polyunsaturated fatty acids, between the omega-6 and the omega-3 families.

Although their structural functions which we already discussed are very similar, their

regulatory role as precursors of the eicosanoids is very different.

Remember that the eicosanoids are important hormone-like substances that orchestrate many

vital metabolic processes at the cardiovascular, immune, and nervous system level.

The main classes of eicosanoids are prostaglandins, prostacyclins, thromboxanes and leukotriens.

We can build all these molecules both from omega-6 and from omega-3 fatty acids, and

these molecules will affect the same areas of metabolsim, but in different ways.

Every cell in our body makes eicosanoids. Their complex biochemistry is often challenging

to understand, because for every molecule in this group that does something, there is

another that does the exact opposite. To complicate things even more, both molecules are potentially

useful, but both are potentially dangerous. I know it sounds like the riddle of the sphinx,

but let me make a couple examples to clarify what I mean.

There are some eicosanoids, called thromboxanes, that promote platelet aggregation and blood

clotting, and then there are others, called prostacyclins, that instead inhibit platelet

aggregation and promote blood fluidity. Which is the good, and which is the bad? If we consider

that formation of clots in the bloodstream can sometimes trigger a heart attack, the

eicosanoids that inhibit clotting could be considered the good guys, since they keep

our blood fluid. But on the other end, even a little cut on our finger would cause us

to bleed to death if it wasn’t for the eicosanoids that promote platelet aggregation and clotting

to close the wound.

Prostacyclins also promote vasodilation in our arteries, while thromboxanes, guess what,

promote vasoconstriction. Excessive vasoconstriction causes high blood pressure and cardiovascular

risk, but on the other hand excessive vasodilation would cause a dangerous blood pressure drop

to the point of fainting. Some eicosanoids promote immune function,

some other depress it. Well, you may think, this one’s easy. The good ones are those

that promote immunity, to help us fight viruses, bacteria and cancer cells. Well, it depends.

If it wasn’t for their counterparts that slow down this immune defense drive, this

could go overboard resulting in autoimmune disease, in which our overstimulated immune

systems starts attacking the healthy cells of our own body.

Some eicosanoids have pro-inflammatory activity, and needless to say, some other are anti-inflammatory.

Inflammation is definitely something we’d prefer to live without, it causes us pain,

fever, and production of free radicals that damage our tissues and accelerate the aging

process and risk for chronic disease. However, when it comes to fighting pathogens that attack

our body, it is precisely the inflammatory response what we need to get rid of these

enemies as soon as possible.

Some eicosanoids promote pain transmission, other suppress it. Nobody likes to suffer,

and the reason we take aspirin when our head aches is precisely to block the production

of this pain promoting eicosanoids. But on the other hand, pain is a life-saving mechanism

that enables us to realize that something’s wrong so that we can take the necessary action.

If we touch a very hot surface, we immediately remove our hand to avoid a serious burn. If

we feel a strong pain in our chest, we can run to the hospital and save us from a heart

attack. As you probably know, those individuals that for genetic defect cannot feel any pain,

usually die within their first years of life.

Some eicosanoids promote cell proliferation, some other inhibit it. Controlled cell proliferation

is necessary so that our body can grow, develop and repair damaged tissues. But if cell proliferation

hadn’t a check, the risk for tumor development and growth would be much higher.

Some prostaglandins promote mucus and bicarbonate secretion in our stomach, protecting it from

acid corrosion that may lead to ulcers. However, an excessive buffering of stomach acidity

would impair its primary physiologic function, which is helping food digestion and at the

same time killing the vast majority of potential pathogens that come with it.

I think you got the idea. Now these opposite actions are often performed by omega-6 derived

eicosanoids and omega-3 derived ones. They way I picture this is sort of a pulling-rope

game, with the omega-3 team at one end of the rope and the omega-6 team at the other.

The omega-6 teams pulls toward inflammation, platelet aggregation, vasoconstriction, pain

transmission and strong immunity, the omega-3 teams pulls toward anti-inflammation, blood

fluidity, vasodilation, pain suppression and immunosuppression.

We don’t really want any of the two teams to win, because any of their effects brought

to the extreme would be bad. What we want instead is a balance between the two. We want

a little bit of both and we should get both of them from diet in appropriate proportions.

The ideal omega-3 to omega-6 ratio is between 1:2 and 1:4, meaning that for every 2 to 4

grams of omega-6 in our diet, we want at least 1 gram of omega-3. Unfortunately the average

US diet is far from this ideal ratio, and we tend to have way too many omega-6 compared

to the omega-3, promoting blood clotting, inflammation, and hypertension.