Beneﬁts and Requirements of Vitamin D for Optimal Health: A Review
William B. Grant, PhD, and Michael F. Holick, PhD, MD
William B. Grant, PhD – Sunlight, Nutrition and Health Research Center (SUNARC) Correspondence address: 2107 Van Ness Ave., Ste. 403B, San Francisco, CA 94109 Email: [email protected]
Michael F. Holick, PhD, MD – Vitamin D, Skin and Bone Research Laboratory, Section of Endocrinology, Diabetes, and Nutrition Department of Medicine, Boston University Medical Center, Boston University School of Medicine
Vitamin D sufﬁciency is required for optimal health. The conditions with strong evidence for a protective effect of vitamin D include several bone diseases, muscle weakness, more than a dozen types of internal cancers, multiple sclerosis, and type 1 diabetes mellitus. There is also weaker evidence for several other diseases and conditions. There are good reasons that vitamin D sufﬁciency be maintained during all stages of life, from fetal development to old age. Adequate calcium intake is also recommended. The current vitamin D requirements in the United States are based on protection against bone diseases. These guidelines are being revised upward in light of new ﬁndings, especially for soft-tissue health. The consensus of scientiﬁc understanding appears to be that vitamin D deﬁciency is reached for serum 25-hydroxyvitamin D (25(OH)D) levels less than 20 ng/mL (50 nmol/L), insufﬁciency in the range from 20-32 ng/mL, and sufﬁciency in the range from 33-80 ng/mL, with normal in sunny countries 54-90 ng/mL, and excess greater than 100 ng/mL. Solar ultraviolet-B (UVB) irradiation is the primary source of vitamin D for most people. In general, the health beneﬁts accruing from moderate UV irradiation, without erythema or excess tanning, greatly outweigh the health risks, with skin pigmentation (melanin) providing much of the protection. In the absence of adequate solar UVB irradiation due to season, latitude, or lifestyle, vitamin D can be obtained from fortiﬁed food, oily ﬁsh, vitamin D supplements, and artiﬁcial sources of UVB radiation. (Altern Med Rev 2005;10(2):94-111)
There is a growing awareness that vitamin D sufﬁciency is required for optimal health. The role of vitamin D in calcium absorption and metabolism for bone health is well known.1 Research during the past two decades has illustrated the importance of vitamin D in reducing the risk of cancer,2-4multiple sclerosis,5,6 and type 1 diabetes mellitus.7 A number of reviews on the role of vitamin D and prevention of disease and maintenance of optimal health have appeared in the past 2-3 years,8-21 and several recent conferences have been devoted solely to exploring the role of vitamin D in health and disease prevention.22-24 Finally, organizations in Australia and New Zealand have recognized a sufﬁciently high prevalence of vitamin D deﬁciency, even in these sunny lands, to have issued guidelines for solar UVB irradiation.25,26
This article discusses the importance of vitamin D sufﬁciency at various stages of life as a guide to health practitioners, policy makers, and interested individuals.
Source: Altern Med Rev 2005;10(2):94-111. © 2005 Thorne Research, Inc.