Krause L J, Forsberg C W, O'Connor D L
Division of Applied Human Nutrition, University of Guelph, Ontario, Canada.
J Nutr. 1996 May;126(5):1505-11. doi: 10.1093/jn/126.5.1505.
The purpose of this investigation was to determine if feeding diets containing human milk resulted in increased numbers of microorganisms implicated in increased folate production and the effect on folate availability. Following a folate-depletion period (5 wk), 30 rats were fed folate-repletion diets (4 wk) with or without 20% milk solids (human, cow or goat) and containing either 906 or 4530 nmol folic acid/kg. At the end of the test period, the cecum and colon were removed in an anaerobic chamber, homogenized, diluted (10(-2) -10(-8)), and the contents of each plated on selective and nonselective media. In addition to enumeration of the total anaerobic load, five genera of bacteria were counted (Bacteroides, Bifidobacterium, Clostridium, Escherichia and Streptococcus). Rats fed human milk solids had at least a seven- and onefold mean increase in the Bifidobacterium concentration in the cecum (P < 0.006) and colon (P < 0.04), respectively, compared with rats fed other diets. The total anaerobic bacterial concentration in the cecum and the colon of rats fed human milk solids was also greater than that of rats fed the other diets (P < 0.05). The single exception was the total anaerobic count in the cecum of rats consuming goat milk solids, which did not differ from that of rats consuming human milk solids. Further, rats fed human milk solids had at least a 42 and 48% higher mean plasma folate concentration and total cecal material folate content, respectively, than rats in other dietary treatments containing 906 nmol/kg folic acid. Therefore, the improved folate status of rats fed human milk-containing diets appears to be due, at least in part, to increased folate synthesis by Bifidobacteria and other folate-synthesizing microbes in the cecum and colon.
本研究的目的是确定喂食含人乳的日粮是否会导致与叶酸产量增加相关的微生物数量增加，以及对叶酸可利用性的影响。在叶酸耗尽期（5周）后，30只大鼠喂食含或不含20%乳固体（人乳、牛乳或羊乳）的叶酸补充日粮（4周），日粮中叶酸含量分别为906或4530 nmol/kg。在试验期结束时，在厌氧箱中取出盲肠和结肠，匀浆，稀释（10^(-2) - 10^(-8)），并将每份内容物接种于选择性和非选择性培养基上。除了计算总厌氧负荷外，还对五类细菌进行了计数（拟杆菌属、双歧杆菌属、梭菌属、大肠杆菌属和链球菌属）。与喂食其他日粮的大鼠相比，喂食人乳固体的大鼠盲肠（P < 0.006）和结肠（P < 0.04）中双歧杆菌浓度的平均增加至少分别为7倍和1倍。喂食人乳固体的大鼠盲肠和结肠中的总厌氧细菌浓度也高于喂食其他日粮的大鼠（P < 0.05）。唯一的例外是食用羊乳固体的大鼠盲肠中的总厌氧菌计数，与食用人乳固体的大鼠没有差异。此外，与其他含有906 nmol/kg叶酸的日粮处理组相比，喂食人乳固体的大鼠血浆叶酸浓度平均至少高42%，盲肠总物质叶酸含量平均至少高48%。因此，喂食含人乳日粮的大鼠叶酸状况改善似乎至少部分归因于盲肠和结肠中双歧杆菌和其他叶酸合成微生物叶酸合成增加。
