New USDA salmon figures based on too-few samples?

Farm-raised salmon is cheap compared to fresh. You might find farm-raised for $9.00 a pound in the fresh case and $5.99 a pound in 2-pound package of individually-wrapped frozen fillets.

But farm-raised salmon has lately been known to have a lot of omega-6 fatty acids, making it very inflammatory -- just the sort of thing you DON'T want if you are looking for heart-healthy diet choices.

So I was surprised to read that they have suddenly gotten better. The newly-updated USDA database says that the ratio of omega-6 to omega-3 fatty acids in farmed Atlantic Salmon is now a favorable 1:2.6 instead of the former, very unfavorable 7:1 (is that right? 7:1? Who's got a copy of the old database?). So a serving farm-raised salmon has gone from being highly inflammatory to being highly anti-inflammatory. The ratio is not quite as good as for wild Atlantic Salmon (1:12), but since the farm-raised salmon is nearly twice as fatty, you get a bigger anti-inflammatory dose per ounce.

Monica Reinagel proposed that big changes in aquaculture practices have accounted for this change. But I am not sure this change is universal. I quickly searched for "salmon USDA" and came up with a USDA poster presentation from Experimental Biology 2007 giving lipid figures for salmon. Turns out, only 2 samples of farm-raised Atlantic Salmon were tested, from shopping trips to 12 different US grocery stores.

Two samples? Is that representative of all the farmed Atlantic salmon available in the US? How can I know if the salmon I see in my grocery store more closely resembles the new farmed salmon or the old?

Is it normal for the USDA to "improve" its database with data from such a narrow sampling? What other USDA figures should I start distrusting?

• The "old" farmed salmon: Quantitative Analysis of the Benefits and Risks of Consuming Farmed and Wild Salmon. J. Nutr. 135:2639-2643, November 2005


• The "new" farmed salmon: Exler, J. 2007. Nutrient content and variability in newly obtained salmon data for USDA Nutrient Database for Standard Reference. Experimental Biology, April 25, 2007, Washington, D.C. (abstract)

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Omega-3 and genetic engineering

Those of us who eat a lot of grains and/or grain-fed livestock are always on the lookout for ways to get more omega-3 fatty acids. That's because grains are skewed toward the omega-6 fatty acids, which are inflammatory, and can contribute to heart disease.

But, wouldn't you know it, Monsanto has been working on the problem. They have developed a soybean that produces a lot of SDA, a compound that like ALA, humans can convert to omega-3 fatty acids EPA and DHA, but which is much more shelf-stable than EPA or DHA. And the soy oil will taste better than fish oil. Their plan is to use it to create a high-omega-3 soybean oil, but perhaps it will find other uses as well. They've concluded their soy oil is safe for rats.

Will they try for a high-omega-3 corn next, for livestock feed to produce high-omega-3 meats?
Is this a good thing or not?

• Monsanto and The Solae Company to Collaborate on Soy-based Omega-3 Portfolio


• Safety assessment of SDA soybean oil: Results of a 28-day gavage study and a 90-day/one generation reproduction feeding study in rats. Fleeman et al. Regul Toxicol Pharmacol. 2008 Aug 31

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