Huffington Post - video at full story link

Omnivores, take note: Embracing a vegetarian diet could make you
happier and less stressed, according to new research published in
Nutrition Journal.

The reason comes down to fatty acids: Diets that include meat and fish
are higher in arachidonic acid (AA), an animal source of omega-6 fatty
acids. Much of the meat Americans eat today is quite high in AA: The
average omega-6 to omega-3 fatty acid profile of modern grain-fed meat
is 5 times higher than grass-fed meat, like our ancestors ate. And
previous research has shown high levels of AA can cause
mood-disturbing brain changes.

High-fish diets also mean higher levels of long-chain, or omega-3
fatty acids, like eicosapentaenoic acid (EPA) and docosahexaenoic acid
(DHA). Both EPA and DHA combat the negative effects of AA. High
dietary levels of omega-3 fatty acids are linked to better brain
health, better mood and a host of other health benefits. Most health
experts recommend an omega-6/omega-3 ratio of about 4:1.

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full story:
http://www.huffingtonpost.com/2012/03/11/vegetarianism-stress-happiness-_n_1335664.html