Only about 10 percent of Americans take in enough vitamin D each day to ward off breast cancer and other diseases, according to a study released Tuesday by UC San Diego's School of Medicine and Creighton University in Omaha, Neb.
The research showed daily intakes of 4,000-8,000 international units of vitamin D are needed to reduce the risk of breast and colon cancers, multiple sclerosis and Type 1 diabetes in half, according to Dr. Cedric Garland, professor of family and preventive medicine at UC San Diego Moores Cancer Center.
International units were the measuring system used in the study, but they are not easily converted into recommended dosages of supplements.
Garland said most people with that amount of vitamin D in their systems work outdoors. Sunlight is a major source of vitamin D.
"I was surprised to find that the intakes required to maintain vitamin D status for disease prevention were so high -- much higher than the minimal intake of vitamin D of 400 IU per day that was needed to defeat rickets in the 20th century," Garland said.
The recommended daily intake of vitamin D is 600 IU.
The 4,000 IU daily intake of vitamin D is considered safe, and there is not believed to be a risk until 10,000 IU are consumed, Garland said.
Vitamin D is found in high amounts in fish oil and cod liver oil, raw oysters and salmon.
The study appears in the journal Anticancer Research.
