Insulin-like Growth Factor 1 (IGF-1) is a naturally occurring peptide hormone that has become a popular, yet often misunderstood, compound in the dietary supplement market. This hormone is structurally similar to insulin and plays a major role in the body’s growth and development. It functions as a primary mediator of the effects of Growth Hormone (GH), linking the central control of growth to the cellular processes throughout the body. The controversy surrounding IGF-1 supplements stems from claims of performance enhancement and anti-aging effects, which clash with fundamental scientific principles regarding how the body handles ingested protein hormones. This article examines the science behind endogenous IGF-1 and evaluates the actual efficacy and safety of its oral supplement forms.
The Biological Role of Endogenous IGF-1
Insulin-like Growth Factor 1 is a single-chain protein composed of 70 amino acids, and it is a central component of the Growth Hormone–IGF-1 axis, a complex regulatory system in the human body. The liver is the main source of circulating IGF-1, producing it primarily in response to stimulation from Growth Hormone secreted by the pituitary gland. Once released, IGF-1 circulates in the bloodstream, mostly bound to a family of six specific IGF-binding proteins (IGFBPs), which regulate its half-life and availability to tissues.
The hormone acts as an anabolic agent, stimulating cell growth, proliferation, and survival in nearly every cell type in the body. It is particularly active in promoting systemic body growth during childhood and puberty, and it continues to maintain tissue homeostasis in adulthood. For example, IGF-1 is involved in stimulating osteoblasts and chondrocytes to support bone growth, and it plays a significant part in the maintenance and repair of skeletal muscle and nerve tissues. This action involves binding to the IGF-1 receptor on the cell surface, initiating intracellular signaling cascades that ultimately drive protein synthesis and reduce cellular breakdown.
Sources and Marketing Claims of Oral Supplements
Commercial IGF-1 supplements are typically sourced from animal products that naturally contain the hormone, most notably extracts of deer antler velvet. Deer antler velvet is the soft, cartilaginous tissue covering growing antlers, which is rich in IGF-1 due to the rapid growth rate of the antlers themselves. This biological source is the basis for its inclusion in dietary supplements, where manufacturers suggest it can be orally consumed to achieve systemic effects.
Manufacturers promote the idea that ingesting IGF-1 can replicate the hormone’s natural anabolic and reparative functions. Specific claims include increasing lean muscle mass, accelerating recovery time after intense exercise, and enhancing strength and physical performance. Some manufacturers also advertise anti-aging benefits, joint support, and improved vitality. These claims leverage the hormone’s natural role in tissue regeneration and often reference the established science of injectable, pharmaceutical-grade IGF-1 used to treat specific medical conditions.
Scientific Efficacy and Bioavailability of Oral IGF-1
The fundamental challenge for any oral IGF-1 supplement lies in the process of digestion, which severely compromises its systemic efficacy. As a peptide hormone, IGF-1 is a protein, and when ingested, it is subjected to the same breakdown processes as any other dietary protein. Enzymes in the stomach and small intestine, such as proteases, rapidly break down peptide bonds, dismantling the IGF-1 molecule into inactive amino acid fragments.
For the hormone to exert a systemic effect, the intact IGF-1 molecule must survive this digestive process and be absorbed into the bloodstream. Scientific consensus indicates that very little, if any, of the intact IGF-1 from an oral supplement is absorbed in a biologically active form capable of significantly raising circulating levels. The minuscule amounts of IGF-1 often found in products like deer antler velvet extract are generally too low to have a measurable impact on the body’s overall IGF-1 status, even if they were fully absorbed.
To address the lack of bioavailability, some manufacturers utilize specialized delivery systems, such as liposomal encapsulation. This technology involves wrapping the IGF-1 molecule in a lipid bilayer, theoretically protecting it from enzymatic destruction and facilitating absorption. While this approach is sound in theory, robust clinical evidence demonstrating that these methods effectively increase systemic IGF-1 to a performance-enhancing level remains largely absent from peer-reviewed literature. Scientific data does not support the notion that orally consuming IGF-1, even with advanced delivery methods, provides the claimed benefits of its injectable counterpart.
Safety Concerns and Regulatory Status
The body tightly regulates IGF-1 levels because unnaturally high concentrations are associated with serious health risks. Since IGF-1 promotes cell growth and inhibits cell death, chronically elevated systemic levels have been linked to an increased risk for several types of cancer. Large-scale studies confirm associations between higher IGF-1 levels and an increased risk for developing colorectal, prostate, breast, and thyroid cancers. This risk stems from the hormone’s ability to promote the proliferation and survival of potentially malignant cells.
From a regulatory standpoint, IGF-1 in supplements is often derived from animal sources, allowing it to be marketed as a dietary ingredient and bypass the stringent approval process required for a drug. Synthetic IGF-1, however, is classified as a drug and is illegal to sell as a dietary supplement without a prescription. Furthermore, the lack of quality control means the actual concentration of IGF-1 in these products can be highly variable or non-existent, and products may be contaminated with undeclared substances.
The World Anti-Doping Agency (WADA) has explicitly placed IGF-1 on its Prohibited List, classifying it as a peptide hormone and growth factor banned at all times for competitive athletes. The use of exogenous IGF-1 is considered a doping violation due to its potential to enhance athletic performance and associated health risks like acromegaly and cardiovascular issues. Athletes are warned that even supplements containing natural sources, such as deer antler velvet, may lead to a positive test and subsequent sanction.