Macronutrients such as fatty acids and the effects of oils on human health and the immune system .  Fish and flaxseed oil are great sources of omega-3 fatty acids, whereas plant oils,  including chia seed oil, sunflower oil, and sesame oil, are excellent sources of omega-6 fatty acids. Randomization was used to divide the 42 adult male Sprague-Dawley rats into seven major groups (n = 7). As a negative control, Group 1 (healthy rats) was fed only a baseline diet. The other six groups received a The other six groups received a basic diet containing 2% cholesterol before to the experiment's start in order to elevate their cholesterol levels. . Six rats made up the second group, which was kept under positive control. For six weeks, the diets of groups (3), (4), (5), and (6) included 10% fish oil, flaxseed oil, chia seed oil, sunflower oil, and sesame oil, respectively. Following the trial, biochemical evaluations and histological studies were carried out to ascertain the effects of the examined oils. Results revealed that rats fed a supplemented diet with  plant oils  and fish oil, especially those with high contents of  unsaturated and polyunsaturated fatty acids, reduced hypercholesterolemic levels in the blood, and the  Contents of  omega -3 and omega-6 reduced the risk of coronary heart disease and immune-regulatory properties. Omega- 6 fatty acids had an improved effect on the immune system than Omega- 3 fatty acids.