标题: Can you get the same benefits of fish oil from plant foods [打印本页] 作者: ZHANGXS05 时间: 10-9-25 16:03 标题: Can you get the same benefits of fish oil from plant foods Check out a list of good sources of omega 3 fats and it’slikely to include plant foods like flax seed and walnuts, along with the usualoily fish.
But can flax meal in yourmuesli provide the same fatty acid hit as an entree of grilled sardines? In aword: no.
The science of omega-3 fats isn’tsimple, so to get a basic grasp of what’s different about plant and fish formsof omega-3s I asked Michelle Keske, a senior research fellow with the MenziesResearch Institute at the University of Tasmania.
The story goes something likethis.
There are four major omega-3 fattyacids, but plant foods like walnuts,
flax seed, canola and
some
leafy greens contain only one of them – ALA, short for alpha-linolenic acid.
When you eat
walnuts or cook with canola, your body takes this ALA
and turns it into other important omega-3fats with tongue twisting names like DHA (docosahexaenoic acid) and EPA(eicosapentaenoic acid) – fats that are essential for good health, Keskeexplains.
When it comes to reducing heartdisease, for instance, both DHA and EPA appear to be important, while DHAis important for brain and eyes, she says.
But there’s a catch - humans don’tdo a great job of converting ALAinto EPA and DHA. Although we can make some EPA and DHA, it’s not enough toreach Australia’sdaily target of 430mg of long chain omega-3s for women and 610 mg formen. To get enough of these fats we need to eat them pre-formed, Keskesays – and that’s where fish come in. Oily fish are a rich source of EPA andDHA - which they obtain from the marine algae they eat.
This is fine if you’re happy to eata few meals of seafood each week – or take a fish oil supplement, but that’snot everyone. What if you’re a vegetarian – or someone who’s concernedabout over fishing?
“There’s currently a push todevelop an alternative source of DHA and EPA partly because of thesustainability issue, but also because many people don’t want to usesupplements based on animal derived foods,” says Keske, a former researcher forthe US biotech company Martek which farms marine algae to make a DHAsupplement based on plants, not fish. In Australia, this algal supplement isonly available in a few foods (some eggs, as well as some yoghurts and milkmarketed for children) but there are plans to launch a capsule here nextyear.
As for other renewable options,research is under way in both the USand Australia to geneticallymodify ALAcontaining plants to enable them to produce both DHA and EPA.
Meanwhile, one way to enhance yourintake of omega-3s is to go easy on consumption of omega-6 fats like vegetableoils made from corn, sunflower and safflower. While we need some omega-6 fats,eating too much limits your ability to absorb and use omega-3 fats, says nutritionist Dr Joanna McMillan Price, co-author of Star Foods. Her advice: use a ‘neutral’ mono-unsaturated oil like olive oil forgeneral use, rather than an omega-6 fat like sunflower oil.
And keep up the walnuts and flax.They may not deliver as much omega-3 as oily fish, but they're still a source - and there are other good reasons to include them. Walnuts are high inprotein, fibre and are heart healthy - like all nuts, they help to lowerlevels of ‘bad’ LDL cholesterol. Meanwhile, a new review of research intolignans (a type of plant hormone) found in flax seed, as well as whole grainsand legumes, found that women whose diets included plenty of lignans had alower risk of post-menopausal breast cancer.
Are you concerned about where youromega-3 fats come from?