GcMAF – the magic silver bullet?

Enforcement | 06/04/2017

For the past few years informations concerning a substance called “GcMAF” have been circulating the internet. Several online sources denote GcMAF as harmless treatment for diverse illnesses, such as autism, different viral infections (HIV, Hepatitis B and C, influenza, etc.), chronic fatigue syndrome, autoimmune diseases (ALS, MS, etc.) and especially various cancers.

The Facts

GcMAF (Gc-protein derived macrophage activating factor) is a naturally occurring protein of the human body. It is formed through modification of the so-called vitamin D-binding protein (Gc protein). Macrophage activating factors (MAFs) cooperating with several other factors are involved in the activation of macrophages. Macrophages are components of the innate immunity which together with adaptive immunity reperesents the immune system. As soon as exogenous substances or organisms invade the body, innate immunity is responsible for an early-onset but rather unspecific immune response. Pathogen specific defence mediated by adaptive immunity kicks in a little deferred and is conveyed by B- and T-lymphocytes.

According to distributors, GcMAF induces activation of endogenous macrophages which is the basis for promised treatment successes. The activated macrophages are supposed to specifically eliminate either cancerous or virus-infected cells, depending on the disease at issue. In case of autoimmune disorders the activated macrophages are even supposed to have a regulatory effect upon the overshooting immune system. In any case, the result is presumed complete cure within a short period of time.

New Findings

Most online information about GcMAF properties refers to the publications of one Dr. Nobuto Yamamoto. However, recent internet research by the Austrian Federal Office for Safety in Health Care (BASG) revealed that three of four journals have already retracted the publications of Dr. Yamamoto due to various reasons.1-3

In a letter to the editors, members of the Anticancer Fund Belgium list several inconsistencies in a publication of Yamamoto et al.4 Besides formal research errors, the authors point out that the natural concentration of GcMAF in the blood (approximately 4mg/L) exceeds the recommended therapeutic dose of 100ng by a factor of 40.000, even in cancer patients. As a result, it is considered implausible that a treatment according to the recommendations of Dr. Yamamoto might yield any therapeutic effects.

Moreover, several suppliers of GcMAF provide the information that GcMAF-treatment cannot cause any side effects because the protein is also produced endogenously. The Belgian authors do not support this rationale since it is an established fact that endogenously produced substances, such as insulin, can cause serious side effects and even death. Provided that GcMAF really is a potent immunotherapeutic drug, there remains the danger of excessive activation of the immune system comparable to autoimmune reactions.

Besides, GcMAF and its successors, such as GcOleic, RERUM or BRAVO, are generally not provided by registered online pharmacies. Thus, the risk of dubious sources and, consequently, technically or hygienically inadequate manufacturing quality, which may cause serious health effects in patients, must be taken into account.


There are no proofs for the efficacy and safety of GcMAF-based therapies available in the relevant literature. Furthermore, online distribution of medicinal products apart from registered online pharmacies poses an additional source of danger since an adequate surveillance of manufacturing quality cannot be guaranteed.


  1. RETRACTED ARTICLE Yamamoto N et al., Immunotherapy of HIV-infected patients with Gc protein-derived macrophage activating factor (GcMAF). J Med Virol 2009, 81(1):16-26
  2.  RETRACTED ARTICLE Yamamoto N et al.: Immunotherapy of metastatic colorectal cancer with vitamin D-binding protein-derived macrophage-activating factor, GcMAF. Cancer Immunol Immunother 2008, 57(7):1007-16
  3.  RETRACTED ARTICLE Yamamoto N et al.: Immunotherapy of metastatic breast cancer patients with vitamin D-binding protein-derived macrophage activating factor (GcMAF). Int J Cancer 2008, 122(2):461-7
  4.  Ugarte A et al., Inconsistencies and questionable reliability of the publication “Immunotherapy of metastatic colorectal cancer with vitamin D-binding protein-derived macrophage-activating factor, GcMAF” by Yamamoto et al. Cancer Immunol Immunother 2014, 63(12):1347-8

Further inquiry note