There has been a spate of marketing for some herbal products in recent months as companies prepare to profit from a gap left by ephedra, subject to a US ban that came into force last week.
But acting commissioner for the US Food and Drug Administration Lester Crawford warned that the agency will in future 'aggressively enforce DSHEA against unsafe or mislabeled products' and increase scrutiny of supplement labeling.
The FDA is also said to be gathering evidence on the safety of kava, used as a remedy for stress but previously linked to liver damage, as well as the ephedra alternatives bitter orange and usnic acid, according to a Reuters report. Bitter orange is thought to increase blood pressure while usnic acid has been linked to liver damage.
In a speech to the American Society for Pharmacology and Experimental Therapeutics in Washington on Monday, Crawford is reported to have said: "Never again will one of these (supplements) as bad as ephedra take two years" to ban.
Industry associations have previously warned that the ban on ephedra would trigger an industry-wide clampdown on herbal and other supplements, and faster rule-making.
"The industry can expect further rule-making instead of waiting for case-by-case enforcement when a widely publicized ingredient safety issue arises," said the National Nutritional Foods Association earlier this year.
The ban on ephedra is the first carried out by the Food and Drug Administration under powers declared in the 1994 Dietary Supplement Health and Education Act (DSHEA). While the ban proved that the much criticized regulation could indeed be used to protect consumers, the FDA chose to also examine benefit as well as risk in their evaluation of ephedra.
It has also "raised the bar on safety substantiation", according to NNFA.
"A key indicator for future supplement challenges is FDA's rejection of the safety studies [on ephedra] because they were not designed to detect serious effects in susceptible individuals-and because the studies were too small," it explained.
A recent Institute of Medicine report, sponsored by FDA, estimated that the number of supplements available on the market has jumped from 4,000 when DSHEA was passed to about 29,000 now, with a further 1,000 new products being introduced each year.
This has made the industry difficult to regulate, according to Crawford.
Two weeks ago, FDA sent warning letters to 16 firms to stop making false claims for weight loss. It is also planning to issue guidance on what data would substantiate such claims.