As a rule of thumb, whole foods are the best source of nutrition. Every rule has an exception, however. When it comes to a balanced diet, fish oil is one nutrient that consumers may have no choice but to purchase in supplement form. This is because fish oil is essential in promoting holistic health and well being, yet the body does not naturally produce it. High quality fish oil supplements can also provide the optimal balance of essential oils (omega-3s and 6s), which is something that is lacking in most American diets.