ALAs are found in some non-marine sources, but EPAs and DHAs are more confined to aquatic sources like fish and algae.
Were landlocked countries just missing out on these nutrients for thousands of years, when trade from the coast was not as easy? Though they might have been considered essential nutrients for optimal health, it is clear from these people’s survival that they did not need these non-ALA omega-3s to survive.
I guess one possibility is that EPAs and DHAs are found in some freshwater fish, so maybe this is how they got their intake? But some places like deserts have barely any fish, so I don’t know if that completely solves things.
Edit: I also remembered that ALAs can be converted to EPAs and DHAs in small amounts. So my best guess is that landlocked peoples were able to get small amounts from ALAs, even though they might have benefited from higher amounts in marine sources.
​
I definitely not an expert on this but I believe grass fed beef is actually high in omega 3. It’s only recently (relatively speaking) after the revolution in farming were animals were fed grain like many are today which means they are no longer high in Omega 3. So most animals that were kept would be grass fed so higher in omega 3 than the (beef) animals you may find to eat in the supermarket today
A quick google give me this
“Studies have shown that meat from grass-fed animals has two to four times more omega-3 fatty acids than meat from grain-fed animals”
http://www.pastureforlife.org/media/2016/07/the-human-health-benefits.pdf
Only a very small amount of ALA will be converted to DHA. Absolutely 0-9% according t research literature. Those relying on ALA can find themselves having a fatty acid deficiency and psychiatric or cognitive issues.
Even in land locked areas there existed freshwater fish. Trade could exist between communities. Dried and preserved fish would keep fatty acid ratios. That’s my guess.