ELDON G. HILL, SUSAN B. JOHNSON ANDRALPH T. HOLMAN The Hormel Institute, University of Minnesota, Austin, Minnesota 55912 ABSTRACT Two studies were conducted using male rats to assess the effect of trans fatty acids upon essential fatty acid (EFA) deficiency. In the first study 5% corn oil (CO), hydrogenated coconut oil (HCNO) or mar garine stock ( MS, partially hydrogenated soybean oil ) were fed, and the levels of trans fatty acids in tissue lipids were measured. The trans fatty acids present in MS were found to intensify EFA deficiency and to be retained in tissue lipids to a high degree, especially in heart phospholipids (PL). In the second study, as the level of trans fatty acids increased in the diet, increasingly higher levels of trans fatty acids were deposited in the heart PL. As dietary trans acids increased, a decrease in total -3 ro

40

0

CM i

LÜ

I

CD "3

cn Q -30

CM * CD -3 OJ • •

u

to 3

.-EFA

oo % DIETARY

TRANS ACIDS

Fig. 6 Effect of dietary trans fatty acids on the % o>6 fatty acids in heart PL ±SEM. N = 5 per group. The points labeled + EFA are from rats fed 0.5% com oil; the points labeled —EFA are from rats fed no corn oil.

10 I % DIETARY

TRANS ACIDS

Fig. 7 Effect of dietary trans fatty acids on the sum of 18:2tti6 + 20:4w6-20:3w9 fatty acids in heart PL ±SEM. N = 5. The points labeled + EFA are from rats fed 0.5% corn oil; the points labeled —EFA are from rats fed no corn oil.

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HCNO)11.52 (25% 12345678O.I2 MS)0.1 (25%

116:1

1 14:1

1764

HILL, JOHNSON AND HOLMAN TABLE 5

the rats fed different levels of trans fatty acids as MS. The trans 14:1 and trans 16:1 were constant in all groups, even the EFA deficient ones. The cis, irons-18:2 increased of 20:3o>6 generally as dietary trans acids increased. converted to 20: luti Percent irons The minimal level of linoleate in group 8 perproteinMean minute per mg fatty acid reduced the c, M8:2 content to one-third SEM'0.216 indiet0.1 that of group 2 which had an equal amount of dietary iron* acids but no supplement of ±0.02 linoleate. The major change among the 1.0 0.355 ±0.02 5.6 0.424 ±0.04 trans acids was in the content of trans 18:1 7.9Nanomoles 0.469 ±0.03 in heart PL. Two biochemical parameters other than 1SEMrefers to standard error of mean of repeated the triene/tetraene ratio of fatty acids (23) analyses of pooled samples. have been used to detect the onset or mea sues analyzed. Because both the CO and sure the degree of EFA deficiency in ani mals. These are the content of total 9fatty fed the CO and HCNO contained low levels of these trans acids. The heart was acids in tissue lipid (25). Figure 6 shows found to accumulate a high level of trans the effect upon total