An FDA warning letter and a raid of a California company’s offices highlight issues concerning the supplements some feel are a healthy substitute for steroids.

Move over steroids.

The popularity of gray-market research chemicals known as selective androgen receptor modulators (SARMs) among bodybuilding and fitness buffs is growing.

Healthcare professionals and national regulatory bodies, including the U.S. Food and Drug Administration (FDA) and the U.S. Anti-Doping Agency (USADA), are watching closely.

SARMs are a novel class of drugs similar to androgenic steroids, including testosterone. They aren’t currently approved for use in humans in the United States or any other country.

Nonetheless, they remain available through various outlets on the internet as well as some supplement companies in the United States.

The drugs are touted as an aid for muscle building without many of the side effects of traditional steroids.

Researchers and bodybuilders both appear to be interested in them for this reason.

“SARMs have been shown in early clinical studies to build lean mass and muscle strength,” James Dalton, PhD, dean of pharmaceutical sciences at the University of Michigan, told Healthline.

“They differ from commonly used androgenic steroids by their ability to stimulate muscle and bone growth with lesser prostatic effects in males and virilizing effects in females,” he added.

Androgenic steroids are known to increase muscle development but are accompanied by a host of undesirable effects.

For men, this often means things like acne, breast development (gynecomastia), enlarged prostate, and shrinking of the testicles.

Women may experience increased body hair growth, acne, and increased clitoral size.

More serious health concerns include liver damage and numerous cardiovascular complications, including increased risk of heart attack and blood clots.

SARMs potentially represent a step toward a safer class of androgenic drugs. They have “revived an almost dormant search for improved androgens,” wrote researchers in the Journal of Medicinal Chemistry.

Dalton notes that so far the drugs are “generally well-tolerated” in clinical trials, but none of them have ever reached final approval by a regulatory body.

One SARM in particular, known by a variety of names including enobosarm, ostarine, and S-22, has made it through phase III clinical trials.

However, clinical research on SARMs, including their potential use for preventing muscle wasting on cancer patients, has recently been overshadowed by their off-label popularity among bodybuilders.

Last fall, the FDA issued warning letters to three supplement companies in the United States that were offering the drugs for sale.

“We are extremely concerned about unscrupulous companies marketing body-building products with potentially dangerous ingredients,” they said in a press statement.

“Life threatening reactions, including liver toxicity, have occurred in people taking products containing SARMs. SARMs also have the potential to increase the risk of heart attack and stroke, and the long-term effects on the body are unknown,” FDA officials said.

In December, the FDA reportedly conducted a raid on several facilities operated by Sacramento-based supplement company Enhanced Athlete for allegedly selling the drug ostarine. The FDA declined to comment or confirm this to Healthline, citing a policy against commenting on potentially ongoing criminal investigations.

Representatives for Enhanced Athlete didn’t return numerous inquiries by Healthline.

In a public statement, the company announced that the FDA had confiscated caches of Ostamuscle (their own brand of ostarine) and “many other research chemicals.”

The company has framed their sale of the drugs as an issue of personal freedom for consumers.

“We feel that freedom of information and choice, as long as provided within the context of the law, is imperative. This means that we intend to carry on doing what we have always done until told to do otherwise by the proper authorities,” the company writes.

Nonetheless, they also expect a growing federal crackdown on the sale of SARMs, at which point they admit “we will have no choice but to concede.”

Many chemicals and substances are able to get around FDA oversight when being classified as a “dietary supplement.”

Due to legislation from 1994 known as the Dietary Supplement Health and Education Act (DSHEA), products classified as dietary supplements are exempted from pre-market studies prior selling to the public.

In a prior interview with Healthline, Dr. Carl Baum, a member of the American Academy of Pediatrics (AAP) said, “All bets are off,” when it comes to knowing what’s really in a dietary supplement.

The FDA does take action against dangerous or misbranded supplements using their own criminal investigation unit.

While not commenting on specifics about Enhanced Athlete, an FDA spokesperson told Healthline, “The use of SARMs in products marketed as dietary supplements and other products that have not received FDA approval is illegal.”

That is, SARMs sold in the United States are “dietary supplements” in name only and not considered as such by the government.

This presents additional problems. A recent study in the Journal of the American Medical Association evaluated the chemical composition of products being marketed as SARMs.

They found that only half of them actually contained SARMs. About 60 percent contained ingredients different from what was featured on the label.

Nearly 10 percent of the products tested didn’t contain an active ingredient of any kind.

In a strange twist, Enhanced Athlete actually used these findings to promote their own products, writing, “the popularity of SARMs is growing and the Fake News is using scare tactics and misinformation in order to provoke the government into action.… We are dedicated to continuing to fight for your right to experiment and to retain your right to choose.”

However, the FDA spokesperson contacted by Healthline didn’t mince words:

“Consumers should stop using these body-building products immediately and consult a healthcare professional if they are experiencing any adverse reactions that may be associated with their use.”