Over roughly the last 100 years, the United States, and the rest of the world, has undergone a dramatic dietary change. We eat less at home and more at restaurants. We eat fewer foods made from scratch and more that are processed and packaged at a factory far, far away. There are of course many other changes (frequent dieting being equally if not more significant). But the biggest change of all is a change that you’ve probably never heard of, or were aware of in the slightest. The biggest change seems to have been our collective increased consumption of two fatty acids in particular – linoleic acid (LA) and Arachidonic acid (AA).
The primary sources of LA are vegetable oils (corn, soy, canola, sunflower, cottonseed, etc.) and peanut butter, and the primary sources of AA are pork, eggs, and poultry.
In the last 100 years, official U.S. data notes an increase in vegetable oil consumption of 1,450%, an increase in margarine consumption (manufactured from vegetable oil) by 800%, and an increase in shortening consumption (also manufactured from vegetable oil) by 275%.
Pork and egg consumption changed an insignificant amount, while poultry intake increased by 278%. More important than the changes here though is the fact that the fatty acid composition of these meats/products and the fat in these meats/products has changed dramatically due to the big change in the type of feed given to pigs and chickens (they now get fed lots of corn and soy and other foods rich in LA). The result is that eggs and meat from pork and poultry especially is much higher in AA than ever before. AA is a byproduct of LA metabolism – generally the more LA an animal consumes the more AA there is in the organs and tissues.
The same is true for a human. The more LA we eat the more AA we can expect to find in our fats, tissues, and organs. Of course eating more AA seems to do it in an expedited manner.
While the buildup in these types of fatty acids in our organs, tissues, and fat cells is quite significant, and significant for reasons we won’t necessarily delve into in this post, these fatty acids have made it into something else besides our farm animals and our bodies…
They have made it into breast milk.
Prior to the widespread replacement of traditional fats (butter, rendered beef and pork fat, coconut oil, olive oil) with modern vegetable oils, breast milk samples show linoleic content somewhere around 6%, perhaps even less prior to the agricultural revolution. Now we’re seeing LA content well above 15%, and sometimes considerably higher in some women, such as diabetic mothers who seem to have particularly high levels. Unfortunately, makers of infant formula have increased their LA content to try to mimic the changing breast milk over the years. Some makers are even considering going over 20% as LA.
Perhaps the most interesting connection here is that…
1) Proneness to obesity, diabetes, and other related conditions is predictable at a very young age (2 years of age or younger)
2) Number of fat cells and size of fat cells seems to be amongst the best of all indicators as to what the future body composition of an infant will be
3) This seems to be primarily controlled by type and quantity of fatty acids – lots of LA and AA in a mother’s tissues and breast milk leads to adipocyte (fat cell) hyperplasia and hypertrophy. In English… bigger fat cells and more of them – two major hallmarks of obesity, are all set into motion long before McDonald’s and soft drinks and video games come into the picture
No really. We actually seem to be intentionally putting more of these fatty acids into infant formula, and people are being told to avoid saturated fats and eat more plant-sourced fats. In laboratory animals body weight follows an almost linear curve that is neatly tied to the amount of LA that it is fed. Tissue levels of these fats in a mother also seem to be rather directly related to the obesity-proneness of her offspring. You can read about some of these relationships in an extensive review of Polyunsaturated fats in the Development of Obesity.
Anyway, I once went overboard with my vilification of these types of fats, listing extensive charts showing the foods with the highest and lowest content of LA (in an Appendix in Diet Recovery for example). In doing so, I probably also overestimated the benefits that one can expect to personally experience from reducing LA and AA in the diet.
But, no longer coming from a dietary extremist’s point of view – instead looking for practical, sustainable, and doable simple changes that the majority of society can implement, the take away message here is very simple…
- Cook your food in butter and coconut oil at home, and quit buying and using vegetable oil, margarine, and shortening
- Eat fewer fried foods out at restaurants (notice I didn’t say “don’t eat fried foods”)
- Eat fewer packaged commercial products that are cooked in or made with vegetable oil (chips, commercial cookies)
- Don’t buy mayonnaise or commercial salad dressings – make your own
- Eat more red meat, seafood, and dairy products as your sources of animal foods
Simple changes are all that is needed here on an individual level. No need to become an uptight health hermit or diet weirdo. But hopefully the voices of people like myself, Danny Roddy, Ray Peat, Josh Rubin, Stephen Guyenet, Chris Masterjohn, David Brown, Evelyn Tribole, Bill Lands, and dozens of others will eventually be heard. Countries like the United States and Israel, with their extremely high intake of LA and unsurprisingly high rates of diabetes, obesity, hypertension, and cardiovascular disease, should help to warn the rest of the world of the potential dangers of diets high in polyunsaturated fats.
I truly suspect that a national change in attitude about fats – favoring the saturated fats in our food supply (coconut, red meat, dairy, chocolate) instead of recklessly pouring corn oil in infant formula in unprecedented amounts, can go a long way in letting people “eat, drink, and be merry” without suffering so many ill consequences. It’s certainly a matter worthy of a more thorough examination in terms of how these fats affect our bodies on a fundamental physiological level than it has yet to receive.
But I guess I’m just dreaming. I don’t envision any major food corporations or restaurateurs volunteering to switch to using more expensive fats any time soon.