Fish oil is a rich source of omega-3 fatty acids. These fatty acids are super beneficial for human health.
Fish oil comes from the tissues of oily fish such as mekeral, tuna, herring, salmon, whale blubber, lake trout, seal blubber, sardines, anchovies, and from the livers of cod and shark fish. 
Eating these fish regularly is the best way to prevent omega-3 deficiency in the body. In case you are not a fish lover, you may consume omega-3 fish oil supplements. 
According to Harvard research, omega-3 deficiency is one of the main causes of chronic diseases and deaths in the United States. 
The American Heart Association stresses the beneficial effects of fish consumption at least twice a week to maintain a healthy heart. 
The nutritionists suggest that fish oil is a concentrated source of two important omega-3 fatty acids — docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). These therapeutic properties are especially beneficial for good cardiovascular health. 
Clinical research confirms numerous benefits of fish oil for preventing chronic heart diseases, stroke, clogged arteries, regulating the blood system, and to maintain overall good health.  
Here are some evidence supported the health benefits of fish oil.
1. Fish Oil May Maintain a Good Heart Health.
Various cardiovascular diseases (CVD) are the main causes of death worldwide. A 2001 statistic shows chronic heart diseases are responsible for 30% death in the world. The researchers predict that by 2020 it’ll be the singular reason for death and disability in the low and middle-income countries. 
Omega-3 rich fish oil can support heart health in a number of ways.
It can reduce the high level of triglyceride, abnormal heart rate, the formation of plaque in the arteries and the chances of cardiac arrest in heart patients.[6, 7, 8, 9]
A 2014 research study published in Acta Physiologica Journal (Oxford, England) investigated the beneficial effects of anti-inflammatory polyunsaturated fatty acids (FA) in the prevention of heart diseases.
In another 2016 clinical trial reported in the Circulation research journal, omega-3 fatty acids have proven to be beneficial for heart health.
Coronary heart diseases are associated with a low level of good cholesterol (HDL) in the blood of type 2 diabetic patients. Researchers in Denmark investigated the beneficial effects of fish oil in increasing HDL level.
A research journal of the British Cardiac Society establishes that omega-3 fatty acids from fish oil supplementation may prevent arterial plaques in cigarette smoker.
20 male smokers participated in the study and consumed fish oil 2 g per day for 6 weeks. The results showed significant improvement in the arterial function of the smokers.
2. Fish Oil May Reduce Symptoms of Depression.
Omega-3 fatty acids are beneficial for reducing symptoms of depression.
The Journal of Affective Disorders reports that omega-3 fish oil supplementation has potent antidepressant effects on patients suffering from Parkinson’s disease depression. 29 participants experienced a significant reduction in their depression score in the 12-day trial study.
Several other research studies suggest that an increased dietary consumption of omega-3 polyunsaturated fatty acids can treat the symptoms of depression. [10, 11]
According to the Journal of the American College of Nutrition, it’s the eicosapentaenoic acid or EPA that is more effective in relieving depression than docosahexaenoic acid in fish oil.
3. Fish Oil Treat ADHD or Attention Deficit-Hyperactivity Disorder in Children.
ADHD is a behavioral disorder in children. The disorder can continue through the adolescent years.
Several research studies show omega-3 fatty acids may have beneficial effects in improving ADHD symptoms and other mental health problems in children in their growing years.
A 2012 study in the Journal of Child Neurology reports the positive effects of a combined preparation of omega-3 and omega-6 supplementation in treating ADHD children.
Children between 6-12 years received the preparation for 3 and 6 months. The result showed a significant improvement in the behavioral and academic performance of the children. There was a reduction in their aggressiveness, restlessness, inattention, and impulsiveness as well. 
In another study, the Australian researchers found out that DHA or docosahexaenoic fatty acid in omega-3 is responsible for improving behavior, mental function, and literacy in ADHD children. 
4. Fish Oil May Relieve Menstrual Pain, Prevent Miscarriage, and Support Pregnancy.
Fish oil is beneficial for numerous women health issues.
Researchers suggested the beneficial effects of fish oil consumption in reducing period pain. 
Pregnant women with antiphospholipid syndrome are at higher risk of miscarriage. Regular omega-3 consumption can prevent the risk of miscarriage in such patients. 
Fish oil is good for pregnant and nursing mothers too.
It can positively contribute in the child’s growth and development such as hand-eye coordination and the vision. Fish oil may reduce the chances of allergic sensitivity in children. 
5. Fish Oil May Be Effective for Weight Loss.
Fish oil can help you lose weight in a number of ways — It can suppress your appetite, build your muscles, and lower the bad cholesterol level in the body.
Moreover, fish oil can prevent the risk of chronic diseases related to obesity such as type 2 diabetes, heart diseases, cancer, etc.
Several clinical research support the systematic dietary supplementation of fish oil along with exercise can help you lose weight and improve body structure. [16, 17]
A 2005 study in the International Journal of Obesity reported that fatty fish and fish oil may be part of a nutritional energy-restricted diet to lose weight.
324 overweight men and women participated in the trial and consumed either 3 x 150 g portions of cod and 3 x 150 g portions of salmon or fish oil capsules.
The 8-week treatment reduced approximately 1 kg. Body weight of the participants.
Researchers at the University of South Australia confirm that a combination of aerobic exercises, healthy diet, and fish oil supplementation can help reduce body fat and cardiovascular diseases.
Other Promising Health Benefits of Fish Oil
There are conflicting results and insufficient evidence for these health benefits of fish oil— treating cancer, schizophrenia, bipolar disorder, skin diseases such as eczema, psoriasis, asthma, osteoporosis, Alzheimer’s disease, and Rheumatoid Arthritis (RA). 
How Much Fish Oil to Consume Daily?
According to the American Heart Association, a daily intake of up to 3 grams of fish oil supplement is considered safe.  WHO suggests daily consumption of 0.2–0.5 grams supplement.
If you are pregnant, breastfeeding mother or a heart patient, you may increase the dose after consulting a doctor.
The health experts also stress on having 1-2 portions of fatty fish in your diet every week.
Possible Side Effects of Fish Oil
Exceeding a daily dose of 3 grams of fish oil can result in adverse side effects such as stomach upset, loose motion, fishy taste in the mouth and breath, nausea, gas, and body rash, etc. 
You should always follow the recommended dosage inscribed in the label or consult a doctor.
Fish oil is one of the richest sources of Polyunsaturated Omega-3 fatty acids.
In America omega-3 fish oil supplements are getting immensely popular among the health-conscious individuals and community.
Fish oil has numerous benefits for the growth and development of the body and prevention of diseases.
Scientific research confirms the beneficial effects of fish oil consumption for cardiovascular health, various mental disorders, diabetes, weight loss, and women’s health issues.