Is the omega-6:omega-3 ratio of beef relevant?

Although it's still debatable what the optimal dietary ratio of omega-6 to omega-3 fatty acids is, there's good evidence that the contemporary dietary intake of polyunsaturated fatty acids has over time become heavily skewed towards a higher intake of omega-6 than omega-3 fatty acids (Cordain et al., 2005; Simopoulos, 2002). The current US diet is estimated to have a omega-6:omega-3 ratio between 10:1 to 12:1, while Cordain and colleagues estimate a ratio of between 2:1 and 3:1 for a traditional hunter-gatherer diet. There is growing consensus that reducing the omega-6:omega-3 dietary ratio may reduce the morbidity and mortality associated with a wide range of metabolic disorders.

This is all well and good, but ratios can be misleading and it's important to keep in mind the absolute mass of fatty acids consumed (Mozaffarian & Rimm, 2006; Wijendran & Hayes 2004). Case in point: one of the purported benefits of grass-fed beef is that grass-fed beef has a better omega-6:omega-3 ratio than grain-fed beef. This is also one of the reasons that wild-caught salmon is recommended over farm-raised salmon. What do the actual data look like? The table below shows the fatty acid profiles of the aforementioned meats.


A few things to note. First, the total PUFA content of grass and grain-fed beef is pretty low. Second, grass-fed beef only contains marginally more omega-3 fatty acids than grain-fed beef. This, together with a marginally lower omega-6 content results in a slightly lower omega-6:omega-3 ratio for grass-fed beef. In addition, the two samples of grain-fed beef are very similar in most respects, but one sample has an omega-6:omega-3 ratio of >17 while the other is <5. Does that mean one is healthier to eat than the other? Not in any meaningful way, looking at the ratio alone is misleading since it conceals the fact that this difference is due to a mere 30 mg of omega-3 fatty acids. To get a sense of how small that is, recall that current recommendations for daily omega-3 intake are over 2000 mg (ALA+EPA+DHA). The absolute amount of omega-3 fatty acids derived from beef is just too small, regardless of whether it is grass or grain-fed. A one pound steak only has between 70-225 mg of omega-3 fatty acids (most of which isn't the more beneficial marine omega-3s, EPA and DHA). Compare this to the amount of omega-3s you get from either wild-caught or farmed salmon. So while it's true that the omega-6:omega-3 ratios are lower for grass-fed beef, a look at the absolute masses of the separate fatty acid classes suggests that this isn't really practically relevant.

Now don't get me wrong, there are many other benefits of grass-fed beef. If money weren't a constraint, I would eat it all the time. However, I don't think that the omega-3 content of beef should be a factor when deciding whether to buy grass-fed over grain-fed. If you want to improve your omega-6:omega-3 dietary ratio, you would do better to eat more seafood and reduce your intake of vegetable oils.