Fish oil supplements, con't
I've been wanting to write a follow-up to my last post about fish oil supplements, but whew, I've had a busy week.
The following is my understanding of how all this omega-3 stuff applies to humans:
There are several types of omega-3 fatty acids, but three in particular are considered beneficial to our health. These essential fatty acids (called such because our bodies cannot synthesize them, so it is essential we get them in our diet) are alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Our bodies can, however, create DHA and EPA from ALA, but are not very efficient at doing so.
In nature, both DHA and EPA are produced by a type of microalgae. They work their way up the food chain, and are available to humans in the form of fish or fish oil. Small amounts of DHA is present in eggs, but EPA is not present in any type of vegetarian foods. Vegetarian foods rich in other omega-3s (such as flax seed/oil) do not include EPA or DHA, however, they do include their precursor, ALA.
One hypothesis as to why humans evolved to require a nutrient that is only available from marine sources when humans did not evolve near the ocean is that our modern diets have failed us. Normally our bodies can create EPA and DHA from readily available ALA, but research indicates that the modern Western diet includes too much of the omega-6 fatty acids, and this excess throws off our bodies ability to synthesize DHA and EPA, thus requiring us to supplement our diets.
As a result of an earlier discussion, friends have sent me some interesting links regarding this stuff:
Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of alpha-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. - Difference in omega-3 levels between people with various diets were smaller than expected.
Do vegetarians have to eat fish for optimal cardiovascular protection? - Unfortunately, the evidence is unclear.
DHA status of vegetarians. - "There is no evidence of adverse effects on health or cognitive function with lower DHA intake in vegetarians."
Bioavailability of alpha-linolenic acid from flaxseed diets as a function of the age of the subject. - Eating flaxseed seems to increase the level of EPA in the blood.
And finally, this British company sells a vegan DHA/EPA supplement derived directly from algae: Omega-3 algae oil. I have not seen anything like this for sale in the US, so maybe this is worth trying once it is back in stock.
The following is my understanding of how all this omega-3 stuff applies to humans:
There are several types of omega-3 fatty acids, but three in particular are considered beneficial to our health. These essential fatty acids (called such because our bodies cannot synthesize them, so it is essential we get them in our diet) are alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Our bodies can, however, create DHA and EPA from ALA, but are not very efficient at doing so.
In nature, both DHA and EPA are produced by a type of microalgae. They work their way up the food chain, and are available to humans in the form of fish or fish oil. Small amounts of DHA is present in eggs, but EPA is not present in any type of vegetarian foods. Vegetarian foods rich in other omega-3s (such as flax seed/oil) do not include EPA or DHA, however, they do include their precursor, ALA.
One hypothesis as to why humans evolved to require a nutrient that is only available from marine sources when humans did not evolve near the ocean is that our modern diets have failed us. Normally our bodies can create EPA and DHA from readily available ALA, but research indicates that the modern Western diet includes too much of the omega-6 fatty acids, and this excess throws off our bodies ability to synthesize DHA and EPA, thus requiring us to supplement our diets.
As a result of an earlier discussion, friends have sent me some interesting links regarding this stuff:
Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of alpha-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. - Difference in omega-3 levels between people with various diets were smaller than expected.
Do vegetarians have to eat fish for optimal cardiovascular protection? - Unfortunately, the evidence is unclear.
DHA status of vegetarians. - "There is no evidence of adverse effects on health or cognitive function with lower DHA intake in vegetarians."
Bioavailability of alpha-linolenic acid from flaxseed diets as a function of the age of the subject. - Eating flaxseed seems to increase the level of EPA in the blood.
And finally, this British company sells a vegan DHA/EPA supplement derived directly from algae: Omega-3 algae oil. I have not seen anything like this for sale in the US, so maybe this is worth trying once it is back in stock.