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relatively high concentrations sufficient to provoke vascular damage; and (3) the massive destruction of trypanosomes which occurs at the termination of a parasitsemic wave may also result in a transient but great increase in the release OfF.F.A. Department of Veterinary Microbiology and Immunology, University of Guelph, Guelph, Ontario, Canada
I. R. TIZARD K. NIELSEN
Department of Chemistry, University of Guelph
A. MELLORS
Department of Animal Science, University of Ghana, Legon, Ghana
R. K. ASSOKU
POLYUNSATURATED FATTY ACIDS AND THE BRAIN
S)R,—Crawford and his colleagues 1have claimed that animal fat, in particular long-chain polyunsaturated fatty acids (L.c.P.), may be necessary in the diet for the normal development of the human brain. The human brain contains substantial amounts of L.c.p. associated with membrane phosphclipids.’ There are two series of L.c.p. derived from two parent short-chain polyunsaturated fatty acids (s.c.p.)-namely, linoleic (18:2w6) and linolenic (18:3c.>3) acids, which are not synthesised de novo in the mammal. 3Although the two series are not interconvertible, competition and inhibition between the two series does occur. A requirement for linoleic acid only has been shown in man.45 L.C.P. are absent from higher plants yet their short-chain precursors are abundant in the vegetable kingdom.’ It has been contended that L.C.P. may not be readily synthesised from s.c.p. because the rate of desaturation is low
relatively high concentrations sufficient to provoke vascular damage; and (3) the massive destruction of trypanosomes which occurs at the termination of a parasitsemic wave may also result in a transient but great increase in the release OfF.F.A. Department of Veterinary Microbiology and Immunology, University of Guelph, Guelph, Ontario, Canada
I. R. TIZARD K. NIELSEN
Department of Chemistry, University of Guelph
A. MELLORS
Department of Animal Science, University of Ghana, Legon, Ghana
R. K. ASSOKU
POLYUNSATURATED FATTY ACIDS AND THE BRAIN
S)R,—Crawford and his colleagues 1have claimed that animal fat, in particular long-chain polyunsaturated fatty acids (L.c.P.), may be necessary in the diet for the normal development of the human brain. The human brain contains substantial amounts of L.c.p. associated with membrane phosphclipids.’ There are two series of L.c.p. derived from two parent short-chain polyunsaturated fatty acids (s.c.p.)-namely, linoleic (18:2w6) and linolenic (18:3c.>3) acids, which are not synthesised de novo in the mammal. 3Although the two series are not interconvertible, competition and inhibition between the two series does occur. A requirement for linoleic acid only has been shown in man.45 L.C.P. are absent from higher plants yet their short-chain precursors are abundant in the vegetable kingdom.’ It has been contended that L.C.P. may not be readily synthesised from s.c.p. because the rate of desaturation is low
