In my research I have been reading quite a bit on top nutrient sources (trying to make sure I don't have any deficiencies). What I've been finding is that animal sources generally have superior absorption when it comes to nutrients.
Examples( > indicating superior absorption/conversion into usable forms):
DHA and EPA from fish/algae/grassfed meat > ALA
Retinol form of vitamin A > beta carotene vitamin A
Amino acid profile in animal foods > incomplete amino acid profile found in most plant foods
Heme Iron > non-heme plant iron
Vitamin D3 > plant-based Vitamin D2
Absence of phytates,oxalates etc. which can inhibit nutrient absorption
General higher presence of fat in animal products and thus greater absorption of Vitamin A/D/K.
This seems like a common trend. More research would be needed to reach a conclusive answer obviously, but based on this alone I wonder if we were meant to eat more animal products as opposed to the mostly plant/grain-based diet recommended by CW? It seems like our body favors those nutrients found in animal sources and it takes more work to make use of/convert those same nutrients found in plant sources.
asked bypaleolx (0)
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on April 13, 2014
at 09:16 PM
Animals bioaccululate/concentrate nutrients, we humans also do it. The question is then do we need to consume animal products to get sufficient amounts of nutrients.
EPA/DHA (animal) versus ALA (plant). Actually there's quite a bit of ALA in animals too, simply because, animals, like humans, have to convert ALA to EPA/DHA. The question is, do humans need to consume EPA/DHA for optimal health? Did we do so during our evolution? Probably not. Our DHA/EPA needs are modest, and with sufficient ALA consumption, we make enough DHA/EPA ourselves. No surprise that DHA/EPA conversion ramps up in women during pregnancy and lactation, when the fetus/infant is growing/developing most.
Retinol versus carotenes. Brought up not too long ago… Kresser was pushing bad science on the matter in fact, claiming that only 3% of carotenes are converted to retinoids in humans (when it was actually an in vitro study) and that 45% of humans did not convert carotenes to retinoids at all (in a study with 11 men.) Again, retinoid needs are low, and carotenes are plentiful in plants. We don't need to convert all carotenes to retinoids to meet our dietary needs. In fact, that's probably an indicator of how deficient our diets are in terms of carotenes!
Amino acids… most plants are complete, and those that aren't have complimentary sources of missing amino acids.
Vitamin D from food is just icing on what we should already be making endogenously.
Heme vs non-heme iron. Do we really need to absorb that much iron nowadays? Men in particular don't need excess iron.
Phytates, oxalates, chelators… we evolved exposed to these, why should they be a problem?
Don't get me wrong… animal sources are great for nutrition, but you don't need all that much to meet nutritional needs in the context of a rich, varied plant-centered diet.