Prevention of nutritional rickets in Nigerian children with dietary calcium supplementation

doi:10.1016/j.bone.2012.02.010

Bone

Volume 50, Issue 5, May 2012, Pages 1074-1080

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Abstract

Nutritional rickets in Nigerian children usually results from dietary calcium insufficiency. Typical dietary calcium intakes in African children are about 200 mg daily (approximately 20–28% of US RDAs for age). We sought to determine if rickets could be prevented with supplemental calcium or with an indigenous food rich in calcium. We enrolled Nigerian children aged 12 to 18 months from three urban communities. Two communities were assigned calcium, either as calcium carbonate (400 mg) or ground fish (529 ± 109 mg) daily, while children in all three communities received vitamin A (2500 IU) daily as placebo. Serum markers of mineral homeostasis and forearm bone density (pDEXA) were measured and radiographs were obtained at enrollment and after 18 months of supplementation. The overall prevalence of radiographic rickets at baseline was 1.2% and of vitamin D deficiency [serum 25(OH)D < 12 ng/ml] 5.4%. Of 647 children enrolled, 390 completed the 18-month follow-up. Rickets developed in 1, 1, and 2 children assigned to the calcium tablet, ground fish, and control groups, respectively (approximate incidence 6.4/1000 children/year between 1 and 3 years of age). Children who developed rickets in the calcium-supplemented groups had less than 50% adherence. Compared with the group that received no calcium supplementation, the groups that received calcium had a greater increase in areal bone density of the distal and proximal 1/3 radius and ulna over time (P < 0.04). We conclude that calcium supplementation increased areal bone density at the radius and ulna, but a larger sample size would be required to determine its effect on the incidence of rickets.

Highlights

► Rickets in African children is often due to insufficient dietary calcium. ► Rickets might be prevented with increased dietary or supplemental calcium. ► Nigerian toddlers were given calcium tablets, ground fish, or placebo for 18 months. ► Calcium resulted in a greater increase in forearm bone density over time.

Introduction

Nutritional rickets remains prevalent throughout the world, and in several tropical countries is a consequence of inadequate dietary calcium rather than vitamin D deficiency [1]. Rickets in these children can be effectively treated by calcium supplementation with or without vitamin D [2]. Calcium deficiency occurs in the context of a diet lacking in dairy products. In Nigerian children, the daily dietary intake of calcium is about 200 mg [3], well below the recommended intake of 700–1000 mg for children between one and eight years of age [4]. Though calcium is effective in treating rickets in Nigeria, it is unknown whether calcium supplementation can prevent rickets.

Sustainable, feasible interventions to improve calcium status should be food-based. A study of young children in Bangladesh suggested that rickets could be prevented with a milk-powder-based supplement [5]. Enriching the diet with inexpensive, locally acceptable food sources of calcium may prevent rickets in African children. Dried fish is a common dietary ingredient in Nigeria that could provide calcium if the bones were also consumed [6].

We conducted a controlled clinical trial of calcium supplementation at a community level in urban Nigerian children, enrolled between 12 and 18 months of age. Our primary objective was to test the hypothesis that calcium supplementation, during the age interval of greatest risk for development of rickets, could prevent rickets in Nigerian children. Secondary objectives were to determine if ground fish would be as effective as calcium tablets in preventing rickets, to determine the effect of calcium supplementation on bone mineral acquisition in the forearm, and to assess the effect of calcium supplementation on the calcium-vitamin D axis.

Section snippets

Subjects

Three geographically separate urban communities (Nassarawa, Gangare, and Dogon Agogo) in the city of Jos, Nigeria (2000 population 600,155), where rickets is prevalent, were selected for intervention. We chose communities with similar ethnic, religious, and socioeconomic characteristics and with well-functioning primary health facilities. Each community had one primary health center. Personnel in each center were trained in data collection, assessment of adherence, and conduct of the study, and

Study subjects

A total of 297, 187, and 229 children were screened for enrollment in the calcium tablet, ground fish, and control groups, respectively (Fig. 1). Active rickets was found radiographically in 7, 0, and 1 of the children in each of these groups, respectively (1.2% prevalence, 95% confidence interval 0.6 to 2.3%). Only two children with rickets had clinical features (enlarged wrists or curved legs) suggestive of the disease, while 10 children with clinical signs suggesting possible rickets had

Discussion

In this trial of calcium supplementation for prevention of rickets, we were unable to demonstrate a protective effect of calcium supplementation on the occurrence of rickets between the ages of 12 and 36 months. Bone density, however, did improve with calcium supplementation, as compared with placebo-treated children. The increase in forearm bone density was mediated by an increase in bone mineral content rather than through changes in projected bone area.

Several possibilities could explain the

Conflict of interest

The authors declare no conflict of interest.

Acknowledgments

The authors are grateful to the community health workers who assisted with bone densitometry and data collection; Joseph Bot and Priscilla Dakahop, for contacting subjects that did not return for follow-up; Drs. Abdulkareem Gambazai and Bukar Grema for assistance with data collection and examination of subjects; Margaret Williams and Hauwa Auwal for preparation and packaging ground fish; Yakubu Idoko, Naomi Danjuma, Obi Uzoigwe for collection and processing of blood samples; Brian Netzel for

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Citation Excerpt :
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^☆: Supported by a grant from the Thrasher Research Fund, Salt Lake City, Utah.

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Original Full Length ArticlePrevention of nutritional rickets in Nigerian children with dietary calcium supplementation☆

Abstract

Highlights

Introduction

Section snippets

Subjects

Study subjects

Discussion

Conflict of interest

Acknowledgments

J Pediatr

J Nutr

J Pediatr

J Nutr

Poult Sci

Am J Clin Nutr

Am J Clin Nutr

Nutritional rickets around the world: causes and future directions

Ann Trop Paediatr

A comparison of calcium, vitamin D, or both for nutritional rickets in Nigerian children

N Engl J Med

Original Full Length Article
Prevention of nutritional rickets in Nigerian children with dietary calcium supplementation☆