Vitamin Supplements May Slow Middle-Age Weight Gain Four common ones tied to healthier weights over 10-year period    HealthDayNews -- Four common supplements -- chromium, vitamin B-6, vitamin B-12 and multivitamins -- may help slow weight gain in middle-age adults, claims a study by researchers at the Fred Hutchinson Cancer Research Center in Seattle.    Researchers reviewed questionnaire responses from about 15,000 people, average age 55, in Washington state...