Is vitamin D deficiency a major global public health problem?

Highlights

• Vitamin D deficiency is a major public health problem worldwide in all age groups.

• Low vitamin D status is a problem even in countries with sun exposure all year round.

• This problem is particularly high in the Middle East, specially among girls and women.

• There is striking lack of vitamin D status data in infants, children and adolescents.

• There is also lack of data in most countries of South America and Africa.

Abstract

Vitamin D deficiency is a major public health problem worldwide in all age groups, even in those residing in countries with low latitude, where it was generally assumed that UV radiation was adequate enough to prevent this deficiency, and in industrialized countries, where vitamin D fortification has been implemented now for years. However, most countries are still lacking data, particularly population representative data, with very limited information in infants, children, adolescents and pregnant women. Since the number of recent publications is escalating, with a broadening of the geographic diversity, the objective of the present report was to conduct a more recent systematic review of global vitamin D status, with particular emphasis in at risk groups. A systematic review was conducted in PubMed/Medline in April–June 2013 to identify articles on vitamin D status worldwide published in the last 10 years in apparently healthy individuals. Only studies with vitamin D status prevalence were included. If available, the first source selected was population-based or representative samples studies. Clinical trials, case-control studies, case reports or series, reviews, validation studies, letters, editorials, or qualitative studies were excluded. A total of 103 articles were eligible and included in the present report. Maps were created for each age group, providing an updated overview of global vitamin D status. In areas with available data, the prevalence of low vitamin D status is a global problem in all age groups, in particular in girls and women from the Middle East. These maps also evidenced the regions with missing data for each specific population groups. There is striking lack of data in infants, children and adolescents worldwide, and in most countries of South America and Africa. In conclusion, vitamin D deficiency is a global public health problem in all age groups, particularly in those from the Middle East.

This article is part of a Special Issue entitled ‘16th Vitamin D Workshop’.

Introduction

Vitamin D is an essential fat-soluble vitamin for calcium maintenance homeostasis, for bone health and for preventing falls and fractures, and it has also been related to hypertension, diabetes, metabolic syndrome, cancer, autoimmune and infectious diseases, among others [1]. These conditions are major public health problems worldwide.

Several reviews have found high prevalence of vitamin D deficiency worldwide [2], [3], [4], even in countries with low latitude, where it was generally assumed that UVB radiation was adequate enough to prevent vitamin D deficiency, and in industrialized countries, where vitamin D fortification has been implemented now for years; although substantial fortification has only occurred in a few countries. However, prevalence of vitamin D deficiency worldwide is still uncertain, as there is data lacking from many countries. About 1 billion people have low vitamin D levels and this is found in all ethnicities and age groups [1].

The available reviews illustrate the lack of data in most countries, particularly population representative data, with very limited information in infants, children, adolescents and pregnant women. However, the number of recent publications in this area is escalating, with a broadening of the geographic diversity. Therefore, the objective of the present report was to conduct a systematic review of recent literature on global vitamin D status, with a particular emphasis on at risk groups.