Vegan omega-3 supplements are made from algae, which are the original source of the oils for all fish as well.
The chemical synthesis of the omega-3 acids is too expensive, so all commercial products claiming to contain omega-3 acids contain such acids that have been extracted from living beings. Therefore all commercial omega-3 acids are organic.
Because the omega-3 acids are expensive, they frequently are sold diluted in some other kind of oil.
The oil used for dilution should be some good quality vegetable oil. Unfortunately there are cases when some junk oil is used for dilution, possibly including various garbage, e.g. colorants or flavors.
Therefore, when choosing an omega-3 supplement, it is good to check the list of ingredients to see whether the good omega-oil is not mixed with a bunch of undesirable, possibly non-organic, substances.
The main component, i.e. the omega-3 acids, can be found in one of 3 sources:
1. A few vegetable sources with short-chain omega-3 acids, e.g. walnut cores, flax seed or hemp seed
2. Fish oil, e.g. cod liver oil or salmon oil
3. "Algae" omega-3 oil
The first group of omega-3 sources does no harm and people who eat enough animal food might not need anything else.
On the other hand, people who eat little or no animal food must eat some omega-3 supplements belonging either to the second or to the third group.
There is no efficiency difference between fish oil and "algae" oil. The only difference is that the "algae" oil is more expensive, but it is available for those who do not want fish oil.
Like I have said, it is imperious to check the composition of any supplement, to see which is the real content in EPA and DHA and whether they are not mixed with some junk.
Many omega-3 supplements appear to be cheaper, but they are diluted and their real cost per EPA+DHA may be higher than of other non-diluted supplements.
These "algae" are cultivated in sea water. They might use synthetic sea water, but they might just take water from the sea, which contains mercury.
Some "algae" concentrate the mercury from sea water, others do not.
The only completely risk-free supplement would be if you could afford a chemical analysis for it.
As long as you do not analyze it and you do not inspect the production facilities, there is a non-zero risk of toxic substances included in your food.
But of course it is good to also verify whatever you can, because food standards may be too lax or not enforced well enough.
So I agree with the other poster that mentioned the risk of mercury content for fish products, which however exists for all marine products, including algae products, even if it is lower than for small fish and even lower than for large fish.
Nevertheless, I hope that any fish product or algae product that is sold would be sampled and analyzed from time to time to verify that it does not contain harmful substances.
During digestion, the fatty acids are separated from the food and they are absorbed as such by your intestine.
So unlike for some vitamins or minerals, which might behave differently in the form included in dietary supplements versus the form included in natural food, for fatty acids there are no such concerns.
The only thing is that many omega-3 supplements are sold as ingestible capsules, for the benefit of those who do not like to eat oil.
In my opinion eating capsules is a bad choice. I believe that it is better to buy bottled oil containing omega-3 acids. Both fish oil, e.g. cod liver oil, and "algae" oil are available in bottles.
Then you can mix a little omega-3 oil with olive oil or another kind of oil that you use at cooking (by mixing it to the food after cooking and cooling, otherwise the omega-3 oil would be degraded by heating).
If you do like this, then really there exists no difference between the omega-3 from a supplement and the omega-3 from meat, because they would be digested and absorbed in identical environments.
Otherwise, when the oil is released from capsules, the local concentration might be too high overloading the absorption system in the intestine, so some of the oil could be wasted compared to the case when the oil is mixed with other food.
Did you mean "important"?
(My aim is to be helpful given the many non-native English speakers on HN.)
However, I have encountered a lot of uses of "imperious" instead of "imperative", coming from native speakers, which is why I happened to make this choice of words, which is not the right one.
The fish oil that was available when I was a child had a much stronger and less pleasant smell.
(Or maybe it does not matter) but I read multiple suggestions: in the morning after breakfast or at least 1-2 hours _before_ a meal or at least 1-2 hours _after_ a meal.
Can you please share when do you give this? ( I am assuming that you have a better tradition/understanding of this)
Usually EPA and DHA coming from 2 different cultures are mixed into a commercial "algae oil", together with some vegetable oil.
Most of those unicellular organisms are not algae, but there is no better name that could be understood by the general public.
For example, EPA is extracted from thraustochytrids, which are non-photosynthetic unicellular distant relatives of the brown algae.
The only problem with the "algae" oil is that for now it is very expensive. In Europe it is 8 times more expensive than fish oil. While I eat mostly vegan food, I make a couple of exceptions and one of them is fish oil. I have tried algae oil. It was good, but I could not afford to pay for an adequate daily dose of it.
I do not know how much of this premium price is due to the cultivation costs and how much is due to vegans accepting to pay more for a vegan solution.
https://www.amazon.co.uk/dp/B07BRY1FRZ
I also saw normal fish oil in similar price range but that could just be Amazon inflating prices?
At your link, the price is GBP 17 per 24 g DHA, which results in about EUR 0.82 per gram of omega-3.
I have paid about the same price, i.e. 8 times higher than fish oil, for a similar algae oil.
So the price seems right. However the product from your link has a problem, it contains only DHA.
There are 2 omega-3 acids that are required by the human body, DHA and EPA. Fish oil contains both and also vitamin D.
The cultivated algae produce either DHA or EPA, not both. Some vendors mix oils from 2 algae cultures, to sell supplements with both DHA and EPA.
Others sell DHA and EPA separately, like in your link.
If you choose this DHA supplement, you must also search an EPA supplement, to take them both.
Otherwise you must search a supplement with both DHA and EPA. The prices are about the same so it is just a matter of convenience to choose separate or combined supplements.
Unfortunately, I have not seen any algae oil at a significantly different price, so the only cheaper solution is fish oil, at an 8-times lower price.
Hardly or just in small quantities?
With flaxseed oil, you could just consume more of it in order to offset the low ALA/DHA conversion rate. Or is there a downside to the idea?
Eating too much ALA, with the hope that this will be enough to ensure the DHA & EPA that you need, even in the worst case, can be harmful.
Nevertheless, this is a problem mostly for those who eat little or no animal foods. Otherwise you might get enough DHA and EPA from the normal food. Actually the best source of omega-3 acids are the animal brains, which are very tasty when well cooked.
However, since the Mad Cow disease, the popularity of eating brains has strongly declined, even among non-vegans.
That is why I'm curious. I've been living nearly-vegan for 15 years now and I've been "supplementing" with flaxseed oil for a few years now as well (still can't get used to the taste).