In episode 7 of the Eat Better Podcast, Chloe and I discuss fish:
• Why is fish an important part of the diet?
• Where should you get your fish from?
• How much should you worry about dioxins and mercury?
• What about fish oil supplements?
Notes
One part of the discussion got lost in the edit: Many trials have shown that adding DHA (and EPA) to the diet (as krill oil, cod liver oil, or fish oil) can both increase HDL and reduce triglycerides. This lowers the Triglyceride/HDL ratio, which is an important potential marker of future heart disease.
Fish oil supplements
At the end we touch upon fish oil supplements. As with everything, it is best to get your DHA and EPA from whole foods. The benefits of real seafood have consistently been shown to be better than supplementing. Two or three portions of fatty fish per week should be plenty for most people, as we mention in the podcast. If you’re not a regular fish eater or want to boost your DHA intake for various reasons, I personally think that minimally-processed cod liver oil is best. Get the best you can afford, and shop around, as analyses have shown that fish oil supplements are often oxidised (damaged), and don’t get the DHA/EPA you pay for (http://www.ncbi.nlm.nih.gov/pubmed/25604397).
Fermented cod liver oil is very popular at the moment, but that process potentially increases the likelihood that the DHA will no longer be in the ideal sn-2 position I mention. It may also make the fats more likely to be rancid and oxidised. However, the Weston A. Price foundation have released an analysis of Green Pasture fermented cod liver oil, which shows no evidence of rancid fats (http://www.westonaprice.org/uncategorized/concerns-about-cod-liver-oil/).
On the other side of the argument, here is a release from Nordic Naturals describing their take on fermented fish oils (http://www.bolderbrokers.com/uploads/4/1/3/0/41303351/nn_fermentedclo-2.15.pdf). I won’t weigh in on the debate, but I like my DHA as minimally processed as possible. Therefore I take something like Icelandic Lysi, from a bottle in the fridge (http://www.lysi.com/consumer-products/cod-liver-oil/liquid-cod-liver-oil). No pills or extra manufacturing steps.
Finally, there is also some debate about vitamin D to A ratios in cod liver oils, with a risk of relatively large doses of vitamin A, which can inhibit the proper function of vitamin D. Norwegian and Icelandic bottled cod liver oils usually contain 1,000-1,200IU of vitamin D (400-600% of recommended daily allowance) and 2,000-2,500IU of vitamin A (around 100% of recommended daily allowance) per tablespoon, in a 1:2 ratio. This is well within appropriate intakes for most people. However, it is worth checking your own brand.
If you are supplementing with any product that includes vitamin D or A (like cod liver oil), it is important to make sure you are getting enough vitamin K2, as the three play important roles together. Get more K2 from:
• Grass-fed full-fat dairy (http://drragnar.weebly.com/podcast/eat-better-podcast-episode-1)
• Eggs, particularly free-range eggs (and probably fish eggs)
• Goose or duck liver
• Natto (http://en.wikipedia.org/wiki/Natt%C5%8D)