ESSENTIAL FATTY ACIDS

ESSENTIAL FATTY ACIDS (EFA, Vitamin F)

Essential fatty acids are a collective association of 4 known fatty acids that are required by the human body for health. They are:

  1. OMEGA-3
  2. OMEGA-6
  3. OMEGA-9
  4. OMEGA 12

Although a low-fat diet is generally healthier than one that is higher in fat, our bodies require a certain amount of fat for proper growth and functioning. Those fats that are necessary for good health and cannot be manufactured by the body are called essential fatty acids (EFAs). They are termed essential because, like vitamins and minerals, they must be provided by the diet. This chapter focuses on the two groups of essential fatty acids that have received the most attention: omega-3 fatty acid and omega-6 fatty acid.

The omega-3 family includes alpha-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). In certain plants, omega-3 fatty acids are found in the form of alpha-linolenic acid. In the body, this fatty acid is converted to EPA, which is then converted to DHA. The oils of certain fish contain preformed EPA and DHA, which are the active and most desirable forms of the omega-3 family. Ultimately, DHA is converted to a group of anti-inflammatory prostaglandins, hormone-like substances used throughout the body. It is this final conversion to prostaglandins that is responsible for omega-3’s therapeutic effects.

The omega-6 family includes cis-linoleic acid, linoleic acid, and gamma-linolenic acid (GLA). Cis-linoleic acid is found in certain plants and vegetable oils. Linoleic acid is found in most plants and vegetable oils. In the body, some cis-linoleic acid is converted to GLA, the most therapeutic form of the omega-6 family. Preformed GLA can also be found in certain plants, with evening primrose, black currant, and borage oils being the most commonly used sources. The body ultimately converts GLA to another group of anti-inflammatory prostaglandins. Again, it is this final conversion that is responsible for omega-6’s therapeutic effects. However, it should be noted that cis-linoleic acid and linoleic acid could also be converted to pro-inflammatory prostaglandins.

A balance of essential fatty acids is needed for good health. Unfortunately, the average American diet does not provide a balance. Instead, because it is so high in certain vegetable oils, it provides an excess of linoleic acid, which is generally metabolized into pro-inflammatory substances, and an insufficient amount of those fatty acids that are needed to make anti-inflammatory substances. Depending on your particular needs, you may want to add omega-3 EFAs, omega-6 EFAs, or both EFAs to your supplementation program.

FUNCTIONS AND USES OF FATTY ACIDS

As already explained, chief among the roles of the EFAs is the part they play in the body’s manufacture of prostaglandins, hormone-like substances that are produced and used by all cells. Once manufactured, the prostaglandins regulate all of our body functions, including those of the cardiovascular, reproductive, immune, and nervous systems. In addition, fatty acids serve as structural parts of cell membranes, and therefore help protect the cells from invading toxins, bacteria, viruses, carcinogens, and allergens. It’s easy to understand why research has linked fatty acid imbalances to a variety of chronic diseases, including heart disease, cancer, arthritis, allergies, and various immunological disorders.

Cardiovascular Disease

Interest in fatty acids began when researchers observed that in spite of a diet incredibly rich in fat, the Greenland Eskimos had a very low rate of heart disease, as well as a low incidence of cancer and diabetes. Intrigued by this apparent paradox, researchers studied the Eskimo diet and discovered that it was high in EPA and DHA-omega-3 fatty acids found in the cold-water fish and marine mammals that form the bulk of the Eskimo diet. Subsequent studies in Japan, Sweden, and the Netherlands confirmed that the higher the consumption of omega-3-rich fish, the lower the incidence of heart disease.

Many studies have shown that EPA protects against heart disease. Platelets-the blood cells that enable our blood to clot and aggregate-can adhere to artery walls, contributing to atherosclerosis, or hardening of the arteries. By preventing this adhesion, EPA acts as a natural “”blood thinner,”” and thus helps prevent atherosclerosis. Studies with GLA have yielded results similar to those achieved with EPA. Also, studies on evening primrose oil-a rich source of GLA-as well as studies on fish oil have demonstrated positive results in improving lipid abnormalities in certain diabetic patients, provided they received vitamin E supplementation, as well.

It is interesting to note that because aspirin thins the blood, it has been widely touted as a heart-attack preventive. Yet several studies have suggested that fish oil-whether consumed in fish or in fish-oil supplements is superior to aspirin in preventing heart disease, and is not associated with the ulcers, gastrointestinal bleeding, anemia, and other side effects that occur with aspirin use. In studies that used both aspirin and fish oil, the combination was more effective than aspirin alone. These factors, along with the fact that EPA appears to lower high levels of triglycerides, a risk factor in heart disease, makes fish oil a better, safer option in preventing cardiovascular disorders in people at high risk.

EFAs also appear to be effective in the treatment of existing heart disease. There is evidence that fish oil lowers blood pressure, and can reduce chest pain during exercise in people with angina. Because of its blood-thinning abilities, EPA may also be of use after bypass surgery and as an adjunct to angioplasty. In addition, GLA has been shown to reduce stress-induced hypertension in animals, and to help relieve the pain of angina in humans.

The Immune System and Inflammation

Both EPA and GLA appear to have positive effects on immune function and inflammation. By blocking the pro-inflammatory prostaglandins, EPA tends to improve symptoms of asthma, atopic dermatitis, rheumatoid arthritis, Raynaud’s disease, Systemic Lupus Erythematosus, psoriatic arthritis, psoriasis, and gout. In a recent study using high levels of GLA (1.4 grams) from borage seed oil, patients with rheumatoid arthritis experienced a significant improvement of symptoms. In several studies, GLA relieved the symptoms of eczema and atopic dermatitis and reduced the amount of skin area that was affected. Studies using GLA have also shown clinical benefits in patients with autoimmune disorders such as lupus and multiple sclerosis since GLA’s anti-inflammatory mechanism is slightly different from that of EPA; it appears to complement EPA’s anti-inflammatory activities.

Cancer

Numerous test tube and animal studies have shown that EPA and GLA may prevent or inhibit the growth of cancer, particularly breast cancer. It appears that GLA “”normalizes”” cancer cells without harming healthy cells, suggesting the possibility of an effective yet nontoxic treatment. EPA has shown promise in preventing bowel cancer. Human studies have shown that EPA helps prevent metastasis-the spread of cancer.

PMS and Dysmenorrhea

In several studies, evening primrose oil, high in GLA, has reduced symptoms of premenstrual syndrome (PMS), including depression and irritability. Researchers believe that a deficiency of GLA causes an abnormal sensitivity to the hormone prolactin, which leads to symptoms of PMS. There are also reports that GLA may be an effective treatment for fibrocystic breasts.

Supplementation with essential fatty acids also appears to be beneficial in cases of dysmenorrhea-painful menstrual periods. In a study of adolescent girls, the group that received supplements of EPA, DHA, and vitamin E experienced a marked reduction of menstrual pain after two months of supplementation. The supplements apparently prevented a buildup of the pro-inflammatory prostaglandins in the cell membranes of the uterus-a buildup that produces symptoms such as cramps, nausea, vomiting, bloating, and headaches.

Other Uses Of Fatty Acids

GLA may also prove to be an important component of weight-loss programs. Preliminary data suggests that this nutrient enhances weight loss by stimulating fat metabolism, and thus burning extra calories. Animal studies suggest that both EPA and GLA may slow the progress of the kidney disease glomerulonephritis, and may help patients avoid dialysis. Finally, there is evidence that these essential fatty acids may be useful in the treatment of certain disorders of the central nervous system. There are reports that both EPA and GLA affect schizophrenia. Furthermore, EPA may help in cases of manic-depressive illness, and GLA in cases of hyperactivity in children.

RDIs AND DEFICIENCY SYMPTOMS

There are no established RDIs for the essential fatty acids, and no deficiency symptoms have been identified.

WHICH FATTY ACIDS SHOULD YOU TAKE?

The properties of omega-3 and omega-6 fatty acids overlap to a great degree. Both enhance the body’s own anti-inflammatory process, acting like cortisone, but without the undesirable side effects. Both have cardioprotective and anticancer properties. So you might be left wondering: Which one should I take? The truth of the matter is that essential fatty acid supplementation is often a case of trial and error. As a general rule of thumb, I tend to use EPA when there is a family tendency of high cholesterol (170 or above), high triglycerides, heart arrhythmias, or other heart disease. For those with low cholesterol, I generally use GLA. For hormonal problems, I usually try GLA first. However, keep in mind that researchers and clinicians have observed individual responses to the different fatty acids, so you must be willing to experiment. Try one type of supplement for one month, and then switch to the other. Compare the results and stick with whichever one is most effective. If the results are not clear-cut, you may have to use both to achieve the balance that is right for you. In fact, some practitioners suggest giving EPA/DHA and GLA supplements together and studies have shown that EPA and GLA used together yield the best results for some purposes, such as decreasing the inflammation of rheumatoid arthritis.

OMEGA-3 FATTY ACIDS (EPA AND DHA)

Food Sources: Animals-primarily cold-water fish and seafood such as herring, salmon, tuna, cod, mackerel, and shrimp-generally have the highest levels of EPA. Flaxseeds and flaxseed oils are the richest sources of alpha-linolenic acid, which can be converted to EPA and DHA in the body. However, many factors may inactivate this process, including smoking, environmental toxins, aging, excessive saturated fat intake, alcohol, and certain medications. Fish oil, rich in the already active forms of EPA and DHA, is the more dependable source of this essential nutrient.

Supplements

It is essential that EPA and DHA supplements include vitamin E to prevent rancidity, and that supplements be taken with additional vitamin E supplements to prevent oxidation in the body. In fact, some of the conflicting results of studies using fish oil may be due to the fact that in some cases, the supplements used did not contain any vitamin E to protect them. Study results have been superior when EPA has been consumed with a vitamin E supplement.

Per capsule, fish oil supplements generally contain between 180 and 400 milligrams of EPA plus 120 to 300 milligrams of DHA. Although cod liver oil contains EPA and DHA, large doses should be avoided, because the oil contains high amounts of vitamins A and D, which, if ingested in very high amounts, could be toxic.

Optimum Daily Intake-ODI

There is no Optimum Daily Intake for omega-3 fatty acids. Population studies have generally shown that eating cold-water fish as little as two or three times a week-the equivalent of about one ounce per day could have beneficial effects, especially regarding heart disease prevention. For people who prefer not to rely on fish as a source of EPA and DHA, we generally recommend four to six fish oil capsules. Most studies used eighteen or more fish oil capsules without controlling dietary fat intake. You can achieve the same clinical benefits by eating a low-fat diet and using lower amounts (four to six capsules). Because of this nutrient’s blood-thinning effect, higher amounts should be taken only under professional supervision, especially if you are also taking blood-thinning medication.

Remember: If you have a medical condition, and particularly if you are on blood-thinning medication, please consult your physician before taking supplements.

Toxicity and Adverse Effects

There are no known toxic effects of EPA, DHA, or alpha-linolenic acid. Blood-clotting times do decrease with supplementation, but are still within normal range. Some of my patients have complained that high-potency EPA supplements are difficult to digest and leave a fishy odor and taste.

OMEGA-6 FATTY ACIDS (GLA & ALA)

Food Sources: With the exception of human milk, most foods contain very little active GLA. Plants from which we extract vegetable oils generally have the highest levels of omega-6 fatty acids, with corn oil and canola oil being the most commonly used. However, oils from these plants contain mostly linoleic acid and small amounts of cis-linoleic acid, which must first be converted in our bodies to the more active, potent gamma-linolenic acid before they can be further converted to prostaglandins. This conversion-like the conversion of alpha-linolenic acid to EPA and then DHA-may be inhibited by many factors, including aging; stress; alcohol; and diets high in saturated fat, trans-fatty acids (found in margarine), cholesterol, and sugar. Other vegetable oils (see below) are more potent sources of GLA, but these are not generally used as food.

Supplements

Both in scientific studies and in clinical practice, capsules of evening primrose oil have been the mainstay of GLA supplementation. The problem is that each evening primrose oil capsule contains only 45 milligrams of GLA along with over 100 milligrams of linoleic acid-the essential fatty acid that has inflammatory effects. However, other, richer sources of GLA have been discovered, including borage oil and black currant oil. These oils supply more GLA-240 to 300 milligrams per capsule-while containing less linoleic acid-50 milligrams per capsule. Since most of us already have an overabundance of linoleic acid in our diet, we prefer to use GLA from borage and black current oils to correct the imbalance and obtain the desired therapeutic effect.

Optimum Daily Intake-ODI

There is no Optimum Daily Intake for omega-6 fatty acids. For people at risk for the conditions mentioned earlier, it is generally recommended to take 70 to 240 milligrams of GLA as a preventive measure. This is approximately two to six evening primrose oil capsules per day, or one GLA capsule from borage or black currant oil. Higher amounts should be taken only under professional supervision to avoid upsetting the fatty acid balance in your body.

Remember: If you have a medical condition, please consult with your physician before taking supplements.

Toxicity and Adverse Effects

There are no known toxic or adverse effects for GLA.


ESSENTIAL FATTY ACIDS (EFA, vitamin F) Two fatty acids that cannot be synthesized by the body and must be provided by the diet. The essential fatty acids LINOLEIC ACID and ALPHA LINOLENIC ACID are polyunsaturated FATTY ACIDS, that is, they possess two or more double bonds and lack several hydrogen atoms found in saturated fatty acids. They differ in their location of double bonds, that is, bonds between carbon atoms that are deficient in hydrogen atoms. This small chemical difference has a huge nutritional impact. Linoleic acid contains 18 carbon atoms and belongs to the omega-6 family of fatty acids, in which the first double bond occurs at the sixth carbon atom of the molecular chain. Linoleic acid serves as the parent of a large polyunsaturated fatty acid, called ARACHIDONIC ACID. Arachidonic acid in turn forms PROSTAGLANDINS (PGE2) and thromboxanes (TXA,), hormone-like lipids that tend to promote blood clotting, induce pain and inflammation and cause smooth muscle contraction. Another pathway converts arachidonic acid to LEUKOTRIENES, one of the most powerful inflammatory agents. Events triggering inflammation stimulate cells to synthesize prostaglandins (PGE2) and thromboxanes (TXA2). As a component of membrane lipids, linoleic acid helps maintain flexibility of cell membranes. Arachidonic acid is not a dietary essential unless a deficiency of linoleic acid exists.

The second essential fatty acid, alpha linolenic acid, is the major polyunsaturated fatty acid of plants. It contains 18 carbon atoms and three double bonds and belongs to the omega-3 family of fatty acids, in which the first double bond occurs at the third carbon of the fatty acid. Alpha linolenic acid is converted to a very long fatty acid, EICOSAPENTANEONIC ACID (EPA), which forms prostaglandins (PGE3) and thromboxane (TXA3) that counterbalance the effects of proinflammatory products derived from arachidonic acid by reducing the tendency to clot, reducing pain and inflammation. Dietary alpha linolenic acid will tend to inhibit arachidonic acid conversion to inflammatory agents, and thus further limit inflammation. Alpha linolenic acid occurs in high levels in BORAGE oil and flaxseed oil, while EPA occurs in high levels in fish and shellfish.

If the diet lacks adequate amounts of either linoleic or alpha linolenic acid, deficiency symptoms will develop that include scaly skin, hair loss and slow wound healing. Omega-3 fatty acid deficiency leads to impaired brain and retinal development in experimental animals and possibly in premature births.

Polyunsaturated seed oils and fish oils supply the essential fatty acids in the typical U.S. diet. There is no RECOMMENDED DIETARY ALLOWANCE for linoleic acid or alpha linolenic acid. However, the amount of linoleic acid and related omega-6 fatty acids needed to prevent deficiency in adults is estimated to be I to 3% of calories, equivalent to approximately 6 g/day. Linoleic acid in typical American diets ranges from 5 to 10% of calories due to a high consumption of vegetable oils. It has been proposed that alpha linolenic acid represent 0.25 to 0.54% of daily calories for optimal health. Large amounts of polyunsaturated fatty acids may increase the requirement for antioxidants like VITAMIN E to prevent their chemical degradation.

ARACHIDONIC ACID A long chain POLYUNSATURATED FATTY ACID that is the parent of important hormone-like agents called PROSTAGLANDINS and LEUKOTRIENES. It is a complex fatty acid, with 20 carbons and four double bonds. Arachidonic acid belongs to the Omega-6CLOTily of unsaturated fatty acids, which are derived from the ESSENTIAL FATTY ACID, LINOLEIC ACID. Because arachidonic acid can be made in the body, it is not classified as one of the essential nutrients. MEAT and dairy products are rich sources and they contribute to the body’s supply.

Arachidonic acid is processed by the “”cyclooxygenase pathway,”” a series of enzymes that yield prostaglandins and related compounds. Prostaglandin PGE2 and its relatives can increase BLOOD PRESSURE, induce BLOOD CLOTTING and cause pain and inflammation. ASPIRIN and non-steroidal antiinflammatory drugs are effective pain relievers because they specifically block the cyclooxygenase enzyme. Another prostaglandin from arachidonic acid, PG12, helps to counterbalance blood clotting, while still another derivative of arachidonic acid, prostacyclin, blocks blood clotting. Therefore, aspirin use carries the added risk of increased bleeding.

A second chain of reactions, the “”lipooxygenase pathway,”” converts arachidonic acid to leukotrienes, extremely powerful inflammatory agents linked to the allergic response including swelling and pain. Fish oils are rich in the omega-3 family of unsaturated fatty acids, rather than the omega-6 fatty acids. Because they block leukotriene production from arachidonic acid, fish oils can reduce excessive chronic inflammation.

LINOLEIC ACID A dietary ESSENTIAL FATTY ACID. Polyunsaturated fatty acids like linoleic acid help maintain the flexibility of cell membranes, which is essential for their normal function. Therefore linoleic acid is essential for normal growth and development. Certain details of the molecular structure are important in order to understand its role. This 18-carbon acid contains two double bonds in which pairs of carbons are deficient in hydrogen atoms. Therefore, it is classified as a polyunsaturated FATTY ACID. It belongs to the omega-6 family of fatty acids because the first double bond begins six carbon atoms from the end of the fatty acid. Linoleic acid is classified as a dietary essential because the body is unable to insert double bonds in fatty acids at the sixth carbon of this long chain fatty acid. While the body cannot manufacture linoleic acid, it can convert linoleic acid to longer, more complex fatty acids, especially ARACHIDONIC ACID. In turn the body transforms arachidonic acid to a class Of PROSTAGLANDINS of the PG2 series, hormone-like substances that stimulate inflammation, pain, BLOOD CLOTTING, smooth muscle contraction, elevated blood pressure and other physiological processes. Other derivatives of arachidonic acid, hence of linoleic acid, are called LEUKOTRIENES. These are extremely powerful inflammatory agents.

Linoleic acid is the raw material for more complex lipids. The body converts linoleic acid to a close relative called gamma linolenic acid by an enzyme (delta 6 desaturase) as the first step in the synthesis of longer fatty acids from which regulatory substances like prostaglandins are made. This critical step is slowed by AGING, hormonal imbalance, and dietary factors such as zinc deficiency, ALCOHOLISM, excessive sugar consumption and conditions like DIABETES.

Symptoms of essential fatty acid deficiency include severe, resistant ECZEMA, hair loss and impaired wound healing. Deficient animals reveal retarded growth and development. Deficiencies have been reported in infants fed non-fat milk, which lacks linoleic acid.

Many polyunsaturated seed oils supply linoleic acid in the typical American diet. SAFFLOWER oil, SOYBEAN oil, SUNFLOWER Oil, CORN OIL and MARGARINE prepared from these oils are typical sources. Linoleic acid consumption typically ranges from 5 to 10% of calories when American diets supply 25 to 50% of the daily calories as fat. Dietary recommendations generally specify that for a healthy adult the total polyunsaturated fat intake should be about 6 to 7% of daily calories, not to exceed 10%. Research suggests that linoleic acid should represent 5% of calories or 14 g/day. There is no RECOMMENDED DIETARY ALLOWANCE for this or any other polyunsaturated fatty acid, yet. Note that a high intake of polyunsaturated oils increases the need for a fat-soluble ANTIOXIDANT like VITAMIN E because polyunsaturates are more susceptible to oxidation and destruction.

A modified form of linoleic acid, called conjugated linoleic acid, can offer protection against breast cancer in lab animals. Conjugated linoleic acid occurs in animal products like meat and dairy products. However, it should be noted that these animal products contain large amounts of saturated fat and cholesterol, which are risk factors for heart disease.

Roberts, T.L., et al., “”‘Linoleic Acid and Risk of Sudden Cardiac Death,”” British Health journal, 70 (1993), pp. 524-29.

LINOLENIC ACID (ALPHA LINOLENIC ACID) Chemically speaking this fatty acid has 18 carbons and a pair of double bonds. It cannot be synthesized by the body and must be obtained from the diet. A POLYUNSATURATED FATTY ACID, it is classified as an essential dietary nutrient. Alpha linolenic acid is the smallest of the omega-3 family of polyunsaturated FATTY ACIDS, distinguished by subtle structural differences in which the double bonds begin at the third carbon from the end. It is the building block of larger omega-3 acids, including EICOSOPENTAENOIC ACID and docosohexaenoic acid (DHA), which in turn form the PG3 class of PROSTAGLANDINS, hormone-like substances that decreases inflammation, decreases blood clotting and lowers blood cholesterol. PG3 prostaglandins help return the body to equilibrium after physical stress or injury.

Omega-3 fatty acids are deficient in the standard American diet, and this deficiency may be linked to an increased risk of heart attacks and inflammation associated with degenerative disease. Chronic, severe deficiencies impair vision, increase infla¥E!?ion, and diminish learning curves in experimental animals. The utilization of alpha linolenic acid may be limited in some disease states. The nervous system and brain contain high levels of the omega-3 fatty acids, and there is a positive relationship between the content of these fatty acids in the diet and vision and brain function. Pre-term babies need DHA because their livers are not mature enough to synthesize it from alpha linolenic acid.

Good dietary sources of the omega-3 fatty acids are limited. Breast milk contains omega-3 fatty acids, suggesting their importance in the infant’s growth and development. Food processing destroys or removes the omega-3s, and there are none present in fast foods like pizza, fried fish sandwiches, fried chicken or hamburgers. The most common sources are FISH and FISH OILS, FLAXSEED OIL and pumpkin seeds; fish oil and flaxseed oil are sold as supplements. The American Heart Association recommends eating several servings of fish weekly. Because oils containing essential fatty acids readily oxidize and become rancid they need to be protected from oxygen and heat. They are usually packaged with ANTIOXIDANTS such as VITAMIN E. Buying small quantities of these oils and refrigerating them in sealed containers after opening reduces the risk of rancidity. These oils should not be used for cooking.

Kinsella, John E., “”‘Alpha Linolenic Acid: Recent Overview,”” Nutrition, 8:3 (1992), pp. 195-96.
LINOLENIC ACID (ALPHA LINOLENIC ACID) Chemically speaking this fatty acid has 18 carbons and a pair of double bonds. It cannot be synthesized by the body and must be obtained from the diet. A POLYUNSATURATED FATTY ACID, it is classified as an essential dietary nutrient. Alpha linolenic acid is the smallest of the omega-3 family of polyunsaturated FATTY ACIDS, distinguished by subtle structural differences in which the double bonds begin at the third carbon from the end. It is the building block of larger omega-3 acids, including EICOSOPENTAENOIC ACID and docosohexaenoic acid (DHA), which in turn form the PG3 class of PROSTAGLANDINS, hormone-like substances that decreases inflammation, decreases blood clotting and lowers blood cholesterol. PG3 prostaglandins help return the body to equilibrium after physical stress or injury.

Omega-3 fatty acids are deficient in the standard American diet, and this deficiency may be linked to an increased risk of heart attacks and inflammation associated with degenerative disease. Chronic, severe deficiencies impair vision, increase inflammation, and diminish learning curves in experimental animals. The utilization of alpha linolenic acid may be limited in some disease states. The nervous system and brain contain high levels of the omega-3 fatty acids, and there is a positive relationship between the content of these fatty acids in the diet and vision and brain function. Pre-term babies need DHA because their livers are not mature enough to synthesize it from alpha linolenic acid.

Good dietary sources of the omega-3 fatty acids are limited. Breast milk contains omega-3 fatty acids, suggesting their importance in the infant’s growth and development. Food processing destroys or removes the omega-3s, and there are none present in fast foods like pizza, fried fish sandwiches, fried chicken or hamburgers. The most common sources are FISH and FISH OILS, FLAXSEED OIL and pumpkin seeds; fish oil and flaxseed oil are sold as supplements. The American Heart Association recommends eating several servings of fish weekly. Because oils containing essential fatty acids readily oxidize and become rancid they need to be protected from oxygen and heat. They are usually packaged with ANTIOXIDANTS such as VITAMIN E. Buying small quantities of these oils and refrigerating them in sealed containers after opening reduces the risk of rancidity. These oils should not be used for cooking.

Kinsella, John E., “”‘Alpha Linolenic Acid: Recent Ovl foew,”” Nutrition, 8:3 (1992), pp. 195-96.

ESSENTIAL FATTY ACIDS – REFERENCE LIST