EFA Balancing Act

Youd have to live under a rock to avoid hearing about the growing list of benefits linked to omega-3 fatty acids. But some health experts are looking at the overall balance of omega-3 and omega-6 in the American diet, and asking how the shifting of this balance affects health.

Omega-3 and omega-6 fatty acids are important essential fatty acids (EFAs) that fall under the class of polyunsaturated fatty acids (PUFAs). Just like the name implies, EFAs are required by the human body. The body cannot make them, so EFAs must be consumed through the diet. Insufficient intake can cause problems with growth, dermatitis, infertility, fighting infection and wound healing. In the United States, its rare to find omega-6 fatty-acid deficiency. In fact, Americans tend to get too much omega-6 relative to their omega-3 fatty acid intake. This imbalance may be related to the development of chronic diseases, such as heart disease, cancer, asthma, arthritis and depression.

The tipping point

An optimal diet for general health should provide somewhere between a ratio of 1:1 to 4:1 omega-6 to omega-3 fatty acids. Anthropological and epidemiological studies, and studies at the molecular level, point out that humans evolved on a diet with a ratio of 1:1. But todays typical American diet contains about 11 to 30 times more omega-6 than omega-3 fatty acids.

Whos to blame for this skewed balance? If you look at the change in American agriculture from the 1900s to the current time, there has been an enormous increase in the production of oilseeds, predominantly soybean, says Dr. Joyce Nettleton, editor, Fats of Life Newsletter and PUFA Newsletter. As people were urged to increase their intake of vegetable oils to lower their blood cholesterol levels, soybean oil became the dominant food oil. Consequently, it is estimated that 20% of calories in the American diet comes from soybean oil alone. Polyunsaturated fatty acids typically make up 60% to 65% of conventional soybean oil, most of which is in the form of linoleic acid (an omega-6 fatty acid).

In a study published in Psychosomatic Medicine (2007, 69(3):217-24), researchers from Ohio State University College of Medicine, Columbus, investigated depression and inflammation in older adults in relationship to omega- 6/omega-3 fatty-acid intake. Based on data from blood samples of 43 adults, researchers concluded diets with high omega-6 to omega-3 ratios may enhance the risk for both depression and inflammatory diseases.

In the November 2006 issue of Biomedicine & Pharmacotherapy (60(9):502-7), scientists from the Center for Genetics, Washington, D.C., reported a high omega-6 to omega-3 ratio promotes diseases such as cardiovascular disease, cancer, osteoporosis, and inflammatory and autoimmune diseases.

Omega-6 under fire

Beware of lumping omega-6 fatty acids into the bad category. Omega-6 fatty acids tend to be depicted as the bad guys, but its never that simple, says Nettleton. They are importantwe just dont need them in such whopping amounts.

There are several kinds of omega-6 fatty acids. Most of them are consumed in the diet through vegetable oils as linoleic acid (LA). LA is converted to gamma-linolenic acid (GLA) and further into arachidonic acid (AA) in the body. GLA can be found in plant oils, such as primrose oil, borage oil and black currant seed oil, as well as spirulina. AA can be is found in egg yolk, meats and organ meats. The adequate intake level for LA is 17 grams per day for men 19 to 50 years old and 12 grams per day for women 19 to 50 years old.

Too much LA and AA can promote inflammation, while GLA appears to reduce inflammation. Much of GLA does not convert to AA, but rather to dihomogammalinolenic acid (DGLA), which competes with AA and prevents negative inflammatory effects on the body. DGLA also becomes part of prostaglandins, which also reduce inflammation.

Among the areas of interest arising in omega-6 fatty acid research is attention deficit/hyperactivity disorder (ADHD), as some studies indicate children with ADHD have lower levels of both omega-3 and omega-6 fatty acids. GLA may also help prevent nerve disease in diabetics, treat dry-eye conditions, maintain and increase bone mass, and relieve pain, swelling and stiffness in rheumatoid arthritis. Studies have suggested that up to 2,800 mg of GLA per day is well tolerated, although it is contraindicated with some medications.

Focus on omega-3

Its not just a case of people overdoing omega-6; they are not consuming enough omega-3. We never have been big consumers of omega-3 fatty acids, especially those from fish, says Nettleton. A century ago, we didnt have such high levels of omega-6 fatty acids. It would be better to offset our high intake of omega- 6s by increasing our consumption of omega-3 fatty acids, particularly the long-chain ones from seafood.

The important long-chain omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic (DHA), which can be found in seafood, such as salmon, tuna, sardines, mackerel or shellfish. Vegetarian sources, such as walnuts and flaxseed, contain a precursor omega-3 fatty acid, alpha-linolenic acid (ALA), that the body must convert to EPA and DHA.

Healthy people should get about 300 to 500 mg of long-chain omega-3 fatty acids per day, with 500 mg to 1 gram for people at higher risk, says Nettleton, who suggests that, optimally, people should eat three or more servings of fish per week.

The list of conditions that seem to benefit from omega- 3 fatty acid supplementation continues to swell. It has clearly been shown that omega-3 fatty acid provides a protective benefit in heart disease, in particular sudden cardiac death. FDA concluded there is sufficient evidence for a qualified health claim for omega- 3 fatty acids and the risk of coronary heart disease (CHD).

The American Heart Association, Dallas, recommends people without documented CHD should eat a variety of fish (preferably oily fish) at least twice a week; people with documented CHD should consume about 1 gram of EPA and DHA per day; and those with elevated triglycerides may need 2 to 4 grams of EPA and DHA per day under a physicians care.

Omega-3 fatty acids also show positive results in treating symptoms of rheumatoid arthritis and psychiatric disorders, including schizophrenia and major depressive disorder. Nettleton reports other promising fields of research for omega-3 fatty acids include visual function, degenerative neuropathy, preterm infants and preterm birth. I dont know of a single compound that has the diversity of beneficial effects more than any pharmacological agentas these long-chain omega-3s, says Nettleton.

Experts are predicting a slightly positive shift in the balance of omega-6 to omega-3 fatty acids, thanks in part to a resurgence in use of monounsaturated fats, such as olive oil, and the phasing out of trans fat, which has prompted the return of other fats like palm oil. And, hopefully, the scales will also tip toward an increase in omega-3 fatty acids, probably the healthiest way to balance out the essential fatty acid equation.

Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California and can be reached at [email protected].