HealthCentral.com, Emeryville, CA, agreed yesterday to buy Vitamins.com, Falls Church, VA, an online provider of minerals and supplements, for $103.5 million in stock. HealthCentral.com expects to add 200,000 new Internet customers to its database through the deal. Vitamins.com has an Internet site, catalog and a mail-order business with 175,000 active customers. HealthCentral.com offers health information for consumers and provides Internet services to hospitals and health systems. The transaction is subject to approval by Health-Central.com's shareholders and could close before the end of the second quarter. The company launched an online drugstore,www.healthcentralrx.com, in January.