母乳和配方奶粉对肥胖和肠道菌群的影响

母乳喂养的益处很多。本文回顾Forbes等人发表于 JAMA Pediatrics的文章，指出母乳喂养具有防止婴儿超重的优势，这一优势的作用机制很可能与肠道菌群的早期定植与发育相关。本文还指出了超重的主要原因在于能量摄入过多，强调了对于婴儿早期喂养方式的探究需要进行深入的长期研究，进一步理解肠道菌群的作用。值得专业人士关注。

论文摘要

The relationship between breastfeed-ing and protection from subsequent obesity alone is important, as yet anotherobservation linking breastfeeding to improved health in babies, but the studyalso provides insights into the mechanisms that lead to protection. The authorsexamined the intestinal micro- biome in all of the children in the study at 3months of age to assess whether links existed between the weight outcomes tothe different exposures, the overall communities within the microbiota and thespecific microorganisms present. In doing so, they confirmed previousobservations and substantially extended our knowledge of the relationshipbetween the microbiome and outcomes in children.

One characteristic of any microbiome isits diversity, which can be measured in several ways. A relatively simplemetric is the alpha diversity, which can be a measurement of the overallrichness of the collection of taxa that are present in a given sample, or canreflect the evenness of the populations (for example, are all of the taxapresent in more or less the same proportions or do some members dom- inate overothers?). High richness and high evenness usually, but not always, go together.Intuitively, we think that a population with high alpha diversity is better, butnature does not always comply with our pre-set beliefs.

In fact, confirming prior studies2, the authors found that the alpha diversity pres- entin breastfed babies was lower in early life than in the formula-fed infants,who as a group develop overweight to a greater extent as young children. Howcan we explain this seemingly paradoxical result? In reality, nature is not ademocracy — all microorganisms were not created equal. Every species, includ-ing us humans, has an evolutionary history, and in fact, we co-evolved overmillions of years with particular intestinal microorgan- isms3. As a consequence of co-evolution, some organisms aregenerally beneficial for us4, and these organismsdominate the intestine of healthy babies, thus creating a micro- biome ofapparently low alpha diversity. The dominance of these healthy organisms is atleast in part created through the co-evolved micronutrients present in breastmilk and by the resistance of these organisms to the antimicrobial compoundspresent5.

实验综述

① Forbes等人的研究指出，与母乳喂养相比，婴儿早期喂食配方奶在1岁时更易超重，母乳喂养有效防止肥胖；

②缺乏母乳中的营养物质和抗菌物质，会导致有益肠道菌失去早期定植优势，因此配方奶喂养的婴儿肠道菌群的α多样性高于母乳喂养婴儿；

③相比出生后一年，3-4月龄婴儿的肠道菌群多样性与肥胖的相关性更高；

④尽管研究表明肠道菌群影响肥胖状况，肥胖最主要诱因是能量的摄入超过消耗；

⑤需要开展深入的长期研究，探索喂养方式对超重的影响。