Optimizing Nuclear Techniques to Assess Vitamin A Status

Closed for proposals

Project Type

Coordinated Research Project

Project Code




Approved Date

6 February 2015


3 - Active - Ongoing

Start Date

6 February 2015

Expected End Date

6 February 2020

Completed Date

28 May 2020

Participating Countries

South Africa
United Kingdom of Great Britain and Northern Ireland
United States of America


The proposed CRP will contribute to a better understanding of the appropriate use of the stable isotope dilution technique to assess vitamin A status across the continuum from deficiency to toxicity in children under the age of 5 years. The findings will provide guidance for programme managers and public health nutrition policy makers to optimize the evaluation of their vitamin A programmes, in particular in countries where multiple vitamin A interventions are in place, and enable them to improve national nutrition strategies and plans.  The combination of malnutrition, including micronutrient malnutrition, and infectious diseases is the most prevalent and preventable public health problem in the world; responsible for millions of deaths annually, particularly in infants and children. Infections affect nutritional biomarkers making it difficult to assess the real magnitude of some nutritional problems, for example vitamin A deficiency. Vitamin A is involved in numerous physiological processes essential for normal growth and development, the immune system, the visual system, and other functions in the human body. Vitamin A deficiency is a major nutritional concern in low-resource households in low-income countries. Vitamin A fortified foods such as sugar, margarine, vegetable oil, milk, and wheat flour as well as micronutrient powders and supplements, have been used as a complementary approach. The potential risk of excess vitamin A intake is increased due to a lack of coordination to avoid overlap of intervention coverage. Additionally, assessing vitamin A status, and the effectiveness of government interventions, is challenging in settings where infectious diseases and micronutrient deficiencies are endemic, as in most low-income countries.  The isotope dilution technique, which will be used in this CRP, is among the most accurate techniques for assessing total body vitamin A pool size in individuals. However, it is not known whether the method is valid under conditions of hypervitaminosis A, inflammation and selected micronutrient deficiencies. Therefore, this CRP will address methodological issues in the application of the stable isotope dilution technique to accurately determine vitamin A stores in children and thus, provide important new knowledge on optimising the stable isotope dilution technique for the assessment of vitamin A status. The CRP will be complementary to a grant of the Bill & Melinda Gates Foundation that assesses the risk of vitamin A toxicity due to large scale food fortification and other interventions with the University of Newcastle as grantee.

Specific objectives

Obtain new information on the validity of the stable isotope dilution technique to assess total body stores of vitamin A across the continuum from deficient to sub-toxic and toxic status in the context of selected micronutrient deficiencies, inflammation and infection.

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