Shares of nutritional supplement maker Herbalife Ltd. plunged more than 20 percent Friday after the company slashed its sales projections for 2007 due to slower-than-expected growth in Mexico.

Shares fell $7.92 to $31.38 in afternoon trading. Late Thursday, Herbalife reaffirmed its fourth-quarter 2006 guidance, which was in line with Wall Street expectations, but also lowered 2007 sales growth expectations to between 6 and 10 percent. That compares to a prior range of 10 to 15 percent, well below analysts expectations.

The company, which sells manufactures weight loss and nutritional supplements via a direct distributor network, attributed slowing sales in Mexico to problems with distributors engaging in unethical marketing practices. Potentially offsetting that slowdown is the company’s fast-growing market in China.

Herbalife said fourth quarter 2006 net sales, which it plans to report in February, likely will range between $482.7 million and $484.7 million, reflecting a year-over-year increase of at least 18 percent.