"We follow established written quality assurance and quality control procedures.
We stand behind the safety of our ingredients and products," the company said.
The allegations, published by a Californian company called Fraud Discovery Institute (FDI), said Herbalife's products contained more than the permitted 0.5mg per day of lead, and when used as suggested, could lead to health concerns.
FDI reported independent testing carried out in Swiss and Israeli labs that found the Herbalife weight loss products breached Californian Proposition 65 permitted levels and therefore the products should carry warning labels.
Proposition 65 is a controversial, and some would say, anachronistic, Californian law enacted in 1986 that lists 800 potential contaminants, many of which are considered safe under Food and Drug Administration (FDA) law.
Herbalife spokesperson George Fischer told NutraIngredients-USA.com Herbalife's own lab tests contradicted those referenced by FDI and that it was conducting its own investigations into the matter now that it had been brought to the public by FDI.
"We are looking into this but in the meantime the products in question remain on market as they have been for many years," Fischer said.
"Herbalife operates in 65 countries and we comply with any applicable laws."
No action has been taken by either Californian or federal regulators.
Fraud discovery Despite any possible transgressions in regard to Proposition 65, Herbalife noted that its products were in accordance with FDA regulations, a discrepancy that has led to the Californian rule being criticized for creating a two-tier system that only creates confusion for both business and consumers alike.
Proposition 65 has also been criticized as being a law that is open to exploitation via the rift it creates with federal rules.
One legal firm said the law was open to exploitation by "litigation bounty hunters".
Indeed, Reuters reported today that FDI founder and president, Barry Minkow, had invested in Herbalife in such a way that if its shares went down, he stood to make substantial gains - something that happened today.
Minkow served more than seven years in prison for frau, said Reuters.
The products The six products named by FDI were ShapeWorks Protein Drink Mix, Healthy Meal Nutritional Shake Mix, Tang Kuei Plus herbal tablets, Thermojetics Nature's Raw Guarana instant tea mix, ShapeWorks Cell Activator and Multivitamin Complex.
"We have confidence in the safety of our products," Herbalife said.
"It is irresponsible to equate Prop 65, which concerns disclosure, with the safety of our products.
Our products include natural ingredients, and trace levels of naturally occurring lead is present in virtually all natural ingredients."
The $2.15bn company added: "This is not a question of contamination resulting from the manufacturing process or as a result of unsafe handling.
In the past, several common foods, such as chocolate, have come under question of Prop 65."