Lipid Solubility
Coenzyme Q10 is Lipid (Fat) Soluble
You may be aware that “like dissolves like”, or witnessed the fact that oil and water don’t mix. Biological molecules (such as coenzyme Q10 and the fat soluble vitamins A,D,E, and K) which cannot be dissolved in water but can be dissolved in organic solvents are classified as lipid soluble.
Lipids include fats and oils, waxes, steroids (like cholesterol and testosterone), and related compounds. Although the word lipid is commonly used as a synonym for fat, fats are actually a subgroup of lipids. Compounds that are lipid (fat) soluble are sometimes called lipophillic meaning “lipid loving” or hydrophobic meaning “water fearing”.
Lipids, which are ingested in the diet, are essential to the structure and function of living cells. The lipids that are important to humans have four major functions:
- Structural components of biological membranes
- Serve as a barrier for the cell
- Control flow of material in and out of the cell
- Form membrane of organelles (tiny structures within cells)
- Energy storage (for instance fats stored in adipose tissue)
- Vitamins, which assist in the regulation of biological processes, and hormones which act to communicate between cells
- Bile acids, which aid in dissolving and digesting dietary lipids
Lipids and fat soluble nutrients are digested and absorbed differently than water soluble nutrients such as proteins and carbohydrates. Digestion occurs in the gastrointestinal tract and is separated into five separate processes:
- Ingestion: Placing food into the mouth.
- Mechanical digestion: Mastication (chewing), the use of teeth to tear and crush food, and churning of the stomach.
- Chemical digestion: Addition of chemicals (acid, bile, enzymes, and water) to break down complex molecules into simple structures small enough to be absorbed.
- Absorption: Movement of nutrients from the gastrointestinal tract to the bloodstream.
- Elimination: Removal of undigested materials from the digestive tract through defecation.
Most nutrient absorption takes place in the small intestines. By the time the partially digested food reaches the small intestines, it has been broken down into smaller units of sugars, amino acids and lipids. The water soluble sugars and amino acids are transported directly through the intestinal wall into the bloodstream. The nutrient-containing blood is carried away from the small intestine to the liver for filtering, removal of toxins, and nutrient processing.Lipid absorption into the circulation is different from that of sugars and amino acids. Lipids are digested and absorbed more slowly because they must be first be physically broken down and held in suspension (called emulsification), then chemically broken down by enzymes such as bile and lipases, and finally repackaged into smaller fat droplets called micelles. It is these micelles that allow the water insoluble lipids to be absorbed into the enterocyte. Finally, the absorbed lipids are repackaged into lipid and protein containing globules called chylomicrons which transport them through the lymphatic system into the blood.
Because coenzyme Q10 is insoluble in water, absorption by the body can be slow and limited. Since oil and water don’t mix, coenzyme Q10 is not well absorbed when ingested with liquid drinks or low fat meals. Like the fat soluble vitamins such as vitamin E, absorption of coenzyme Q10 by the body can be improved by ingestion with a fatty meal. 1
References:
1. Bhagavan HB and Chopra RK. Coenzyme Q10 : Absorption, tissue putake, metabolism, and pharmacokinetics. Free Radic Res. 2006;40(5):445-453.