The term “Vitamin F” originated during an early period of nutritional science but is not recognized as a true vitamin today. It is an outdated name for two specific polyunsaturated fats—Linoleic Acid (LA) and Alpha-Linolenic Acid (ALA)—that the human body cannot produce. These compounds are classified as essential fatty acids (EFAs) that must be obtained through diet, serving as the foundation for the entire Omega-6 and Omega-3 fatty acid families, respectively.
The Identity Crisis: Why the Name Changed
The classification of these compounds as “Vitamin F” originated in the 1920s following the work of researchers George and Mildred Burr. They showed that animals fed a fat-free diet developed deficiency symptoms, which were resolved by adding certain fats back into the diet. The Burrs hypothesized that these fats contained a previously unidentified, fat-soluble compound, naming it “Vitamin F” in line with the alphabetical system of vitamin discovery.
The reclassification occurred because the compounds failed to meet the strict biochemical criteria established for vitamins. A vitamin is defined as an organic compound required in relatively small amounts, and it does not provide caloric energy. Conversely, LA and ALA are polyunsaturated fatty acids, which are macronutrients that the body requires in much larger quantities and serve as a source of calories.
The scientific community ultimately reclassified “Vitamin F” into its two distinct chemical components: Linoleic Acid (LA) and Alpha-Linolenic Acid (ALA). This change accurately reflects their chemical structure as long-chain fats rather than the small, non-caloric organic molecules that define true vitamins. The term “essential fatty acids” replaced the historical name to emphasize that humans lack the necessary enzymes to synthesize these specific fats and must acquire them from external sources.
Primary Food Sources
The two components of the former “Vitamin F” are found in different food groups, and their consumption ratio is a significant factor in nutritional balance. Linoleic Acid (LA), the omega-6 component, is widely abundant in many common vegetable and seed oils.
Sources particularly rich in LA include safflower oil, sunflower oil, corn oil, and soybean oil. Many nuts and seeds also provide substantial amounts of this fatty acid, such as pecans, pine nuts, and Brazil nuts.
Alpha-Linolenic Acid (ALA), the omega-3 component, is found in fewer common dietary items, primarily in certain plant-based foods. Excellent sources include flaxseeds and flaxseed oil, chia seeds, and walnuts, which are one of the few nuts that offer a beneficial balance of both LA and ALA. Hemp seeds and canola oil also contribute meaningful amounts of ALA to the diet. While ALA is a plant-based omega-3, it is the foundational precursor for the long-chain omega-3s, Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA), which are most readily obtained by consuming fatty fish. A healthy diet should aim for a balanced ratio of LA and ALA, as a disproportionately high intake of LA can interfere with the body’s utilization of ALA.
Key Physiological Roles
Both LA and ALA are integral components of every cell membrane throughout the body. They provide the necessary fluidity and flexibility to these membranes, which is crucial for nutrient transport, waste removal, and cell-to-cell communication.
Beyond their structural capacity, these essential fatty acids act as precursors for powerful signaling molecules called eicosanoids. Eicosanoids derived from LA and its subsequent products, like arachidonic acid (AA), are often involved in processes that promote inflammation and blood clotting, both necessary components of a healthy immune response. Conversely, eicosanoids derived from ALA and its long-chain derivatives, EPA and DHA, generally exert anti-inflammatory effects and support vascular health.
The body can convert ALA into the longer-chain omega-3s, EPA and DHA, through a series of metabolic steps. These derivatives are important for neurological health, as DHA is a major structural component of the brain and the retina. Adequate intake of both LA and ALA is important for supporting brain development, visual acuity, and maintaining overall cardiovascular function.