Food Lipids: Chemistry, Nutrition, and Biotechnology

IV. NUTRITIONAL AND MEDICAL APPLICATIONS
Structured lipids can be synthesized to target specific metabolic effects or to improve
physical characteristics of fats. An SL made from fish oil and MCTs was compared
with conventional LCTs and found to decrease tumor protein synthesis, reduce tumor
growth in Yoshida sarcoma-bearing rats, decrease body weight, and improve nitrogen
maintenance (30). In addition, the effects of fish/MCT on tumor growth was synergistic
with tumor necrosis factor (TNF). A similar study by Mendez et al. (112)
compared the effects of a structured lipid (made from fish oil and MCFAs) with a
physical mix of fish oil and MCTs and found that the SL resulted in improved
nitrogen balance in animals, probably because of the modified absorption rates of
SL. Gollaher et al. (113) reported that the protein-sparing action associated with SL
administration are not seen when the structured lipids provide 50% of protein calories
and suggested that the protein-sparing action of SLs may be dependent on the ratio
of MCTs to LCTs used to synthesize the SL.
Jandacek et al. (89) demonstrated that a structured lipid containing octanoic
acid at the 1- and 3-positions and a long chain fatty acid in the 2-position is more
rapidly hydrolyzed and efficiently absorbed than a typical LCT. They proposed that
the SL may be synthesized to provide the most desirable features of LCFAs and
MCFAs for use as nutrients in cases of pancreatic insufficiency (89). Metabolic
infusion of an SL emulsion in healthy humans showed that the capacity of these
subjects to hydrolyze SL is at least as high as that to hydrolyze LCT (114). This
finding is significant because of evidence of interaction and interference in the metabolism
of LCT and MCT when both are present in a physical mix (115,116). An
investigation into the in vivo fate of fat emulsions based on SL showed potential for
use of SL as core material in fat emulsion–based drug delivery systems (117).
An SL made from safflower oil and MCFAs was fed to injured rats, and the
animals receiving the structured lipid were found to have greater gain in body weight,
greater positive nitrogen balance, and higher serum albumin concentration than controls
receiving a physical mix (111). Enhanced absorption of 18:2n-6 was observed
in cystic fibrosis patients fed structured lipids containing LCFAs and MCFAs (25).
A mixed acid type of triacylglycerol composed of linoleic acid and MCFAs has been
reported to improve immune functions (118), and evaluations in clinical nutrition are
ongoing. However, a 3:1 admixture of MCT-LCT emulsions was reported to elevate
plasma cholesterol concentrations compared to LCT emulsions in rats fed by intravenous
infusion (119).
SL appears to preserve reticuloendothelial function while improving nitrogen
balance as measured by the organ uptake of radiolabeled Pseudomonas in comparison
to LCT (120). Long-term feeding studies with an SL containing MCFAs and fish oil
fatty acids showed that SL modified plasma fatty acid composition, reflecting dietary
intake and induced systemic metabolic changes that persisted after the diet was
discontinued (121). An SL made by reacting tripalmitin with unsaturated fatty acids
using an sn-1,3 specific lipase closely mimicked the fatty acid distribution of human
milk was commercially developed for application in infant formulas under the trade
name Betapol (122). HDL cholesterol decreased by 14% when a diet containing
Caprenin as 40% of total calories was fed to healthy men, compared to no change
in levels when an LCT diet was fed (43). Table 8 lists the potential and other reported
benefits of SL (1,25,32,89,106,107,111,120,123–129).
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.