I have many patients who began taking fish oil supplements the moment they found their cholesterol levels to be “abnormal” during an annual blood test. Concerned about heart disease, they started taking fish oil capsules daily after hearing from friends and online sources that they are “good for the heart.” A few months later, they felt reassured simply because they were taking a supplement, even though they did not fully understand which part of their lipid profile was abnormal in the first place. And then they came to see me after their second test showed little to no improvement.Cases like these reflect a very common misunderstanding: many people assume fish oil can solve every cholesterol-related problem, when heart health is actually far more complex. The problem is that cholesterol itself is often treated like one single number. In reality, not all blood fats behave the same way, and not every supplement works in the way people expect.What fish oil actually doesFish oil contains Omega-3 fatty acids, mainly EPA and DHA, which are associated with cardiovascular health. One of their benefits is that they reduce inflammation that is considered one of the key factors involved in developing heart diseases.Another common use of fish oil is for its ability to reduce triglycerides. Triglycerides are fats present in the body, and they could cause cardiovascular risks to individuals suffering from high triglyceride levels.However, triglycerides and low-density lipoprotein or LDL cholesterol (also known as bad cholesterol) are not the same. Even though triglycerides and bad cholesterol are tested in blood lipid profile tests, they cannot be managed in the same way.Looking beyond the common assumptionsFish oil cannot lower LDL. In some cases, especially at higher doses, certain formulations may even increase LDL levels. Why does this happen? While reducing triglycerides, fish oil reduces the liver’s production of triglyceride-rich particles called VLDL (very low-density lipoproteins). As these particles are broken down and cleared from the bloodstream more efficiently, some of them get converted into LDL particles, which can lead to a rise in LDL cholesterol levels. This effect appears to be more common with supplements containing DHA and at higher doses used for treating elevated triglycerides. However, the increase in LDL does not always mean cardiovascular risk rises in the same way, because some studies suggest fish oil may also shift LDL particles toward a larger and potentially less harmful form. Nevertheless, this is one reason why fish oil is mainly used for managing high triglycerides rather than as a general cholesterol-lowering supplement.Another point that is often overlooked is that while fish oil may be useful in specific situations, it has not consistently shown benefits in reducing overall deaths related to heart disease. This reminds us that improving one number on a blood test does not always mean overall heart health outcomes will improve.Story continues below this adAlso Read | Those fish oil supplements are actually dangerous for your heartSupplements can also have side effectsBecause fish oil supplements are easily available, they are often perceived as completely harmless. However, like any supplement or therapy, they can have side effects.Higher doses may increase bleeding tendency in some individuals, particularly those already taking blood-thinning medications. Certain studies have also raised concerns regarding heart rhythm disturbances in selected patients.This does not mean fish oil supplements should be avoided altogether. Rather, it highlights the importance of using them appropriately and under medical guidance when required.Food sources and supplements are not always the sameA natural source of Omega-3 like fatty fish might be better compared to supplements. When nutrients are consumed via food, they come along with several other components, such as proteins, fats, and vitamins, which complement each other as a result of being part of the same diet.Story continues below this adThis is why people are suggested to maintain a balanced diet based on their natural sources rather than taking supplements alone. Although there can be some situations where taking fish oil capsules becomes necessary for people, the consumption of nutrients via food and natural sources can be good for heart health.Heart health is rarely about one nutrient, one supplement, or one number on a report. It is about understanding the larger picture and making choices that can be a preventive tool.(Dr Chatterjee is senior consultant, internal medicine, Indraprastha Apollo Hospital, New Delhi)