Besides flaxseeds, walnuts have also a large content of short-chain omega-3 fatty acids. Walnuts were my preferred source of omega-3 fatty acids when I was young.
The problem is that the short-chain fatty acids must be elongated in the liver to become useful.
For many people, the elongation capacity per day of the liver is not enough to provide a sufficient quantity of long-chain fatty acids.
Because the fatty-acid elongation capacity of the liver decreases with age, for older people it is much more important to eat food with long-chain omega-3 fatty acids, e.g. fish oil or oily fish, than it is for young people, for whom flaxseeds or walnuts may be enough.
That is why in the parent article the conclusion was that the long-chain omega-3 fatty acid supplements have been more effective for older people.
There are unicellular micro-organisms which produce long-chain omega-3 fatty acids. They can be cultivated and the oil extracted from them is available commercially, but at prices 8 times higher than the price of fish oil (for the same quantity of DHA or EPA).
Moreover, different cultures must be used for DHA and for EPA, so for a complete supplement 2 oils would have to be mixed. Because a single producer usually has only the technology for a single type of culture, in most cases one would have to buy both a DHA oil and an EPA oil and consume both supplements.
In contrast, fish oil from oily fish has both DHA and EPA, while cod liver oil has DHA, EPA and also vitamin D.
Besides flaxseeds, walnuts have also a large content of short-chain omega-3 fatty acids. Walnuts were my preferred source of omega-3 fatty acids when I was young.
The problem is that the short-chain fatty acids must be elongated in the liver to become useful.
For many people, the elongation capacity per day of the liver is not enough to provide a sufficient quantity of long-chain fatty acids.
Because the fatty-acid elongation capacity of the liver decreases with age, for older people it is much more important to eat food with long-chain omega-3 fatty acids, e.g. fish oil or oily fish, than it is for young people, for whom flaxseeds or walnuts may be enough.
That is why in the parent article the conclusion was that the long-chain omega-3 fatty acid supplements have been more effective for older people.
There are unicellular micro-organisms which produce long-chain omega-3 fatty acids. They can be cultivated and the oil extracted from them is available commercially, but at prices 8 times higher than the price of fish oil (for the same quantity of DHA or EPA).
Moreover, different cultures must be used for DHA and for EPA, so for a complete supplement 2 oils would have to be mixed. Because a single producer usually has only the technology for a single type of culture, in most cases one would have to buy both a DHA oil and an EPA oil and consume both supplements.
In contrast, fish oil from oily fish has both DHA and EPA, while cod liver oil has DHA, EPA and also vitamin D.