omega-3 fatty acids

Foods Richest in omega-3 fatty acids

Nutrient Amount DV% Rating
Flaxseeds 3.19 133% Excellent
Walnuts 2.72 113% Excellent
Sardines 1.46 61% Very Good
Salmon 1.32 55% Very Good
Beef 1.10 46% Very Good
Brussels Sprouts 0.27 11% Very Good
Cauliflower 0.21 9% Very Good
Mustard Seeds 0.15 6% Very Good
Soybeans 1.03 43% Good
Tofu 0.66 28% Good
Shrimp 0.34 14% Good
Winter Squash 0.19 8% Good
Broccoli 0.19 8% Good
Cod 0.19 8% Good
Collard Greens 0.18 8% Good
Spinach 0.17 7% Good
Summer Squash 0.15 6% Good
Raspberries 0.15 6% Good
Kale 0.13 5% Good
Romaine Lettuce 0.11 5% Good
Green Beans 0.11 5% Good
Strawberries 0.09 4% Good
Turnip Greens 0.09 4% Good
Miso 0.08 3% Good
Bok Choy 0.07 3% Good
Leeks 0.07 3% Good
Basil 0.07 3% Good
Bok Choy 0.07 2.92% Good
Flax Seeds, ground 3.19 132.9% Excellent
Walnuts 2.27 94.6% Excellent
Salmon 1.47 61.2% Very Good
Sardines 1.34 55.8% Very Good
Beef, grass-fed 1.10 45.8% Very Good
Cloves 0.18 7.5% Very Good
Soybeans 1.03 42.9% Good
Halibut 0.62 25.8% Good
Scallops 0.41 17.1% Good
Shrimp 0.37 15.4% Good
Tofu 0.36 15% Good
Tuna 0.33 13.8% Good
Cod 0.32 13.3% Good
Winter Squash 0.19 7.9% Good
Collard Greens 0.18 7.5% Good
Spinach 0.17 7.1% Good
Raspberries 0.15 6.2% Good
Kale 0.13 5.4% Good
Mustard Seeds 0.11 4.6% Good
Romaine Lettuce 0.11 4.6% Good
Turnip Greens 0.09 3.8% Good
Strawberries 0.09 3.8% Good
Brussels Sprouts 0.09 3.8% Good
Miso 0.08 3.3% Good
Green Beans 0.07 2.9% Good
Summer Squash 0.06 2.5% Good
Flax seeds 4.79 199.6% Excellent

About omega-3 fatty acids

Basic description

No type of fat has been getting more recent publicity than omega-3s, and you’re very likely to have seen TV ads or heard radio infomercials about this unique type of fat. However, much of the omega-3 publicity you’ve heard has probably been focused on dietary supplements rather than food. In this profile, we’ll provide you with a fresh look at omega-3s from the perspective of food and the best ways to balance your meal plan for strong omega-3 support.

Omega-3s belong to a broader group of fats called polyunsaturated fats. Sometimes you’ll hear this group called “poly” fats. The specific members of this group are called polyunsaturated fatty acids, or PUFAs. What’s most important about PUFAs—including omega-3s—is one special aspect of their chemical structure. They contain what are called “double bonds”—special connections that make them more flexible and interactive as fatty acids; they also make them more delicate and susceptible to damage. All PUFAs—including all omega-3s—contain at least two double bonds. But the position of the double bonds in omega-3s is unique and simply not found in other fats.

Some omega-3s are simpler than others. The simplest is called alpha-linolenic acid, or ALA. Like most vitamins, ALA is especially important in our diet because the body cannot make it from scratch. Either we consume it, or we don’t have enough. Fortunately for us, many commonly eaten plant and animal foods contain ALA.

For other omega-3s, this all-or-nothing scenario is not the case. Under the right circumstances, the body can usually take ALA and transform it into other omega-3s. These other omega-3s are more complicated than ALA and contain more double bonds. The best studied are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). EPA has five double bonds and DHA has six. In a large number of research studies, there are clear health benefits provided by EPA and DHA that are not provided by ALA. These health benefits involve support of many body systems and decreased risk of many chronic diseases.

So without question, the body need ALA, EPA, and DHA to stay healthy, and we need to consume ALA-containing foods no matter what because the body lack the ability to make ALA. But what about EPA and DHA? Are we absolutely required to eat foods containing EPA and DHA?

The answer to that question is particularly important since it can affect our entire approach to eating. If we only need to eat ALA-containing foods—and can trust the body to make all of the EPA and DHA that we need—we become free to choose whatever type of diet we would like, including a strict vegan diet that contains no animal foods whatsoever (including no milk, no cheese, and no eggs). That’s because a wide variety of plant foods contain small-to-moderate amounts of ALA. However, if we need to obtain EPA and DHA directly from food, we become much more restricted in our food choices. For example, if we are trying to implement a strict vegan diet with no animal foods whatsoever and want to obtain DHA from our diet, our choices would most likely be limited to sea plants (which can contain DHA) or some fermented foods (like fermented soy foods) which had been allowed to ferment with the help of specific fungi that were capable of producing DHA. The absence of DHA in land plants is the reason for these very limited options.

Let’s take some other examples. If we wanted to consume a generally vegetarian diet while still allowing ourselves to consume some fish, we would be able to get EPA and DHA from our food since fish can be a rich source of EPA and DHA. Similarly, if we wanted to consume a generally vegetarian diet while still allowing ourselves to consume some cheese, yogurt, milk, or eggs, we could also figure out how to obtain sufficient amounts of EPA and DHA from our food since these foods can contain both EPA and DHA. Or if we chose to eat meat while avoiding all fish, it would still be possible for us to get our EPA and DHA since meats can contain both EPA and DHA. (Their EPA and DHA content require that the cattle to have eaten a healthy amount plants that contain omega-3s.) The table below summarizes some of these basic relationships between omega-3s and diet types.

Diet Type

ALA Food Sources

EPA and DHA Food Sources

Vegan

many plants

sea plants; possibly land plant foods when fermented with the help of certain fungi

Generally vegetarian but including fish

many plants and most fish

most fish; sea plants; possibly land plant foods when fermented with the help of certain fungi

Generally vegetarian but including eggs, cheese, milk and yogurt (without fish, sea plants, or meat)

many plants; eggs, cheese, milk, and yogurt

eggs, cheese, milk, and yogurt, especially when obtained from grass-fed animals but in varying amounts depending on additional factors; possibly land plant foods when fermented with the help of certain fungi

Plant-eating and meat-eating (but without fish or sea plants)

many plants; many meats

many meats, especially when obtained from grass-fed animals, but in varying amounts, depending on additional factors; possibly land plant foods when fermented with the help of certain fungi

As you can see from the table above, our food choices can change quite dramatically if we are required to obtain EPA and DHA from our diet. But are we required to do so? Unfortunately, the answer to this question is not 100% clear from the research studies.

In principle, most healthy persons should be able to eat ALA-containing foods (like flaxseeds, walnuts, tofu, and spinach) and then rely on their bodies to convert ALA into EPA and DHA. Yet there is considerable scientific debate about our ability to get optimal amounts of EPA and DHA by relying exclusively on ALA-containing foods. That’s because the body’s ability to make EPA and DHA from ALA can become compromised under a variety of common circumstances.

For example, the body’s ability to make EPA and DHA from ALA partly depends on the other types of fat that we eat. One of those other fat types is omega-6 fat. Omega-6 fats are more plentiful in foods than omega-3 fats. Because they are more plentiful, we often find ourselves consuming much more of them. Yet high consumption of omega-6 fats can directly reduce the amount of ALA that the body converts into EPA and DHA.

Or, to take another example: the body cannot do an effective job of converting ALA into EPA and DHA without a satisfactory supply of certain nutrients. These nutrients include vitamin B3, vitamin B6, vitamin C, and the minerals zinc and magnesium. If we are deficient in one or more of these nutrients, the body may not be able to provide us with optimal amounts of EPA and DHA, even when our ALA intake is sufficient.

Different people will want to use different dietary approaches to obtain their omega-3s. But based on a review of the research and on the chart information presented above, here are our basic recommendations:

Omega-3 fatty acids are a group of polyunsaturated fats found in a wide variety of foods, most famously in fish. Because of recent research suggesting potential cardiovascular prevention and other health benefits, omega-3 fatty acids are currently a hot topic in nutrition research.

Of the WHF, two (flaxseeds and walnuts) rate as excellent sources. We rate five of our listed foods as very good sources of omega-3, and 19 as good sources. This should give you plenty of choices to make sure your diet contains good sources of these important fats.

Role in health support

ALA, EPA, and DHA all play important roles in support of our health. Yet these roles are somewhat different.

Alpha-linolenic acid (ALA)

A large amount of ALA is sometimes used strictly for energy purposes. Our bodies can take ALA and use it to produce energy for cells. In some situations, most of the ALA that we consume will get used in this way. ALA is also the primary building block for EPA and DHA. It’s difficult to overstate the importance of ALA in this regard. Our immune, inflammatory, cardiovascular, and nervous systems simply cannot function correctly without sufficient amounts of EPA and DHA. When we don’t have enough ALA, we don’t have enough EPA and DHA (unless we’ve eaten foods that contain them). So ALA has a critical role to play in the health of many body systems as the key building block for EPA and DHA. There are basically two important metabolic roles for dietary ALA. The first is the breakdown of ALA to be used as an energy source. As much as 85% of dietary ALA is broken down to be used as an energy source.

The other major role for ALA is to be elongated to the related omega-3 fats EPA and DHA. The efficiency of this process will be discussed in more detail below.

Eicosapentaenoic acid (EPA)

Proper function of our inflammatory system depends on the presence of messaging molecules called prostaglandins. Many of these prostaglandins are made directly from EPA. Equally important, most of the prostaglandins made from EPA tend to be anti-inflammatory in their effect. Therefore, your risk of excessive inflammation and inflammation-related disease can be lowered through consumption of foods rich in EPA.

Docosahexaenoic acid (DHA)

Proper function of our nervous system—including our brain—depends on the presence of DHA. DHA is particularly important to brain function. Our brain is 60% fat by weight, and DHA makes up an average of 15 to 20% of all fat in our brain. If we tie these two facts together, we arrive at the following conclusion: DHA accounts for 9-12% of our brain’s total weight! Drops in brain DHA levels are known to associate with cognitive impairment or slower neurological development in children. Nervous system deficiencies of DHA have been associated with a wide variety of problems, including neurodegenerative diseases like Parkinson’s disease; cognitive problems including reasoning ability in children; and severity of multiple sclerosis.

A special note about omega-3s and cardiovascular support

Prevention of cardiovascular diseases is one of the best-studied and substantiated role for omega-3s in the diet. Especially strong is the research supporting EPA and DHA in lowering heart disease risk. There is less research on ALA and heart disease, but research in this area still shows the ability of ALA intake to decrease risk. Unfortunately, the research we see in this area continues to focus more on dietary supplements than food, and in the future, we hope to see a much stronger emphasis on omega-3s from food.

The most crucial role for omega-3 fatty acids in health is arguably in prevention of cardiovascular diseases like heart attack and stroke. Much of the research in this area looks specifically at total EPA + DHA intake from diet and/or supplements.

Although there is comparatively less research on the topic, ALA intakes are associated with lower risk of cardiovascular disease independently of the other omega-3 fats. Still, the beneficial effects of diets high in ALA are likely to be more modest than diets rich in EPA and DHA.

Summary of food sources

Excellent sources of alpha-linolenic acid (ALA) include flaxseeds and walnuts. Very good sources of ALA include sardines and salmon, as well as cauliflower, Brussels sprouts, and mustard seeds. Good sources include a wide variety of vegetables (collard and turnip greens, spinach, kale, green beans, romaine lettuce, summer squash, and winter squash), fish (scallops, shrimp, and cod), legumes and foods made from legumes (soybeans, tofu, and miso), and fruits (strawberries and, raspberries). While seafood is known for its EPA and DHA content, smaller amounts of ALA are provided by numerous seafoods. While not ranked on our Rating System Chart, animal foods including beef, dairy, and eggs may also provide varying amounts of ALA. Outside of the U.S., one study in Britain found that about 25% of ALA intake in the UK population came from fish and meat dishes, with another 8% from eggs and dairy foods. While we do not have a similar study from the U.S., we do know that the quantity of ALA in animal foods depends on the diet consumed by the animals. As a general rule, animals raised in a natural setting throughout their lives and pasture-fed on a variety of grasses, legumes, and other plants will contain more ALA in their bodies, and will therefore provide food that is richer in ALA, eicosapentaenioc acid (EPA) and docosahexaenoic acid (DHA). Seafood is the food group most concentrated in EPA and DHA.

Like all creatures, fish have an omega-3 content that is highly dependent on their diet. If they eat algae, sea plants, and other foods that are rich in omega-3s, they are able to store more omega-3s in their tissue. If they live in a habitat where omega-3s are not widely available, they store much less. The close relationship between their diet and their omega-3 content applies to all specific omega-3s found in fish, including ALA, EPA, and DHA. It also applies to all types of fish including wild-caught and farmed. Some farmed fish are fed processed omega-3 concentrates to boost their omega-3 content. Other farmed fish are fed few omega-3s and have lower-than average omega-3 content.

Land animals are no different than fish in terms of their omega-3 content. Their diet is the key controlling factor—the same as it is for ocean creatures. Cows and chickens consuming diets that are rich in omega-3s tend to produce milk and eggs that are higher in omega-3 fats. Levels of omega-3s in eggs can reach levels of 350 milligrams per egg, depending on the hen’s diet. In cow’s milk, omega-3 levels have been shown to reach 155 milligrams per 8-ounce cup in some grass-fed heifers. About half of these omega-3s are typically present in the form of ALA, with the other half being divided between EPA, DHA, and other omega-3s. As a general rule, the milk, cheese, yogurt, and eggs obtained from land animals that have been grass-fed and have had natural access to pasture plants containing omega-3s are going to be your best bet for omega-3s from land animals.

Other omega-3 fortified foods are becoming available on the market, including margarine spreads, juices, and snack foods. These foods are generally made by adding the fatty acids during the manufacturing process. As with all nutrients, we believe that your omega-3s are best obtained from whole, natural foods. Unless a food is whole and natural, there is no way to guarantee that its nutrients will be found in optimal ratios and balanced proportions, or even incorporated into the food matrix in an optimal way.

We would like to add a special note about one food that does not appear on our ranking list as a good, very good, or excellent source of omega-3s. That food is tuna. In our nutrient analysis, we used baked yellowfin tuna. A 4-ounce serving of this form of tuna provided 140 milligrams of omega-3s and 147 calories. When we put these numbers into our rating system formula, tuna provided too few omega-3s in comparison with its calorie content to rank as a good source of omega-3s. However, we do not believe that this outcome would automatically be true for all tuna. We’ve seen studies on canned light tuna that showed about 345 milligrams of omega-3s in 4 ounces, and in the case of canned albacore tuna, we’ve seen studies showing about 975 milligrams of omega-3s in 4 ounces. Their higher levels of omega-3s would change the status of tuna in our rating system. However, our approach to healthy eating is always focused on fresh, natural, and minimally processed foods rather than canned or other versions.

Nutrient rating chart

Introduction to nutrient rating system chart

Read more background information and details of our rating system

WHF ranked as quality sources of
omega-3 fats

Food

Serving
Size

Cals

Amount
(g)

DRI/DV
(%)

Nutrient
Density

World’s
Healthiest
Foods Rating

Flaxseeds

2 TBS

74.8

3.19

133

32.0

excellent

Walnuts

0.25 cup

196.2

2.72

113

10.4

excellent

Sardines

3.20 oz

188.7

1.46

61

5.8

very good

Salmon

4 oz

157.6

1.32

55

6.3

very good

Beef

4 oz

175.0

1.10

46

4.7

very good

Brussels Sprouts

1 cup

56.2

0.27

11

3.6

very good

Cauliflower

1 cup

28.5

0.21

9

5.5

very good

Mustard Seeds

2 tsp

20.3

0.15

6

5.5

very good

Soybeans

1 cup

297.6

1.03

43

2.6

good

Tofu

4 oz

164.4

0.66

28

3.0

good

Shrimp

4 oz

134.9

0.34

14

1.9

good

Winter Squash

1 cup

75.8

0.19

8

1.9

good

Broccoli

1 cup

54.6

0.19

8

2.6

good

Cod

4 oz

96.4

0.19

8

1.5

good

Collard Greens

1 cup

62.7

0.18

8

2.2

good

Spinach

1 cup

41.4

0.17

7

3.1

good

Summer Squash

1 cup

36.0

0.15

6

3.1

good

Raspberries

1 cup

64.0

0.15

6

1.8

good

Kale

1 cup

36.4

0.13

5

2.7

good

Romaine Lettuce

2 cups

16.0

0.11

5

5.2

good

Green Beans

1 cup

43.8

0.11

5

1.9

good

Strawberries

1 cup

46.1

0.09

4

1.5

good

Turnip Greens

1 cup

28.8

0.09

4

2.3

good

Miso

1 TBS

34.2

0.08

3

1.8

good

Bok Choy

1 cup

20.4

0.07

3

2.6

good

Leeks

1 cup

32.2

0.07

3

1.6

good

Basil

0.50 cup

4.9

0.07

3

10.8

good

World’s Healthiest
Foods Rating

Rule

excellent

DRI/DV>=75% OR
Density>=7.6 AND DRI/DV>=10%

very good

DRI/DV>=50% OR
Density>=3.4 AND DRI/DV>=5%

good

DRI/DV>=25% OR
Density>=1.5 AND DRI/DV>=2.5%

Impact of cooking, storage and processing

Omega-3 fatty acids are very susceptible to free radical damage. Oxidation of omega-3 fats limits their shelf life and their ability to provide you with the nourishment you need. Damage to the omega-3s in your food can be caused by light, oxygen, or heat. For this reason, foods that are rich in omega-3s should usually be stored in the refrigerator in a sealed container. This rule not only applies to animal foods like fish, dairy, eggs, and meat but also to plant foods like nuts and seeds.

The grinding of nuts and seeds deserves special mention in terms of its impact on omega-3 nourishment. As described earlier, many nuts and seeds contain valuable amounts of omega-3s in the form of ALA. However, in the case of small seeds like flax or chia seeds, it can be very difficult to chew the seeds and grind them sufficiently with your teeth to help increase the availability of their ALA. For this reason, many people choose to grind seeds (for example, in a coffee grinder) prior to eating or incorporating into a recipe. If you decide to grind your omega-3 rich seeds, their shelf life will be reduced and it becomes especially important to store them in a sealed, opaque container in your refrigerator. To give you a more practical idea of shelf life, pre-ground flaxseeds—packaged by the manufacturer in a gas-flushed, light-protective pouch—will typically last for 6-16 weeks before going bad. By comparison, whole flaxseeds will last 6-12 months when stored properly. If you are grinding your own seeds, the recommendation is a more modest storage time of 1-2 months.

Risk of dietary deficiency

If your meal plan resembles that of the average U.S. adult, you are highly likely to be deficient in omega-3s. The reason is simple: the average U.S. adult consumes too few foods that are good sources of omega-3s, and excessive amounts of total fat that contain too many omega-6s.

In the U.S., our ratio of omega-6:omega-3 fat has been estimated to fall between 20:1 and 8:1. (Those numbers mean that we eat at least eight times more omega-6 than omega-3, and perhaps as much as 20 times more.) Most studies suggest that a healthier ratio of omega-6:omega-3 lies between 4:1 and 2:1. Taken as a whole, the dietary circumstances described above leave the average U.S. adult with an insufficient intake of ALA and a compromised ability to convert ALA into other health-supportive omega-3s like EPA and DHA due to excessive intake of omega-6s.

A further problem with the average U.S. diet and omega-3s is deficient intake of nutrients required to convert ALA into EPA and DHA. This list of nutrients includes vitamins B3, B6, and C, and the minerals zinc and magnesium.

Reasons for low omega-3 intake in the U.S. diet vary, but some key reasons that apply to many meal plans are as follows:

Your best ways of increasing omega-3 nourishment are to reverse all of the above practices. Consider increasing your intake of nuts (like walnuts) or seeds (like flaxseeds). Consumption of these foods on a daily basis can work well in most meal plans. Also consider fish like salmon, sardines, shrimp, or cod on a more frequent basis. Finally, consider purchase of grass-fed and/or pastured-raised animal foods including meats, cheeses, yogurt, and eggs.

If you are following a fairly strict vegetarian or vegan diet, it may be especially difficult for you to get EPA and DHA you directly from food. (That’s because animal foods are typically richer sources of these omega-3s than plant foods.) For this reason, the recommendation is that you increase your intake of ALA-containing foods to a level that will provide you with approximately 4 grams of ALA per day. Here are some choices that can help you reach that 4 gram level.

Food

ALA Serving Size

ALA

Flaxseeds

2 tablespoons

3.19 grams

Walnuts

1/4 cup

2.72 grams

Tofu

8 ounces

1.32 grams

Brussels sprouts

2 cups cooked

0.54 grams

Cauliflower

2 cups cooked

0.52 grams

Although we have partially addressed the following issue earlier in this article, we would like to emphasize one ongoing controversy that continues to hang over omega-3 research related to risk of dietary deficiency. That controversy involves metabolism of omega-3s. Researchers know that humans need all forms of omega-3s—including the forms ALA, EPA, and DHA. Researchers also know that humans can take ALA and convert it into EPA and DHA under favorable circumstances. But researchers still don’t know is exactly how often these favorable circumstances exist. Because the research jury on omega-3 metabolism is still out, the recommendation is taking one of two approaches to your omega-3 nourishment. A first approach is to focus on including not only ALA-rich plant foods in your meal plan, but EPA-rich and DHA-rich animal foods as well. A second approach is to focus exclusively on ALA-rich foods in your meal plan, but greatly increase your intake to the 4 gram level described earlier.

Other circumstances that might contribute to deficiency

Since omega-3s are a type of fat, some conditions that involve poor absorption of fats from our digestive tract can increase our risk of omega-3 deficiency. Included in this list of conditions would be inflammatory bowel disease, celiac disease, and cystic fibrosis.

Relationship with other nutrients

Since omega-3 fats are delicate and susceptible to damage from oxygen-containing molecules, our need for dietary antioxidants becomes greater as our intake of polyunsaturated fats goes up. Especially important within this increased antioxidant intake is increase intake of vitamin E. WHF richest in vitamin E include sunflower seeds, spinach, Swiss chard, turnip greens, asparagus, mustard greens, chili peppers, almonds, broccoli, and bell peppers. For more information about vitamin E-containing foods, please see our nutrient profile for vitamin E.

As described earlier, excessive intake of omega-6 fats in comparison to omega-3s can compromise your omega-3 nourishment. In practical terms, excessive intake of omega-6s typically comes from one or more of three places. First is excessive intake of total fat. (Too much overall fat consumption can result in excessive intake of omega-6s because most fat-containing foods provide more omega-6s than omega-3s.) Second is excessive use of cooking oils high in omega-6s (including corn oil, safflower oil, sunflower seed oil, and soybean oil). Third is excessive intake of fried foods. (The oils used for frying are typically richest in omega-6s.) Cutting back in any or all of these three areas can greatly reduce your omega-6 intake.

Risk of dietary toxicity

There is no known toxicity risk consistently associated with diets high in omega-3 fatty acids. Like any fatty acids, omega-3s are densely packed calorie sources, and too much dietary fat can be associated with weight gain. However, if you restrict your intake of high-fat foods to foods that are rich in omega-3s, you’re less likely to overdo it on the calories. It’s almost never the omega-3 rich foods that we tend to consume in excess.

Disease checklist

ALA forms of omega-3 fatty acids may play a role in the prevention and/or treatment of the following health conditions:

EPA and DHA forms of omega-3 fatty acids may play a role in the prevention and/or treatment of the following health conditions:

Public health recommendations

We’ve found specific omega-3 recommendations from a variety of public health organizations, including the National Academy of Sciences, American Heart Association, American Dietetic Association, World Health Organization, and National Institutes of Health. These recommendations are relatively similar, but by no means identical. We’ve provided you with more details below, but we also want to give you our own WHF recommendations based on the research studies that we have reviewed.

Summary of omega-3 reccomendations

For total omega-3 fat, the recommendation is an average of at least 2.4 grams per day. On some days you might get slightly less, but over the course of an entire week, you’ll want to average at least this amount.

Within these 2.4 grams of total omega-3s, the recommendation is an average daily intake of 400-500 milligrams of EPA and DHA combined. Since you can get over 1,000 milligrams from a 4-ounce serving of fish like salmon, three servings of salmon per week could bring your daily EPA and DHA average to this level all by itself. Grass-fed beef and dairy products cannot usually provide you with amounts of EPA and DHA equivalent to fish, but they can still increase your EPA and DHA intake substantially.

More details about public health organizations and their recommendations are as follows.

The National Academy of Sciences has established a Dietary Reference Intake (DRI) level for ALA at 1.6 grams per day for men ages 19-70 and to 1.1 grams per day for women ages 19-70. An expert working group at the National Institutes of Health (NIH) has suggested an intake of 2.2 grams of ALA per 2000 dietary calories for both women and men.

There are several recommendations for intake of EPA and DHA from different groups. These recommendations include:

There are also some specific recommendations for target populations. These include:

The National Academy of Sciences has not issued a Tolerable Upper Intake Limit (UL) for omega-3 fatty acids. Similarly, none of the other experts listed above have recommended limiting omega-3 intake below a certain standard.

Description

How it functions

What are the functions of omega-3 fatty acids?

Every cell in the body is surrounded by a cell membrane composed mainly of fatty acids. The cell membrane allows the proper amounts of necessary nutrients to enter the cell, and ensures that waste products are quickly removed from the cell.

Promoting healthy cell membranes

To perform these functions optimally, however, the cell membrane must maintain its integrity and fluidity. Cells without a healthy membrane lose their ability to hold water and vital nutrients. They also lose their ability to communicate with other cells. Researchers believe that loss of cell to cell communication is one of the physiological events that leads to growth of cancerous tumors.

Because cell membranes are made up of fat, the integrity and fluidity of our cell membranes is determined in large part by the type of fat we eat. Remember that saturated fats are solid at room temperature, while omega-3 fats are liquid at room temperature. Researchers believe that diets containing large amounts of saturated or hydrogenated fats produce cell membranes that are hard and lack fluidity. On the other hand, diets rich in omega-3 fats produce cell membranes with a high degree of fluidity.

In addition, recent in vitro (test tube) evidence suggests when omega-3 fatty acids are incorporated into cell membranes they may help to protect against cancer, notably of the breast. They are suggested to promote breast cancer cell apoptosis via several mechanisms including: inhibiting a pro-inflammatory enzyme called cyclooxygenase 2 (COX 2), which promotes breast cancer; activating a type of receptor in cell membranes called peroxisome proliferator-activated receptor (PPAR), which can shut down proliferative activity in a variety of cells including breast cells; and, increasing the expression of BRCA1 and BRCA2, tumor suppressor genes that, when functioning normally, help repair damage to DNA, thus helping to prevent cancer development.

Animal and test tube studies published in the November 2005 issue of the International Journal of Cancer suggest yet another way in which the omega-3 fatty acids found in cold water fish—docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)—help protect against breast cancer development.

All dietary fatty acids are incorporated into cell membranes, and the type of fatty acids dictates how a cell responds and grows. Researchers found that omega-3 fatty acids affect cell growth by activating an enzyme called sphingomyelinase, which then generates the release of ceramide, a compound that induces the expression of the human tumor suppressor gene p21, which ultimately causes cancer cell death.

In the animal experiments, mice were fed diets rich in either omega-3 (fish oil) or omega-6 (corn oil) fatty acids after which breast cancer cells were implanted. Three weeks later, tumor volume and weight was significantly lower in mice on the omega-3 rich diet. In the lab culture experiments, when cells were treated with DHA or EPA, sphingomyelinase activity increased by 30-40%, and breast cancer cell growth dropped 20-25%.

Prostaglandin production

Omega-3 fats also play an important role in the production of powerful hormone-like substances called prostaglandins. Prostaglandins help regulate many important physiological functions including blood pressure, blood clotting, nerve transmission, the inflammatory and allergic responses, the functions of the kidneys and gastrointestinal tract, and the production of other hormones.

In essence, all prostaglandins perform essential physiological functions. However, depending on the type of fat in the diet, certain types of prostaglandins may be produced in large quantities, while others may not be produced at all. This can set up an imbalance throughout the body that can lead to disease.

For example, EPA and DHA serve as direct precursors for series 3 prostaglandins, which have been called “good” or “beneficial” because they reduce platelet aggregation, reduce inflammation and improve blood flow. The role of EPA and DHA in the prevention of cardiovascular disease can be explained in large part by the ability of these fats to increase the production of favorable prostaglandins.

The omega 6 fats serve as precursors for series 1 and series 2 prostaglandins. Like the series 3 prostaglandins produced from omega-3 fats, series 1 prostaglandins are believed to be beneficial. On the other hand, series 2 prostaglandins are usually considered to be “bad” or “unhealthy,” since these prostaglandins promote an inflammatory response and increase platelet aggregation. As a result, it is important to ensure proper balance of omega-3 and omega-6 fats in the diet.

EPA Directly Anti-Inflammatory

A recently identified lipid (fat) product the body make from EPA, called resolvins, helps explain how this omega-3 fat provides anti-inflammatory effects on our joints and improves blood flow.

Resolvins, which have been shown to reduce inflammation in animal studies, are made from EPA by our cellular enzymes, and work by inhibiting the production and regulating the migration of inflammatory cells and chemicals to sites of inflammation. Unlike anti-inflammatory drugs, such as aspirin, ibuprofen and the COX-2 inhibitors, the resolvins the body produce from EPA do not have negative side effects on our gastrointestinal or cardiovascular systems.

EPA directly anti-inflammatory

A recently identified lipid (fat) product the body make from EPA, called resolvins, helps explain how this omega-3 fat provides anti-inflammatory effects on our joints and improves blood flow.

Resolvins, which have been shown to reduce inflammation in animal studies, are made from EPA by our cellular enzymes, and work by inhibiting the production and regulating the migration of inflammatory cells and chemicals to sites of inflammation. Unlike anti-inflammatory drugs, such as aspirin, ibuprofen and the COX-2 inhibitors, the resolvins the body produce from EPA do not have negative side effects on our gastrointestinal or cardiovascular systems.

Deficiency symptoms

What are deficiency symptoms for omega-3 fatty acids?

Recent statistics indicate that nearly 99% of people in the United States do not eat enough omega 3 fatty acids. However, the symptoms of omega-3 fatty acid deficiency are very vague, and can often be attributed to some other health conditions or nutrient deficiencies.

Consequently, few people (or their physicians, for that matter) realize that they are not consuming enough omega-3 fatty acids. The symptoms of omega-3 fatty acid deficiency include fatigue, dry and/or itchy skin, brittle hair and nails, constipation, frequent colds, depression, poor concentration, lack of physical endurance, and/or joint pain.

Toxicity symptoms

What are toxicity symptoms for omega 3 fatty acids?

In its 2002 guidelines for omega-3 fatty acid intake, the Institute of Medicine at the National Academy of Sciences declined to establish a Tolerable Upper Intake Level (UL) for omega-3s. However, research was cited showing increased risk of bleeding and hemorrhagic stroke in a few studies following supplementation with omega-3s. Individuals who have disorders involving bleeding, who bruise very easily, or who are taking blood thinners should consult with a medical practitioner before taking supplemental omega-3 fatty acids.

Factors that affect function

What factors might contribute to a deficiency of omega-3 fatty acids?

The conversion of alpha-linolenic acid to EPA and DHA involves a series of chemical reactions. One of the first reactions in this series is catalyzed by the enzyme delta-6 desaturase. Further down the line is a reaction that is catalyzed by the enzyme delta-5 desaturase. Unfortunately, it is now well-known that these enzymes do not function optimally in many people, and, consequently, only a small amount of the alpha-linolenic acid consumed in the diet is converted to EPA, DHA, and ultimately to the anti-inflammatory prostaglandins.

To increase the activity of your desaturase enzymes, be sure that your diet includes a sufficient amount of vitamin B6, vitamin B3, vitamin C, magnesium and zinc. In addition, limit your intake of saturated fat and partially hydrogenated fat, as these fats are known to decrease the activity of delta-6 desaturase. Also, to be on the safe side, consider including a direct source of EPA and DHA if your diet, such as wild-caught salmon, halibut, or tuna.

Nutrient interactions

How do other nutrients interact with omega-3 fatty acids?

Vitamin E

Health conditions

What health conditions require special emphasis on omega-3 fatty acids?

Omega-3 fatty acids may play a role in the prevention and/or treatment of the following health conditions:

Food sources

What foods provide omega-3 fatty acids?

Flax seeds and walnuts are excellent sources of omega-3 fatty acids. Very good sources of these healthy fats include salmon, sardines, cloves, and grass-fed beef. Good sources of these fats include halibut, shrimp, cod, tuna, soybeans, tofu, kale, collard greens, and winter squash.

Studies have proven that a relatively small number of omega-3 food sources can have a measurable impact on your blood levels of omega-3s, including those two key omega-3 fatty acids, EPA (eicosaenoic acid) and DHA (docosahexaenoic acid). For example, two weekly servings of a non-fried, omega-3 containing fish (like wild-caught Pacific salmon) is enough to boost your blood levels of omega-3s.

Related Articles

References

  1. Barcelo-Coblijn G, Murphy EJ. Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: Benefits for human health and a role in maintaining tissue n-3 fatty acid levels. Prog Lipid Res 2009;48:355-74. https://doi.org/10.1016/j.plipres.2009.07.002
  2. Baux A, Hebeisen T, Pellet D. Effects of minimal temperatures on low-linolenic rapeseed oil fatty-acid composition. Eur J Agron 2008;29:102-7. https://doi.org/10.1016/j.eja.2008.04.005
  3. Bozan B, Temelli F. Chemical composition and oxidative stability of flax, safflower and poppy seed and seed oils. Bioresource Technology 2008;99:6354-9. https://doi.org/10.1016/j.biortech.2007.12.009
  4. Burdge AC, Calder PC. Dietary alpha-linolenic acid and health-related outcomes: a metabolic perspective. Nutr Res Rev 2006:19:26-52. https://doi.org/10.1017/s0029665110001539
  5. Daley CA, Abbott A, Doyle PS, et al. A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutr J 2010;9:10-21. https://doi.org/10.1186/1475-2891-9-10
  6. Davis BC, Kris-Etherton P. Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications. Am J Clin Nutr 2003;78:640S-646S. https://doi.org/10.1093/ajcn/78.3.640s
  7. Kitson AP, Patterson AC, Izadi H, Stark KD. Pan-frying salmon in an eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) enriched margarine prevents EPA and DHA loss. Food Chem 2009;114:927-32. https://doi.org/10.1016/j.foodchem.2008.10.039
  8. Kris-Etherton PM, Grieger JA, Etherton TD. Dietary reference intakes for DHA and EPA. Prostaglandins Leukot Essent Fatty Acids 2009;81:99-104. https://doi.org/10.1016/j.plefa.2009.05.011
  9. Rodriguez-Leyva D, Bassett CMC, McCullough R, Pierce GN. The cardiovascular effects of flaxseed and its omega-3 fatty acid, alpha-linolenic acid. Can J Cardiol 2010; 26:489-96. https://doi.org/10.1016/s0828-282x(10)70455-4
  10. Sanders TAB. DHA status of vegetarians. Prostaglandins Leukot Essent Fatty Acids 2009;81:137-41. https://doi.org/10.1016/j.plefa.2009.05.013
  11. Sebedio JL, Ratnayake WMN, Ackman RG, Prevost J. Stability of polyunsaturated omega-3 fatty acids during deep fat frying of Atlantic mackerel. Food Res Int 1993;26:163-72. https://doi.org/10.1016/0963-9969(93)90049-o
  12. Simopoulos AP, Leaf A, Salem N. Workshop on the essentiality of and recommended dietary intakes for omega-6 and omega-3 fatty acids. J Am Coll Nutr 1999;18:487-9. https://doi.org/10.1080/07315724.1999.10718888
  13. Valk EE, Hornstra G. Relationship between vitamin E requirement and polyunsaturated fatty acid intake in man: a review. Int J Vitam Nutr Res. 2000 Mar;70(2):31-42. https://doi.org/10.1024/0300-9831.70.2.31
  14. Weaver KL, Ivester P, Chilton JA, et al. The content of favorable and unfavorable polyunsaturated fatty acids found in commonly eaten fish. J Am Diet Assoc 2008;108:1178-85. https://doi.org/10.1016/j.jada.2008.04.023
  15. Welch, AA, Shakya-Shrestha S, Lentjes MA, et al. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of alpha-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr 2010;92:1040-51. https://doi.org/10.3390/nu11102365
  16. Whelan J, Jahns L, Kavanagh K. Docosahexaenoic acid: measurements in food and dietary exposure. Prostaglandins Leukot Essent Fatty Acids 2009:81:133-6. https://doi.org/10.1016/j.plefa.2009.05.008
  17. Zheng J, Huang T, Yu Y, et al. Fish consumption and CHD mortality: an updated meta-analysis of seventeen cohort studies. Public Health Nutr. 2012 Apr;15(4):725-37. https://doi.org/10.1017/s1368980011002254
  18. Arita M, Bianchini F, Aliberti J, Sher A, Chiang N, Hong S, Yang R, Petasis NA, Serhan CN. Stereochemical assignment, antiinflammatory properties, and receptor for the omega-3 lipid mediator resolvin E1. J Exp Med. 2005 Mar 7;201(5):713-22. 2005. PMID:15753205. https://doi.org/10.1084/jem.20042031
  19. Bernard-Gallon DJ, Vissac-Sabatier C, Antoine-Vincent D et al. Differential effects of n-3 and n-6 polyunsaturated fatty acids on BRCA1 and BRCA2 gene expression in breast cell lines. Br J Nutr 2002 Apr;87(4):281-9. 2002. https://doi.org/10.1079/bjn2002522
  20. Chung H, Nettleton JA, Lemaitre RN et al. Frequency and Type of Seafood Consumed Influence Plasma (n-3) Fatty Acid Concentrations. The Journal of Nutrition. Bethesda: Dec 2008. Vol. 138, Iss. 12; p. 2422-2427. 2008. https://doi.org/10.3945/jn.108.089631
  21. Elvevoll EO, Barstad H, Breimo ES, Brox J, Eilertsen KE, Lund T, Olsen JO, Osterud B. Enhanced incorporation of n-3 fatty acids from fish compared with fish oils. Lipids. 2006 Dec;41(12):1109-14. 2006. PMID:17269556. https://doi.org/10.1007/s11745-006-5060-3
  22. Erkkila A, Lichtenstein A, Mozaffarian D, Herrington D. Fish intake is associated with a reduced progression of coronary artery atherosclerosis in postmenopausal women with coronary artery disease. Am J Clin Nutr , Sept. 2004; (80(3):626-32. 2004. PMID:15321802. https://doi.org/10.1093/ajcn/80.3.626
  23. Fickova M, Hubert P, Cremel G, Leray C. Dietary (n-3) and (n-6) polyunsaturated fatty acids rapidly modify fatty acid composition and insulin effects in rat adipocytes. J Nutr 1998 Mar;128(3):512-9. 1998. PMID:8980. https://doi.org/10.1001/archpedi.1976.02120100055008
  24. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995. 1995.
  25. Heller A, Koch T. [Immunonutrition with omega-3-fatty acids. Are new anti-inflammatory strategies in sight?]. Zentralbl Chir 2000;125(2):123-36. 2000. PMID:15830. https://doi.org/10.1159/000458774
  26. Lawson LD, Hughes BG. Absorption of eicosapentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl esters co-ingested with a high-fat meal. Biochem Biophys Res Commun. 1988 Oct 31;156(2):960-3. 1988. PMID:2847723. https://doi.org/10.1016/s0006-291x(88)80937-9
  27. Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000. 2000.
  28. Mahan K, Escott-Stump S. Krause's Food, Nutrition, and Diet Therapy. WB Saunders Company; Philadelphia, 1996. 1996.
  29. Maillard V, Bougnoux P, Ferrari P et al. N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France. Int J Cancer 2002 Mar 1;98(1):78-83. 2002. https://doi.org/10.1002/ijc.10130
  30. Matute P. Consumption of fish to allay obesity. Paper presented at the 6th Congress of the International Society for the Study of Fatty Acids and Lipids, Brighton, Great Britain, December 12, 2004. 2004. https://doi.org/10.1098/rstb.2010.0149
  31. Meng L, Wilkens L, and Kolonel L. How fish is cooked affects heart-health benefits of omega-3 fatty acids. American Heart Association�s Scientific Sessions 2009. Abstract 1404/Poster 2071. Orlando, FL. 2009.
  32. Osmundsen H, Clouet P. Metabolic effects of omega-3 fatty acids. Biofactors 2000;13(1-4):5-8. 2000. PMID:15800.
  33. Popp-Snijders C, Schouten JA, Heine RJ, et al. Dietary supplementation of omega-3 polyunsaturated fatty acids improves insulin sensitivity in non-insulin-dependent diabetes. Diabetes Res 1987 Mar;4(3):141-7. 1987. PMID:8990. https://doi.org/10.1152/ajplegacy.1976.231.1.209
  34. Serhan CN, Hong S, Gronert K, Colgan SP, Devchand PR, Mirick G, Moussignac RL. Resolvins: a family of boactive products of omega-3 fatty acid transformation circuits initiated by aspirin treatment that counter proinflammation signals. J Exp Med. 2002 Oct 21;196(8):1025-37. 2002. PMID:12391014. https://doi.org/10.1084/jem.20020760
  35. Severus WE, Littman AB, Stoll AL. Omega-3 fatty acids, homocysteine, and the increased risk of cardiovascular mortality in major depressive disorder. Harv Rev Psychiatry 2001 Nov-2001 Dec 31;9(6):280-93. 2001. PMID:15780. https://doi.org/10.1016/0306-4492(77)90037-5
  36. Stoll BA. n-3 fatty acids and lipid peroxidation in breast cancer inhibition. Br J Nutr 2002 March;87(3):193-8. 2002.
  37. Stoll BA. Essential fatty acids, insulin resistance, and breast cancer risk. Nutr Cancer. 1998;31(1):72-77. 1998. https://doi.org/10.1080/01635589809514681
  38. Vaddadi KS, Soosai E, Chiu E et al. A randomised, placebo-controlled, double blind study of treatment of Huntington's disease with unsaturated fatty acids. Neuroreport 2002;13:29-33. 2002. https://doi.org/10.1097/00001756-200201210-00011
  39. Watkins BA, Li Y, Lippman HE, Seifert MF. Omega-3 polyunsaturated fatty acids and skeletal health. Exp Biol Med (Maywood) 2001 Jun;226(6):485-97. 2001. PMID:15790. https://doi.org/10.1159/000428582
  40. Watkins BA, Li Y, Seifert MF. Nutraceutical fatty acids as biochemical and molecular modulators of skeletal biology. Am J Clin Nutr 2001;20(5):410S-420S. 2001. https://doi.org/10.1080/07315724.2001.10719177
  41. Wu M, Harvey KA, Ruzmetov N, Welch ZR, Sech L, Jackson K, Stillwell W, Zaloga GP, Siddiqui RA. Omega-3 polyunsaturated fatty acids attenuate breast cancer growth through activation of a neutral sphingomyelinase-mediated pathway. Int J Cancer. 2005 Nov 10;117(3):340-8. 2005. PMID:15900589. https://doi.org/10.1002/ijc.21238
  42. Bernard-Gallon DJ, Vissac-Sabatier C, Antoine-Vincent D et al. Differential effects of n-3 and n-6 polyunsaturated fatty acids on BRCA1 and BRCA2 gene expression in breast cell lines. Br J Nutr 2002 Apr;87(4):281-9 2002. https://doi.org/10.1079/bjn2002522
  43. Fickova M, Hubert P, Cremel G, Leray C. Dietary (n-3) and (n-6) polyunsaturated fatty acids rapidly modify fatty acid composition and insulin effects in rat adipocytes. J Nutr 1998 Mar;128(3):512-9 1998. PMID:8980. https://doi.org/10.1001/archpedi.1976.02120100055008
  44. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995 1995.
  45. Heller A, Koch T. [Immunonutrition with omega-3-fatty acids. Are new anti-inflammatory strategies in sight?]. Zentralbl Chir 2000;125(2):123-36 2000. PMID:15830. https://doi.org/10.1159/000458774
  46. Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000 2000.
  47. Mahan K, Escott-Stump S. Krause's Food, Nutrition, and Diet Therapy. WB Saunders Company; Philadelphia, 1996 1996.
  48. Maillard V, Bougnoux P, Ferrari P et al. N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France. Int J Cancer 2002 Mar 1;98(1):78-83 2002. https://doi.org/10.1002/ijc.10130
  49. Meng L, Wilkens L, and Kolonel L. How fish is cooked affects heart-health benefits of omega-3 fatty acids. American Heart Association's Scientific Sessions 2009. Abstract 1404/Poster 2071. Orlando, FL. 2009.
  50. Osmundsen H, Clouet P. Metabolic effects of omega-3 fatty acids. Biofactors 2000;13(1-4):5-8 2000. PMID:15800.
  51. Popp-Snijders C, Schouten JA, Heine RJ, et al. Dietary supplementation of omega-3 polyunsaturated fatty acids improves insulin sensitivity in non-insulin-dependent diabetes. Diabetes Res 1987 Mar;4(3):141-7 1987. PMID:8990. https://doi.org/10.1152/ajplegacy.1976.231.1.209
  52. Severus WE, Littman AB, Stoll AL. Omega-3 fatty acids, homocysteine, and the increased risk of cardiovascular mortality in major depressive disorder. Harv Rev Psychiatry 2001 Nov-2001 Dec 31;9(6):280-93 2001. PMID:15780. https://doi.org/10.1016/0306-4492(77)90037-5
  53. Stoll BA. n-3 fatty acids and lipid peroxidation in breast cancer inhibition. Br J Nutr 2002 March;87(3):193-8 2002.
  54. Vaddadi KS, Soosai E, Chiu E et al. A randomised, placebo-controlled, double blind study of treatment of Huntington's disease with unsaturated fatty acids. Neuroreport 2002;13:29-33 2002. https://doi.org/10.1097/00001756-200201210-00011
  55. Watkins BA, Li Y, Lippman HE, Seifert MF. Omega-3 polyunsaturated fatty acids and skeletal health. Exp Biol Med (Maywood) 2001 Jun;226(6):485-97 2001. PMID:15790. https://doi.org/10.1159/000428582
  56. Watkins BA, Li Y, Seifert MF. Nutraceutical fatty acids as biochemical and molecular modulators of skeletal biology. Am J Clin Nutr 2001;20(5):410S-420S 2001. https://doi.org/10.1080/07315724.2001.10719177