Effects of Dietary Linoleic Acid on Conversion of Omega-3 Fatty Acids to Long Chain Fatty Acids
Open Access
- Author:
- Flaherty, Elizabeth Ann
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Kevin John Harvatine, Thesis Supervisor
Robert John Vansaun, Thesis Honors Advisor - Keywords:
- omega-3 fatty acids
nutrition
chicken - Abstract:
- With the modern diet that is high in total fats, high in omega-6 fatty acids (FA), and low in omega-3 FA, there is a high prevalence of metabolic and cardiovascular disease. Certain dietary acids are beneficial, while others may contribute to these disease processes. Eggs are an important part of the human diet as they are protein and nutrient dense and are a good source of vitamins and minerals. It is possible to manipulate the nutrients and composition of FA in the eggs by modifying the balance of the hens diets. This makes them a good target for experiments with fatty acids (FA). A diet high in omega-3 (n-3) FA has many beneficial effects including plasma lipid reduction, reduction in some types of cancer mortality, anti-inflammatory effects, antiarrhythmic effects, antithrombotic effects, antiatheromatous effects, and less severe manifestations of autoimmune diseases and inflammatory diseases. Due to the benefits of n-3 FA, it is important to understand the effects of oleic acid and linoleic acid (LA; C18:2n-6) on the deposition of n-3 FA in egg yolks. The goals of the experiment are to determine the effect of these FA on deposition of ALA and VLC n-3 FA in yolks. It is hypothesized that LA will have a negative impact on the deposition of ALA in yolks as they compete for elongase and desaturase enzymes. Additionally, it is expected that oleic acid will also have a negative effect on n-3 deposition in yolks. Fifty hens were randomly assigned to one of five dietary treatments that included a control, two levels of high oleic safflower oil (HOSO; 2% and 4%), and two levels of high linoleic safflower oil (HLSO; 2% or 4%). All diets contained 4% flaxseed oil (FLAX) to provide α-linolenic acid (ALA; C18:3n-3) as a substrate for synthesis of the very long chain omega-3(VLC n-3) FA. Egg samples were collected on day 0 and day 28 of the experiment and were analyzed for yolk weights and FA composition. Samples of adipose and liver tissue were collected on day 28 for FA analysis. Increasing dietary oleic acid (18:1n-9), provided by HOSO, had a positive effect on deposition of oleic acid in the yolk. Increased dietary linoleic acid (LA; C18:3n-6), provided by HLSO, had a negative effect on oleic acid deposition. HOSO and HLSO also negatively affected the deposition of ALA and VLC n-3 FA in yolks. This supports previous experiments that showed dietary n-6 FA had a negative effect on deposition of n-3 FA in yolks as a result of competition for the elongase and desaturase enzymes. The diet that is most conducive to developing a high n-3 fatty acid egg is a diet with a high level of ALA and a low level of oleic and linoleic acid.