Dear Dietitian,

I enjoyed your column last week on omega-3 fatty acids. We don’t hear as much about omega-6 fatty acids. Are they healthy? Also, I read that grass-fed beef is better for us than grain-fed beef because it has more omega-3 fats. Is that true?

Thomas

Dear Thomas,

Omega-3 fatty acids have indeed enjoyed much of the spotlight when it comes to heart health. How does its cousin, the omega-6-fatty acid, compare? Both are polyunsaturated fats. Omega-3s are found abundantly in walnuts, flax seeds, chia seeds, and fatty fish, such as salmon, mackerel, sardines, and trout. Omega-6s are found in plant oils like corn, safflower, and soybean oils.

Two essential fatty acids are needed for good health: linoleic (an omega-3 fatty acid) and alpha-linolenic (an omega-6 fatty acid). They are essential because our bodies cannot make them; therefore, they must be obtained in the diet. Linoleic is needed for our largest organ, the skin. It prevents water from entering the first layer of skin, the epidermis, thereby preventing our bodies from being overloaded with fluid. Alpha-linolenic acid is essential in brain development and function. It is also converted to EPA and DHA, which have anti-inflammatory effects.

At one time, it was believed that Omega-6s should be limited because linolenic acid is converted to arachidonic acid, an inflammatory substance that may contribute to chronic diseases. More research discovered that only minimal amounts of linolenic acid are converted to arachidonic acid. Furthermore, omega-6s have a protective effect on the heart. Many studies revealed that rates of heart disease went down as consumption of omega-6-fats went up. A meta-analysis of six randomized trials found that replacing saturated fat with omega-6-fats reduced heart attack and stroke by 24%. Another study revealed that replacing saturated fats with polyunsaturated fats reduced heart disease rates more than replacing them with monounsaturated fats or carbohydrates (1).

While we are used to associating omega-3s with fish, beef also contains some of the healthy fat. Grass-fed beef contains more omega-3s than grain-fed. Estimates vary, with some claiming grass-fed beef has two to three times more omega-3s than its counterpart. Both pale in comparison to the amount of omega-3s in salmon, which contains 10-20 times more than either type of beef. That said, any lean cut of beef is nutritious, high in protein, iron, zinc, and vitamins B3, B6, and B12.

Finally, there is no evidence that grass-fed beef is better than grain-fed in the context of a balanced diet. Another fact to consider is its cost, as grass-fed beef is about 50% more expensive than conventional beef. 

Until next time, be healthy!

Dear Dietitian

Reference

1. No need to avoid healthy omega-6 fats (August 20, 2019). https://www.health.harvard.edu/newsletter_article/no-need-to-avoid-healthy-omega-6-fats