Your body is made of cells. Cellular metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to environmental changes.
Where are phospholipids found?
Each one of your cells is encased in a lipid layer called the cell membrane. The health of our cell membrane and the specific phospholipid content of it is integral to cellular metabolism. We are going to dive into a little biology lesson in this blog post, to help you understand the importance of nourishing lipids, the cell membrane, and how it ties into your health.
The membrane of every cell and organelle including your mitochondria serves as a “wall” that encases and protects everything inside the cell. Inside the cell is what makes us tick, outside the cell is our bloodstream. The structure is called a "lipid bilayer" because it is composed of two layers of fat cells organized in two sheets. The cell membrane is composed of a bilayer of phospholipids, cholesterol, sphingomyelin, and proteins.
What does the bilayer do?
Cell membranes protect and organize cells. All cells have an outer plasma membrane that regulates not only what enters the cell, but also how much of any given substance comes in allowing only certain molecules to cross.
In addition to lipids, which account for approximately half the mass of the cell membrane, there are also peptides (proteins) from DNA, cholesterol, and fatty acids to help our cells perform the integral metabolic functions of life. Cholesterol helps regulate the rigidity of membranes, while other less prominent lipids play roles in cell signaling and cell recognition.
The outer part of the cell membrane contains phosphatidylcholine (PC) and sphingomyelin (SM). The inner contains phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS). The outer cell membrane leaflet predominantly contains PC and sphingomyelin while the inner membrane leaflet contains PE and PI.
Types of phospholipids
Major phospholipids include phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidic acid (PA), cardiolipin (CL), sphingomyelin (SM) and phosphatidylserine (PS).
Of the tens of thousands of molecules that make up the life of a cell, PC is one of the most important. PC is the main phospholipid in the outer leaflet of the cell membrane and accounts for ~50% of its concentration. SM is also a part of the outer membrane and as we age, levels of PC decrease, and levels of SM, and cholesterol increase, a shift that is not good for our health. The decrease in PC may not be felt but it will be evident with age, in decreased brain function, failing eyesight and hearing, and with the onset of degenerative disease.
Phosphatidylcholine’s headgroup, choline, is not synthesized by the body. It is an essential nutrient that must be supplied by dietary sources. Choline, from liver, muscle meat, fish, nuts, beans, wheat germ, or spinach, can be methylated from ethanolamine to make PC, but it is not the same as taking a concentrated liposomal PC like BodyBio PC. Egg yolks carry the most PC, followed by soy and sunflowers. Food-derived choline goes to acetylcholine, the neurotransmitter but only a little is converted to PC, a process that decreases as we age. Do not be fooled by most supplements on the market that are actually triple lecithin. Some are choline (which has been involved with CVD), or Citicoline, which is a PC precursor. Dietary lecithin will break down during digestion to yield fatty acids and choline, thus is a source of choline. Glycero-PC is a breakdown product of PC and is not a phospholipid, but a sugared (glycerol-) choline. That makes choline available for conversion to Acetylcholine. True “PC”, or phospholipid PC, is intended to re-integrate a damaged cell membrane, to put cell signaling in order, and to enhance membrane fluidity and permeability.
Phosphatidylethanolamine (PE) is the second most abundant phospholipid, after PC, and is located in the inner leaflet of the cell membrane and the inner membrane of mitochondria. It can amount to 20% of liver phospholipids and as much as 45% of those of the brain; higher proportions are found in mitochondria. PE is vital to mitochondrial function, membrane structure, and acts as a basis for several biological pathways, making it integral to our cellular health. PE can be synthesized by the decarboxylation of phosphatidylserine (PS) in the inner mitochondrial membrane.
Phosphatidylinositol (PI) is supportive to the brain and neurotransmission. It is a minor element of the inner side of the membrane, but still considered one of the more interesting phospholipids metabolically because its actions are stimulated by the cell membrane itself through a complex interaction of proteins and enzymes that directs the cell’s metabolic changes, including the ability to change our sense of smell, sight, taste, touch, and hearing. PS is particularly abundant in brain tissue, where it can amount to 10% of the phospholipids.
Phosphatidylserine is important to cognitive function and has many biological functions in the cell. Like PE, PS is found in the inner part of the membrane. PS is formed from PE by swapping the ethanolamine head for L-serine, which then enhances acetylcholine release and improves cell signaling to rectify faulty cognitive activity. PS is critical for apoptosis, programmed death of a cell which occurs as a normal and controlled part of an organism's growth and development. We often create cells that are not needed later, especially when healing. When apoptosis is called for, PS is switched from the inner membrane to the outer, thereby sending the signal to macrophages, our cell clean-up structure, that this cell must leave. Too, PS is a component of platelet membranes and, therefore, plays a role in clotting.
The concentration of PS in membranes is usually less than 10% of the total phospholipids positioned on the inner leaflet of the cell membrane, the endoplasmic reticulum, with the greatest concentration being in myelin from brain tissue.
Phosphatidic acid (PA)
Phosphatidic acid is a unique lipid molecule that accounts for ~.25% of phospholipids in the lipid bilayer. PA is an intermediate in the biosynthesis of other phospholipids, especially for PC, but also PE and also acts as a direct regulator of mTOR signaling.
Cardiolipin, or diphosphatidylglycerol, is found exclusively in the inner membrane of mitochondria and myelin. Mitochondria are our cellular powerhouses and 80% of the cardiolipin 4 fatty-acid side chains are linoleic acid, aka omega-6. Our mitochondria cannot function without omega-6 and this is why we talk about the importance of essential fatty acids and dietary intake of unprocessed sunflower, safflower, hemp, chia, pumpkin, soy, sesame seeds.
Sphingomyelin plays a critical role in the brain (myelin) in the early stages of development. However, as we age SM raises raft functions in the membrane, a slowing down characteristic. In addition, SM and PC sit on the outside of the membrane leaflet facing the bloodstream, however, SM attracts Ca, while PC rejects Ca. This growth of Ca sitting on the membrane may grow substantially over time and lead to artery and vein disturbances, eventually contributing to atherosclerosis.
BodyBio PC contains 5 of the main 6 phospholipids throughout the body, PC, PE, PS, PI, PA in a true liposomal form.
Phospholipids and your health: How it’s used
Low PC stores and impaired PC biosynthesis reduce levels of circulating HDL. PC, as reported in European trials, has the capacity to attenuate arterial plaque. As an emulsifier, PC breaks down fats.
Besides forming bilayers, all phospholipids maintain a gradient of chemical and electrical processes that ensure cell survival. PC enhances cognition, response time, learning, memory, and executive function.
Phosphatidylcholine is a major lipid in the protective mucus of the gastrointestinal tract, has been shown to exert an anti-inflammatory effect. Studies have shown that PC can be helpful to those with gastrointestinal issues as well as by providing protection against NSAIDs, which can be detrimental to the GI system.
The best documented clinical use of PC is its significant amelioration of liver damage, primarily because damage demands substantial restoration of cell membrane mass. This eventuates to the improvement of enzyme function and related biochemical indicators of liver health, applicable in hepatitis, drug-induced insults, alcoholic steatosis, and NAFLD.
The bottom line on phospholipids
As we age, cells change in size and function and become less able to divide and multiply. Derogating fats increase inside the cell, and waste accumulates. Connective tissue stiffens, organs become more rigid, and membranes have more difficulty passing oxygen and nutrients in and out of the cell. Illness, environmental insults, medications, increase in physical demands, and diet influence the manner of a cell's aging and the time it takes to do so.
Replacing lost lipids with mixtures of cell membrane phospholipids, such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and phosphatidic acid restores membrane, cellular and mitochondrial functions while enhancing the removal of waste materials and toxins, thereby reducing symptoms of degeneration.