PUFA is no doubt a primary cause of the widespread slowing of the metabolic rate of modern humans.
As we discussed in the last lesson, polyunsaturated fat has a specific role in ecosystems. The primary fatty acid of concern in plants–linoleic acid (LA), appears in the food chain in the fall when seeds, nuts, grains, acorns, and such form. The plant employs these fats to enable sprouting in cold, spring soils.
To best demonstrate the effect this fat has on mammals that share a similar physiology to our own, we need look no further than the organisms that seasonally eat lots of these nuts, seeds, and acorns–bears, ground squirrels, and other hibernators primarily.
Yeah, they go into hibernation–a state of extreme metabolic downregulation. Body temperature, pulse rate, respiratory rate, etc. fall to next to nothing, keeping these creatures from starving during their long, restless, winter nap.
But you’re thinking that animals just go into hibernation because day length shortens. Well, that may be part of it, but it’s not the whole story. In fact, hibernating animals have trouble entering a state of torpor (hibernation) when linoleic acid isn’t present.Keep giving them a steady supply of coconut oil with no PUFA and they can’t go into hibernation at all!
This makes sense of course if you are of the opinion that nature is intricate and smart. Coconut grows in places where there is no winter. No winter, no need to hibernate. And in the plant kingdom, no cold winter, no need to produce a bunch of linoleic acid.
Linoleic acid really is the trigger to induce the characteristics of hibernation, including reduced body temperature, as you can see in this interesting review.
But humans, so unaware of nature’s intricacy as we can often be, started storing nuts and seeds and also extracting their oils. Instead of consuming them seasonally and maybe even doing ourselves a metabolic favor with a carbless winter approaching, we now consume unfathomable buttloads of these types of fats every single day.
They are in everything, and some of the world’s richest sources of linoleic acid are now the most-consumed fats in the global food supply. It is wildly significant, as this type of fat gets stored in our fat cells and tissues and has a huge influence over core biological functions–such as the regulation of inflammation and metabolic rate (arguably the most important of all functions in a discussion about degenerative disease).
LA is also found in much higher concentrations in human breast milk than ever before seen. This is highly significant, as the amount of LA in mother’s milk seems to be directly and almost single-handedly responsible for the size and number of the offspring’s fat cells–the most important of all factors in accumulating excess fat later in life as any obesity researcher could tell you.