Plasma and neutrophil fatty acid composition in advanced cancer patients and response to fish oil supplementation

Abstract

Metabolic demand and altered supply of essential nutrients is poorly characterised in patients with advanced cancer. A possible imbalance or deficiency of essential fatty acids is suggested by reported beneficial effects of fish oil supplementation. To assess fatty acid status (composition of plasma and neutrophil phospholipids) in advanced cancer patients before and after 14 days of supplementation (12+/-1 g day(-1)) with fish (eicosapentaenoic acid, and docosahexaenoic acid) or placebo (olive) oil. Blood was drawn from cancer patients experiencing weight loss of >5% body weight (n=23). Fatty acid composition of plasma phospholipids and the major phospholipid classes of isolated neutrophils were determined using gas liquid chromatography. At baseline, patients with advanced cancer exhibited low levels (<30% of normal values) of plasma phospholipids and constituent fatty acids and elevated 20 : 4 n-6 content in neutrophil phospholipids. High n-6/n-3 fatty acid ratios in neutrophil and plasma phospholipids were inversely related to body mass index. Fish oil supplementation raised eicosapentaenoic acid and docosahexaenoic acid content in plasma but not neutrophil phospholipids. 20 : 4 n-6 content was reduced in neutrophil PI following supplementation with fish oil. Change in body weight during the supplementation period related directly to increases in eicosapentaenoic acid in plasma. Advanced cancer patients have alterations in lipid metabolism potentially due to nutritional status and/or chemotherapy. Potential obstacles in fatty acid utilisation must be addressed in future trials aiming to improve outcomes using nutritional intervention with fish oils.

Figure 1

Advanced cancer patients were stratified at baseline into high and low BMI groups based on the group mean (20.7 kg m⁻²; n=23). Subjects with BMIs above the group mean represent the low BMI group (n=12) and subjects with BMIs above the group mean comprise the high BMI group (n=11). Columns represent mean±s.e.m. of the high and low BMI groups. The range of mean caloric intakes (days 1, 2 and 3 of supplementation) within each BMI grouping are shown for each patient using data points. Caloric intakes were estimated using 3 day food records and analysed using the Food Processor II Nutrient Analysis Program with the Canadian Nutrient Data File. Significant differences (P<0.05) between BMI groupings and corresponding caloric intakes were detected using a t-test.

Figure 2

Data points represent the change in body weight from day 1 to day 14 of fish oil supplementation and the change in plasma EPA for subjects in the fish oil group (n=9). Body weight at either days 1 or 14 was not available for the four subjects missing in the analysis. There was a significant positive relationship between change in body weight and the change in plasma EPA.