In the United States it is allowed to market supplements that improve weight loss, enhance athletic performance, and promise other benefits without giving evidence of efficacy or safety. Medications and other active pharmaceutical ingredients can be found in supplements to boost sales.The stimulant 1,3-dimethylamylamine (DMAA), introduced in 1948 as a nasal decongestant and withdrawn from the US market over 40 years ago, was reintroduced as a dietary supplement in 2006. It was banned again and continues to be investigated as a cause of strokes, heart failure, and sudden death.

Pieter A. Cohen, Harvard Medical School, Cambridge, MA, USA, and colleagues have analyzed supplements for the presence and quantity of an analogue of DMAA, 1,3-dimethylbutylamine (DMBA), also known as 2-amino-4-methylpentane and 4-methyl-2-pentanamine. DMBA has not previously been described in dietary supplements, but the researchers hypothesized that AMP Citrate, 4-amino-2-methylpentane citrate, and several other marketing names listed on supplement labels might refer to DMBA.

DMBA was detected in 12 out of 14 tested supplements (85.7 %) in the range of 13 to 120 mg DMBA per serving (as the free base). Following recommendations on the label for maximum daily intake, customers would consume up to 320 mg of DMBA.
The health risks from DMBA in pharmacological doses are unknown; it has never been studied in humans and its physiologic effects are only briefly mentioned in two small animal studies from the 1940s.

Given the potential health risks of untested pharmacologic stimulants, the researchers recommend that manufactures immediately recall all DMBA containing supplements, that regulatory bodies should warn consumers about the presence of DMBA in dietary supplements and clarify the legal status of DMBA, and that consumers should avoid sports supplements, weight loss supplements, and brain enhancers until then.

• A synthetic stimulant never tested in humans, 1,3-dimethylbutylamine (DMBA), is identified in multiple dietary supplements,
  Pieter A. Cohen, John C. Travis, Bastiaan J. Venhuis,
  Drug Test. Analysis 2014.
  DOI: 10.1002/dta.1735