lipidischsoluble

Lipid-soluble, sometimes written lipid-soluble or lipophilic, describes a property of compounds that preferentially dissolve in fats and oils rather than in water. Such substances are typically nonpolar or only weakly polar and show high lipophilicity, often indicated by a high partition coefficient (logP).

In biology, lipid-soluble compounds tend to accumulate in adipose tissue and other lipid-rich compartments. They readily cross cellular membranes, including the intestinal epithelium, the blood-brain barrier, and the placental barrier, which influences their distribution, duration of action, and potential for toxicity.

Absorption and distribution: Fat-soluble nutrients are usually digested with dietary fats, emulsified by bile salts, and incorporated into micelles for uptake by enterocytes. They are then packaged into chylomicrons and enter the lymphatic system, gradually reaching the bloodstream. In circulation, lipid-soluble substances are transported by lipoproteins or albumin and tend to distribute to tissues rich in lipids.

Metabolism and excretion: The liver and other organs metabolize lipophilic compounds to more hydrophilic metabolites to facilitate excretion, primarily via urine or bile. Because of storage in fat, many lipid-soluble substances have longer half-lives and may be released slowly, influencing both therapeutic effects and risk of accumulation.

Examples and relevance: Fat-soluble vitamins A, D, E, and K are classic examples. Many steroids, lipophilic drugs, and several environmental chemicals share this property. Clinically, adequate dietary fat is often required to absorb lipid-soluble vitamins, while excessive accumulation can lead to toxicity; conversely, poor absorption can cause deficiency.

See also: lipophilicity, fat-soluble vitamins, solvent partitioning.