PREFERENTIAL REDUCTION IN ADIPOSE-TISSUE ALPHA-LINOLENIC ACID (18/3-OMEGA-3) DURING VERY-LOW-CALORIE DIETING DESPITE SUPPLEMENTATION WITH 18/3-OMEGA-3

We have previously reported that the relative content of 18:3 omega 3 in adipose triglyceride (TG) of women was reduced following major weight loss while on a very low calorie diet (VLCD). In an attempt to prevent this loss of 18:3 omega 3 reserves, we have tested two VLCD supplemented with varying amounts of 18:3 omega 3. The formula (FORM) and food VLCD (2.1-3.0 MJ or 500-700 kcal/d) contained 20 g/d of fat and provided the recommended dietary allowance for minerals and vitamins. FORM subjects (Group 1) were 5 women [initial body mass index (BMI) of 36.8, 168% ideal body weight (IBW) who received 20 g/d of canola oil (1.6 g 18:3 omega 3). Their mean weight loss was 23.9 kg in a 4-5 mon period. Food VLCD subjects (Group 2) were 6 women (BMI 33.9, 155% IBW) supplemented with 2 g/d of linseed oil (1.1 g 18:3 omega 3). Their mean weight loss was 17.4 kg in a 2-3 mon period. Needle biopsies of adipose tissue were obtained from Group 1 before, at midpoint and after weight loss; and from Group 2 before and after weight loss. The adipose TG and serum (Group 1) were separated and their fatty acid composition determined by thin-layer and gas chromatography. In Group 1, adipose 18:3 omega 3 fell from 0.65 to 0.59 wt%, then to 0.52 wt% during weight loss. In Group 2, it fell from 0.77 to 0.64 wt%. The fall in adipose 18:3 omega 3 with weight loss was significant at P = 0.01 (Group 1) and P < 0.01 (Group 2). There were no differences between responses to the 1.1 gld or 1.6 gld 18:3 omega 3 supplements. The relative content of 18:3 omega 3 in serum free fatty acids from Group 1 was reduced after major weight loss. Thus, in both groups the omega 3 supplementation did not help to maintain adipose tissue 18:3 omega 3 during rapid weight loss, and its decrement may affect circulating lipid pools. As adipose 18:2 omega 6 did not change with weight loss, this reduction in the ratio of omega 6 precursor to omega 3 precursor could eventually alter the balance of their products as well.