NEW YORK, July 21 (Reuters) - Thorne HealthTech Inc , a provider of at-home health tests and nutritional supplements, is exploring a sale, according to people familiar with the matter.

The New York-based company is working with investment bank CG Sawaya Partners as it fields interest from other companies and private equity firms, the sources said.

Thorne's shares are up 45% year-to-date, outperforming an 18% rise in the S&P 500 Index and giving it a stock market value of around $300 million.

The sources, who asked not to be identified because the matter is confidential, added that no deal is certain. A Thorne spokesperson said the company does not comment on rumors or speculation. CG Sawaya did not respond to requests for comment.

Founded in 1984, Thorne listed on the stock market in 2021 after it acquired Onegevity, a health analytics platform co-founded by Thorne Chief Executive Paul Jacobson.

The company provides at-home health tests to assess - and supplements to aid - sleep, fertility, stress, gut health and other areas to create a personalized wellness plan. It sells its products directly to consumers, rather than relying on retailers and e-commerce firms.

Thorne's at-home tests compete with Hims & Hers Health Inc , 23andMe Holding Co and Livongo Health Inc , while its rivals in the nutritional supplements market include Nestle Health Science and Metagenics.

Thorne has projected net sales of between $280 million and $290 million in 2023, up from $228.7 million in 2022, and adjusted earnings before interest, taxes, depreciation and amortization of $30 million to $32 million in 2023, up from $24.5 million in 2022.

Thorne's top shareholders are Japanese firms Kirin Holdings Co Ltd and Mitsui & Co Ltd, each with a 29% stake.

Kirin, one of Japan's major beer makers, has already shown an interest in taking over companies in the nutraceutical sector. In April, it acquired Australian vitamin Blackmores for $1.2 billion. (Reporting by Abigail Summerville; Editing by David Holmes)