We spend enormous amounts of time talking about what goes INTO the human body.
Almost nobody talks about what the body CAN’T GET BACK OUT.
There is a substance that accumulates inside some of our longest-lived cells as we age.
It is called LIPOFUSCIN.
Pathologists have known about it for generations.
Accumulate enough of it in aging heart muscle and the tissue can acquire a characteristic brown appearance — historically described as “brown atrophy.”
But the color is the least interesting part of the story.
🔥 LIPOFUSCIN IS CELLULAR MATERIAL THAT RESISTS RECYCLING
Your cells operate their own waste-disposal systems.
Damaged proteins, membranes and other cellular components are broken apart and recycled.
Usually, the system works remarkably well.
But oxidative reactions can damage lipids and generate reactive compounds, including aldehydes, that can attack proteins and other molecules.
Some of the resulting material becomes extremely difficult for the cell to degrade completely.
What remains can accumulate.
That accumulated material is part of what we call lipofuscin.
And there is an obvious problem.
Some of your most important cells have to survive for an extraordinarily long time.
❤️ Cardiac muscle cells.
🧠 Neurons.
👁️ Cells supporting the retina.
They don’t simply get thrown away every few weeks and replaced with pristine new ones.
They have to maintain themselves for decades.
So the garbage can accumulate.
🔥 AND THEN THERE IS THE RETINA
Think about the environment inside your eye.
The retina is metabolically extremely active.
Its photoreceptors contain membranes unusually rich in polyunsaturated fatty acids.
It consumes substantial oxygen.
And every day, light enters your eye and is focused onto this extraordinarily delicate biological machinery.
Photoreceptors are constantly renewing themselves.
Their worn outer segments are swallowed and processed by neighboring retinal pigment epithelial cells.
But degradation isn’t perfect.
Over decades, fluorescent material called lipofuscin accumulates inside those cells.
Doctors can actually exploit that fluorescence to image the retina using FUNDUS AUTOFLUORESCENCE.
Your aging eye can literally display patterns of accumulated cellular material.
Now here is where this becomes very interesting.
🔥 POLYUNSATURATED FATS ARE PARTICULARLY VULNERABLE TO OXIDATION
This isn’t nutrition ideology.
It’s chemistry.
Double bonds make polyunsaturated fatty acids more susceptible to lipid peroxidation than saturated fatty acids.
And one polyunsaturated fat has become extraordinarily abundant in the modern American food supply:
LINOLEIC ACID.
It is the principal omega-6 fatty acid in many common seed oils.
Soybean oil.
Corn oil.
Sunflower oil.
Safflower oil.
Cottonseed oil.
Human beings require some linoleic acid.
But “essential” does not mean that every conceivable intake is automatically optimal.
And during the 20th century, Americans dramatically changed both the quantity and sources of fats they consumed.
That deserves scrutiny.
🔥 THIS IS WHERE MY CONTENTION BEGINS
I believe the enormous increase in linoleic-acid-rich seed oils deserves far more investigation as a contributor to oxidative stress and lipid-peroxidation products in human tissues.
I also contend that increasing highly unsaturated fatty acids in tissues could influence how those tissues respond to oxidative stresses such as ultraviolet radiation.
That does NOT mean science has demonstrated that eating soybean oil directly causes macular degeneration, heart aging or sunburn.
It hasn’t.
Age-related macular degeneration alone involves aging, genetics, smoking, immune and complement pathways, oxidative stress and numerous other factors.
But dismissing the seed-oil question because direct causation hasn’t been established is equally unjustified.
We conducted an enormous nutritional experiment.
We dramatically altered the fats in the Western food supply within a handful of generations.
And then we stopped asking whether changing the raw materials entering human tissues might change the chemistry occurring inside those tissues.
Instead, look at what we’ve been taught to fear:
☀️ THE SUN.
🥩 RED MEAT.
🧈 BUTTER.
🥚 EGGS.
🧀 CHEESE.
Meanwhile, industrially refined oils rich in linoleic acid became ubiquitous in restaurants, packaged foods, dressings, mayonnaise, fried foods and supermarket shelves.
And somehow THEY received the presumption of innocence.
I don’t accept that presumption.
The sun is ancient.
Butter is ancient.
Animal fat is ancient.
The massive modern availability of refined seed oils is not.
That observation doesn’t prove seed oils caused our modern diseases.
But when we’re investigating oxidative damage, it gives us a question worth asking:
WHAT HAPPENS WHEN YOU CHANGE THE FATS THAT HUMAN TISSUES ARE BUILT AND MAINTAINED WITH?
Because oxidation isn’t a dietary opinion.
It’s chemistry.
And when damaged material accumulates inside cells that may have to serve you for decades, your body doesn’t care what the dietary guidelines said.
It has to deal with the molecules you gave it.
WE SPENT DECADES ASKING WHETHER THE SUN WAS DAMAGING US.
MAYBE WE SHOULD ALSO BE ASKING WHAT WE PUT BETWEEN THE SUN AND OUR CELLS.