3. Antioxidants cannot stop the chain reaction of lipid peroxidation
Why do antioxidants fail against lipid peroxidation?
Antioxidants cannot pack tightly enough into cell membranes to guard every PUFA molecule. Once a chain reaction starts, the exponential rate of lipid peroxidation overwhelms antioxidant defenses, while free copper and iron ions catalyze further damage.
For several fundamental reasons, antioxidants cannot stop the chain reaction (see Chapter 2.8 in the book).
As the toxic oxygen molecules act randomly, hitting PUFA-loaded membranes anywhere, one would need to park a fire-retarding antioxidant next to every lipid molecule in the membrane. Not only cannot this be achieved quantitatively, but even if it could have happened, the membranes would then be too badly swollen and distorted to function, for antioxidants are shaped differently to lipid molecules, and cannot be tightly packed into the membrane, disturbing the barrier function.
Metals that fan the flames
Various factors further exacerbate the lipid peroxidation problem for cells. To function properly, many enzymes require small quantities of various metals, such as iron and copper. And many of those metals can trigger the chain reaction of lipid peroxidation.
Sun light, environment, life style, tattoos, bad luck and bad habits, the list of lipid peroxidation triggers is long.
Essential yet vulnerable
PUFAs are the best fuel for the chain reaction, yet the above-mentioned omega-3 and omega-6 essential fatty acids are both the essential components of our diet (our body cannot produce them), and essential building blocks of our lipid membranes (they make the membranes less stiff).
So, lipid peroxidation just marches on, inexorably and ineluctably.
Organs large (skin, muscle) and small (retina, ear hair cells), as well as tissues, cells, organelles (mitochondria) and various processes (sleep, pain transduction) are all indiscriminately targeted by LPO. The list of LPO targets is only a little shorter than the complete inventory of body parts. The chain reaction progresses non-stop, relentlessly oxidising us into our aged selves.
Perniciously, the most important organs (brain and eyes) are very high in PUFAs (DHA), and so are even more vulnerable to the ravages of LPO.
Sadly, this area does not get the attention it deserves, for the top biologists are mostly pre-occupied with the mechanics of information transfer. DNA, RNA and proteins keep the best minds busy and the funds spoken for (see Chapter 1.1). Yet the chain reaction just keeps taking its toll…
What can we do?
Want the full picture?
This article covers just one piece of the puzzle. The book connects all the dots: from the chemistry of aging to the deuterium approach.