Vitamin D – Are Hong Kong Kids Getting Enough?


Vitamin D has held considerable interest in the scientific community this past decade with new studies continually showing new roles of this vital nutrient. We know it is particularly important for infants and young children, who need vitamin D to utilize calcium for strong bones and teeth. It’s also been shown to affect immunity and mood, with growing research on its role in cancer prevention, weight management and heart health.

Despite the plethora of health benefits vitamin D confers, it is one of the largest deficiencies worldwide. You may have heard the common advisory statement that those living in Northern climates should supplement with Vitamin D3, especially during winter when the UV light is not strong enough to initiate biosynthesis.

But is vitamin D supplementation still necessary in tropical climates like Hong Kong?

Vitamin D Deficiency Risk Factors

Cultural Risk Factors: As a lighter complexion is coveted by many, it is common for many Hongkongers to actively avoid sun exposure by staying indoors, wearing sun-protective clothing and applying high SPF sunscreen when outdoors. While these behaviours can protect against skin cancer, excessive sun avoidance will eliminate the body’s ability to produce vitamin D from sunlight creating a high risk of deficiency.

Environmental Risk Factors: Tall buildings that block direct light, indoor walkways, cloud cover and pollution all act to reduce sun exposure on our skin. In fact, average city smog and dust has been estimated to cut the UV index in half, greatly reducing our ability to biosynthesize it[1].

Research Evidence

A research study conducted in the south-eastern province of China outlined a poor vitamin D status of infants and children – 34% of infants, 69% of children aged 2-6 and 88% of children aged 6-11 had vitamin D level below the recommended value of 75nmol/L for optimal health outcomes[2]. Moreover, despite the area’s sunnier climate, these statistics were worse than Canada, England and even Alaska[3]. Although a Hong Kong specific study on infants and children has not been conducted, we can assume similar rates to the study with only 9% of Hong Kong children supplementing with Vitamin D[4].

How can you protect your children against vitamin D deficiency?

As vitamin D is limited in food sources, we concur with the American Academy of Paediatrics’ recommendation that infants and children should take 400-600 IU of vitamin D daily (see table). When choosing a supplement look for Vitamin D3, which is 87% more effective at raising vitamin D levels than other forms[5] and always go for a pharmaceutical-grade supplement to ensure purity.


Written by Rachel Erwin, Nutritionist



[1] Steele, D. (1997). Summer in the city: Pollution acts as sunscreen. The University of Chicago Chronicle, 16(19). Retrieved from

[2] Zhu Z, Zhan J, Shao J, Chen W, Chen L, Li W, Ji C, Zhao Z. High prevalence of vitamin D deficiency among children aged 1 month to 16 years in Hangzhou, China. BMC Public Health. 2012;12 126-2458-12-126.

[3] Palacios, C., & Gonzalez, L. (2014). Is vitamin D deficiency a major global public health problem? The Journal of Steroid Biochemistry and Molecular Biology, 144, 138-145. doi:10.1016/j.jsbmb.2013.11.003

[4] Xu, C, Perera, RAPM, Chan, YH, Fang, J, Ng, S, Ip, DKM, . . . Cowling, BJ. (2015). Determinants of serum 25-hydroxyvitamin D in Hong Kong. The British Journal of Nutrition, 114(1), 144-151.

[5] Heaney R.P., Recker R.R., Grote J., Horst R.L., Armas L.A. Vitamin D(3) is more potent than vitamin D(2) in humans. J. Clin. Endocrinol. Metab. 2011;96:E447–E452. doi: 10.1210/jc.2010-2230

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