Dear Dietitian,

We hear so much about omega-3 fatty acids being good for us, but 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 a heart-healthy diet. How does its cousin, the omega-6-fatty acid, compare? Both are polyunsaturated fats found in our diets. Their names simply indicate where the first double carbon bond is located from the terminal, or omega end. In the case of the omega-3, the first carbon: carbon double bond is third from the end of the carbon chain.

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 oil, safflower oil, and soybean oil. There are two essential fatty acids we need for good health, linoleic (an omega-3 fatty acid) and alpha-linolenic (an omega-6 fatty acid). These are called essential because our bodies cannot make them, and they must be obtained in our 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 needed for 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. However, with further research, it has been discovered that minimal amounts of linolenic acid are converted to arachidonic acid. Furthermore, omega-6s have a protective effect on the heart. Many studies showed 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 found 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-3- fats than does grain-fed. Estimates vary, with some claiming that grass-fed beef has two to three times more omega-3s than its counterpart. But 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 type of beef is very nutritious, high in protein, iron, zinc, and vitamins B3, B6, and B12.

Finally, there is no evidence that grass-fed beef is better for you in the context of a balanced diet. Another fact to consider is its cost. Be prepared with deep pockets, 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