Alterations in fatty acid metabolism in response to obesity surgery combined with dietary counseling

Abstract

Background: The effects of obesity surgery on serum and adipose tissue fatty acid (FA) profile and FA metabolism may modify the risk of obesity-related diseases.

Methods: We measured serum (n=122) and adipose tissue (n=24) FA composition and adipose tissue mRNA expression of genes regulating FA metabolism (n=100) in participants of the Kuopio Obesity Surgery Study (KOBS, age 47.2±8.7 years, BMI 44.6±6.0, 40 men, 82 women) before and one year after obesity surgery. As part of the surgery protocol, all the subjects were instructed to add sources of unsaturated fatty acids, such as rapeseed oil and fatty fish, into their diet. The results were compared with changes in serum FA composition in 122 subjects from the Finnish Diabetes Prevention study (DPS) (age 54.3±7.1 years, BMI 32.2±4.6, 28 men, 94 women).

Results: The proportion of saturated FAs decreased and the proportion of n-3 and n-6 FAs increased in serum triglycerides after obesity surgery (all P<0.002). Weight loss predicted changes in quantitative amounts of saturated FAs, monounsaturated FAs, n-3 and n-6 FAs in triglycerides (P<0.002 for all). Moreover, the changes in adipose tissue FAs reflected the changes in serum FAs, and some of the changes were associated with mRNA expression of elongases and desaturases in adipose tissue (all P<0.05). In line with this the estimated activity of elongase (18:1 n-7/16:1 n-7) increased significantly after obesity surgery in all lipid fractions (all P<4 × 10^-7) and the increase in the estimated activity of D5D in triglycerides was associated with higher weight loss (r=0.415, P<2 × 10^-6). Changes in serum FA profile were similar after obesity surgery and lifestyle intervention, except for the change in the absolute amounts of n-3 FAs between the two studies (P=0.044).

Conclusions: Beneficial changes in serum and adipose tissue FAs after obesity surgery could be associated with changes in endogenous metabolism and diet.

Figure 1

Change in serum fatty acid composition (+s.d.) during the first year after obesity surgery. (a) Changes in the absolute amounts (mg l⁻¹) of lipid classes and (b) changes in fatty acid proportions (mol%). SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; n-3, omega-3 fatty acids; n-6, omega-6 fatty acids. *P<0.002 in paired samples t-test.

Figure 2

Changes in serum lipid profile after obesity surgery and weight reduction achieved by healthy diet and increased physical activity. Black bars for Kuopio Obesity Surgery Study (KOBS, mean weight loss 23.4%) and white bars for Finnish Diabetes Prevention Study (DPS, mean weight loss 8.4%). SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; n-3, omega-3 fatty acids; n-6, omega-6 fatty acids. Statistical significance between changes in n-3 FAs was calculated with independent samples t-test. *P<0.05 in one-sample t-test for change in both studies separately.