前の日記で書いたとおり、大豆のタンパク質は含硫アミノ酸が少ないため、あまり良質のタンパク源とは言えない。
データによると、国産大豆１００ｇあたり、タンパク質は35.3g。うち含硫アミノ酸はメチオニンが560mg、システインが610mgで合計約1200mgだ。
計算すると、大豆タンパク100gあたり、3.4g（3400mg)が含硫アミノ酸となる。
http://www.geocities.jp/jr2bvb/syokuhin/aminosan/a-mame.htm
そして大豆タンパクのプロテインスコアが５６ということは、
3400/0.56=6071
6071-3400=2671
大豆タンパク100gあたり、2670mgを追加して摂取すれば良いということになる。
まぁでも、含硫アミノ酸を別に追加して飲むよりは、「含硫アミノ酸の多いホエイプロテインと混ぜて飲む」ようにすればＯＫだ。
そのコンセプトで作られたのが、「フュージョンＡＤ」。
http://www.reallife.co.jp/products/detail.php?product_id=7
最後にメチオニンと大豆プロテインに関する参考文献をひとつ。
Methionine fortification of a soy protein formula fed to infants
SJ Fomon, EE Ziegler, LJ Filer Jr, SE Nelson and BB Edwards
Data from study of nine normal full-term infants fed a soy isolate- based formula unsupplemented with methionine were compared with similar data from study of 10 similar infants fed the same formula supplemented with L-methionine and with data from previous studies of larger groups of infants receiving various other feedings. Food intake, growth, and serum chemical values were studied from 8 through 111 days of age. In addition, nitrogen balance studies were carried out. Statistically significant differences were as follows: lesser weight gain per 100 kcal by infants fed the unsupplemented soy isolate-based formula than by infants fed milk-based or other soy isolate-based formulas; lesser serum concentrations of albumin at age 28 days by infants fed the unsupplemented soy isolate-based formula than by breast-fed infants; greater serum concentrations of urea nitrogen by infants receiving the unsupplemented soy isolate-based formula than by those receiving the same formula supplemented with L-methionine. A number of other differences was noted but were not statistically significant. The results suggest that normal infants fed a formula providing 2.25 /100 kcal of a soy protein isolate not fortified with methionine performed less well during the first 6 weeks of life than did breast-fed infants and infants fed milk-based formulas or other soy isolate-based formulas fortified with methionine. The limiting nutrient appears to have been methionine.