The most realistic approach to boosting the nation’s intake of vitamin D is for food manufacturers to increase the dose of vitamin D per serving, says a leading expert on the sunshine vitamin.
“This would have a substantial impact on the US population,” said Michael Holick PhD, MD, Professor of Medicine at Boston University Medical Center and a world-renowned expert in vitamin D.
At this month’s Nutracon in Anaheim, Prof Holick will present on the topic, “Vitamin D: A D-Lightful Solution for Health” as part of the Healthy Aging track.
“I will provide a broad overview of vitamin D, including the main issues such as vitamin D intakes during pregnancy, for neonates, the impact of vitamin D deficiency for bone health and osteoporosis, as well as my perspective on the Institutes of Medicine (IoM) update on vitamin D DRIs,” said Prof Holick.
The U.S. Institute of Medicine (IOM) recently announced updated Dietary Reference Intakes (DRIs) for vitamin D that tripled the recommended daily allowance across all groups, except those over 50 years of age, for whom the updated allowance increased by 200 IU. Upper intake levels were also raised for all groups.
Dr Holick said the new recommendations indicate that “the IOM recognized that the previous recommendations were inadequate”, and he describes the new recommendations as “a step in the right direction”.
But while he welcomed the progress, Dr Holick acknowledges he led calls for a higher increase. Indeed, the Boston-based scientist authored a review in the prestigious New England Journal of Medicine in 2007 (Vol. 357, No. 3, pp. 266-281), and contributed to a call for action from 15 experts from universities, research institutes, and university hospitals around the world published in the American Journal of Clinical Nutrition (Vol. 85, No. 3, pp. 649-650), with recommendations for a DRI of 1,000 IU and more.
Data on D
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former is produced in the skin on exposure to UVB radiation (290 to 320 nm). The latter is derived from plants and only enters the body via the diet.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.
In adults, vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.
While our bodies do manufacture vitamin D on exposure to sunshine, the levels in some northern countries are so weak during the winter months that our body makes no vitamin D at all, meaning that dietary supplements and fortified foods are seen by many as the best way to boost intakes of vitamin D.
Dr Holick notes that milk is already fortified with vitamin D, as is some orange juice , and some yogurt. “The issue is can we expand the number of foods that are fortified with vitamin D,” he added.
At the upcoming Nutracon, Dr Holick will discuss strategies to diagnose, treat and prevent vitamin D deficiency in children and adults.
Professor Holick’s presentation forms part of Nutracon’s Healthy Aging track. Nutracon takes place from March 9-10, 2011. For more information and to register: www.nutraconference.com