Inflammation is the "new cholesterol" in matters of eating to protect the heart (and other chronic diseases for that matter).  Notably many inflammation medications work by blocking the effects of excess omega-6 fat, including statins, aspirin, and asthma inhalers.  (See Medications that Block Effects of Omega-6 Fat)

Brody explains in her column, how the landmark Lyon Diet Heart study diet trumped the American Heart Association diet for reducing death rates from all-causes, including cardiac death and cancer.

Here's the glitch.  A hallmark feature of the Lyon Diet is its low omega-6 fat content, because it was patterned after the diet eaten by the inhabitants from the Greek island of Crete (they have one of the lowest rates of heart disease).  Therefore the researchers limited the omega-6 fat content to 4% of calories, which is about 7 grams/day (that’s about the amount in one tablespoon of soybean oil). 

Just last month, the lead scientists of the Lyon Diet Heart study chastised researchers for ignoring the omega-6 factor, "...the epidemiologists does not capture one major lipid characteristic of the Mediterranean diet, which is actually low in omega-6”. (See The Mediterranean Diet is Low in Omega-6 Fat, Say Lyon Diet Heart Study Scientists)
Ironically, omega-6 fats are the same polyunsaturated fats, touted indiscriminately, for years by the American Heart Association, for heart health.  (While polyunsaturated fats technically consist of both omega-6 fats and omega-3 fats, our diets are in very short supply of omega-3 fats.)   Therefore it was no accident that the folks relegated to eating the American Heart Association diet, did not fare well compared to those eating the Lyon Diet.

In 1999, there was enough scientific evidence to prompt scientists to recommend an upper limit for omega-6 fats, to no more than 6.7 grams per day. This ceiling is based on eating a maximum of 3% fat calories from omega-6 fat on a 2000 calorie diet.  (Note, this is similar to the the Lyon Diet Heart study.) Here we are ten years later, and many people have not heard of omega-6 fat, or they assume any “omega fat” is associated with health benefits.  Not so.

What’s the Harm?  The Polyunsaturated Fat Paradox

Cultures that suddenly increase their polyunsaturated fat intake (which is synonymous with omega-6 fat) experience markedly health problems. When the inhabitants of Okinawa tripled their omega-6 fat intake, they experienced a rise in cancer and cardiovascular disease, which Japanese researchers called “excess linoleic acid syndrome”.  (Linoleic acid is the common chemical name for the plant-based omega-6 fat.)

Israel embraced eating a high polyunsaturated fat diet (at the expense of saturated fats), and achieved one of the highest omega-6 fat intakes in the world.  Consequently, they also experienced an unexpected high incidence of chronic western diseases, which researchers term the “Israeli paradox”.

Greenland Inuit Eskimos are famous for their high omega-3 fat diet, but just as importantly, their diet was also low in omega-6 fat.

Omega-6 fats are the most commonly eaten polyunsaturated fat in westernized countries. Prior to industrialization, no population has been exposed to the current high levels of omega-6 polyunsaturated fats. We evolved on a diet with a balanced proportion of omega-6 to omega-3 fats of about 1:1. Today, that ratio in westernized countries is out of whack, near 20:1 of omega-6 to omega-3 fats.

Different farming practices, new food processing and the urging by health authorities to use vegetable oils in place of animal fats--triggered an onslaught of omega-6 fats into the food we eat. Consider that today:

• We eat oils that did not exist 100 years ago, like cottonseed oil, which is one of the top three sources of omega-6 fat in the American diet (along with soybean oil and corn oil).

• Most cattle no longer graze in pastures, they eat feedlot-cuisine of corn, which is high in omega-6 fat.  The longer a cow grazes in the pasture, the lower the omega-6 fat content of its meat and milk. 
  

How to Lower Omega-6 Fat
Fortunately, eating a lower omega-6 fat diet is very doable—if you know what to look for.  You won’t find “omega-6 fat” on the Nutrition Facts list, because it’s not required on the food label. 

You’ll need to turn to the ingredient list and check for one of these top sources of omega-6 fat: soybean oil, corn oil, cottonseed oil, safflower oil or sunflower oil.  Especially, check the ingredients in your margarine, mayonnaise and salad dressing---and you’ll likely find one of those oils (or “vegetable oil”, which is typically a soybean oil blend). 

You can also use the Omega-6 Fat Tracker widget to help you identify sources of omega-6 fat in oils.  If you are vegetarian or a health-conscious eater, you are not off the hook, as these foods tend to be especially high in omega-6 fat.

Yes, it's time to say goodbye to the dogma of polyunsaturated-fats-are-heart-healthy. 


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