RONKONKOMA, N.Y. — Vitamin and nutritional supplement maker NBTY Inc. has entered a joint venture to spur the growth of its Nature’s Bounty and MET-Rx brands in China.

NBTY said Friday that it has partnered with Hong Kong-based By-Health Co. Ltd., a leading dietary supplement company in China. NBTY will hold a 40% stake in the venture, which will contribute its Nature’s Bounty and MET-Rx brands plus a portion of its current organization.  By-Health will hold a 60% interest and provide a portion of its sales force and its distribution system.

Plans call for joint venture to begin the transition next month and start operations in the second half of this year. NBTY said none of its other brands will be part of the venture and will continue to be marketed via current channels.

“This partnership with By-Health is the perfect way to expand upon the current strong position of our premium Nature’s Bounty and MET-Rx brands,” NBTY president and chief executive officer Steve Cahillane said in a statement. “We at NBTY are honored to be partnering with By-Health, which is the leader in the nutrition supplements industry in China.”

The companies said the venture brings together the brand, marketing and sales strength of NBTY’s Nature’s Bounty and MET-Rx brands with By-Health’s sales, distribution and operational capabilities.

“Partnering with NBTY is an important milestone in By-Health’s company history, and represents the beginning of a great relationship between two successful companies,” By-Health CEO Zhicheng Lin stated. “This partnership enables both parties to leverage their unique strengths in assisting each other to achieve phenomenal success.”