Williams R J, Heffley J D, Yew M L, Bode C W
Proc Natl Acad Sci U S A. 1973 Mar;70(3):710-3. doi: 10.1073/pnas.70.3.710.
Foods must furnish (i) calories, which can readily be measured, and (ii) raw materials necessary for the building and maintenance of metabolic machinery which makes possible fuel utilization. We have called this "beyond-calorie" quality of food its "trophic" value. This concept has more unity than appears on the surface, and is capable of approximate measurement by biological testing as our experiments show. The trophic value of a food cannot be ascertained from food composition tables because only a smattering of the necessary information is commonly furnished. A food cannot support life if it is missing, or deficient with respect to, any one of the necessary nutrients. A tabulation which includes only a few nutrients-e.g., calcium, thiamin, riboflavin, niacin, phosphorus, and iron-can be woefully misleading, especially if these individual nutrients have been added by way of fortification. THE MEASUREMENT WE HAVE APPLIED TO A NUMBER OF FOODS IS POTENTIALLY VALUABLE FOR COMPARING SIMILAR FOOD PRODUCTS: two grains, two breads, two milk products, or for comparison of the same food grown, processed, or preserved in different ways. By using essentially this method we have found that barnyard eggs are somewhat superior to battery eggs, but that whether they are fertile or infertile makes no difference. We are of the opinion that extensive biological testing of many commercial food products is highly desirable to help promote human health and better internal environments for our cells and tissues.
（i）热量，这很容易测量；以及（ii）构建和维持使燃料利用成为可能的代谢机制所需的原材料。我们将食物这种“超出热量”的品质称为其“营养”价值。正如我们的实验所示，这个概念比表面上看起来更具统一性，并且能够通过生物学测试进行近似测量。食物的营养价值无法从食物成分表中确定，因为通常只提供了少量必要信息。如果一种食物缺少任何一种必需营养素或含量不足，它就无法维持生命。仅包含几种营养素（例如钙、硫胺素、核黄素、烟酸、磷和铁）的列表可能会极具误导性，特别是如果这些个别营养素是通过强化添加的。我们应用于多种食物的这种测量方法对于比较类似的食品具有潜在价值：两种谷物、两种面包、两种奶制品，或者用于比较以不同方式种植、加工或保存的同一种食物。通过基本上使用这种方法，我们发现谷仓鸡蛋在某种程度上优于笼养鸡蛋，但它们是否受精并无差异。我们认为，对许多商业食品进行广泛的生物学测试非常有必要，以帮助促进人类健康并为我们的细胞和组织创造更好的内部环境。
