The analysis of experimental diets for long chain fatty acids

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Virginia Tech


The Southern Regional Nutrition Research Project Number S-28 has as its objective the study of metabolic patterns in preadolescent children. In the summer of 1962, twelve preadolescent girls were housed and cared for in one of the women's residences at the Virginia Polytechnic Institute. During a period of almost seven weeks the subjects consumed controlled diets; excreta were collected and blood samples were obtained for future analysis. The experimental diets were designed to include only foods from plant sources. This part of the metabolic study was planned to determine the amount and distribution of the fatty acids in those diets.

Methods and procedures were developed for extracting the fatty acids from the lyophilized food composite composed of plant foods only. The fatty acids were extracted and methylated. Their methyl esters were separated and determined quantitatively by gas-liquid chromatography.

The total amount of fatty acids in Diet 11 and 12 was twice that of Diet 9 and 10. The most abundant fatty acid was oleic, accounting for nearly SO percent of the total fatty acids in the food composites. Linoleic acid was the next most abundant fatty acid present in the diets. The average values for the six days of the two diets had almost identical fatty acid patterns. As would be expected, the ratio of polyunsaturated to saturated fatty acids was very high for these two diets (1.17) as compared to ratios found for representative American diets of plant and animal foods (0.20 - 0.41).