Evidence

These uses have been tested in humans or animals.  Safety and effectiveness have not always been proven.  Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Key to grades

A
Strong scientific evidence for this use
B
Good scientific evidence for this use
C
Unclear scientific evidence for this use
D
Fair scientific evidence against this use (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
A

Coronary heart disease

Evidence suggests that people who have low levels of EPA and DHA may have a higher risk of coronary heart disease and heart failure. Clinical trials suggest that omega-3 fatty acids may have benefits in terms of reducing total and heart disease mortality (death). It is believed that omega-3 fatty acids may help lower triglycerides and inflammation. Daily intake has been linked to a reduced risk of sudden heart failure.
A

High blood pressure

Many studies report that omega-3 fatty acids may help reduce blood pressure. However, effects have generally been small, and other trials reported no benefit. Effects may be greater in people who have higher blood pressure and may depend on the dose. DHA may have greater benefits than EPA.
A

Hyperlipidemia (triglyceride lowering)

There is strong scientific evidence that omega-3 fatty acids from fish or fish oil supplements can significantly reduce triglyceride levels. Higher doses have been found to have greater effects, and a dose of four grams daily may lower triglyceride levels by up to 40%. Effects may be increased when taken with statin drugs such as simvastatin and atorvastatin.It is unclear how fish oil therapy compares to other agents used to lower triglycerides. Some studies suggest that fish oil may increase LDL levels.
A

Rheumatoid arthritis

Many studies report improvements in morning stiffness and joint tenderness with regular intake of fish oil supplements for up to three months. Benefits may increase with use of anti-inflammatory medications such as ibuprofen or aspirin. Benefits have also been seen with fish oil given through an intravenous tube. Fish oil has been found to have effects on the immune system and on fats in the blood in people with rheumatoid arthritis. However, effects beyond three months of treatment are unclear. More research is needed before a firm conclusion may be made.
A

Secondary cardiovascular disease prevention (fish oil / EPA plus DHA)

Fish oil has been studied for use in protecting people who have had past heart problems from new ones, such as heart attack or sudden death.Many studies report that regularly eating oily fish or taking fish oil supplements may help reduce the risk of nonfatal and fatal heart attack, sudden death, and mortality in people with a history of heart attack. There is evidence that an increased intake of fish or omega-3 may be linked to a lower risk of heart failure. These therapies may add to the effects of other treatments, and benefits have been reported after three months of use.
C

Abnormal heart rhythms

There is promising evidence that omega-3 fatty acids may reduce the risk of abnormal heart rhythms. This effect is believed to contribute to the reduced number of heart attacks in people who regularly consume fish oil or EPA and DHA. However, not all studies have found positive results, as some reported that fish oil may be linked to abnormal heart rate in older people and people with a history of some heart problems. More studies are needed in this area before a firm conclusion may be made.
C

Acute respiratory distress syndrome (low oxygen in blood)

Early evidence suggests that taking fish oil may benefit adults who have acute respiratory distress syndrome. More research is needed to confirm this finding.
C

Age-related macular degeneration (loss of vision)

There is evidence that a diet high in omega-3 may reduce the risk of age-related macular degeneration (AMD). A combination product called Photorop, which contains omega-3, has been studied for use in people with this eye disease. DHA has been found to benefit eye health in nonsmoking older women. However, evidence on the use of omega-3 alone is limited. More studies are needed in this area.
C

Aggression

Early research suggests that fish oil may reduce stress-related aggression and help regulate mood and impulse control. More research is needed before firm conclusions can be made.
C

AIDS/HIV

Studies looking at the use of fish oil combined with other nutritional supplements in people with HIV have found conflicting results. More information is needed on the potential benefits of fish oil alone in this population.
C

Allergies

Research suggests that eating fish at least once per week may reduce the risk of eczema, an allergic condition causing dry and itchy skin, in children. However, a significant link between mother's fish intake and child eczema was lacking. Evidence is mixed in terms of whether mother's consumption of omega-3 may have effects on allergies in the infant. More research is needed in this area.
C

Antisocial personality disorder

Limited research suggests that omega-3 may help reduce some symptoms of personality disorder. However, more research is needed before firm conclusions can be made.
C

Anxiety

Omega-3 has been found to reduce tension in people attending an abuse clinic. More studies are needed in this area.
C

Asthma

There is conflicting evidence on the use of omega-3 for asthma. More research is needed before conclusions can be made.
C

Athletic performance

Research is limited on the use of fish oil for the improvement of athletic performance. Omega-3 has been found to have benefits on lung function in wrestlers and may improve muscle soreness. However, more studies are needed in this area.
C

Attention-deficit hyperactivity disorder (ADHD)

Fish oil may help increase levels of EPA, DHA, and total omega-3 fatty acids in people who have attention-deficit hyperactivity disorder (ADHD), which has been linked to lower omega-3 levels. However, significant differences were found to be lacking between healthy people and those with mental health problems such as dementia, ADHD, and depression. A combination product containing both omega-6 and omega-3 has been found to benefit people with ADHD. An Indonesian study reported that DHA-rich fish oil improved school attendance. More research is needed to determine the effect of omega-3 on learning and behavioral problems in ADHD.
C

Autism

Fish oil has been shown to help improve levels of omega-3 in people who have autism. However, conclusions are lacking in terms of benefits of omega-3 for autism. More research is needed.
C

Bipolar disorder

There is limited evidence to support the use of fish oil for bipolar disorder. One study reported longer recovery periods with use of fish oil. However, other research has produced conflicting results. More studies are needed before firm conclusions can be made.
C

Cancer

Conflicting results have been found for the effects of omega-3 on quality of life and mortality in people with cancer. More research is needed in this area.
C

Cancer prevention

Several studies report that fish oil may reduce the risk of breast, colon, prostate, or other cancers. However, results have been conflicting. Further research is needed before the use of fish oil can be supported for this purpose.
C

Chest pain

Early studies report a possible link between fish oil intake and reduced chest pain. More research is needed before further conclusions can be made.
C

Clogged arteries

Early research suggests that regular intake of fish oil supplements may lower the risk of clogged arteries. The role of supplements in preventing and treating clogged arteries has also been studied. However, more evidence is needed before the use of omega-3 can be supported for this purpose.
C

Cognition

EPA and DHA were found to lack effect on brain function in older people and healthy children. Some benefit was seen in children with metabolic disorders. More research is needed to determine the effect of omega-3 fatty acids on cognition in healthy people.
C

Critical illness

Omega-3 fatty acids in combination with other nutrients may help reduce the risk of serious complications in acutely ill people. Some studies report that omega-3 may decrease inflammation and the length of hospital stay. However, other findings are mixed, and further research is needed to support the use of fish oil in people with critical illness.
C

Cystic fibrosis (disease of the lungs and digestive system)

Limited research reports some benefit of fish oil for use in cystic fibrosis. However, evidence is still inconclusive, and more research is needed.
C

Dementia

There is some evidence that regular fish and omega-3 fatty acid consumption may help reduce dementia risk. However, results are conflicting. One review reported that firm conclusions are lacking in terms of the potential benefits of omega-3 on Alzheimer's disease. Another study found that omega-3 may help improve weight and appetite in people with Alzheimer's. Other studies found that significant differences were lacking between healthy people and those with mental health problems such as dementia and depression. While some findings are promising, more research is needed in this area.
C

Depression

There is inconclusive evidence to support the use of fish oil in people who have depression, although some early results are promising. Low levels of DHA and omega-3 have been linked to predicted suicide, and lower EPA has been linked to depressive symptoms in older people. Dietary intakes of fish and omega-3 have been found to help reduce depressive symptoms in women. Some studies report that fish and fish oil may help reduce risk of psychiatric disorders (including depression), as well as depression in people with heart disorders or type 2 diabetes. Omega-3 may benefit women who have depression in after giving birth. EPA is thought to have greater benefit than DHA. More research is needed.
C

Dialysis

Early evidence reports that fish oil may lack significant benefit in people on dialysis. People undergoing dialysis have been found to consume less omega-3 in the diet, and the possible link between omega-3 and mortality in this population has been studied. More research is needed to understand the potential benefits of fish oil use in these people.
C

Dyslexia

Early studies have found that a combination treatment containing EPA may lack benefit in dyslexic children with reading and spelling problems. More research is needed in this area.
C

Eczema

There is evidence that taking fish oil in infancy may help prevent the development of eczema, an itchy skin condition. Studies suggest that fish consumption in infancy may be more important than the mother's fish intake during pregnancy. However, results are still inconclusive at this time, and more information is needed.
C

Energy

Studies suggest that athletes who take fish oil may reduce oxygen consumption during exercise. However, other research has found a lack of effect of fish oil on energy or metabolism in healthy people. Further research is needed.
C

Epilepsy

Omega-3 supplements may help improve brain energy and health in people who have epilepsy. More research is needed to determine whether omega-3 may be an effective treatment for people with this condition.
C

Fatigue

There is limited evidence supporting the use of fish oil and other essential fatty acids for treating chronic fatigue. More research is needed before conclusions can be made.
C

Heart disease (risk)

Omega-3 fatty acids may benefit some heart disease risk factors. However, conclusive evidence is lacking. Some studies have found benefit for risk factors such as triglyceride levels, but more research is needed to determine whether the actual heart disease risk is reduced.
C

High blood pressure associated with pregnancy

There is not enough evidence to support the use of fish oil for high blood pressure during pregnancy. Further research is needed in this area.
C

High cholesterol

As discussed earlier, there is strong scientific evidence that omega-3 fatty acids from fish or fish oil supplements help reduce triglyceride levels. Some studies report that fish oil may increase LDL cholesterol, possibly by increasing the size of LDL particles. More research is needed to determine potential benefits of omega-3 for lowering cholesterol.
C

Immune function

There is evidence that fish oil may help reduce inflammation. Although not well studied in humans, fish oil may also improve survival after infection, prolong survival after an organ transplant, and benefit autoimmune disease. More human research is needed in this area.
C

Infant development / neonatal care

One study found that taking DHA during the first year of life may reduce time to the first occurrence of sitting without support. However, effects on other measures such as crawling or standing and walking alone were lacking. The use of omega-3 fatty acids has also been studied for health issues during infancy. Findings on the effects of omega-3 for later body composition of the infant are mixed. More research is needed.
C

Infant eye / brain development

Early research suggests that DHA taken by pregnant and breastfeeding mothers may reduce the body mass index of infants. However, effects are lacking on length or head size of infants. The mother's fish oil intake during pregnancy has been found to lack effect on infant language development. The effect of DHA-enriched formulas has been studied for the safety, growth, and development of preterm and term infants. More research is needed in this area.
C

Inflammation

Omega-3 fatty acids have been found to lack significant effects on inflammation and outcome in people in intensive care. Further research is needed.
C

Inflammatory bowel disease

Many studies have looked at the possible benefit of omega-3 fatty acids in people who have inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease, when used with standard therapy. Although some positive effects have been found, results are conflicting, and more evidence is needed.
C

Kidney disease (IgA nephropathy)

Results are conflicting on the use of fish oil to treat IgA nephropathy, a kidney disease in which there is a buildup of IgA antibodies. More research is needed before firm conclusions can be made.
C

Kidney disorders (nephrotic syndrome)

There is not enough reliable evidence to support the use of omega-3 for nephrotic syndrome, a condition in which kidney problems lead to high protein levels in urine. More research is needed in this area.
C

Kidney stones

The effect of fish oil on kidney stones has limited clinical evidence. More research is needed before a conclusion can be made.
C

Liver disease

Early research reports that fish oil may help reduce liver disease linked to tube feeding in children. EPA has been studied for liver health in people who have nonalcoholic liver disease. A combination of both omega-3 and omega-6 used in tube feeding lacked evidence of a large benefit on recovery after a liver transplant. Further research is needed.
C

Lung conditions

Omega-3 has been found to benefit people who have chronic obstructive pulmonary disorder (COPD), a lung condition that makes it difficult to breathe. Further research is needed in order to confirm these findings.
C

Lupus (chronic disease causing inflammation)

Reliable evidence is lacking to support the use of fish oil for people who have lupus. More research is needed before a conclusion can be made.
C

Menopause

Conclusions on the potential benefits of omega-3 for symptoms of menopause cannot be drawn at this time. Further research is needed.
C

Menstrual pain

It has been suggested that omega-3 fatty acids may help manage painful menstrual cramps. Early evidence suggests that fish oil may benefit women who have menstrual pain. However, more research is needed before a firm conclusion can be made.
C

Migraine

Omega-3 supplementation has been found to lack significant effect on migraines. More research is needed before a conclusion may be made.
C

Movement disorders

Omega-3 fatty acids have been studied for use in children with dyspraxia, a movement disorder, with some benefits having been seen. However, more research is needed in this area.
C

Multiple sclerosis

One study reported that a link between fatty acid levels and depression was lacking in people with multiple sclerosis. However, some omega-3 fatty acids were lower in those with the condition, compared to healthy controls. Early research has found a lack of benefit of omega-3 in the treatment of multiple sclerosis. More research is needed before a conclusion can be made.
C

Neck/shoulder pain

Early research suggests that omega-3 supplementation may help improve neck and shoulder pain. However, more well-designed trials are needed.
C

Nerve pain

Omega-3 fatty acids may benefit people who have nerve pain caused by various conditions, including fibromyalgia, carpal tunnel syndrome, and burn injury. More evidence is needed to support the use of omega-3 for this purpose.
C

Osteoarthritis

Significant effects of fish oil were lacking on pain and functioning in people with osteoarthritis. Larger clinical trials are needed before a conclusion may be made.
C

Osteoporosis

Some studies report a decreased risk of osteoporosis with fish intake and benefits of fish oil supplementation on bone health. Omega-3 intake has been linked to better bone density in older people, although there are some conflicting results. More well-designed clinical trials are needed in this area.
C

Overall well being

One study found that children who drank chocolate milk supplemented with fish oil had fewer illnesses. However, more research is needed in this area.
C

Pancreatitis (inflammation of the pancreas)

Fish oil given with nutrition through tube feeding has been found to reduce the inflammatory response in people with pancreatitis. More research is needed in this field.
C

Peripheral vascular disease (blocked arteries in the legs)

Some evidence suggests that fish oil may improve blood pressure in the legs of people who have peripheral vascular disease and improve the ability to walk long distances. However, more research is needed to better understand this effect.
C

Phenylketonuria (inability to break down the amino acid phenylalanine)

Low DHA levels are common among children with phenylketonuria (PKU) during the first year of life due to dietary restrictions. Early research suggests that supplementing with omega-3 during the first year of life may help improve fatty acids so that they are similar to those of healthy, breastfed infants. Effects of omega-3 fatty acids on brain function in children with PKU are still unclear. More clinical research is needed.
C

Pregnancy and labor

Early evidence suggests that fish oil may lack effect on the timing of spontaneous delivery. Fish intake in the third trimester has been linked to birthweight. Some studies report that intake of omega-3 fatty acids may reduce the risk of preterm (early) birth. However, there is some conflicting evidence. The effect of fish oil supplementation on labor and delivery is still uncertain at this time.
C

Premenstrual syndrome (PMS)

Early studies suggest that fish oil may help reduce emotional symptoms and menstrual cramps. More research is needed in this area.
C

Prevention of graft failure after heart bypass surgery

There is limited research on the use of fish oils in people undergoing coronary artery bypass grafting. Early studies suggest small benefits in reducing blood clot formation in vein grafts. One review found that using EPA before the operation may have benefit. More research is needed before a firm conclusion can be made.
C

Prevention of restenosis after coronary angioplasty (PTCA)

Several studies have looked at whether omega-3 fatty acid intake reduces restenosis, or blood vessel narrowing, after coronary angioplasty. Some research has reported small, significant benefits, while others have not found positive effects. The evidence in this area is still inconclusive at this time.
C

Primary cardiovascular disease prevention (alpha-linolenic acid [ALA])

Research has found a reduced risk of fatal or nonfatal heart attack in people who regularly eat foods high in ALA. However, other studies have found conflicting evidence. More research is needed before a conclusion may be made in this area.
C

Prostate disorders

There is limited evidence in support of the use of fish oil for prostate disorders. Clinical research suggests that EPA may lack significant effect. More research is needed to understand the effect of fish oil in people who have prostate disorders.
C

Psoriasis (autoimmune disease causing flaky, scaly skin)

Several studies looking at psoriasis and fish oil do not provide enough reliable evidence to form a clear conclusion. Further research is needed before conclusions can be made.
C

Psychosis (loss of contact with reality)

People who are at risk of psychosis may benefit from consuming omega-3 fatty acids. However, available information is based on limited research, some of which included people taking antipsychotic medications. More research is needed.
C

Quality of life

Omega-3 fatty acids do not appear to improve quality of life in elderly people. More research is needed.
C

Raynaud's disease (blocked blood flow to the limbs)

Early clinical evidence suggests that omega-3 fatty acids may benefit people who have Raynaud's disease. More research is needed to better understand and confirm this finding.
C

Schizophrenia

There is promising early evidence suggesting that EPA may benefit symptoms of schizophrenia. Clinical trials looking at omega-3 fatty acids that contain a mixture of EPA and DHA are limited, as most studies have looked at EPA alone. DHA levels may change in people who have schizophrenia. Further research is needed before a conclusion can be made.
C

Secondary cardiovascular disease prevention (alpha-linolenic acid [ALA])

Several studies have looked at the effects of ALA in people with a history of heart attack. Although some studies suggest benefits, others do not. More research is needed before a conclusion may be made in this area.
C

Shock

Early research found that omega-3 fatty acids may reduce mortality, antibiotic use, and length of hospital stay in people with sepsis, or shock. DHA was found to increase body fat and length in infants following sepsis. However, further research is needed in this area.
C

Sickle cell disease

Limited evidence suggests that fish oil may benefit people who have sickle cell disease. More research is needed to determine dosing, side effects, and benefits on other sickle cell symptoms.
C

Stroke prevention

Several large studies have looked at the effects of omega-3 fatty acid intake on stroke risk. Some studies suggest benefits, while others do not. Very large intakes of omega-3 fatty acids may actually increase the risk of stroke. It is unclear if there are benefits in people with or without a history of stroke, or if effects of fish oil are comparable to other treatments.
C

Sun protection

Treatment with fish oil may help reduce inflammation caused by the sun in people who have polymorphic light eruption, a condition in which sunlight causes skin rashes. Further research is needed.
C

Surgical recovery

A combination product containing omega-3 fatty acids has been shown to improve inflammation and immune responses before and after surgery. However, in early research, the effects of omega-3 fatty acids were mixed on reduced mortality (death), antibiotic use, and length of hospital stay after stomach surgery. More research is needed.
C

Tardive dyskinesia (uncontrolled, repetitive movements)

Evidence of a link between fatty acid levels, schizophrenia, and movement disorders is inconclusive. Further research is needed in this area.
C

Toxicity

Many studies have looked at the effects of fish oil supplements on toxicity in people who are given drugs that affect the immune system, such as cyclosporine (Neoral®). Most trials report improved kidney function. Although more recent studies report a lack of kidney benefits, the weight of scientific evidence supports the positive effects of fish oil.
C

Vasodilator (widens blood vessels)

In early research, omega-3 fatty acids increased forearm blood flow in people with chronic heart failure. Fish oil appeared to have more significant effects in younger men, compared to older men. More information is needed in this area.
C

Weight loss

Dietary fish has been found to increase the effects of a weight loss program in improving metabolism and cholesterol in obese people. One study reported that fish oil supplementation helped lower fat mass, but combined studies found a lack of effect on weight loss. Research has looked at the effect of omega-3 on weight gain, due to the calorie content of omega-3 fatty acids. When taken with fenofibrate for up to 16 weeks, there was a lack of weight gain. Further research is needed to understand the potential benefits of omega-3 for weight loss.
C

Wound healing

Although it has not been well studied in humans, some research suggests that applying fish oil to the skin may increase wound healing. Early human research reports that omega-3 fatty acids may lack this benefit. More well-designed studies are needed to determine the potential effects of omega-3 for this purpose in humans.
D

Appetite / weight loss in cancer patients

There is mixed evidence in support of fish oil use for improving appetite or preventing weight loss in people with cancer.
D

Diabetes

Available evidence suggests that significant long-term effects of fish oil in people with diabetes are lacking. The effects of fish oil on high triglycerides were similar in people with or without diabetes. Higher consumption of omega-3 fatty acids and fish did not appear to lower the risk of type 2 diabetes in some studies but did modestly increase its risk in others. Dietary intake of omega-3 fatty acids has been studied in children at genetic risk for type 1 diabetes.
D

Transplant rejection prevention

Many studies have looked at the effects of fish oil in people who received a heart or kidney transplant and were taking cyclosporine (Neoral®). The majority of trials reported improved kidney function and less high blood pressure, compared to people not taking fish oil. However, several recent studies reported no benefits to kidney function, and no changes have been found in rates of rejection or graft survival.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Agoraphobia (fear of crowds), antioxidant, bacterial infections, blood clotting disorders, blood thinner, breast pain (mastalgia), breast cysts, breast tenderness, central nervous system disorders, chemotherapy side effects (from anthracycline, isotretinoin, methotrexate), common cold, deficiency (omega-3 fatty acid), dermatomyositis (muscle disease causing rash and inflammation), ear infection, fibromyalgia (long-term joint and muscle pain), gallstones, glaucoma, gout, gum disease, hearing loss (age-related), hepatorenal syndrome (liver disease causing kidney failure), hypoxia (lack of oxygen), ichthyosis (skin disorder), increasing lifespan, infertility, kidney disease (polycystic), kidney inflammation (nephritis), leprosy, malaria, male infertility, memory enhancement, mental retardation, metabolic disorders, muscle weakness, musculoskeletal problems, neurological disorders (Refsum's syndrome), night vision enhancement, panic disorder, Parkinson's disease, psychiatric disorders (childhood), retinal protection, Reye's syndrome (sudden brain damage and liver problems), Sjögren's syndrome (dry eyes and mouth), stomach disorders, substance abuse, suicide prevention, tennis elbow, vasculitis (blood vessel inflammation), vision enhancement.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com