Thread by @Mangan150

A couple of recent meta-analyses found that fish oil had no effect on CVD or mortality.

I've never seen so many MDs so happy.

Here's why these analyses may very well be wrong. /thread

Most trials never measured baseline blood levels of omega-3 fatty acids.

People differ markedly in their levels.

If baseline levels are high, then additional omega-3 isn't likely to make a difference.

In this trial, baseline levels were measured.

After the intervention, there was a large overlap in blood omega-3 between intervention and control groups.

The lower range of the intervention and upper range of controls were virtually the same.

If control and intervention had similar omega-3 levels, you wouldn't expect to see much difference in outcome.

Trials performed before the year 2000 had better outcomes than those done after.

Why?

After 2000, everyone knew about fish oil and large numbers of people were taking it.

Therefore little difference in blood levels between intervention and control.

Doses used were one-size-fits-all.

Absorption of fatty acids varies over ten-fold between people.

You can't just give people fish oil, you have to measure blood levels.

Many people take fish oil capsules at breakfast, and if that's a low-fat meal, which it often is (cereal and skim milk), then very little is absorbed.

This is one reason why eating fish may be better than taking fish oil: fish has fat and promotes better omega-3 absorption.

Another reason for lack of results with omega-3 supplements is failure to control for omega-6 intake & blood levels.

Omega-6 comes mainly from seed oils, and almost everyone uses them.

The amount of o-6/3 fatty acids incorporated into cells is a function of their intake.

Statin use may mitigate the benefits of omega-3 supplementation.

After 2000, more and more people take statins.

If trials don't control for statin use, that could skew results. journals.lww.com/americantherap…

Epidemiological and blood level evidence strongly supports a protective effect of fish and fish oil.

In my opinion, discouraging people from having decent levels of omega-3 will cause harm.

Right now, the establishment both discourages omega-3 and promotes the use of high omega-6 seed oils.

Perverse.

Then they promote statins.

Nutritional trials are fundamentally different from drug trials.

In drug trials, one group gets the drug, the other doesn't.

In nutritional trials, differences between groups may be much less clear cut.