Vitamin D: a natural inhibitor of multiple sclerosis
Author: Hayes C.E.
Source: Proceedings of the Nutrition Society, Volume 59, Number 4, November 2000, pp.
Publisher: CABI Publishing
Inheriting genetic risk factors for multiple sclerosis (MS) is not sufficient to cause this demyelinating disease of the central nervous system; exposure to environmental risk factors is also required. MS may be preventable if these unidentified environmental factors can be avoided. MS prevalence increases with decreasing solar radiation, suggesting that sunlight may be protective in MS. Since the vitamin D endocrine system is exquisitely responsive to sunlight, and MS prevalence is highest where environmental supplies of vitamin D are lowest, we have proposed that the hormone, 1,25-dihydroxycholecalciferol (1,25-(OH)2D3), may protect genetically-susceptible individuals from developing MS. Evidence consistent with this hypothesis comes not only from geographic studies, but also genetic and biological studies. Over-representation of the vitamin D receptor gene b allele was found in Japanese MS patients, suggesting it may confer MS susceptibility. Fish oil is an excellent vitamin D source, and diets rich in fish may lower MS prevalence or severity. Vitamin D deficiency afflicts most MS patients, as demonstrated by their low bone mass and high fracture rates. However, the clearest evidence that vitamin D may be a natural inhibitor of MS comes from experiments with experimental autoimmune encephalomyelitis (EAE), a model of MS. Treatment of mice with 1,25-(OH)2D3 completely inhibited EAE induction and progression. The hormone stimulated the synthesis of two anti-encephalitogenic cytokines, interleukin 4 and transforming growth factor -1, and influenced inflammatory cell trafficking or apoptosis. If vitamin D is a natural inhibitor of MS, providing supplemental vitamin D to individuals who are at risk for MS would be advisable.
Vitamin D nutrition and multiple sclerosis
If vitamin D is a natural inhibitor of MS, it would be reasonable to provide supplemental vitamin D to individuals who are at risk for MS. It is noteworthy that vitamin D supplementation during childhood significantly decreased the risk of type I diabetes mellitus, an autoimmune disease (EURODIAB Substudy 2 Study Group, 1999). A reassessment of vitamin D nutrition is underway, and there is good evidence that the currently recommended adequate intakes are too low (Vieth, 1999). The adequate intake for adults is currently 5 mg/d, but this does not prevent osteoporosis and secondary hyperparathyroidism (Holick, 1998; Malabanan et al. 1998). To prevent secondary hyperparathyroidism a serum 25-hydroxycholecalciferol concentration › 50 nmol/l is required (Malabanan et al. 1998). Adults living or working in sunny environments, where MS prevalence is lowest, have circulating 25-hydroxycholecalciferol levels between 105 and 163 nmol/l (Vieth, 1999).
Thus, a serum 25-hydroxycholecalciferol concentration >= 100 nmol/l may be optimal to prevent MS. To maintain serum 25-hydroxycholecalciferol at approximately 100 nmol/l an adult who is not exposed to sunlight would need to ingest 100 mg/d (Vieth, 1999). This estimate is between the 95 mg/d that Goldberg (1974b) calculated might prevent MS, and the 125mg/d that was given in the small clinical trial of fish oil (Goldberg et al. 1986).
J Nutr. 2005 Nov;135(11):2739S-48S.
The vitamin D epidemic and its health consequences.
Boston University School of Medicine, Department of Medicine, Section of Endocrinology, Vitamin D Laboratory, Boston, MA 02118, USA. firstname.lastname@example.org
Vitamin D deficiency is now recognized as an epidemic in the United States. The major source of vitamin D for both children and adults is from sensible sun exposure. In the absence of sun exposure 1000 IU of cholecalciferol is required daily for both children and adults. Vitamin D deficiency causes poor mineralization of the collagen matrix in young children's bones leading to growth retardation and bone deformities known as rickets. In adults, vitamin D deficiency induces secondary hyperparathyroidism, which causes a loss of matrix and minerals, thus increasing the risk of osteoporosis and fractures. In addition, the poor mineralization of newly laid down bone matrix in adult bone results in the painful bone disease of osteomalacia. Vitamin D deficiency causes muscle weakness, increasing the risk of falling and fractures. Vitamin D deficiency also has other serious consequences on overall health and well-being. There is mounting scientific evidence that implicates vitamin D deficiency with an increased risk of type I diabetes, multiple sclerosis, rheumatoid arthritis, hypertension, cardiovascular heart disease, and many common deadly cancers. Vigilance of one's vitamin D status by the yearly measurement of 25-hydroxyvitamin D should be part of an annual physical examination.