Usana Health Sciences Inc., one of Utah's leading nutritional supplement companies, reported lower earnings for its first quarter.

Usana said net earnings of $15.38 million or 43 cents per share in the quarter that ended April 4. That compares to a profit of $16.45 million or 44 cents a share for the same quarter last year.

In the United States, the biggest market for the Salt Lake City-based company, sales fell from $38.55 million in 2008 to $36.48 million this year.

Overall, net sales for the first quarter decreased 4.2 percent but the company said the decline was primarily due to changes in currency exchange rates.

Usana is a multilevel marketing company, meanings it sells its products to independent distributors who get commissions for sales made to other distributors they recruit.

The company this week also updated its earnings forecast for the year, predicting sales of $390 million to $400 million, a decrease of about 7 percent to 9 percent. Earnings per share were projected at $1.80 to $1.85 a share, comparable to the $1.85 a share of 2008.