Confused by which fats are healthful and which are not? Try remembering the “omega factor.” Two families of fats—the omega-6 and omega-3 families—are arguably the most important of all fats: they are essential—our bodies cannot make them, we get them from food. They play central, if sometimes opposing, roles in regulating inflammation in the body. This is important because out-of-control inflammation is intertwined in every disease process. Inflammation promotes the breakdown of tissues in arthritis, gastritis, dermatitis, and many other diseases.
Ten years ago, researchers discovered that chronic low-grade inflammation—the type that people cannot feel—increases the risk of disease. This more subtle form of inflammation is a major factor in heart disease, type 2 diabetes, obesity, and many other conditions not traditionally viewed as being inflammatory. But you can control inflammation by always keeping in mind the omega factor—and by managing your omega-6 and omega-3 fats.
The role of polyunsaturated fats in inflammation Omega-6s and omega-3s are both polyunsaturated fats (PUFAs), which your body uses to make both pro- and anti-inflammatory compounds. (These fats are technically called fatty acids.) As a general rule, the omega-6 family of PUFAs promotes inflammation. In contrast, the omega-3 family of PUFAs reduces inflammation. However, there is an important exception to the rule: some omega-6 fats do have impressive anti-inflammatory properties.
At one time, people consumed roughly equal amounts of omega-6 and omega-3 fatty acids. Back then, the “on” and “off” switches of our immune systems were in relative balance. However, widespread food processing has shifted the dietary ratio of omega-6 to omega-3 fats, so it’s now approximately 20:1 in favor of proinflammatory omega-6s. This change has primed us for chronic inflammatory diseases.
Unfortunately, PUFAs are one of the most complicated aspects of nutrition, and it takes a little time to figure out exactly how to use dietary PUFAs and supplements to your advantage. In a nutshell, the body converts the omega-6s and omega-3s to more-potent pro- and anti-inflammatory compounds respectively through a series of biochemical steps. Another complicating factor is that the different PUFAs often have similar and confusing names. I’ll go through the key steps, clarify the terms, and explain what can go wrong.
The key omega-6 fats
The omega-6 fats start with linoleic acid. It’s found in seeds and nuts, but the primary dietary source is now common seed oils, such as corn, safflower, and soybean oils. Linoleic acid itself doesn’t have much biological activity, but it’s the “parent” molecule of the entire omega-6 family.
Several enzymes, including the all-important delta-6-desaturase, convert linoleic acid to more useful and potent compounds. This process begins with linoleic acid being changed to gamma-linolenic acid (GLA). Next, GLA gets converted to dihomo-gamma-linolenic acid (DGLA).
Then DGLA comes to a biochemical fork in the road. Some of it gets converted to anti-inflammatory compounds, including a hormone-like substance called prostaglandin E1. That’s good. However, some DGLA also gets converted to arachidonic acid. That’s bad. Arachidonic acid is the hub of the body’s inflammation-promoting network, and it gets converted to very powerful inflammation-causing compounds, including prostaglandin E2.
The key omega-3 fats
The omega-3s form a parallel biochemical pathway. Alpha-linolenic acid is found in leafy green vegetables (e.g., kale and dark lettuces), flaxseed, and algae eaten by cold-water fish, such as salmon and herring. Alpha-linolenic acid doesn’t do much on its own, but it’s the parent molecule of all the other omega-3s.
The same desaturase enzymes that convert omega-6s convert alpha-linolenic acid to eicosapentaenoic acid (EPA) and subsequently to docosahexaenoic acid (DHA). EPA is the precursor to prostaglandin E3, which is anti-inflammatory. Prostaglandin E3 counters inflammation-promoting prostaglandin E2.
Fish oils, whether found in cold-water fish or capsules, contain “preformed” EPA and DHA (meaning that the fish have already converted alpha-linolenic acid to EPA and DHA.) The EPA and DHA in fish (or fish oil capsules) leapfrog many of the steps involved in converting alpha-linolenic acid to more biologically active compounds. That’s why fish oils have significant anti-inflammatory benefits.
What goes wrong?
Unfortunately, several factors disrupt normal fat metabolism and increase inflammation. Because of the following factors, the body can have trouble turning off the inflammatory reaction, even when an inflammatory response is necessary, such as after an injury or infection:
Supplements of omega-3 fish oils and GLA have the advantage of bypassing many of the biochemical bottlenecks that interfere with the body’s processing of PUFAs. Here’s a quick overview of recent research on them.
Omega-3 Fish Oils. Much of the anti-inflammatory effect of omega-3 fish oils derives from EPA, which counteracts arachidonic acid. Many studies have found that high intake of omega-3 fish oils reduces the risk of coronary heart disease. The omega-3s are mild blood thinners, slow the heart rate, improve heart rhythm, and increase blood-vessel flexibility. Some evidence suggests that omega-3 fats might even inhibit the growth of cancers.
Considerable research has also found that omega-3 fish oils, particularly DHA, benefit people with depression, postpartum depression, and bipolar disorder. Some studies have found that the omega-3s can reduce impulsive behavior, hostility, and physical aggressiveness. DHA in particular may improve memory and help cognitive function.
People who consume a lot of omega-3 fish oils have a lower risk of developing Alzheimer’s disease. In a Swedish study, researchers gave omega-3 fish oil supplements to 174 men and women with Alzheimer’s disease. People with mild (but not severe) cognitive impairment improved during six months of supplementation.
In addition, the omega-3s might help with dry eye syndrome. A Harvard University study of more than 32,000 women found that women who consumed a lot of omega-3 fats had a relatively low risk for the condition. In contrast, women who consumed a lot of omega-6 fats but little omega-3 fats were more likely to suffer from dry eyes.
For most people, the beneficial amount of omega-3 fish oils ranges from 1,000 to 3,000 mg of combined EPA and DHA daily.
Gamma-Linolenic Acid. Several studies have found that GLA supplements can significantly lessen symptoms of rheumatoid arthritis. In fact, GLA may have benefits in a range of disorders by inhibiting several promoters of inflammation, including tumor necrosis factor and interleukin-1 beta.
Studies have also found GLA helpful in resolving eczema and psoriasis. The beneficial amount appears to be at least 275 mg taken twice daily. Combining GLA with vitamin D and omega-3 fish oils may enhance GLA’s benefits.
GLA may also help people maintain a healthful weight. In a study at the University of California, Davis, people who had recently lost weight and took GLA supplements were less likely to regain weight compared with people taking placebos.
GLA supplements are obtained from borage seed, black currant seed, and evening primrose seed oils. Ounce for ounce, borage seed oil contains the most GLA. However, it’s important to read supplement labels carefully—the key is the specific amount of GLA, not the total amount of borage, black currant, or evening primrose oil.
The beneficial amount of GLA ranges from about 200 mg to 1.4 g (1,400 mg) daily.