AN INTRODUCTION TO ESSENTIAL FATTY ACIDS IN HEALTH AND NUTRITION
Author: Janice McColl, B.S.P., M.Sc., M.H.
Consumers are increasingly turning to natural health products to maintain or improve their health. Recent research has drawn attention to the potential health benefits of essential fatty acids (EFAs). As a result, consumers should be aware of the role EFAs play in nutrition, health and disease, in order to make informed choices about their health care.
EFAs are a special type of “good fat”. They are also essential nutrients; sometimes called vitamin F. Essential nutrients are necessary for life, but must be obtained through diet because the body cannot make them. EFAs are required for the proper structure and function of every cell in the body, and are important for optimal health. EFAs increase the absorption of vitamins and minerals; nourish the skin, hair and nails; promote proper nerve functioning; help produce hormones; ensure normal growth and development; and prevent and treat disease.
Fats (fatty acids) fall into two main groups – saturated and unsaturated – based on their chemistry. There are three major classes of unsaturated fatty acids: omega-3, omega-6 and omega-9. The omega-6s and omega-3s are essential. The omega-9s are non-essential because the body can make them from other fatty acids. Unsaturated fatty acids are further classified as either monounsaturated or polyunsaturated. EFAs are polyunsaturated. They include:
- the omega-6 fatty acid linoleic acid (LA), and its derivatives, gamma-linolenic acid (GLA) and arachidonic acid (AA)
- the omega-3 fatty acid alpha-linolenic acid (ALA) and its derivatives, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Theoretically, only LA and ALA are absolutely essential. However, the fatty acids derived from them are also generally considered essential.
EFA deficiency is common today because of modern dietary and lifestyle choices, and environmental factors. Many people also have trouble converting LA and ALA to their derivatives. EFA deficiency can eventually lead to disease and even death. (See sidebar for symptoms of EFA deficiency).
LA: LA is present in many vegetables and most vegetable oils – sunflower (65-75%), safflower (79%), evening primrose seed (72%), corn (57%), peanut (31%), canola (19-26%), and olive (8%). LA is abundant in the food supply and thus there is no need to supplement.
GLA: The richest sources of GLA are borage (starflower) oil,GLA (20-24%); evening primrose oil (8-10%); and black currant oil (15-17%). GLA is present in small amounts in human breast milk and some foods, but the typical diet provides very little GLA.
AA: Found in high amounts in eggs, fish and meat, AA is abundant in the food supply and supplementation is not usually necessary.
ALA: ALA is found in flax seed (18-22%) and flax seed oil (50-60%), and in small amounts in some nuts, green leafy vegetables, canola, wheat germ and black current seeds.
EPA and DHA: EPA and DHA are found in fatty fish like salmon, mackerel and tuna. Depending on the source, fish oils vary in the amount of EPA and DHA they provide. Fish oil supplements often contain 18% EPA and 12% DHA, with more concentrated oils containing 30% EPA and 20% DHA. Algal sources of EPA and DHA are also widely available.
EFAs in the treatment and prevention of disease
EFA deficiency has been identified in many diseases including mental disorders, diabetes, atherosclerosis, hypertension, eczema, PMS, immune dysfunction, and inflammatory conditions such as rheumatoid arthritis. EFAs may help improve these conditions, and EFA supplementation has been studied in hundreds of clinical trials. Because of the often-impaired conversion of LA and ALA to their derivatives, much of the recent research on EFAs has focused on GLA, EPA and DHA, which are also absorbed and utilized more efficiently than LA and ALA.
Population studies have shown that a diet rich in ALA, EPA and DHA helps maintain a healthy heart and may protect against heart disease by reducing high blood lipids and blood pressure, and by decreasing blood clotting. Evidence supporting the benefits of EFAs for the the heart was so compelling that in October, 2000 the American Heart Association updated its dietary guidelines, recommending healthy adults consume at least two servings of fatty fish per week. At the same time, the U.S. Food and Drug Administration (FDA), finding the evidence suggestive, but not conclusive, allowed a qualified claim linking omega-3 fatty acids to a reduction in the risk of coronary heart disease.
Arthritis and other joint conditions
GLA is converted to eicosanoids with potent anti-inflammatory properties. It also modulates the immune response, which can decrease joint inflammation and destruction. Many rheumatoid arthritis sufferers are deficient in GLA, and respond favorably to GLA treatment. Placebo-controlled studies have demonstrated that supplementation with GLA may reduce the symptoms of rheumatoid arthritis in both children and adults. Reductions in the duration of morning stiffness, joint swelling, tenderness and pain have been noted. Supplementation with GLA also reduced the use of non-steroidal anti-inflammatory drugs (NSAIDS) and corticosteroids in many cases.
Deficiencies of EFAs, most notably GLA, have been related to eczema and other skin disorders. EFAs help alleviate dry, itchy, and inflamed skin and help reduce moisture loss. Although various EFAs and skin disorders have been examined, by far the most studied is the use of GLA for eczema. At least 22 randomized, placebo-controlled trials have been conducted, with the majority showing significant benefit. In several studies, patients taking GLA were able to reduce the use of drugs such as antibiotics, oral steroids and topical steroids.
Although omega-3 EFAs are best known for their heart-protecting benefits, they may also play a role in mental health. Many disorders such as depression, bipolar disorder, Alzheimer’s, dementia, cognitive impairment, and behavioral and learning disorders (such as dyslexia and attention deficit disorder), have been linked to EFA deficiency. Recent research demonstrates that EPA and DHA may be useful in treating depression and other mental disorders.
Other health conditions
Research using EFAs is underway in many other areas, including gastrointestinal disorders, diabetes, obesity, PMS, mastalgia (breast tenderness), hypertension, multiple sclerosis, lupus, asthma, allergies and cancer. Recent human clinical trials done in the area of cancer, although preliminary in nature, are encouraging. GLA has demonstrated anticancer effects, both alone and in combination with drug therapy, such as tamoxifen. Other areas of research include supplementation during pregnancy and breastfeeding, and for infants and young children.
Suggested EFA Requirements
Because the typical North American diet is substantially different from the diet of our ancestors (more trans and saturated fats, less EFA-containing seeds, berries and fish) and because so many other factors interfere with fatty acid metabolism, most diets may not contain sufficient EFAs. Unfortunately, the exact requirements for individual EFAs are not clearly defined, despite the large volume of literature available on the subject.
In 1999, an international working group of scientists met at the National Institute of Health in Bethesda, Maryland to discuss dietary recommendations for EFAs. Although they concluded that there was insufficient scientific evidence to establish Dietary Reference Intakes (DRIs), there was enough data to establish Adequate Intake (AI) recommendations for adults. Based on a daily 2000 kcal diet, their recommended daily AI was defined as 4.44 grams of LA; 2.22 grams of ALA; and 0.65 grams of DHA/EPA combined. The working group also recognized that there is too much trans fat in the food supply, and recommended an upper limit of 2 grams per day.
Side effects of EFA supplementation
EFAs can be consumed in large amounts (as much as 50 grams per day) with no serious side effects. Occasional minor side effects may include stomach upset, burping, flatulence, soft stools and diarrhea. These side effects often lessen with continued use and occur more often at higher doses. To minimize side effects, consume with food, start with smaller doses, and increase the dose gradually over several weeks. Persons on anticoagulant or blood thinning medications should consult a health care practitioner before taking EFA supplements from fish since they can thin the blood.
While more research is needed on the role of EFAs in specific diseases, it is clear most individuals can benefit from EFA supplementation to maintain optimal health and nutrition. There is also strong evidence that EFAs can help prevent or treat specific health conditions. Furthermore, they are safe and well tolerated, and readily available wherever health supplements are sold. Consult your health care practitioner or the resource guide in this booklet for more information.