How much dha

Several different omega-3s exist, but the majority of scientific research focuses on three: alpha-linolenic acid ALA , eicosapentaenoic acid EPA , and docosahexaenoic acid DHA. PUFAs are frequently designated by their number of carbon atoms and double bonds. ALA, for example, is known as Cn-3 because it has 18 carbons and 3 double bonds and is an n-3, or omega-3, fatty acid.

Omega-6 fatty acids omega-6s have a carbon—carbon double bond that is six carbons away from the methyl end of the fatty acid chain. Linoleic acid Cn-6 and arachidonic acid Cn-6 are two of the major omega-6s. The human body can only form carbon—carbon double bonds after the 9th carbon from the methyl end of a fatty acid [ 1 ]. Therefore, ALA and linoleic acid are considered essential fatty acids, meaning that they must be obtained from the diet [ 2 ]. ALA is present in plant oils, such as flaxseed, soybean, and canola oils [ 3 ].

DHA and EPA are present in fish, fish oils, and krill oils, but they are originally synthesized by microalgae, not by the fish. When fish consume phytoplankton that consumed microalgae, they accumulate the omega-3s in their tissues [ 3 ].

After ingestion, dietary lipids are hydrolyzed in the intestinal lumen [ 1 ]. The hydrolysis products—monoglycerides and free fatty acids—are then incorporated into bile-salt— containing micelles and absorbed into enterocytes, largely by passive diffusion.

Within intestinal cells, free fatty acids are primarily incorporated into chylomicrons and enter the circulation via the lymphatic system [ 1 , 4 ]. Once in the bloodstream, lipoprotein particles circulate within the body, delivering lipids to various organs for subsequent oxidation, metabolism, or storage in adipose tissue [ 4 , 5 ]. Omega-3s play important roles in the body as components of the phospholipids that form the structures of cell membranes [ 5 ].

DHA, in particular, is especially high in the retina, brain, and sperm [ 3 , 5 , 6 ]. In addition to their structural role in cell membranes, omega-3s along with omega-6s provide energy for the body and are used to form eicosanoids.

Eicosanoids are signaling molecules that have similar chemical structures to the fatty acids from which they are derived; they have wide-ranging functions in the body's cardiovascular, pulmonary, immune, and endocrine systems [ 1 , 2 ]. The eicosanoids made from omega-6s are generally more potent mediators of inflammation, vasoconstriction, and platelet aggregation than those made from omega-3s, although there are some exceptions [ 3 , 7 ].

Because both classes of fatty acids compete for the same desaturation enzymes, ALA is a competitive inhibitor of linoleic acid metabolism and vice versa [ 8 ]. Thus, higher concentrations of EPA and DHA than arachidonic acid tip the eicosanoid balance toward less inflammatory activity [ 9 ].

Others have concluded that such ratios are too non-specific and are insensitive to individual fatty acid levels [ ]. Most agree that raising EPA and DHA blood levels is far more important than lowering linoleic acid or arachidonic acid levels. Currently, most clinicians do not assess omega-3 status, but it can be done by measuring individual omega-3s in plasma or serum phospholipids and expressing them as the percentage of total phospholipid fatty acids by weight [ ].

Plasma and serum fatty acid values, however, can vary substantially based on an individual's most recent meal, so they do not reflect long-term dietary consumption [ 3 , 17 ]. It is also possible to assess omega-3 status via analysis of erythrocyte fatty acids, a measurement that reflects longer-term intakes over approximately the previous days [ 18 , 19 ]. The "omega-3 index" proposed by Harris and von Schacky reflects the content of EPA plus DHA in erythrocyte membranes expressed as a percentage of total erythrocyte fatty acids [ 20 , 21 ].

DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and sex, include:. Table 1 lists the current AIs for omega-3s in grams per day. For infants, the AIs apply to total omega-3s. Food Plant oils that contain ALA include flaxseed linseed , soybean, and canola oils [ 2 , 3 ]. Chia seeds and walnuts also contain ALA. The omega-3 content of fish varies widely. Cold-water fatty fish, such as salmon, mackerel, tuna, herring, and sardines, contain high amounts of LC omega-3s, whereas fish with a lower fat content—such as bass, tilapia and cod—as well as shellfish contain lower levels [ 3 ].

The omega-3 content of fish also depends on the composition of the food that the fish consumes [ 24 ]. Farmed fish usually have higher levels of EPA and DHA than wild-caught fish, but it depends on the food they are fed [ 24 , 25 ]. An analysis of the fatty acid composition of farm-raised Atlantic salmon from Scotland showed that the EPA and DHA content significantly decreased between and due to the replacement of traditional marine ingredients in fish feed with other ingredients [ 26 ].

Beef is very low in omega-3s, but beef from grass-fed cows contains somewhat higher levels of omega-3s, mainly as ALA, than that from grain-fed cows [ 27 ]. Some foods, such as certain brands of eggs, yogurt, juices, milk, and soy beverages, are fortified with DHA and other omega-3s. The U. Thus, Table 2 presents the amounts of omega-3 fatty acids in grams per serving only and not the percent of the DV. Department of Agriculture's FoodData Central website [ 29 ] lists the nutrient content of many foods and provides a comprehensive list of foods containing ALA arranged by nutrient content and by food name , foods containing DHA arranged by nutrient content and by food name , and foods containing EPA arranged by nutrient content and by food name.

Dietary Supplements LC omega-3s are present in several dietary supplement formulations, including fish oil, krill oil, cod liver oil, and vegetarian products that contain algal oil. A typical fish oil supplement provides about 1, mg fish oil, containing mg EPA and mg DHA, but doses vary widely [ 30 ]. Cod liver oil supplements provide vitamin A and vitamin D in addition to LC omega-3s.

Although seafood contains varying levels of methyl mercury a toxic heavy metal [ 31 ], omega-3 supplements have not been found to contain this contaminant because it is removed during processing and purification [ 32 ].

Dietary supplements can contain several different forms of omega-3s, including natural triglycerides, free fatty acids, ethyl esters, re-esterified triglycerides, and phospholipids [ ]. Natural triglycerides are the form that occur naturally in fish oil, whereas ethyl esters are synthesized from natural triglycerides by replacement of the glycerol molecule of the triglyceride with ethanol.

Re-esterified triglycerides are formed by the conversion of ethyl esters back to triglycerides. Omega-3s as re-esterified triglycerides, natural triglycerides, and free fatty acids have somewhat higher bioavailability than ethyl esters, but consumption of all forms significantly increases plasma EPA and DHA levels [ 33 , 35 ].

Krill oil contains omega-3s primarily as phospholipids, and limited research suggests that these have somewhat higher bioavailability than the omega-3s in fish oil [ 34 , 36 , 37 ]. These supplements typically contain omega-3s in the triglyceride form [ 32 ]. According to a small study, the bioavailability of DHA from algal oil is equivalent to that from cooked salmon [ 38 ]. Formulations of omega-3 dietary supplements vary widely, so it is important to check product labels to determine the types and amounts of omega-3s in these products.

The Dietary Supplement Label Database from the National Institutes of Health contains label information from many dietary supplements on the market that contain omega-3s. Among children and teens aged 2—19 the average daily ALA intake from foods is 1. In adults aged 20 and over, the average daily ALA intake from foods is 1. Consumption of DHA and EPA from foods contributes a very small amount to total daily omega-3 intakes about 40 mg in children and teens and about 90 mg in adults [ 39 ].

Use of dietary supplements containing omega-3s also contributes to total omega-3 intakes. Data from the National Health Interview Survey indicate that 7. A deficiency of essential fatty acids—either omega-3s or omega-6s—can cause rough, scaly skin and dermatitis [ 5 ]. Plasma and tissue concentrations of DHA decrease when an omega-3 fatty acid deficiency is present. However, there are no known cut-off concentrations of DHA or EPA below which functional endpoints, such as those for visual or neural function or for immune response, are impaired.

Evidence that higher LC omega-3 levels are associated with a reduced risk of several chronic diseases, including coronary heart disease, suggests that many Americans could benefit from slightly higher intakes. However, classical essential fatty acid deficiency in healthy individuals in the United States is virtually nonexistent [ 5 ].

During periods of dietary-fat restriction or malabsorption accompanied by an energy deficit, the body releases essential fatty acids from adipose-tissue reserves. For this reason, clinical signs of essential—fatty-acid deficiency are usually only found in patients receiving parenteral nutrition that lacks PUFAs. This was documented in case reports during the s and s [ 5 ], but all current enteral and parenteral feeding solutions contain adequate levels of PUFAs. The potential health benefits of consuming omega-3s are the focus of a great deal of scientific research.

Many observational studies link higher intakes of fish and other seafood with improved health outcomes. However, it is difficult to ascertain whether the benefits are due to the omega-3 content of the seafood which varies among species , other components in the seafood, the substitution of seafood for other less healthful foods, other healthful behaviors, or a combination of these factors.

Data from randomized clinical trials are needed to shed light on these questions. This section focuses on areas of health in which omega-3s might be involved: cardiovascular disease and its risk factors ; infant health and neurodevelopment ; cancer prevention ; Alzheimer's disease, dementia, and cognitive function ; age-related macular degeneration ; dry eye disease ; rheumatoid arthritis ; and other conditions.

This interest was spurred by epidemiological research dating back to the s that found low rates of myocardial infarction and other coronary events among Greenland Inuit and other fish-eating populations, such as those in Japan [ 3 ]. Results from observational studies have been consistent with these findings, with several systematic reviews and meta-analyses showing that higher consumption of fish and higher dietary or plasma levels of omega-3s are associated with a lower risk of heart failure, coronary disease, and fatal coronary heart disease [ 43 , 44 ].

The authors of a systematic review that included six secondary-prevention trials and one primary-prevention trial of omega-3 supplementation published between and concluded that consumption of LC omega-3s from fish and fish oil supplements reduces rates of all-cause mortality, cardiac death, sudden death, and stroke [ 45 ]. They noted that the evidence of benefit is stronger for secondary than for primary prevention. Results from the Japan EPA Lipid Intervention Study in supported the growing body of evidence that LC omega-3s reduce the risk of heart disease, especially in people with a history of coronary artery disease [ 51 ].

After a mean of 4. The EPA group also experienced a significant reduction in rates of unstable angina and nonfatal coronary events but not in rates of sudden cardiac death or coronary death in comparison with the control group.

In an analysis of the primary prevention subgroup from this study participants with no history of coronary artery disease , EPA supplementation had no significant effects on any outcome. Several subsequent clinical trials, however, had largely null findings [ ]. For example, the Outcome Reduction with an Initial Glargine Intervention ORIGIN trial included 12, patients who had diabetes or a high risk of diabetes and a high risk of cardiovascular events.

In VITAL, the omega-3 supplement did not significantly reduce the rate of major cardiovascular events combined myocardial infarction, stroke, and cardiovascular mortality after a median of 5. Supplement users also had significant reductions in rates of fatal myocardial infarction, total coronary heart disease, and percutaneous coronary intervention a procedure that widens blocked or narrowed coronary arteries.

No significant reductions in stroke or death rates from cardiovascular causes were observed. After a mean follow-up of 7. Possible reasons for conflicting findings : Dose probably plays a major role in the ability of omega-3 supplementation to confer significant benefits [ 59 ].

The daily dose of 1 g used in many studies of omega-3 dietary supplements might affect some CVD pathways [ 59 ] but has had no significant effect on the primary outcomes in several trials [ 54 , 56 , 57 ]. Other factors, including the omega-3 form, study population, background dietary omega-3 intakes, and use of statins and other cardioprotective therapies might also explain the conflicting findings among studies [ 17 , 54 , 55 , ].

Therefore, use of primary composite endpoints that combine multiple outcomes might dilute significant effects on individual components of those endpoints [ 61 ]. LC omega-3 doses ranged from 0. The authors concluded that LC-omega-3 supplementation reduces the risk of myocardial infarction, coronary heart disease death, total coronary heart disease, CVD death, and total CVD, and the effects appear to be dose related. However, the findings showed no significant associations for risk of fatal and nonfatal stroke.

A Cochrane review of 86 randomized controlled trials published between and found that 0. However, the supplements did not affect all-cause mortality, cardiovascular events, stroke, or arrhythmia. The authors of several earlier meta-analyses and systematic reviews, as well as a report from the Agency for Healthcare Research and Quality, concluded that omega-3 supplements do not appear to significantly reduce the risk of most cardiovascular events [ , ].

Many of these analyses [ , ], however, but not all [ 72 , 79 ], did find that omega-3s reduce the risk of cardiac death. All three advisories recommend one to two servings of seafood per week to reduce the risk of congestive heart failure, coronary heart disease, ischemic stroke, and sudden cardiac death, especially when the seafood replaces less healthy foods [ 60 ].

Although this finding pertains to high-dose prescription omega-3s, an earlier analysis of 58 trials also revealed a dose-response relationship between lower-dose dietary and supplemental omega-3 intakes and triglyceride levels [ 82 ]. The — Dietary Guidelines for Americans states that strong evidence from mostly prospective cohort studies but also some randomized controlled trials shows that eating patterns that include seafood are associated with a reduced risk of CVD [ 83 ].

In addition, consuming about 8 ounces per week of a variety of seafood that provides about mg per day EPA and DHA is associated with fewer cardiac deaths in both healthy individuals and those with preexisting CVD. Conclusions about omega-3s and CVD : Overall, research indicates that consuming fish and other types of seafood as part of a balanced diet promotes heart health, especially when the seafood is consumed in place of less healthy foods. Fish oil and other LC omega-3 supplements lower triglyceride levels and might reduce the risk of some cardiovascular endpoints, especially among people with low dietary omega-3 intakes.

Evidence of a protective effect for omega-3 supplementation is stronger for people with existing coronary heart disease than for healthy individuals. This health claim states, "Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.

Infant health and neurodevelopment Numerous studies have examined the effects of maternal seafood and omega-3 intakes on infant birth weight, length of gestation, visual and cognitive development, and other infant health outcomes. High concentrations of DHA are present in the cellular membranes of the brain and retina [ 5 ], and DHA is important for fetal growth and development.

The accumulation of DHA in the retina is complete by birth, whereas accumulation in the brain continues throughout the first 2 years after birth. Evidence from observational research : Observational studies indicate that maternal consumption, during pregnancy and breastfeeding, of at least 8 ounces per week of seafood that contains DHA is associated with better infant health outcomes [ 83 ].

For example, in a prospective cohort study of mother—child pairs in the United States, maternal fish consumption more than twice per week compared to no weekly consumption was associated with improved visual motor skills in their children at age 3 after adjustment for covariates such as maternal age, education, maternal smoking and alcohol use during pregnancy, paternal education, and fetal growth [ 85 ].

In another observational cohort study in the United Kingdom in 11, pregnant women who reported seafood intakes ranging from none to more than g about 12 ounces per week, lower consumption of seafood during pregnancy was associated with an increased risk of suboptimal communication skills in the offspring at ages 6 and 18 months and suboptimal verbal IQ and prosocial behavior at age 7—8 years [ 86 ].

It is not possible to establish causality, however, because all of these studies were observational. Seafood contains varying levels of methyl mercury [ 31 ]. However, results from numerous studies, including a systematic review of the literature on maternal fish intake and subsequent neurodevelopmental outcomes, show that the health benefits of consuming moderate amounts of seafood during the prenatal period outweigh the risks [ ].

One of these trials examined the effects of fish oil supplementation in 2, pregnant women on the subsequent clinical outcomes and neurodevelopment of their children [ 90 ].

Compared to the placebo group, children of mothers who received fish oil were heavier at birth and less likely to be born very preterm less than 34 weeks' gestation. However, assessments of of the children all 96 preterm children and randomly selected full-term children found no differences between groups in mean cognitive composite scores or mean language composite scores at age 18 months.

A follow-up study of the children at age 4 years found no differences between groups in general conceptual ability score or other assessments of cognition, language, and executive functioning [ 91 ].

In a clinical trial in healthy full-term infants, those who received either DHA-enriched fish oil mg DHA and 60 mg EPA or placebo daily from birth to 6 months had similar scores on neurodevelopment assessments at 18 months [ 93 ]. However, infants receiving fish oil had significantly better performance on language assessments, indicating some benefit for early communication development. The authors of a systematic review and meta-analysis of 11 randomized controlled trials concluded that the evidence neither supports nor refutes the benefits of LC omega-3 supplementation during pregnancy for cognitive or visual development in infants [ 95 ].

Another systematic review and meta-analysis that included two randomized controlled trials in women with a previous preterm birth found no significant differences in rates of recurrent preterm birth between women who took omega-3 supplements during pregnancy and those who did not [ 95 ]. Omega-3 supplementation did, however, increase latency time from randomization to birth by about 2 days and mean birth weight by about g.

This comprehensive report evaluated the findings from 95 randomized controlled trials and 48 prospective longitudinal studies and nested case-control studies.

Most studies examined the effects of fish oil supplements or other DHA and EPA combinations in pregnant or breastfeeding women or of infant formula fortified with DHA plus arachidonic acid, an omega The authors concluded that, except for small beneficial effects on infant birth weight and length of gestation, omega-3 supplementation or fortification has no consistent effects on infant health outcomes. Recommendations from the Dietary Guidelines for Americans : The — Dietary Guidelines for Americans states that women who are pregnant or breastfeeding should consume 8—12 ounces of seafood per week, choosing from varieties that are higher in EPA and DHA and lower in methyl mercury [ 83 ], such as salmon, herring, sardines, and trout.

These women should not consume certain types of fish, such as king mackerel, shark, swordfish, and tilefish that are high in methyl mercury, and they should limit the amount of white albacore tuna they consume to 6 ounces a week [ 31 ]. The American Academy of Pediatrics has similar advice for breastfeeding women, recommending intakes of — mg DHA per day by consuming one to two servings of fish per week to guarantee a sufficient amount of DHA in breast milk [ 89 ].

However, the authors of a paper published by the American Academy of Family Physicians and of two Cochrane reviews one on full-term infants and one on preterm infants have concluded that the evidence is insufficient to recommend the use of infant formulas that are supplemented with these fatty acids [ ].

Cancer prevention Researchers have hypothesized that higher intakes of omega-3s from either foods or supplements might reduce the risk of cancer due to their anti-inflammatory effects and potential to inhibit cell growth factors [ 62 ].

Results from observational studies however, have been inconsistent and vary by cancer site and other factors, including gender and genetic risk. Other studies have found no associations between omega-3s and cancer risk, and some have even found associations in the opposite direction, suggesting that omega-3s might increase the risk of certain cancers such as prostate cancer [ 14 , 15 , ].

The first large-scale clinical trial to examine the effects of omega-3s on the primary prevention of cancer in the general population was the newly published VITAL trial. The study included 25, men aged 50 and older and women aged 55 and older with no previous cancer, heart attacks, or strokes. Compared with placebo, the omega-3 supplement had no significant effect on cancer incidence, cancer mortality rates, or the development of breast, prostate, or colorectal cancers.

Breast cancer : Evidence from several observational studies suggests that higher intakes of LC omega-3s are associated with a lower risk of breast cancer, but clinical trials are needed to confirm this finding. According to a systematic review of three case-control studies and five prospective studies published in —, evidence is increasing that higher intakes of dietary and supplemental LC omega-3s are associated with a lower risk of breast cancer [ ].

These authors also found a dose-response relationship between higher intakes of combined LC omega-3s and reduced breast cancer risk. Intakes of ALA and of fish, however, had no association with differences in breast cancer risk. This finding, which could be due to varying levels of omega-3s in different fish species, warrants further investigation.

Colorectal cancer : Limited evidence from observational studies suggests that greater consumption of fish and LC omega-3s is associated with a reduced risk of colorectal cancer [ ]. The authors of a meta-analysis of 19 prospective cohort studies found no significant association between fish intake and risk of colorectal cancer overall. Results from a more recent systematic review and meta-analysis of 22 prospective cohort studies and 19 case-control studies indicate that fish consumption is inversely associated with colorectal cancer risk.

In this analysis, 21 of the studies distinguished between colon cancer and rectal cancer. Results from the Vitamins And Lifestyle cohort study suggest that associations between fish or LC omega-3 intakes and colorectal cancer risk might vary by such factors as gender and genetic risk. The amount of fatty fish consumed ranged from none to 0. Overall, EPA and DHA intakes from either diet or supplements and fatty fish consumption were not associated with colorectal cancer risk, but associations varied by genetic characteristics certain inherited genetic mutations are associated with an increased risk of colorectal cancer.

For individuals in the lowest two tertiles of genetic risk, higher fatty fish consumption and higher total EPA and DHA intakes were inversely associated with colorectal cancer risk. For individuals in the highest tertile of genetic risk, higher total EPA and DHA intakes were positively associated with colorectal cancer risk.

Risk also varied by gender. Additional research is needed to clarify possible associations between fish and omega-3 intakes and colorectal cancer risk. Prostate cancer : Several prospective and case-control studies have investigated associations between either blood levels or intakes of omega-3s and risk of low-grade or high-grade prostate cancer. Results from these studies have been inconsistent. A few case-control and case-cohort studies have found positive associations between blood levels of LC omega-3s and prostate cancer risk particularly high-grade disease that is more advanced and more likely to spread than low-grade cancer , suggesting that omega-3s might increase prostate cancer risk.

In a nested case-control analysis of men aged 55—84 years participating in the Prostate Cancer Prevention Trial, serum phospholipid levels of DHA were positively associated with risk of high-grade, but not low-grade, prostate cancer [ 14 ].

Serum EPA levels, however, were not associated with risk of either grade of the disease. An analysis of data from the European Prospective Investigation into Cancer and Nutrition cohort also found a higher prostate cancer risk in men with higher plasma levels of LC omega-3s [ ]. Among Whites participating in the Multiethnic Cohort Study, higher levels of omega-3s in erythrocyte membranes and higher ratios of omega-3s to omega-6s were both associated with an increased risk of prostate cancer.

However, the results showed no associations, even with advanced or high-grade disease, for other ethnic groups or for the population as a whole [ ]. Both fish and omega-3 consumption were associated with a lower risk of fatal prostate cancer in a cohort of , men participating in the NIH-AARP study [ ]. In the Health Professionals Follow-up Study, a prospective cohort of over 47, men aged 40—75 years, those who consumed fish more than three times per week had a lower risk of metastatic prostate cancer than those who consumed fish less than twice per month [ ].

However, men who used fish oil supplements did not have a decreased risk of prostate cancer. A number of systematic reviews and meta-analyses of prospective studies of the effects of fish intakes, omega-3 intakes, and omega-3 blood levels on prostate cancer risk have had inconsistent findings as well.

For example, circulating levels of EPA, but not DHA, were positively associated with prostate cancer risk in a meta-analysis of 5, men with prostate cancer and 6, men without prostate cancer from seven studies [ ].

Another meta-analysis of 12 studies that included 4, men with prostate cancer and 5, men without prostate cancer found that high serum levels of these LC omega-3s were positively associated with high-grade disease [ ]. In other analyses, dietary intakes of LC omega-3s had no effect on prostate cancer risk [ ], whereas fish consumption decreased prostate cancer mortality but had no effect on prostate cancer incidence [ ]. A meta-analysis found no significant associations between dietary intakes or blood levels of LC omega-3s and total prostate cancer risk [ ].

The authors noted that most dietary-intake studies included in their meta-analysis found inverse associations, whereas biomarker studies of blood levels of these fatty acids found positive associations. Overall, the evidence to date shows no consistent relationships between prostate cancer risk or mortality and omega-3 intakes or blood levels. Other cancers : Evidence is limited for a role of omega-3s in the prevention of cancers at other sites.

For example, evidence is insufficient to determine whether omega-3s affect the risk of skin cancers, including basal-cell carcinoma, squamous-cell carcinoma, and melanoma [ , ]. Findings from the Australian Ovarian Cancer Study suggest that there is no association between total or individual omega-3 intakes from foods and ovarian cancer risk [ ].

Associations between omega-3 intakes and endometrial cancer have been mixed. Some evidence indicates that dietary intakes of EPA and DHA may provide protection from the development of endometrial cancer [ ].

Other evidence indicates that they decrease risk in normal-weight women but have no effect or even increase risk in overweight or obese women [ , ]. A systematic review and meta-analysis of 9 prospective cohort and 10 case-control studies did not find an association between fish or LC-omega-3 intakes and risk of pancreatic cancer [ ].

Similarly, systematic reviews and meta-analyses have not found significant associations between fish consumption and risk of gastric or esophageal cancers [ , ]. Summary : Overall, data from observational studies show no consistent relationship between omega-3s and overall cancer risk. Although some evidence suggests that higher LC omega-3 intakes reduce the risk of breast and possibly colorectal cancers, a large clinical trial found that LC omega-3 supplements did not reduce the overall risk of cancer or the risk of breast, prostate, or colorectal cancers.

Additional randomized clinical trials in progress will help clarify whether omega-3s affect cancer risk. In this study, Dr. Jackson and her team evaluated blood levels of omega-3s EPA and DHA from almost people, alongside questions about their fish and supplement intake. Individuals reporting no fish intake and taking no omega-3 supplements had an average Omega-3 Index of about 4. At the other extreme, the average Omega-3 Index of people reporting taking a supplement AND eating three fish meals a week was 8.

Thus, in a free living setting, Dr. Jackson explained. This study brings us closer to helping people navigate the omega-3 category to find out what works for them, although this is still a bit generic.

For instance, how much omega-3 EPA and DHA should be in the supplement one takes if they eat 3 fish meals per week vs. The answer for everyone lies in testing their own omega-3 level. Learn more about the Omega-3 Index Test. It contains omega-3 fatty acids, which protect your heart. You must get omega-3s from your diet, as your body cannot make them. Some fish oils also supply vitamin A, an important antioxidant, and vitamin D, which is essential for bone health and overall immunity.

The main omega-3s present in fish oil are eicosapentaenoic acid EPA and docosahexaenoic acid DHA , which impact brain development and function 2 3 , 4. If you do not eat oily fish regularly, it can be very difficult to get enough EPA and DHA — because most other food sources of omega-3 are in the form of alpha-linolenic acid ALA.

Furthermore, the typical Western diet is too low in omega-3 compared to omega Therefore, supplementing with fish oil can be a great boost 7 , 8 , 9. The RDI for total omega-3 is 1, mg for women and 1, mg for men Most people get some omega-3 in their diet from foods such as flax seeds , soybean oil and walnuts — but these contain ALA. Unless you are eating about two portions 8 ounces or grams of oily fish per week, you could be lacking EPA and DHA 4 , 12 , Generally, up to 3, mg of fish oil daily is considered safe for adults to consume DHA, in particular, accumulates in the brain during the last trimester of pregnancy 12 , However, many pregnant women do not meet the RDI for these fatty acids 4.

Potential benefits include improved problem-solving skills and a reduced risk of asthma and food allergies 16 , 17 , Be careful with cod liver oil during pregnancy, as it harbors large amounts of vitamin A. Too much vitamin A can impair fetal development. The adequate intake of omega-3 for infants up to 1 year old is mg, which gradually increases to normal adult intake at 14 years For example, around mg of combined EPA and DHA is required for a 4-year-old, while an 8-year-old child needs about mg Vitamin E keeps the oil stable and may prolong shelf life.

When purchasing a fish oil supplement for infants or children, try to find ones that are specific for the given life stage to ensure the correct amount of nutrients.

While there are set recommendations for EPA and DHA for healthy adults, pregnant women — as well as infants and children — have different needs. Up to 1, mg of total EPA and DHA per day is recommended for people who have coronary heart disease and are at risk of having a heart attack 24 , However, a recent review determined that additional EPA and DHA intake, whether through diet or supplements, had little or no effect on reducing the risk of a heart attack