i）消化而非单糖转运是多糖同化中的限速步骤；（ii）目前的呼气试验适用于研究天然标记碳水化合物的消化率。
