Effects of high- and low-fat diets on the bioavailability of selected fatty acids, including linoleic acid, in adult men
1986
Olubajo, O. | Marshall, M.W. | Judd, J.T. | Adkins, J.T.
Extract: Thirty men, 34 to 61 years old, were fed four diets as follows: diet I - 43% of calories from fat (%FC) with a polyunsaturated to saturated fatty acid (P/S) ratio of 0.3; diet II - 25% FC, P/S 0.3; diet III - 43% FC, P/S 1.0; diet IV - 25% FC, P/S 1.0 to study the effects of level and type of fat and of fiber intake on the excretion of selected fatty acids, including linoleic acid (LOA). Each of the four diets was fed for two 6-week periods (after 7-day pre-study and 21-day stabilization periods), with a random switchover at the end of the first 6-week period. Diets, urine, and feces were analyzed during the last 7 days of each period. Of the saturated fatty acids, stearic acid had the lowest apparent digestibility in all diets. The digestibility of oleic acid was high and was similar for all diet groups despite differences in intakes. LOA excretion was slightly higher (0.81 and 0.86 g/day) with diets III and IV, in which men ate 44 and 24 g of LOA/day, than with diets I and II (0.46 and 0.56 g/day) in which men had 20 and 12 g LOA/day, respectively. Those amounts of LOA excreted represented, however, only a small portion of that eaten. LOA was slightly less digestible in diets II and IV (95.5% and 96.5%), in which the men ate more fiber (11.4 g/day), than in diets I and III (97.7% and 98.2%) in which the men ate less fiber. LOA digestibility was reduced by decreasing fat content of the diet in both high and low P/S diets. Whether those small differences are of physiological importance remains to be seen. Otherwise, this finding emphasizes the need for more research to investigate whether greater absolute amounts of LOA are required when low-fat diets are fed.(author)
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