EXPERT REACTION: Kiwi kids among the unhealthiest in the world

Height, weight and BMI normally increase with age in school age children. It is true that between 1985 and 2019, New Zealand has an unacceptably high and increasing prevalence of excess body weight and rapid growth in our tamariki. This is associated with poverty, food insecurity and is higher in Māori and Pacific children. A greater proportion of Māori and Pacific children live in areas of deprivation than European and Asian children. This is recorded in the annual reports of the New Zealand Health Survey. 

What the analysis undertaken by the Non-Commmunicable Disease Risk Factor collaboration does not take into account is the increasing ethnic diversity of the New Zealand child population and how that has changed between 1985 and 2019. One size does not fit all.

The major ethnic groups are Māori (the Indigenous people) 17%, Pacific 8%, European 70% and Asian 15%. This adds up to more than 100% because many identify with more than one ethnic group. European is an aging population, with 20% of both the European and Asian populations aged between five and 19 years, while Pacific and Māori each have 33% of their population between five and 19 years.

When comparing them at the same age, Pacific and Māori children weigh more than European and Asian for the same body mass index. However, Māori and Pacific children have less fat and more muscle than European and Asian children. Pacific and Māori children are taller and mature earlier than European children, but by age 19 there is little difference in height.

The authors, in the discussion, say that these measures differentiate countries in terms of how they shape determinants of lifelong health. No measures of health, ethnic differences in shape and size, socioeconomic status or food security were assessed. The highest prevalence of type 2 diabetes in New Zealand occurs in Pacific, Māori and Asian, not European. Yet Pacific and Asian are the two extremes of BMI, weight and height measures. Body size and growth trajectories are imperfect measures of ‘nutritional quality and lifelong health advantages and risks’ of Indigenous, multiethnic and migratory populations.

This is a huge study comparing 65 million school-aged children across 200 countries and territories pooling data from 2,181 population-based studies over 34 year period 1985-2019.  It is the first study of this kind comparing age trajectories and time trends in mean height and mean BMI.  It is an important study because it is a rare study of older children and adolescents across several countries.

The study includes sixteen Small Islands Developing States from the Pacific region but the authors acknowledge that there were fewer data sources form this region leading to larger uncertainty of the estimates.

Estimates confirm much of what is already known e.g. BMI was highest in 19 year-old Pacific Island boys often surpassing 28kg/m2. Conversely, boys from PNG and Solomon Islands were among the shortest in the world. A number of unhealthy trends were reported e.g Pacific Island boys and those from New Zealand were among those gaining too much weight for height.

Study findings have important implications for nutrition policies in NZ and the Pacific Islands including considerations for agriculture and food policies.