There is some evidence that omega 3 helps protect the heart. There is
also evidence that, since it is a fat, basically what might be helping
is bringing the mix of omega 3 more in line with the omega 6 found in
vegetable oils, which is a staple of the American diet. It might be
just as beneficial or more so, to limit your total fat in the first
place.

A few days ago, I mentioned how people really don't need to seek fat
for their diet, and insufficient essential fatty acids in a diet is
rare. In fact, it apparently only has occurs in people who can't
digest fat. Why? Fat is in all foods...skim milk, grapes, oats, wheat,
lettuce, etc. Not much of course, but enough to get the essential
fatty acids even on a vegan diet.

Flax is considered by some almost a miracle food additive, but the
benefits of flax might be related to it's high fiber content, not the
omega 3 in it. Fiber can help carry away cholesterol and other fats,
thus lowering BP and cholesterol and presumably the risk of heart
disease and stroke, not to mention the protection that may occur to
defend against colon cancer. If its the fiber at play, you could just
avoid the extra fat in flax seed. Of course there is no fiber in omega
3 oils, whether they are made from flax or anything else.

The jury is still out on whether extra omega 3 is helpful, IMO. I eat
a high fiber, vegetarian diet. I estimate that I get 10-12% of my 2000
cal a day from fat, while purposely avoiding any and all fats except
those in whole grain. My cholesterol, BP and weight are low. I also
exercise moderately 6X a week.

Here is a good general article on very low fat diets:
http://www.fatfree.com/FAQ/fatfree-faq

dkw