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Anthony Norman Leads Call to Increase Daily Vitamin D Intake

Vitamin D Expert at UC Riverside Leads UC Scientists' Call Recommending Increase in Daily Vitamin D Intake

Seventeen researchers join Anthony Norman in declaring that the government’s current recommended daily allowance for the vitamin is inadequate

(November 13, 2008)

Anthony Norman is a distinguished professor emeritus of biochemistry and of biomedical sciences at UC Riverside.  He also holds the title of Presidential Chair in Biochemistry-Emeritus.  Photo credit: UCR Strategic Communications.Enlarge

Anthony Norman is a distinguished professor emeritus of biochemistry and of biomedical sciences at UC Riverside. He also holds the title of Presidential Chair in Biochemistry-Emeritus. Photo credit: UCR Strategic Communications.

RIVERSIDE, Calif. – Increasingly, vitamin D is being recognized by several researchers as an important player in contributing to overall good health. Now a group of 18 vitamin D researchers at the University of California states that the recommended daily intake of the vitamin is inadequate, and asks the government to re-examine its recommendation.

Anthony Norman, a distinguished professor emeritus of biochemistry and of biomedical sciences at UC Riverside, is co-leading the UC group along with Cedric Garland, an adjunct professor of family and preventive medicine at UC San Diego, in its “call to action” recommending that the daily intake of vitamin D for adults be revised by the government to 2000 international units (IU).

Currently, the recommended daily intake of vitamin D is 200 IU for people up to 50 years old; 400 IU for people 51 to 70 years old; and 600 IU for people over 70 years old.

“The consensus among UC scientists who signed this statement is that 2000 IU per day of vitamin D3, a form of vitamin D, is the appropriate intake for most adult Americans,” said Norman, an international expert on vitamin D. “This intake is the National Academy of Sciences/Institute of Medicine’s upper limit for daily intake, and is 400 IU less than the National Academy of Sciences/Institute of Medicine’s ‘no adverse health effect’ level. Scientific concerns about this level of intake are minimal, based on the findings of the National Academy of Sciences.”

Norman explained that a 2000 IU daily intake of vitamin D can be achieved by a combination of sunshine, food, supplements, and possibly even limited tanning exposure. “While more research on this topic is highly desirable, it should not delay recommending a 2000 IU daily intake of vitamin D for most people,” he said.

In its call to action, the group of 18 UC scientists, which includes researchers from the Riverside (3), Davis (3), Los Angeles (4), San Diego (5) and San Francisco (3) campuses, also issued a joint statement in support of the use of vitamin D for reducing incidence of several types of cancer, type 1 diabetes and cardiovascular diseases.

“Our consensus on vitamin D is intended to support public health action,” said Norman, who spoke for the group. “The amount of research that is currently available provides us enough information to release such a consensus at this time. The group of UC scientists is happy to endorse and support the advocacy organization, GrassrootsHealth, in its newly launched ‘D*action’ Community Project. Its goals are coincident with the goals of the group of UC vitamin D researchers, namely, building awareness of the vitamin D deficiency problem and providing vitamin D testing as well as outcome evaluation of the results.”

On Dec. 2, Norman will participate in a seminar for health care professionals – “Diagnosis and Treatment of Vitamin D Deficiency” – being hosted by GrassrootsHealth at UC San Diego. Experts in cardiology, cancer, diabetes, bone and muscle health are scheduled to speak at the seminar

“Continuing medical education credit is available to doctors and other professionals who participate in the seminar,” said Carole Baggerly, director of GrassrootsHealth.

Because vitamin D is found in very few foods naturally, milk and other foods (often orange juice) are fortified with it. The fortification levels aim at about 400 IU per day. The vitamin is found in many dietary sources such as fish, eggs and cod liver oil, with the amounts per serving being generally about 400 IU.

Exposure to the sun is a natural way of producing vitamin D in the body. But due to growing concerns about skin cancer and various lifestyle choices – spending time mostly indoors, wearing clothes that leave little skin exposed to sunlight, and living in high-latitude areas, especially in winters – people are not getting enough of the vitamin.

Norman stressed that several studies have reported substantial reductions in incidence of breast cancer, colon cancer and type 1 diabetes in association with adequate intake of vitamin D, the positive effect generally occurring within five years of initiation of adequate vitamin D intake.

He has been researching vitamin D for more than 45 years. In 1967, his laboratory discovered that the vitamin is converted into a steroid hormone by the body. Two years later, his laboratory discovered the vitamin D receptor (or VDR), an essential receptor in more than 36 target organs of the body that respond biologically to the vitamin.

The December 2008 issue of the American Journal of Clinical Nutrition will feature an editorial by Norman on vitamin D in which he highlights the effect of ethnicity, sex, age, season, and pregnancy status on vitamin D status, and emphasizes that receptors in the immune, pancreas, heart-cardiovascular, muscle and brain systems in the body generate biological responses to vitamin D.

The University of California, Riverside ( is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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