Low-fat diets (fat making up 25-30 percent of your daily calories) help ward off infections. If you want to keep your body in tip-top shape, stay away from any saturated and Trans fatty acids but up your intake of Omega-3 Essential Fatty Acids, proven to have immune-modulating benefits. But don't just grab any omega-3 oil. Studies has shown that omega-3s found in fish oil are slightly more potent than the omega-3 found in plant sources such as flax seed. But regardless of source, they are still effective and good.