Omega-3 and Omega-6 Food Sources

Omega-3 and Omega-6 Food Sources

Finding information about how much omega-3 and omega-6 fatty acids are in a food or oil isn't an easy undertaking. The information is not all that readily available and takes some time to find. Below is the start of a list of foods and fats/oils to start with - as I find more information, I'll update here and include the sources of the additional information. For now, I wanted to provide a list to start with from the information I have gathered. I ask my readers to add to this list in the comments section - place links and any levels of omega-3/6 tested in the comments for other readers to use!

FATS AND OILS (per 100g)

Fish Oils (average cod, halibut, mackerel, rockfish and salmon oils)
1.2g LA (n-6)
0.9g ALA (n-3)
9.9g EPA (n-3)
12.8g DHA (n-3)

Fish Liver Oil (Atlantic Cod)
1.5g LA (n-6)
0.9g ALA (n-3)
8g EPA (n-3)
14.3 DHA (n-3)

Shellfish Oil (Pacific Oyster)
1.2g LA (n-6)
1.6g ALA (n-3)
21.5g EPA (n-3)
20.2g DHA (n-3)

Nut and Seed Oils

Cashew Oil
16g LA (n-6)
0.4g ALA (n-3)

Peanut Oil
29g LA (n-6)
1.1g ALA (n-3)

Pumpkin SeedOil
51g LA (n-6)
0 ALA (n-3)

Sesame Seed Oil
42g LA (n-6)
0.5g ALA (n-3)

Sunflower Oil
53g LA (n-6)
0g ALA (n-3)

Coconut Oil
3g LA (n-6)
0g ALA (n-3)

Flaxseed Oil
15g LA (n-6)
55g ALA (n-3)

Olive Oil
9g LA (n-6)
0.7g ALA (n-3)

Avocado Oil
12.5g LA (n-6)
1g ALA (n-3)

Macadamia Nut Oil
1.5g LA (n-6)
1.5g ALA (n-3)

Vegetable Oils

Corn Oil
57g LA (n-6)
0.8g ALA (n-3)

Cottonseed Oil
48g LA (n-6)
0.4g ALA (n-3)

Canola Oil
22g LA (n-6)
11g ALA (n-3)

Soybean Oil
53g LA (n-6)
7g ALA (n-3)

Walnut Oil
62g LA (n-6)
4g ALA (n-3)

Wheat Germ Oil
54g LA (n-6)
7g ALA (n-3)

Animal Fats

Beef Tallow (grain-fed beef source)
4g LA (n-6)
0.7g ALA (n-3)

Chicken Fat
17g LA (n-6)
1.1g ALA (n-3)

Lard
10g LA (n-6)
1.4g ALA (n-3)

Mutton Fat
5g LA (n-6)
2.9g ALA (n-3)

WHOLE FOOD SOURCES (per 100g)

Dairy

Cheddar cheese, natural
0.5g LA (n-6)
0.4g ALA (n-3)

Cream cheese, regular
0.8g LA (n-6)
0.5g ALA (n-3)

Gruyere cheese, regular
1.3g LA (n-6)
0.4g ALA (n-3)

American cheese, regular
0.6g LA (n-6)
0.3g ALA (n-3)

Heavy Cream, conventional, grain-fed cows
0.9g LA (n-6)
0.6g ALA (n-3)

Light Cream, conventional, grain-fed cows
0.5g LA (n-6)
0.3g ALA (n-3)

Sour Cream, conventional
0.4g LA (n-6)
0.3g ALA (n-3)

Milk, whole, conventional
0.1g LA (n-6)
0.1g ALA (n-3)

Yogurt, plain, whole milk, conventional
0.1g LA (n-6)
0.1g ALA (n-3)

Egg Yolks, conventional (100g = approximately 4 yolks)
2.6g LA (n-6)
0.05g ALA (n-3)

Egg Yolks, pastured or flaxseed included in diet
4.2g LA (n-6)
2.1g ALA (n-3)

Butter, conventional
2.73g LA (n-6)
0.32g ALA (n-3)

Butter, grass-fed organic
1.8g LA (n-6)
1.2g ALA (n-3)

Meats & Game

Elk
0.343g (n-6)
0.056g (n-3)

Bison
0.156g (n-6)
0.026g (n-3)

Beef, grass-fed
0.139g (n-6)
0.052g (n-3)

Beef, grain-fed, conventional
0.275g (n-6)
0.016g (n-3)

omega-3 fatty acids

What can high-omega-3 foods do for you?

• Reduce inflammation throughout your body
• Keep your blood from clotting excessively
• Maintain the fluidity of your cell membranes
• lower the amount of lipids (fats such as cholesterol and triglycerides) circulating in the bloodstream
• decrease platelet aggregation, preventing excessive blood clotting
• inhibit thickening of the arteries by decreasing endothelial cells' production of a platelet-derived growth factor (the lining of the arteries is composed of endothelial cells)
• increase the activity of another chemical derived from endothelial cells (endothelium-derived nitric oxide), which causes arteries to relax and dilate
• reduce the production of messenger chemicals called cytokines, which are involved in the inflammatory response associated with atherosclerosis
• reduce the risk of becoming obese and improve the body's ability to respond to insulin by stimulating the secretion of leptin, a hormone that helps regulate food intake, body weight and metabolism, and is expressed primarily by adipocytes (fat cells)
• help prevent cancer cell growth

What conditions or symptoms indicate a need for more high-omega-3 foods?

• Depression
• Cardiovascular Disease
• Type 2 Diabetes
• Fatigue
• Dry, itchy skin
• Brittle hair and nails
• Inability to concentrate
• Joint pain

Sardines, salmon, flax seeds and walnuts are excellent food sources of omega-3 fatty acids.

Research indicates that omega-3s may be better absorbed from food than supplements. Norwegian researchers compared 71 volunteers' absorption of omega-3s (EPA and DHA) from salmon, smoked salmon, cod (14 ounces of fish per week) or cod liver oil (3 teaspoons per day). Cooked salmon provided 1.2 grams of omega-3s daily, while cod liver oil provided more than twice as much: 3 grams of omega-3s per day.
Despite the fact that the salmon group got less than half the amount of omega-3s as the cod liver oil group, blood levels of omega-3s increased quite a bit more in those eating salmon than those taking cod liver oil. After 8 weeks, EPA levels had risen 129% and DHA rose 45% in those eating cooked salmon compared to 106% and 25%, respectively, in those taking cod liver oil.
In the group eating smoked salmon, blood levels of omega-3s rose about one-third less than in the salmon group. In those eating cod, the rise in omega-3s was very small.
Concurrent with the rise in omega-3s in those eating salmon, a drop was seen in blood levels of a number of pro-inflammatory chemicals (TNFalpha, IL-8, leukotriene B4, and thromboxane B2). Researchers think omega-3s may be better absorbed from fish because fish contains these fats in the form of triglycerides, while the omega-3s in almost all refined fish oils are in the ethyl ester form. Once absorbed, omega-3s are converted by the body from their triglyceride to ester forms as needed. Lipids. 2006 Dec;41(12):1109-14.

World's Healthiest Foods rich in
omega-3 fats

FoodCals%Daily Value

Flax Seeds, ground75132.9%

Walnuts16494.5%

Salmon24561.2%

Sardines18955.8%

Beef, grass-fed17545.8%

Soybeans29842.9%

Halibut15925.8%

Scallops12717%

Shrimp11215.4%

Tofu8615%

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and processing Factors that affect function

Nutrient interaction Health conditions Food Sources Public Health Recommendations References

Description

What are omega-3 fatty acids?

You've probably been hearing about omega-3 fatty acids in recent years. The reason? A growing body of scientific research indicates that these healthy fats help prevent a wide range of medical problems, including cardiovascular disease, depression, asthma, and rheumatoid arthritis.
Unlike the saturated fats found in butter and lard, omega-3 fatty acids are polyunsaturated. In chemistry class, the terms "saturated" and "polyunsaturated" refer to the number of hydrogen atoms that are attached to the carbon chain of the fatty acid. In the kitchen, these terms take on a far more practical meaning.
Polyunsaturated fats, unlike saturated fats, are liquid at room temperature and remain liquid when refrigerated or frozen. Monounsaturated fats, found in olive oil, are liquid at room temperature, but harden when refrigerated. When eaten in appropriate amounts, each type of fat can contribute to health. However, the importance of omega-3 fatty acids in health promotion and disease prevention cannot be overstated.
The three most nutritionally important omega-3 fatty acids are alpha-linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Alpha-linolenic acid is one of two fatty acids traditionally classified as "essential." The other fatty acid traditionally viewed as essential is an omega 6 fat called linoleic acid. These fatty acids have traditionally been classified as "essential" because the body is unable to manufacture them on its own and because they play a fundamental role in several physiological functions. As a result, we must be sure our diet contains sufficient amounts of both alpha-linolenic acid and linoleic acid.
Dietary sources of alpha-linolenic acid include flaxseeds, walnuts, hemp seeds, soybeans and some dark green leafy vegetables. Linoleic acid is found in high concentrations in corn oil, safflower oil, sunflower oil, and canola oil. Most people consume a much higher amount of linoleic acid than alpha-linolenic acid, which has important health consequences. For more information on the proper ratio of these fatty acids in the diet, see our FAQ entitled, A New Way of Looking at Proteins, Fats, and Carbohydrates
The body converts alpha-linolenic acid into two important omega-3 fats, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). These fats can also be derived directly from certain foods, most notably cold-water fish including salmon, tuna, halibut, and herring. In addition, certain types of algae contain DHA. EPA is believed to play a role in the prevention of cardiovascular disease, while DHA is the necessary for proper brain and nerve development.

How it Functions

What are the functions of omega-3 fatty acids?

Every cell in our 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 our bodies 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 our bodies 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.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect omega-3 fatty acids?

Polyunsaturated oils, including the omega-3 fats, are extremely susceptible to damage from heat, light, and oxygen. When exposed to these elements for too long, the fatty acids in the oil become oxidized, a scientific term that simply means that the oil becomes rancid.
Rancidity not only alters the flavor and smell of the oil, but it also diminishes the nutritional value. More importantly, the oxidation of fatty acids produces free radicals, which are believed to play a role in the development of cancer and other degenerative diseases.
Under most circumstances, the problem of rancidity only arises when the oils are removed from their natural food package. For example, the hard shell of the flaxseed protects the oil inside the seed from heat, light, and oxygen. Flaxseeds also contain antioxidant compounds, such as vitamin E, that provide additional protection against oxidation. But, when the seed is pressed to isolate the oil, the oil becomes vulnerable to the elements.
As a result, oils rich in polyunsaturated fatty acids should be stored in dark glass, tightly closed containers in the refrigerator or freezer. In addition, these oils should never be heated on the stove. So, instead of sautéing your vegetables in flaxseed or walnut oil, make a salad dressing using these oils.
Although less a problem with whole foods than processed oils, some foods containing omega-3 fatty acids appear to lose some of their health benefits (like heart protection) when the foods are fried. Fried fish is a good example in this area, since fried fish containing omega-3s have been shown to provide less heart protection than baked or broiled fish containing the same amount of omega-3s.

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, the primary fat-soluble antioxidant, protects omega-3 fats from oxidation. Oxidation is a chemical process that produces free radicals.

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:

• Alzheimer's disease
• Asthma
• Attention deficit hyperactivity disorder (ADHD)
• Bipolar disorder
• Cancer
• Cardiovascular disease
• Depression
• Diabetes
• Eczema
• High blood pressure
• Huntington's disease
• Lupus
• Migraine headaches
• Multiple sclerosis
• Obesity
• Osteoarthritis
• Osteoporosis
• Psoriasis
• Rheumatoid arthritis

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.

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of omega-3 fats. Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of omega-3 fats contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

World's Healthiest Foods ranked as quality sources of omega-3 fats
Food	Serving Size	Cals	Amount (g)	DV (%)	Nutrient Density	World's Healthiest Foods Rating
Flax Seeds, ground	2 tbs	74.8	3.19	132.9	32.0	excellent
Walnuts	0.25 cup	163.5	2.27	94.6	10.4	excellent
Salmon	4 oz-wt	244.9	1.47	61.2	4.5	very good
Sardines	3.20 oz-wt	188.7	1.34	55.8	5.3	very good
Beef, grass-fed	4 oz	175.0	1.10	45.8	4.7	very good
Cloves	2 tsp	13.6	0.18	7.5	9.9	very good
Soybeans	1 cup cooked	297.6	1.03	42.9	2.6	good
Halibut	4 oz-wt	158.8	0.62	25.8	2.9	good
Scallops	4 oz-wt	127.0	0.41	17.1	2.4	good
Shrimp	4 oz-wt	112.3	0.37	15.4	2.5	good
Tofu	4 oz-wt	86.2	0.36	15.0	3.1	good
Tuna	4 oz-wt	157.6	0.33	13.8	1.6	good
Cod	4 oz-wt	119.1	0.32	13.3	2.0	good
Winter Squash	1 cup baked	75.8	0.19	7.9	1.9	good
Collard Greens	1 cup cooked	49.4	0.18	7.5	2.7	good
Spinach	1 cup cooked	41.4	0.17	7.1	3.1	good
Raspberries	1 cup	64.0	0.15	6.2	1.8	good
Kale	1 cup cooked	36.4	0.13	5.4	2.7	good
Mustard Seeds	2 tsp	20.3	0.11	4.6	4.1	good
Romaine Lettuce	2 cups	16.0	0.11	4.6	5.2	good
Turnip Greens	1 cup cooked	28.8	0.09	3.8	2.3	good
Strawberries	1 cup	46.1	0.09	3.8	1.5	good
Brussels Sprouts	1 cup raw	37.8	0.09	3.8	1.8	good
Miso	1 tbs	34.2	0.08	3.3	1.8	good
Green Beans	1 cup raw	31.0	0.07	2.9	1.7	good
Summer Squash	1 cup raw	18.1	0.06	2.5	2.5	good

World's Healthiest Foods Rating	Rule
excellent	DV>=75% OR Density>=7.6 AND DV>=10%
very good	DV>=50% OR Density>=3.4 AND DV>=5%
good	DV>=25% OR Density>=1.5 AND DV>=2.5%

Public Health Recommendations

What are current public health recommendations for omega-3 fatty acids?

In 2002, the Institute of Medicine at the National Academy of Sciences issued Adequate Intake (AI) levels for linolenic acid, the initial building block for all omega-3 fatty acids found in the body. For male teenagers and adult men, 1.6 grams per day were recommended, For female teenagers and adult women, the recommended amount was 1.1 grams per day. These guidelines do not seem as well-matched to the existing health research on omega-3 fatty acids as guidelines issued by the Workshop on the Essentiality of and Recommended Dietary Intakes (RDI) for Omega-6 and Omega-3 Fatty Acids in 1999 sponsored by the National Institutes of Health (NIH). This panel of experts recommended that people consume at least 2% of their total daily calories as omega-3 fats. To meet this recommendation, a person consuming 2000 calories per day should eat sufficient omega-3-rich foods to provide at least 4 grams of omega-3 fatty acids.
This goal can be easily met by adding just two foods to your diet: flaxseeds and wild-caught salmon. Two tablespoons of flaxseeds contain 3.5 grams of omega-3 fats, while a 4 ounce piece of salmon contains 1.5 grams of omega 3 fats. There's research evidence showing that two servings of non-fried fish per week—especially salmon, tuna, and halibut—can be enough to significantly increase the level of omega-3 fatty acids in your blood (including the level of both EPA and DHA).
Vegans and vegetarians relying on ALA as their only source of omega-3 fatty acids should increase their consumption of ALA-rich foods accordingly to ensure sufficient production its important derivatives, EPA and DHA.

Dietary Sources of Omega-3 Fatty Acids

As for saturated and monounsaturated fatty acids, the omega-6 and omega-3 polyunsaturated fatty acids (PUFA) are chemically linked to fat structures known as triglycerides in the various foods and oils that are consumed. The natural triglyceride or fat structure consists of a 3-carbon glycerol backbone onto which 3 long-chain fatty acids of varying types and structures are linked or 'esterified'. These are hydrolyzed by enzymes and digested in the small intestine thereby providing for their absorption, transport in the blood, and assimilation into cells and body tissues. Table 1 lists some common food sources of both the omega-6 and omega-3 fatty acids as found in a typical North American diet.

Table 1: Dietary Sources of Omega-3 and Omega-3 Fatty Acids

Fatty Acid	Food Sources
(i) Omega-6 Types
LA, linoleic acid (18:2 n-6)	Vegetable oils (corn, safflower, sunflower, soybean), animal meats
AA, arachidonic acid (20:4 n-6)	Animal sources only (meat, eggs)
(ii) Omega-3 Types
ALA , (LNA) alpha-linolenic acid (18:3 n-3)	Flaxseed, canola oil, English walnuts, specialty eggs
EPA, eicosapentaenoic acid (20:5 n-3)	Fish, fish oils, marine sources
DHA, docosahexaenoic acid (22:6 n-3)	Fish, fish oils, specialty egg/dairy products

In view of the high intake of vegetable oils containing n-6 PUFA directly and via various processed food products including meats, a typical diet contains 8-15 g/day of LA (omega-6) but much lower intakes of the omega-3 types. ALA consumption ranges from approximately 1.3-2.0 g/day or approximately 0.6% of total energy intake. In contrast to the considerable intake of ALA from plant sources, the intake of fish/fish oil-derived DHA/EPA (combined) represents approximately 0.13-0.15 g/day (130-150 mg/day) which is 0.05% of total energy intake or about 1/10 of the intake of ALA. The vast majority of the DHA plus EPA as consumed in the North American diet is from fish/fish oils with much smaller amounts from selected animal sources (e.g., eggs, some meat sources) and none from plant food/oils regardless of their ALA levels. The overall ratio of omega-6:omega-3 fatty acids in the current North American diet ranges from 6:1 to approximately 10:1.
Selected food sources of a-linolenic acid (ALA) are given in Table 2. Some of the common plant oils have significant levels of ALA - e.g., 7% by weight in soybean oil, 10% in canola oil, and approximately 20% in hemp oil. Much higher amounts are found in the oils from flax, perilla (Japan and elsewhere), and chia (Argentina and elsewhere) with approximately 50-60% of the fatty acids being in the form of ALA.

Table 2: Alpha-Linolenic Acid Content of Various Foods and Oils

Source (100 g raw edible portion)	ALA (g)	Source (100 g raw edible portion)	ALA (g)
Nuts and Seeds		Legumes
Almonds	0.4	Beans, common (dry)	0.6
Beechnuts (dried)	1.7	Chickpeas (dry)	0.1
Butternuts (dried)	8.7	Cowpeas (dry)	0.3
Chia seeds (dried)	3.9	Lentils (dry)	0.1
Flaxseed	22.8	Lima beans (dry)	0.2
Hickory nuts (dried)	1.0	Peas, garden (dry)	0.2
Mixed nuts	0.2	Soybeans (dry)	1.6
Peanuts	0.003
Pecans	0.7	Grains
Soybean kernels	1.5	Barley, bran	0.3
Walnuts, black	3.3	Corn, germ	0.3
Walnuts, English and Persian	6.8	Oats, germ	1.4
		Rice, bran	0.2
Vegetables		Wheat, bran	0.2
Beans, navy, sprouted (cooked)	0.3	Wheat, germ	0.7
Beans, pinto, sprouted (cooked)	0.3	Wheat, hard red Winter	0.1
Broccoli (raw)	0.1
Cauliflower (raw)	0.1	Fruit
Kale (raw)	0.2	Avocados, California (raw)	0.1
Leeks (freeze-dried)	0.7	Raspberries (raw)	0.1
Lettuce, butterhead	0.1	Strawberries (raw)	0.1
Lettuce, red leaf	0.1
Mustard	0.1
Purslane	0.4
Radish seeds, sprouted (raw)	0.7
Seaweed, Spirulina (dried)	0.8
Soybeans, green (raw)	3.2
Soybeans, mature seeds, sprouted (cooked)	2.1
Spinach (raw)	0.1

Data from Kris-Etherton et al. (2000)

Recently, strains of flaxseed oils have become available which contain approximately 70% by weight of the oil as ALA which is significantly higher than the 50-55% found in conventional flax oil varieties. Table 3 gives the levels of EPA plus DHA in a few selected fish and seafood.

Table 3: Fish and Seafood Sources of DHA plus EPA

Source (100 g portion)	DHA + EPA (g)
Fish
Anchovy, European, raw	1.449
Carp, cooked, dry heat	0.451
Catfish, channel, farmed, cooked, dry heat	0.177
Cod, Atlantic , cooked, dry heat	0.158
Eel, mixed species, cooked, dry heat	0.189
Flatfish (flounder and sole), cooked, dry heat	0.501
Haddock, cooked, dry heat	0.238
Halibut, Atlantic and Pacific, cooked, dry heat	0.465
Herring, Atlantic , cooked, dry heat	2.014
Mackerel, Pacific and jack, mixed species, cooked, dry heat	1.848
Mullet, striped, cooked, dry heat	0.328
Perch, mixed species, cooked, dry heat	0.324
Pike, northern, cooked, dry heat	0.137
Pollock, Atlantic , cooked, dry heat	0.542
Salmon, Atlantic , farmed, cooked, dry heat	2.147
Sardine, Atlantic , canned in oil, drained solids with bone	0.982
Sea bass, mixed species, cooked, dry heat	0.762
Shark, mixed species, raw	0.843
Snapper, mixed species, cooked, dry heat	0.321
Swordfish, cooked, dry heat	0.819
Trout, mixed species, cooked, dry heat	0.936
Tuna, skipjack, fresh, cooked, dry heat	0.328
Whiting, mixed species, cooked, dry heat	0.518
Crustaceans
Crab, Alaska king, cooked, moist heat	0.413
Shrimp, mixed species, cooked, moist heat	0.315
Spiny lobster, mixed species, cooked, moist heat	0.480
Mollusks
Clam, mixed species, cooked, moist heat	0.284
Conch, baked or broiled	0.120
Mussel, blue, cooked, moist heat	0.782
Octopus, common, cooked, moist heat	0.314
Oyster, eastern, farmed, cooked, dry heat	0.440
Scallop, mixed species, cooked, breaded and fried	0.180

It should be noted that algal oils have recently become available as a source of DHA (free of EPA) for infant formulas and other functional food fortification. There has been a marked increase in the use of high quality liquid fish oils containing DHA plus EPA as ingredients in a wide variety of functional foods (e.g., liquid eggs). Furthermore, stable and microencapsulated forms of DHA plus EPA (with varying amounts and ratios of DHA:EPA) have been utilized in a whole plethora of processed food formulations (breads, yogurts, snack foods, etc). In view of the resistance of the North American and other populations to increase fish consumption as a source of DHA plus EPA for health despite recommendations by health care agencies and professionals, it is apparent that functional foods will became an ever-increasing source of these important nutrients in the omega-3 family.

Omega-6 fatty acids

Overview:

Omega-6 fatty acids are considered essential fatty acids: They are necessary for human health but the body can' t make them -- you have to get them through food. Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain function, as well as normal growth and development. Also known as polyunsaturated fatty acids (PUFAs), they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.

A healthy diet contains a balance of omega-3 and omega-6 fatty acids. Omega-3 fatty acids help reduce inflammation, and some omega-6 fatty acids tend to promote inflammation. In fact, some studies suggest that elevated intakes of omega-6 fatty acids may play a role in Complex Regional Pain Syndrome. The typical American diet tends to contain 14 - 25 times more omega-6 fatty acids than omega-3 fatty acids.

The Mediterranean diet, on the other hand, has a healthier balance between omega-3 and omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet does not include much meat (which is high in omega-6 fatty acids, though grass fed beef has a more favorable omega-3 to omega-6 fatty acid ratio) and emphasizes foods rich in omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.

There are several different types of omega-6 fatty acids, and not all promote inflammation. Most omega-6 fatty acids in the diet come from vegetable oils, such as linoleic acid (LA). Be careful not to confuse this with alpha-linolenic acid (ALA), an omega-3 fatty acid. Linoleic acid is converted to gamma-linolenic acid (GLA) in the body. It is then further broken down to arachidonic acid (AA). GLA is found in several plant based oils, including evening primrose oil (EPO), borage oil, and black currant seed oil.

GLA may actually reduce inflammation. Much of the GLA taken as a supplement is converted to a substance called DGLA that fights inflammation. Having enough of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps promote the conversion of GLA to DGLA.

Uses:

Omega-6 fatty acids may be useful for the following health conditions:

Diabetic neuropathy

Some studies show that taking gamma linolenic acid (GLA) for 6 months or more may reduce symptoms of nerve pain in people with diabetic neuropathy. People who have good blood sugar control may find GLA more effective than those with poor blood sugar control.

Rheumatoid arthritis

Studies are mixed as to whether evening primrose oil helps reduce symptoms of rheumatoid arthritis. Some preliminary evidence suggests evening primrose oil may reduce pain, swelling, and morning stiffness; but other studies have found no effect. When using GLA for symptoms of arthritis, it may take 1 - 3 months for benefits to appear. It is unlikely that evening primrose oil would help stop progression of the disease, so joint damage would still occur.

Allergies

Omega-6 fatty acids from food or supplements, such as GLA from evening primrose oil or other sources, have a longstanding history of folk use for allergies. Women who are prone to allergies appear to have lower levels of GLA in breast milk and blood. However, there is no good scientific evidence that taking GLA helps reduce allergy symptoms. Well conducted research studies are needed.

If you decide to try GLA for allergies, work with your health care provider to first determine if it is safe for you. Then follow your allergy symptoms closely for any signs of improvement or lack or improvement.

Attention deficit/hyperactivity disorder (ADHD)

Clinical studies suggest that children with ADHD have lower levels of EFAs, both omega-6s and omega-3s. EFAs are important to normal brain and behavioral function. Some studies indicate that taking fish oil (containing omega-3 fatty acids) may help reduce ADHD symptoms, though the studies have not been well designed. Studies that used evening primrose oil have found it was no better than placebo at reducing symptoms.

Breast cancer

One study found that women with breast cancer who took GLA had a better response to tamoxifen (a drug used to treat estrogen sensitive breast cancer) than those who took only tamoxifen. Other studies suggest that GLA inhibits tumor activity among breast cancer cell lines. There is some research suggesting that a diet rich in omega-6 fatty acids may promote breast cancer development.

Eczema

Evidence is mixed as to whether evening primrose oil can help reduce symptoms of eczema. Some early studies found benefit, but they were not well designed. Later studies that examined people who took evening primrose oil for 16 - 24 weeks found no improvement in symptoms. If you want to try evening primrose oil, talk to your health care provider about whether it is safe for you.

High blood pressure (Hypertension)

There is some preliminary evidence that GLA may help reduce high blood pressure, either alone or in combination with omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found in fish oil. In one study, men with borderline high blood pressure who took 6g of blackcurrant oil had a reduction in diastolic blood pressure compared to those who took placebo.

Another study examined people with intermittent claudication, pain in the legs while walking that is caused by blockages in the blood vessels. Those who took GLA combined with EPA had a reduction in systolic blood pressure compared to those who took placebo.

More research is needed to see whether GLA is truly effective for hypertension.

Menopausal symptoms

Evening primrose oil has gained popularity as a way to treat hot flashes associated with menopause, but so far studies have not shown that it works. If you want to try evening primrose oil for hot flashes and night sweats, ask your health care provider whether it is safe and right for you.

Mastalgia

Some evidence suggests that evening primrose oil may reduce breast pain and tenderness in people with cyclic mastalgia. It may also help reduce symptoms to a lesser extent in people with non cyclic mastalgia. However, it does not seem to be effective for severe breast pain.

Multiple Sclerosis

Evening primrose oil has been suggested as an additional treatment (in addition to standard therapy) for multiple sclerosis (MS) although there is no scientific evidence that it works. MS patients who want to add evening primrose oil to their treatment regimens should talk with a health care provider.

Osteoporosis

Some studies suggest that people who don' t get enough of some essential fatty acids (particularly EPA and GLA) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo. Many of these women also experienced an increase in bone density.

Premenstrual syndrome (PMS)

Although most studies have found no effect, some women report relief of PMS symptoms when using GLA. The symptoms that seem to be helped the most are breast tenderness and feelings of depression, as well as irritability and swelling and bloating from fluid retention.

Dietary Sources:

For general health, there should be a balance between omega-6 and omega-3 fatty acids. The ratio should be in the range of 2:1 - 4:1, omega-6 to omega-3 -- and some health educators advocate even lower ratios. The average diet provides plenty of omega-6 fatty acids, so supplements are usually not necessary. People with specific conditions such as eczema or psoriasis, arthritis, diabetes, or breast tenderness (mastalgia) may want to ask their health care providers about taking omega-6 supplements.

Available Forms:

Omega-6 fatty acids are available in supplemental oils that contain linoleic acid (LA) and gamma linolenic acid (GLA), such as evening primrose (Oenothera biennis) and black currant (Ribes nigrum) oils. Spirulina (often called blue-green algae) also contains GLA.

How to Take It:

The average diet provides sufficient omega-6 fatty acids, so supplementation is usually not necessary unless you're treating a specific condition, such as eczema or psoriasis, arthritis, diabetes, or breast tenderness (mastalgia).

The dose and form of omega-6 fatty acids to be supplemented depends on many factors, including condition being treated, age, weight, and other medications and supplements being used. Speak to your doctor to determine what form and what dose of omega-6 fatty acids are most appropriate for you.

Precautions:

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

Do not take omega-6 if you have a seizure disorder because there have been reports of these supplements causing seizures. Several reports describe seizures in people taking evening primrose oil. Some of these seizures developed in people with a previous seizure disorder, or in people taking evening primrose oil in combination with anesthetics. People who plan to undergo surgery requiring anesthesia should stop taking evening primrose oil 2 weeks ahead of time.

Borage seed oil, and possibly other sources of gamma-linolenic acid (GLA), should not be taken during pregnancy because they may harm the fetus and induce early labor.

Avoid doses of GLA greater than 3,000 mg per day. At that level, an increase in inflammation may occur.

Side effects of evening primrose oil can include occasional headache, abdominal pain, nausea, and loose stools. In animal studies, GLA is reported to decrease blood pressure. Early results in human studies do not show consistent changes in blood pressure.

Laboratory studies suggest that omega-6 fatty acids, such as the fat found in corn oil, promote the growth of prostate tumor cells. Until more research is done, health care professionals recommend not taking omega-6 fatty acids, including GLA, if you are at risk of or have prostate cancer.

Possible Interactions:

If you are currently being treated with any of the following medications, you should not use omega-6 supplements without first talking to your health care provider.

Blood thinning medications -- People taking blood thinning medications, including warfarin (Coumadin) or clopidogrel (Plavix), should not take omega-6 fatty acid supplements without consulting a health care provider. Omega-6 and omega-3 fatty acids may increase the risk of bleeding.

Ceftazidime -- Gamma linolenic acid (GLA) may increase the effectiveness of ceftazidime. Ceftazidinme, an antibiotic, is used against a variety of bacterial infections.

Chemotherapy for cancer -- GLA may increase the effects of anti cancer treatments, such as doxorubicin, cisplatin, carboplatin, idarubicin, mitoxantrone, tamoxifen, vincristine, and vinblastine.

Cyclosporine -- Cyclosporine is a medication used to suppress the immune system after organ transplant. Taking omega-6 fatty acids with cyclosporine may increase the immunosuppressive effects of this medication. It may also protect against kidney damage (a potential side effect from this medication).

Phenothiazines -- People taking a class of medications called phenothiazines to treat schizophrenia should not take evening primrose oil. Evening primrose oil may interact with these medications and increase the risk of seizures. The same may be true for other omega-6 supplements. These medications include:

• Chlorpromazine (Thorazine)
• Fluphenazine (Stelazine)
• Perphenazine (Trilafon)
• Promethazine (Compazine)
• Thioridazine (Mellaril)

Source: http://www.umm.edu/altmed/articles/omega-6-000317.htm#ixzz2MnF7Ft00
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