Greiner R C, Winter J, Nathanielsz P W, Brenna J T
Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA.
Pediatr Res. 1997 Dec;42(6):826-34. doi: 10.1203/00006450-199712000-00018.
The dietary bioequivalence during the brain growth spurt of alpha-linolenic (LNA) and docosahexaenoic acids (DHA) as substrates for brain and retinal n-3 fatty acid accretion is reported for the fetal baboons, whose mothers consumed a long chain polyunsaturate-free diet with a n-6/n-3 ratio of 10:1. Pregnant baboons received i.v. doses of U-13C-labeled fatty acids (LNA or DHA), plasma was collected from mother and fetus, and fetal brain (occipital cortex), retina, and liver were analyzed at various times post-dose. Fetal brain DHA plateaued 15-35 d post-dose with 1.6% of the preformed [U-13C-]DHA dose recovered in the brain. In contrast, LNA-derived DHA accretion also plateaued but was 20-fold lower. Liver and retinal results were of the same order of magnitude, but showed evidence of peaks and decline. Conversion products to n-3 long chain polyunsaturate were observed in the maternal circulation at 1 h after administration, as was transfer of both fatty acids to the fetus. From these measurements we estimate that a dietary level of about 0.45% of energy as LNA is sufficient to meet the requirements of the growing fetal brain, whereas 0.03% of energy as DHA would suffice. These data are the first direct measurements of the bioequivalence of DHA and LNA in developing primates and imply that n-3 fatty acid requirements for the developing fetal brain can be met by attainable dietary LNA for diets low in long chain polyunsaturates.
据报道，对于胎儿狒狒，其母亲食用n-6/n-3比例为10:1的无长链多不饱和脂肪酸饮食，在此期间，α-亚麻酸（LNA）和二十二碳六烯酸（DHA）作为大脑和视网膜n-3脂肪酸积累的底物，在大脑发育加速期的膳食生物等效性。怀孕的狒狒接受静脉注射U-13C标记的脂肪酸（LNA或DHA），在给药后的不同时间收集母体和胎儿的血浆，并分析胎儿大脑（枕叶皮质）、视网膜和肝脏。给药后15 - 35天，胎儿大脑中的DHA达到平台期，大脑中回收了1.6%预先形成的[U-13C-]DHA剂量。相比之下，LNA衍生的DHA积累也达到了平台期，但低20倍。肝脏和视网膜的结果在相同数量级，但显示出峰值和下降的迹象。给药后1小时在母体循环中观察到向n-3长链多不饱和脂肪酸的转化产物，同时两种脂肪酸也转移到了胎儿体内。根据这些测量结果，我们估计，饮食中LNA能量含量约为0.45%足以满足发育中胎儿大脑的需求，而DHA能量含量为0.03%就足够了。这些数据是首次对发育中的灵长类动物中DHA和LNA的生物等效性进行直接测量，这意味着对于长链多不饱和脂肪酸含量低的饮食，发育中胎儿大脑对n-3脂肪酸的需求可以通过可获得的膳食LNA来满足。
