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We do require B12, but "found almost exclusively in animal foods" leaves out something important. B12 is produced by bacteria, and is found in natural, untreated water sources, as well as dirt. Our bodies are adapted to preserve B12 in a very elaborate way, (because it is a water-soluble vitamin), meaning that we can survive on the trace amounts found in untreated water and the dirt that sticks to vegetables. This is not to say that I'm recommending drinking untreated water or not washing vegetables. Vegans should absolutely supplement. DHA can be produced by our bodies transforming ALA, which is found in plant sources: https://www.sciencedirect.com/science/article/pii/S016378271... Like the article says, there's debate over whether this is enough, as the conversion is very inefficient. As I understand it, ALA and LA compete for the same pathway, meaning that excess of LA intake (an omega 6 fatty acid, abundant in nuts and seeds, and of course oils processed from them) will reduce our body's ability to produce DHA, so a human eating prehistoric diet would likely have a better conversion ratio than on a modern diet. Also, there's apparently evidence that if we don't eat a lot of DHA, our bodies convert more of our dietary ALA to it to compensate: https://www.ncbi.nlm.nih.gov/pubmed/20861171 But even taking all this into consideration, I'm not very sympathetic to arguments from nature. There's a big difference between saying "primal humans did X" and saying "modurn humans need to do X to be healthy". Even taking everything you said as given, there's overwhelming evidence that meat consumption is a big factor in for modern chronic health problems like heart disease and cancer. Eating whatever you can get your hands on (meat, eggs, fish, insects) makes sense when you just need enough calories to survive and reproduce, but that's not the problem now. We suffer from diseases of abundance. A plant-based diet with B12 and DHA supplementation is much healthier than an omnivorous one. |
I'd not bet my health and my children's development on a novel way of eating without fantastic proof. Have you got any?