Linoleic acid and arachidonic acid, the misjudged “bad” fats
Scientists have long believed that the omega-6 to omega-3 ratio has a huge impact on a person's overall health and well-being. Because people on a Western diet, which is considered unhealthy, consume more omega-6s than omega-3s, the general assumption was that a higher intake of omega-6s increases inflammation while a balanced ratio reduces it.
However, according to one of the study's authors, William Harris, a professor at the University of South Dakota's Sanford School of Medicine and a prominent researcher of omega-3s, it's not all black and white when it comes to the omega-6 to omega-3 ratio. (Related: Clinical trials review confirms: Omega-3 and omega-6 fatty acids are an effective treatment for ADHD.)
“You can have a high amount of both omega-6 and omega-3 in your diet and your blood, or a low amount and still have the same ratio. It's not that our omega-6s are too high; it's that our omega-3s are too low,” he explained.
He also added that there probably isn't an ideal ratio of omega-6 to omega-3. While omega-6s are established pro-inflammatory fats, it is also an established fact that consumption of some oils rich in omega-6s has cholesterol-lowering effects and can reduce the risk of heart disease.
Global dietary recommendations for LA and its metabolite AA remain controversial. To address this and determine, once and for all, the cardiovascular effects of these two omega-6s, Harris and his colleagues looked at the relationship between in vivo circulating and tissue levels of LA and AA and CVD across 30 prospective observational studies from 13 countries.
After performing harmonized de novo analyses and a meta-analysis of study-specific results, the researchers found that higher levels of LA among a total of 68,658 participants were significantly associated with lower risks of CVD, cardiovascular mortality, and ischemic stroke. They were, however, non-significantly associated with a lower risk of coronary heart disease.
The researchers also found that AA levels were not contributory to a higher risk of cardiovascular events. Surprisingly, higher levels of AA were associated with a lower risk of CVD. These results suggest that having higher in vivo circulating and tissue levels of LA and AA can reduce the risk of major cardiovascular events. They also suggest that both omega-6s are wrongly labeled as unhealthy and that dietary LA may actually play a role in the prevention of heart disease.
Omega-6 fatty acids: boons or banes?
The main reason why omega-6 fatty acids are eagerly avoided is that they are involved in inflammation. Chronic inflammation is now widely accepted as the main contributor to the development of serious diseases.
Inside the body, the omega-6 LA is converted into another fatty acid, AA, which is considered the building block of pro-inflammatory molecules. However, what isn't frequently mentioned is that the body also uses AA for the production of anti-inflammatory molecules.
There is also increasing evidence that omega-6 fatty acids are actually safe and beneficial for the heart and blood circulation. Recent studies have revealed that only a small amount of LA is turned into AA by the body, regardless of the abundance of LA in a diet.
Consuming large amounts of LA also doesn't trigger inflammation. In fact, several studies have reported that it not only reduces inflammatory markers, but it also lowers the risk of heart disease. Therefore, omega-6s fats should not be excluded from a healthy diet. They should be used to replace saturated fats, the real bad fats. Research suggests that omega-6s are even better replacements than monounsaturated fats.
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